Memory Game Show v1.0 serial key or number

Windows 10 Product Key Crack {100% Working}

Windows 10 Product Key has now become the world’s most popular operating system as 400 million users. Windows 10 released on July 29, 2015, and it comes with great new features that let the user do things quickly and fast. To activate Windows 10, the user needs a digital license or a product key. If the user is ready to activate, choose Open Activation in Settings. Click Change product key to access a Windows 10 product key. If Windows 10 previously activated on the device, the copy of Windows 10 should be activated automatically. Digital permission (called a digital entitlement in Windows 10, Version 1511) is a method of activation in Windows 10 that doesn’t require the user to enter a product key. If the user upgraded to Windows 10 for free from an activated copy of Windows 7 or Windows 8.1, the user should have a digital license instead of a product key.

The best windows operating system brings the user the most innovative tools and security features that will not only make the device secure but also enables the user to perform the daily task most creatively and productively. Windows 10 uses and joins some great features of windows 7 and windows 8, which present it stand out from other Microsoft Operating Systems.

Windows 10 Product Key 100% Working

There are several ways to get the Windows 10 product key, either user can buy it online from Microsoft, or the user can purchase from any retailer shop. Windows 10 is the most famous operating system, with about 500 million active users around the world. After releasing this, most Windows 7 users immediately move towards this because it has the unique and modern User Interface. This program is because the design of this Operating System is almost the same as Windows 7. Now the problem was the activation just like older versions. It also comes with a free trial of 30 days where the user can use it. When that trial expires, the user will ask to purchase a license key to use this fantastic OS further. So, if the user doesn’t have enough money to buy a license key, but the user still wants to use this OS. Then stick with our article as I am going to share with the user some free and working Windows 10 Product key, which users can use as well. Also, I will show the user how to use them to activate Windows 10. It is the combination of 25 digits (numbers and alphabets as well), which works as the license of the Win Operating System. These keys are the same for the x64 bit or the x32 (x84) bit as well, so don’t get confused between architecture.

Key Features of Windows 10 Product Key

1. Bundled apps

The Mail app combines user-configurable swipe gesture controls and POP3 email supporters. Google Calendar support added to the Calendar app. The Settings app expanded to have similar functionality as the Control Panel, albeit by a Metro-style user interface. The Map application can download maps for offline usage.

1. Microsoft Edge

Microsoft Edge is the modern browser for Windows 10 and is the replacement to Internet Explorer, although Internet Explorer will remain for adaptability and legacy purposes. Cortana has integrated into Edge, obtainable by the option “Ask Cortana” in the right-click menu, as well as a Reading View and the capability to write notes directly on web pages and save to OneNote. A Reading List feature has also added, where users can keep articles or other content to be accessed and read following. Microsoft Edge also includes a shared key on its toolbar where clicking on it will bring up the system share panel. Where client will be able to share a webpage to installed applications such as Reading List or third-party apps like Facebook and Twitter. Since its release, this browser has got 402 out of 555 points on HTML5test.

1. DirectX 12

Windows 10 crack includes DirectX 12 alongside WDDM. Unveiled March at GDC, DirectX 12 aims to give “console-level efficiency” with “closer to the metal” access to hardware resources, and reduced CPU and graphics driver overhead. Most of the performance improvements achieved through low-level programming, which can minimize single-threaded CPU bottlenecking caused by abstraction through higher-level APIs. The performance gains made by allowing developers direct access to GPU resources are similar to other low-level rendering initiatives such as AMD’s Mantle, Apple’s Metal API, or the OpenGL successor, Vulkan.WDDM introduces new virtual memory management and allocation system to decrease the workload on the kernel-mode driver.

1. Cortana

Windows 10 has brought the Cortana assistant of Windows Phone 8.1 to Windows 10. By omission, Cortana appears as a search pane on the taskbar, only can be changed into a button, like in tablet mode, and can activate by voice using the command “Hey Cortana,” when a user seeks the Start menu, or when a user searches the Cortana search glass. With Cortana, users can ask Cortana questions on the weather, calendar events, and other kinds of notifications, along with online information. Cortana currently needs a Microsoft Account to function.

1. Start Menu

Windows 10 reintroduced the start menu, as observed in versions of Windows before 8. However, unlike these versions, the unique start menu combines live tile features from Windows 8. It is likely to resize the Start menu, and view latterly added and most used applications. It can also make a large screen for tablet users or users that prefer a Windows 8-like activity. The right-hand side of the Start menu can use to pin tiles. The list can include a limited number of columns, depending on the screen resolution. These columns can split into groups that can all have their titles. Every group divided into 6 or 8 other columns. It depending on the user to provide either 6 or 8 small sized tiles next to each other.

How to Install or Activate Windows 10 Product Key?

• Download the full setup from this site.
• Run it as administrator and install that on the system.
• Wait until its installation finished.
• Finally, done and enjoy the services of it.

windows 10 product key generator

From top to bottom: SD, miniSD, microSD
Media type	Memory card
Encoding	Bit
Capacity	SD: Up to 2 GB SDHC: 2 GB to 32 GB SDXC: 32 GB to 2 TB SDUC: 2 TB to 128 TB
Block size	Variable
Read mechanism	Standard: > 12.5 MB/s High-speed: > 25 MB/s UHS-I: > 104 MB/s UHS-II: > 312 MB/s UHS-III: > 624 MB/s Express: > 985 MB/s
Write mechanism	Same as Read
Standard	SD Standard
Developed by	SD Association
Dimensions	Standard: 32.0×24.0×2.1 mm (1.260×0.945×0.083 in), 1,612.8 mm3 (0.09842 in3) Mini: 21.5×20.0×1.4 mm (0.846×0.787×0.055 in), 602 mm3 (0.0367 in3) Micro: 15.0×11.0×1.0 mm (0.591×0.433×0.039 in), 165 mm3 (0.0101 in3)
Weight	Standard: ~2 g Mini: ~800 mg Micro: ~250 mg
Usage	Portable devices, such as digital cameras and mobile phones (including most smartphones)
Extended from	MultiMediaCard
Released	August 1999

Secure Digital, officially abbreviated as SD, is a proprietarynon-volatilememory card format developed by the SD Association (SDA) for use in portable devices.

The standard was introduced in August 1999 by joint efforts between SanDisk, Panasonic (Matsushita Electric) and Toshiba as an improvement over MultiMediaCards (MMC),^[1] and has become the industry standard. The three companies formed SD-3C, LLC, a company that licenses and enforces intellectual property rights associated with SD memory cards and SD host and ancillary products.^[2]

The companies also formed the SD Association (SDA), a non-profit organization, in January 2000 to promote and create SD Card standards.^[3] SDA today has about 1,000 member companies. The SDA uses several trademarkedlogos owned and licensed by SD-3C to enforce compliance with its specifications and assure users of compatibility.^[4]

History[edit]

1999–2002: Creation[edit]

In 1999, SanDisk, Matsushita, and Toshiba agreed to develop and market the Secure Digital (SD) Memory Card.^[5] The card was derived from the MultiMediaCard (MMC) and provided digital rights management based on the Secure Digital Music Initiative (SDMI) standard and for the time, a high memory density.

It was designed to compete with the Memory Stick, a DRM product that Sony had released the year before. Developers predicted that DRM would induce wide use by music suppliers concerned about piracy.^[6]

The trademarked "SD" logo was originally developed for the Super Density Disc, which was the unsuccessful Toshiba entry in the DVDformat war. For this reason the D within the logo resembles an optical disc.

At the 2000 Consumer Electronics Show (CES) trade show, the three companies announced the creation of the SD Association (SDA) to promote SD cards. The SD Association, headquartered in San Ramon, California, United States, started with about 30 companies and today consists of about 1,000 product manufacturers that make interoperable memory cards and devices. Early samples of the SD Card became available in the first quarter of 2000, with production quantities of 32 and 64 MB^[7] cards available three months later.

2003: Mini cards[edit]

The miniSD form was introduced at March 2003 CeBIT by SanDisk Corporation which announced and demonstrated it.^[8] The SDA adopted the miniSD card in 2003 as a small form factor extension to the SD card standard. While the new cards were designed especially for mobile phones, they are usually packaged with a miniSD adapter that provides compatibility with a standard SD memory card slot.

2004–2005: Micro cards[edit]

The microSD removable miniaturized Secure Digital flash memory cards were originally named T-Flash or TF, abbreviations of TransFlash. TransFlash and microSD cards are functionally identical allowing either to operate in devices made for the other.^[9] SanDisk had conceived microSD when its chief technology officer and the chief technology officer of Motorola concluded that current memory cards were too large for mobile phones.^{[citation needed]} The card was originally called T-Flash,^[10] but just before product launch, T-Mobile sent a cease-and-desist letter to SanDisk claiming that T-Mobile owned the trademark on T-(anything),^{[citation needed]} and the name was changed to TransFlash. At CTIA Wireless 2005, the SDA announced the small microSD form factor along with SDHC secure digital high capacity formatting in excess of 2 GB^[11] (2000 MB) with a minimum sustained read and write speed of 17.6 Mbit/s.^{[citation needed]} SanDisk induced the SDA to administer the microSD standard. The SDA approved the final microSD specification on July 13, 2005. Initially, microSD cards were available in capacities of 32, 64, and 128 MB.^{[citation needed]}

The Motorola E398 was the first mobile phone to contain a TransFlash (later microSD) card.^{[citation needed]} A few years later, its competitors began using microSD cards.

2006–2008: SDHC and SDIO[edit]

This microSDHC card holds 8 billion bytes. Beneath it is a section of a magnetic-core memory (used until the 1970s) that holds eight bytes using 64 cores. The card covers approximately 20 bits (2 1/2 bytes)

The SDHC format, announced in January 2006, brought improvements such as 32 GB storage capacity and mandatory support for FAT32 filesystems.^{[citation needed]} In April, the SDA released a detailed specification for the non-security related parts of the SD memory card standard and for the Secure Digital Input Output (SDIO) cards and the standard SD host controller.^{[citation needed]}

In September 2006, SanDisk announced the 4 GB miniSDHC.^[12] Like the SD and SDHC, the miniSDHC card has the same form factor as the older miniSD card but the HC card requires HC support built into the host device. Devices that support miniSDHC work with miniSD and miniSDHC, but devices without specific support for miniSDHC work only with the older miniSD card. Since 2008, miniSD cards are no longer produced.

2009–2018: SDXC[edit]

In January 2009, the SDA announced the SDXC family, which supports cards up to 2 TB^[13] and speeds up to 300 MB/s.^{[citation needed]} It features mandatory support for the exFAT filesystem.^{[citation needed]} SDXC was announced at Consumer Electronics Show (CES) 2009 (January 7–10). At the same show, SanDisk and Sony also announced a comparable Memory Stick XC variant with the same 2 TB maximum as SDXC,^[14] and Panasonic announced plans to produce 64 GB SDXC cards.^[15] On March 6, Pretec introduced the first SDXC card,^[16] a 32 GB card with a read/write speed of 400 Mbit/s. But only early in 2010 did compatible host devices come onto the market, including Sony's Handycam HDR-CX55V camcorder, Canon's EOS 550D (also known as Rebel T2i) Digital SLR camera,^[17] a USB card reader from Panasonic, and an integrated SDXC card reader from JMicron.^[18] The earliest laptops to integrate SDXC card readers relied on a USB 2.0 bus, which does not have the bandwidth to support SDXC at full speed.^[19]

In early 2010, commercial SDXC cards appeared from Toshiba (64 GB),^[20][21] Panasonic (64 GB and 48 GB),^[22] and SanDisk (64 GB).^[23] In early 2011, Centon Electronics, Inc. (64 GB and 128 GB) and Lexar (128 GB) began shipping SDXC cards rated at Speed Class 10.^[24] Pretec offered cards from 8 GB to 128 GB rated at Speed Class 16.^[25] In September 2011, SanDisk released a 64 GB microSDXC card.^[26] Kingmax released a comparable product in 2011.^[27]

In April 2012, Panasonic introduced MicroP2 card format for professional video applications. The cards are essentially full-size SDHC or SDXC UHS-II cards, rated at UHS Speed Class U1.^[28][29] An adapter allows MicroP2 cards to work in current P2 card equipment.^[30] Panasonic MicroP2 cards shipped in March 2013 and were the first UHS-II compliant products on market; initial offer includes a 32GB SDHC card and a 64GB SDXC card.^[28][31] Later that year, Lexar released the first 256 GB SDXC card, based on 20 nm NAND flash technology.^[32]

In February 2014, SanDisk introduced the first 128 GB microSDXC card,^[33] which was followed by a 200 GB microSDXC card in March 2015.^[34] September 2014 saw SanDisk announce the first 512 GB SDXC card.^[35] Samsung announced the world's first EVO Plus 256 GB microSDXC card in May 2016,^[36] and in September 2016 Western Digital (SanDisk) announced that a prototype of the first 1 TB SDXC card will be demonstrated at Photokina.^[37] In August 2017, SanDisk launched a 400 GB microSDXC card.^[38] In January 2018, Integral Memory unveiled 512 GB microSDXC card.^[39] In May 2018, PNY launched a 512 GB microSDXC card. In June 2018 Kingston announced the Canvas series for MicroSD cards which both are capable of capacities up to 512 GB, in three variations, Select, Go!, and React.^[40] In February 2019, Micron and SanDisk unveiled their microSDXC cards of 1 TB capacity.^[41]

2018–present: SDUC[edit]

The Secure Digital Ultra Capacity (SDUC) format, described in the SD 7.0 specification, and announced in June 2018, supports cards up to 128 TiB (140737488355328 bytes) and offers speeds up to 985 MB/s.

Capacity[edit]

Secure Digital includes five card families available in three different sizes. The five families are the original Standard-Capacity (SDSC), the High-Capacity (SDHC), the eXtended-Capacity (SDXC), the Ultra-Capacity (SDUC) and the SDIO, which combines input/output functions with data storage.^[42][43][44] The three form factors are the original size, the mini size, and the micro size. Electrically passive adapters allow a smaller card to fit and function in a device built for a larger card. The SD card's small footprint is an ideal storage medium for smaller, thinner and more portable electronic devices.

SD (SDSC)[edit]

Secure Digital Standard Capacity (SD) logo; the specification defines cards with a capacity of up to 2 GB

The second-generation Secure Digital (SDSC or Secure Digital Standard Capacity) card was developed to improve on the MultiMediaCard (MMC) standard, which continued to evolve, but in a different direction. Secure Digital changed the MMC design in several ways:

• Asymmetrical shape of the sides of the SD card prevent inserting it upside down (while an MMC goes in most of the way but makes no contact if inverted).
• Most SD cards are 2.1 mm (0.083 inches) thick, compared to 1.4 mm (0.055 inches) for MMCs. The SD specification defines a card called Thin SD with a thickness of 1.4 mm, but they occur only rarely, as the SDA went on to define even smaller form factors.
• The card's electrical contacts are recessed beneath the surface of the card, protecting them from contact with a user's fingers.
• The SD specification envisioned capacities and transfer rates exceeding those of MMC, and both of these functionalities have grown over time. For a comparison table, see below.
• While MMC uses a single pin for data transfers, the SD card added a four-wire bus mode for higher data rates.
• The SD card added Content Protection for Recordable Media (CPRM) security circuitry for digital rights management (DRM) content-protection.
• Addition of a write-protect notch

Full-size SD cards do not fit into the slimmer MMC slots, and other issues also affect the ability to use one format in a host device designed for the other.

SDHC[edit]

Secure Digital High Capacity (SDHC) logo; the specification defines cards with a capacity of more than 2 GB up to 32 GB

The Secure Digital High Capacity (SDHC) format, announced in January 2006 and defined in version 2.0 of the SD specification, supports cards with capacities up to 32 GiB (34359738368 bytes).^[42] The SDHC trademark is licensed to ensure compatibility.^[45]

SDHC cards are physically and electrically identical to standard-capacity SD cards (SDSC). The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card-Specific Data (CSD) register in version 2.0 (see below), and the fact that SDHC cards are shipped preformatted with the FAT32 file system.

Version 2.0 also introduces a High-speed bus mode for both SDSC and SDHC cards, which doubles the original Standard Speed clock to produce 25 MB/s.^[46]

SDHC host devices are required to accept older SD cards.^[47] However, older host devices do not recognize SDHC or SDXC memory cards, although some devices can do so through a firmware upgrade.^[48] Older Windows operating systems released before Windows 7 require patches or service packs to support access to SDHC cards.^[49][50][51]

SDXC[edit]

Secure Digital eXtended Capacity logo; the specification defines cards with a capacity of more than 32 GB up to 2 TB

The Secure Digital eXtended Capacity (SDXC) format, announced in January 2009 and defined in version 3.01 of the SD specification, supports cards up to 2 TiB (2199023255552 bytes), compared to a limit of 32 GiB for SDHC cards in the SD 2.0 specification. SDXC adopts Microsoft's exFAT file system as a mandatory feature.^[52]

Version 3.01 also introduced the Ultra High Speed (UHS) bus for both SDHC and SDXC cards, with interface speeds from 50 MB/s to 104 MB/s for four-bit UHS-I bus.^[53]

Version 4.0, introduced in June 2011, allows speeds of 156 MB/s to 312 MB/s over the four-lane (two differential lanes) UHS-II bus, which requires an additional row of physical pins.^[53]

Version 5.0 was announced in February 2016 at CP+ 2016, and added "Video Speed Class" ratings for UHS cards to handle higher resolution video formats like 8K.^[54][55] The new ratings define a minimum write speed of 90 MB/s.^[56][57]

SDUC[edit]

Secure Digital Ultra Capacity (SDUC) logo; the specification defines cards with a capacity of more than 2 TB up to 128 TB

The Secure Digital Ultra Capacity (SDUC) format, described in the SD 7.0 specification, and announced in June 2018, supports cards up to 128 TiB (140737488355328 bytes) and offers speeds up to 985 MB/s, regardless of form factor, either micro or full size, or interface type including UHS-I, UHS-II, UHS-III or SD Express.^[58] The SD Express interface can also be used with SDHC and SDXC cards.

exFAT filesystem[edit]

SDXC and SDUC cards are normally formatted using the exFAT file system, thereby limiting their use to a limited set of operating systems. Therefore, exFAT-formatted SDXC cards are not a 100% universally readable exchange medium. However, SD cards can be reformatted to any file system required.

Windows Vista (SP1) and later^[59] and OS X (10.6.5 and later) have native support for exFAT.^[60][61] (Windows XP and Server 2003 can support exFAT via an optional update from Microsoft.)^[62] Most BSD and Linux distributions did not, for legal reasons; though in Linux kernel 5.4 Microsoft open-sourced the spec and allowed the inclusion of an exfat driver.^[63] Users of older kernels or BSD can manually install third-party implementations of exFAT (as a FUSE module) in order to be able to mount exFAT-formatted volumes.^[64] However, SDXC cards can be reformatted to use any file system (such as ext4, UFS, or VFAT), alleviating the restrictions associated with exFAT availability.

Except for the change of file system, SDXC cards are mostly backward compatible with SDHC readers, and many SDHC host devices can use SDXC cards if they are first reformatted to the FAT32 file system.^[65][66][67]

Nevertheless, in order to be fully compliant with the SDXC card specification, some SDXC-capable host devices are firmware-programmed to expect exFAT^{[clarification needed]} on cards larger than 32 GiB.^{[citation needed][disputed – discuss]} Consequently, they may not accept SDXC cards reformatted as FAT32, even if the device supports FAT32 on smaller cards (for SDHC compatibility). Therefore, even if a file system is supported in general, it is not always possible to use alternative file systems on SDXC cards at all depending on how strictly the SDXC card specification has been implemented in the host device. This bears a risk of accidental loss of data, as a host device may treat a card with an unrecognized file system as blank or damaged and reformat the card.

The SD Association provides a formatting utility for Windows and Mac OS X that checks and formats SD, SDHC, SDXC, and SDUC cards.^[68]

Comparison[edit]

Speed[edit]

SD card speed is customarily rated by its sequential read or write speed. The sequential performance aspect is the most relevant for storing and retrieving large files (relative to block sizes internal to the flash memory), such as images and multimedia. Small data (such as file names, sizes and timestamps) falls under the much lower speed limit of random access, which can be the limiting factor in some use cases.^[70][71][72]

With early SD cards, a few card manufacturers specified the speed as a "times" ("×") rating, which compared the average speed of reading data to that of the original CD-ROM drive. This was superseded by the Speed Class Rating, which guarantees a minimum rate at which data can be written to the card.^[73]

The newer families of SD card improve card speed by increasing the bus rate (the frequency of the clock signal that strobes information into and out of the card). Whatever the bus rate, the card can signal to the host that it is "busy" until a read or a write operation is complete. Compliance with a higher speed rating is a guarantee that the card limits its use of the "busy" indication.

Bus[edit]

Default Speed[edit]

SD Cards will read and write at speeds of 12.5 MB/s.

High Speed[edit]

High Speed Mode (25 MB/s) was introduced to support digital cameras with 1.10 spec version.^[74]

Ultra High Speed (UHS)[edit]

Back side of a Lexar UHS-II microSDHC card, showing the additional row of UHS-II connections

The Ultra High Speed (UHS) bus is available on some SDHC and SDXC cards.^[75][76][77] The following ultra-high speeds are specified:

UHS-I[edit]

Specified in SD version 3.01.^[78] Supports a clock frequency of 100 MHz (a quadrupling of the original "Default Speed"), which in four-bit transfer mode could transfer 50 MB/s (SDR50). UHS-I cards declared as UHS104 (SDR104) also support a clock frequency of 208 MHz, which could transfer 104 MB/s. Double data rate operation at 50 MHz (DDR50) is also specified in Version 3.01, and is mandatory for microSDHC and microSDXC cards labeled as UHS-I. In this mode, four bits are transferred when the clock signal rises and another four bits when it falls, transferring an entire byte on each full clock cycle, hence a 50 MB/s operation could be transferred using a 50 MHz clock.

There is a proprietary UHS-I extension primarily by Sandisk that increases transfer speed further called DDR200 (DDR208?).^{[citation needed]} It does not use additional pins.

UHS-II[edit]

Specified in version 4.0, further raises the data transfer rate to a theoretical maximum of 156 MB/s (full-duplex) or 312 MB/s (half-duplex) using an additional row of pins^[79][80] (a total of 17 pins for full-size and 16 pins for micro-size cards).^[75]

UHS-III[edit]

Version 6.0, released in February 2017, added two new data rates to the standard. FD312 provides 312 MB/s while FD624 doubles that. Both are full-duplex. The physical interface and pin-layout are the same as with UHS-II, retaining backward compatibility. ^[81]

Cards that comply with UHS show Roman numerals 'I', 'II' or 'III' next to the SD card logo,^[75][73] and report this capability to the host device. Use of UHS-I requires that the host device command the card to drop from 3.3-volt to 1.8-volt operation over the I/O interface pins and select the four-bit transfer mode, while UHS-II requires 0.4-volt operation.

The higher speed rates are achieved by using a two-lane low voltage (0.4 V pp) differential interface. Each lane is capable of transferring up to 156 MB/s. In full-duplex mode, one lane is used for Transmit while the other is used for Receive. In half-duplex mode both lanes are used for the same direction of data transfer allowing a double data rate at the same clock speed. In addition to enabling higher data rates, the UHS-II interface allows for lower interface power consumption, lower I/O voltage and lower electromagnetic interference (EMI).

SD Express[edit]

The SD Express bus was released in June 2018 with SD specification 7.0. It uses a single PCIe lane to provide full-duplex 985 MB/s transfer speed. Supporting cards must also implement the NVM Express storage access protocol. The Express bus can be implemented by SDHC, SDXC, and SDUC cards. For legacy application use, SD Express cards must also support High Speed bus and UHS-I bus. The Express bus re-uses the pin layout of UHS-II cards and reserves the space for additional two pins that may be introduced in the future. ^[82]

Hosts which implement version 7.0 of the spec allow SD Cards to do direct memory access, which increases the attack surface of the host dramatically in the face of malicious SD cards.^[83]

Version 8.0 was announced on 19th May 2020, with support for two PCIe lanes with additional row of contacts and PCIe 4.0 transfer rates, for a maximum bandwidth of 3938 MByte/s.^[84]

microSD Express[edit]

In February 2019, the SD Association announced microSD Express.^[85] The microSD Express cards offer PCI Express and NVMe interfaces, as the June 2018 SD Express release did, alongside the legacy microSD interface for continued backwards compatibility. The SDA also released visual marks to denote microSD Express memory cards to make matching the card and device easier for optimal device performance.^[86]

Bus speed Comparison[edit]

Compatibility[edit]

Class[edit]

64GB SanDisk Ultra microSDXC card (with UHS-I and UHS Speed Class 1 markings)

32GB Lexar 1000x microSDHC card (with UHS-II and UHS Speed Class 3 markings)

The front and back of the Sony 128GB SF-G Tough Series UHS-II SDXC Memory Card.

The SD Association defines standard speed classes for SDHC/SDXC cards indicating minimum performance (minimum serial data writing speed). Both read and write speeds must exceed the specified value. The specification defines these classes in terms of performance curves that translate into the following minimum read-write performance levels on an empty card and suitability for different applications:^{[78][73][89][90]}

The SD Association defines three types of Speed Class ratings: the original Speed Class, UHS Speed Class, and Video Speed Class.

Speed Class[edit]

Speed Class ratings 2, 4, and 6 assert that the card supports the respective number of megabytes per second as a minimum sustained write speed for a card in a fragmented state. Class 10 asserts that the card supports 10 MB/s as a minimum non-fragmented sequential write speed and uses a High Speed bus mode.^[78] The host device can read a card's speed class and warn the user if the card reports a speed class that falls below an application's minimum need.^[78] By comparison, the older "×" rating measured maximum speed under ideal conditions, and was vague as to whether this was read speed or write speed. The graphical symbol for the speed class has a number encircled with 'C' (C2, C4, C6, and C10).

UHS Speed Class[edit]

UHS-I and UHS-II cards can use UHS Speed Class rating with two possible grades: class 1 for minimum write performance of at least 10 MB/s ('U1' symbol featuring number 1 inside 'U') and class 3 for minimum write performance of 30 MB/s ('U3' symbol featuring 3 inside 'U'), targeted at recording 4K video.^[91] Before November 2013, the rating was branded UHS Speed Grade and contained grades 0 (no symbol) and 1 ('U1' symbol). Manufacturers can also display standard speed class symbols (C2, C4, C6, and C10) alongside, or in place of UHS speed class.

UHS memory cards work best with UHS host devices. The combination lets the user record HD resolution videos with tapeless camcorders while performing other functions. It is also suitable for real-time broadcasts and capturing large HD videos.

Video Speed Class[edit]

Video Speed Class defines a set of requirements for UHS cards to match the modern MLC NAND flash memory^[56] and supports progressive 4K and 8K video with minimum sequential writing speeds of 6-90 MB/s.^[54][73][89] The graphical symbols use 'V' followed by a number designating write speed (V6, V10, V30, V60, and V90).

Comparison[edit]

Application Performance Class[edit]

Application Performance Class is a newly defined standard from the SD Specification 5.1 and 6.0 which not only define sequential Reading Speeds but also mandates a minimum IOPS for reading and writing. Class A1 requires a minimum of 1500 reading and 500 writing operations per second, while class A2 requires 4000 and 2000 IOPS.^[93] A2 class cards require host driver support as they use command queuing and write caching to achieve their higher speeds. If used in an unsupported host, they might even be slower than other A1 cards.^[94]

Manufacturer	Commodore Business Machines (CBM)
Type	Home computer
Release date	August 1982; 38 years ago (1982-08)[1]
Introductory price	US$595 (equivalent to $1,576 in 2019)
Discontinued	April 1994; 26 years ago (1994-04)
Units sold	12.5[2] – 17[3] million
Operating system	Commodore KERNAL/BASIC 2.0 GEOS (optionally)
CPU	MOS Technology 6510/8500 @ 1.023 MHz (NTSC version) @ 0.985 MHz (PAL version)
Memory	64 KB (65,536 bytes) (IEC: KiB)RAM + 20 KB ROM
Graphics	VIC-II (320×200, 16 colors, sprites, raster interrupt)
Sound	SID 6581/8580 (3× osc, 4× wave, filter, ADSR, ring)
Connectivity
Predecessor	Commodore VIC-20
Successor

The Commodore 64, also known as the C64 or the CBM 64, is an 8-bithome computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, in Las Vegas, January 7–10, 1982).^[4] It has been listed in the Guinness World Records as the highest-selling single computer model of all time,^[5] with independent estimates placing the number sold between 10 and 17 million units.^[2] Volume production started in early 1982, marketing in August for US$595 (equivalent to $1,576 in 2019).^[6][7] Preceded by the Commodore VIC-20 and Commodore PET, the C64 took its name from its 64 kilobytes(65,536 bytes) of RAM. With support for multicolor sprites and a custom chip for waveform generation, the C64 could create superior visuals and audio compared to systems without such custom hardware.

The C64 dominated the low-end computer market (except in the UK) for most of the 1980s.^[8] For a substantial period (1983–1986), the C64 had between 30% and 40% share of the US market and two million units sold per year,^[9] outselling IBM PC compatibles, Apple computers, and the Atari 8-bit family of computers. Sam Tramiel, a later Atari president and the son of Commodore's founder, said in a 1989 interview, "When I was at Commodore we were building 400,000 C64s a month for a couple of years."^[10] In the UK market, the C64 faced competition from the BBC Micro and the ZX Spectrum,^[11] but the C64 was still the second most popular computer in the UK after the ZX Spectrum.^[12]

Part of the Commodore 64's success was its sale in regular retail stores instead of only electronics or computer hobbyist specialty stores. Commodore produced many of its parts in-house to control costs, including custom integrated circuit chips from MOS Technology. It has been compared to the Ford Model T automobile for its role in bringing a new technology to middle-class households via creative and affordable mass-production.^[13] Approximately 10,000 commercial software titles have been made for the Commodore 64, including development tools, office productivity applications, and video games.^[14]C64 emulators allow anyone with a modern computer, or a compatible video game console, to run these programs today. The C64 is also credited with popularizing the computer demoscene and is still used today by some computer hobbyists.^[15] In 2011, 17 years after it was taken off the market, research showed that brand recognition for the model was still at 87%.^[5]

History[edit]

The Commodore 64 startup screen

In January 1981, MOS Technology, Inc., Commodore's integrated circuit design subsidiary, initiated a project to design the graphic and audio chips for a next generation video game console. Design work for the chips, named MOS Technology VIC-II (Video Integrated Circuit for graphics) and MOS Technology SID (Sound Interface Device for audio), was completed in November 1981.^[6] Commodore then began a game console project that would use the new chips—called the Ultimax or the Commodore MAX Machine, engineered by Yash Terakura from Commodore Japan. This project was eventually cancelled after just a few machines were manufactured for the Japanese market.^[16] At the same time, Robert "Bob" Russell (system programmer and architect on the VIC-20) and Robert "Bob" Yannes (engineer of the SID) were critical of the current product line-up at Commodore, which was a continuation of the Commodore PET line aimed at business users. With the support of Al Charpentier (engineer of the VIC-II) and Charles Winterble (manager of MOS Technology), they proposed to Commodore CEO Jack Tramiel a true low-cost sequel to the VIC-20. Tramiel dictated that the machine should have 64 KB of random-access memory (RAM). Although 64-Kbitdynamic random-access memory (DRAM) chips cost over US$100 (equivalent to $237.72 in 2019) at the time, he knew that 64K DRAM prices were falling and would drop to an acceptable level before full production was reached. The team was able to quickly design the computer because, unlike most other home-computer companies, Commodore had its own semiconductor fab to produce test chips; because the fab was not running at full capacity, development costs were part of existing corporate overhead. The chips were complete by November, by which time Charpentier, Winterble, and Tramiel had decided to proceed with the new computer; the latter set a final deadline for the first weekend of January, to coincide with the 1982 Consumer Electronics Show (CES).^[6]

The product was code named the VIC-40 as the successor to the popular VIC-20. The team that constructed it consisted of Yash Terakura,^[17]Shiraz Shivji,^[18] Bob Russell, Bob Yannes, and David A. Ziembicki. The design, prototypes, and some sample software were finished in time for the show, after the team had worked tirelessly over both Thanksgiving and Christmas weekends. The machine used the same case, same-sized motherboard, and same Commodore BASIC 2.0 in ROM as the VIC-20. BASIC also served as the user interfaceshell and was available immediately on startup at the prompt. When the product was to be presented, the VIC-40 product was renamed C64. The C64 made an impressive debut at the January 1982 Consumer Electronics Show, as recalled by Production Engineer David A. Ziembicki: "All we saw at our booth were Atari people with their mouths dropping open, saying, 'How can you do that for $595?'"^[6][19] The answer was vertical integration; due to Commodore's ownership of MOS Technology's semiconductor fabrication facilities, each C64 had an estimated production cost of US$135.^[6]

Reception[edit]

In July 1983, BYTE magazine stated that "the 64 retails for $595. At that price it promises to be one of the hottest contenders in the under-$1000 personal computer market." It described the SID as "a true music synthesizer ... the quality of the sound has to be heard to be believed", while criticizing the use of Commodore BASIC 2.0, the floppy disk performance which is "even slower than the Atari 810 drive", and Commodore's quality control.^[20]Creative Computing said in December 1984 that the 64 was "the overwhelming winner" in the category of home computers under $500. Despite criticizing its "slow disk drive, only two cursor directional keys, zero manufacturer support, non-standard interfaces, etc.", the magazine said that at the 64's price of less than $200 "you can't get another system with the same features: 64K, color, sprite graphics, and barrels of available software".^[21]

Market war: 1982–1983[edit]

Commodore had a reputation for announcing products that never appeared, so sought to quickly ship the C64. Production began in spring 1982 and volume shipments began in August.^[6] The C64 faced a wide range of competing home computers,^[22] but with a lower price and more flexible hardware, it quickly outsold many of its competitors.

In the United States the greatest competitors were the Atari 8-bit 400, the Atari 800, and the Apple II. The Atari 400 and 800 had been designed to accommodate previously stringent FCC emissions requirements and so were expensive to manufacture. Though similar in specifications, the two computers represented differing design philosophies; as an open architecture system, upgrade capability for the Apple II was granted by internal expansion slots, whereas the C64's comparatively closed architecture had only a single external ROM cartridge port for bus expansion. However, the Apple II used its expansion slots for interfacing to common peripherals like disk drives, printers, and modems; the C64 had a variety of ports integrated into its motherboard which were used for these purposes, usually leaving the cartridge port free. Commodore's was not a completely closed system, however; the company had published detailed specifications for most of their models since the Commodore PET and VIC-20 days, and the C64 was no exception. Initial C64 sales were nonetheless relatively slow due to a lack of software, reliability issues with early production models, particularly high failure rates of the PLA chip, which used a new production process, and a shortage of 1541 disk drives, which also suffered rather severe reliability issues. During 1983, however, a trickle of software turned into a flood and sales began rapidly climbing, especially with price cuts from $600 to just $300 ($1500 to $800 in 2019).

Commodore sold the C64 not only through its network of authorized dealers, but also through department stores, discount stores, toy stores and college bookstores. The C64 had a built-in RF modulator and thus could be plugged into any television set. This allowed it (like its predecessor, the VIC-20) to compete directly against video game consoles such as the Atari 2600. Like the Apple IIe, the C64 could also output a composite video signal, avoiding the RF modulator altogether. This allowed the C64 to be plugged into a specialized monitor for a sharper picture. Unlike the IIe, the C64's NTSC output capability also included separate luminance/chroma signal output equivalent to (and electrically compatible with) S-Video, for connection to the Commodore 1702 monitor, providing even better video quality than a composite signal.

Aggressive pricing of the C64 is considered to have been a major catalyst in the North American video game crash of 1983. In January 1983, Commodore offered a $100 rebate in the United States on the purchase of a C64 to anyone that traded in another video game console or computer.^[23] To take advantage of this rebate, some mail-order dealers and retailers offered a Timex Sinclair 1000 (TS1000) for as little as $10 with purchase of a C64. This deal meant that the consumer could send the TS1000 to Commodore, collect the rebate, and pocket the difference; Timex Corporation departed the computer market within a year. Commodore's tactics soon led to a price war with the major home computer manufacturers. The success of the VIC-20 and C64 contributed significantly to the exit from the field of Texas Instruments and other smaller competitors.

The price war with Texas Instruments was seen as a personal battle for Commodore president Jack Tramiel.^[24] Commodore dropped the C64's list price by $200 within two months after its release.^[6] In June 1983 the company lowered the price to $300, and some stores sold the computer for $199. At one point, the company was selling as many C64s as all computers sold by the rest of the industry combined. Meanwhile, the TI lost money by selling the 99/4A for $99.^[25] TI's subsequent demise in the home computer industry in October 1983 was seen as revenge for TI's tactics in the electronic calculator market in the mid-1970s, when Commodore was almost bankrupted by TI.^[26]

All four machines had similar memory configurations which were standard in 1982–83: 48 KB for the Apple II+^[27] (upgraded within months of C64's release to 64 KB with the Apple IIe) and 48 KB for the Atari 800.^[28] At upwards of $1,200,^[29] the Apple II was about twice as expensive, while the Atari 800 cost $899. One key to the C64's success was Commodore's aggressive marketing tactics, and they were quick to exploit the relative price/performance divisions between its competitors with a series of television commercials after the C64's launch in late 1982.^[30] The company also published detailed documentation to help developers,^[31] while Atari initially kept technical information secret.^[32]

Although many early C64 games were inferior Atari 8-bit ports, by late 1983 the growing installed base caused developers to create new software with better graphics and sound.^[33] It was the only non-discontinued, widely available home computer by then, with more than 500,000 sold during the Christmas season;^[34] because of production problems in Atari's supply chain, by the start of 1984 "the Commodore 64 largely has [the low-end] market to itself right now", The Washington Post reported.^[35]

1984–1987[edit]

Some of the graphics modes on the 64 are really strange, and they have no analogs to the Atari or Apple, like the ability to change color of the character basis across the screen. That gave us a lot of color capability that had not been exploited.

With sales booming and the early reliability issues with the hardware addressed, software for the C64 began to grow in size and ambition during 1984. This growth shifted to the primary focus of most US game developers. The two holdouts were Sierra, who largely skipped over the C64 in favor of Apple and PC compatible machines, and Broderbund, who were heavily invested in educational software and developed primarily around the Apple II. In the North American market, the disk format had become nearly universal while cassette and cartridge-based software all-but disappeared. So most US-developed games by this point grew large enough to require multi-loading.

By 1985, games were an estimated 60 to 70% of Commodore 64 software.^[36] The year, UK-based Gremlin Graphics released the game Monty on the Run, which was noteworthy for marking a turning point in music composition for the SID chip as musician Rob Hubbard discovered a method of "over driving" the SID to produce music more advanced than the default sound envelopes. The revolution that Hubbard started quickly spread to most European developers, although more conservative American programmers seldom composed SID music with anything other than the default envelopes.^{[citation needed]} At a mid-1984 conference of game developers and experts at Origins Game Fair, Dan Bunten, Sid Meier), and a representative of Avalon Hill said that they were developing games for the C64 first as the most promising market.^[37]Computer Gaming World stated in January 1985 that companies such as Epyx that survived the video game crash did so because they "jumped on the Commodore bandwagon early."^[38] Over 35% of SSI's 1986 sales were for the C64, ten points higher than for the Apple II. The C64 was even more important for other companies,^[39] which often found that more than half the sales for a title ported to six platforms came from the C64 version.^[40] That year, Computer Gaming World published a survey of ten game publishers that found that they planned to release forty-three Commodore 64 games that year, compared to nineteen for Atari and forty-eight for Apple II,^[41] and Alan Miller stated that Accolade developed first for the C64 because "it will sell the most on that system".^[42]

In Europe, the primary competitors to the C64 were British-built computers: the Sinclair ZX Spectrum, the BBC Micro and the Amstrad CPC 464. In the UK, the 48K Spectrum had not only been released a few months ahead of the C64's early 1983 debut, but it was also selling for £175, less than half the C64's £399 price. The Spectrum quickly became the market leader and Commodore had an uphill struggle against it in the marketplace. The C64 did however go on to rival the Spectrum in popularity in the latter half of the 1980s. Adjusted to the size of population, the popularity of Commodore 64 was the highest in Finland at roughly 3 units per 100 inhabitants,^[43] where it was subsequently marketed as "the Computer of the Republic".^[44]

Rumors spread in late 1983 that Commodore would discontinue the C64.^[45] By early 1985 the C64's price was $149; with an estimated production cost of $35–50, its profitability was still within the industry-standard markup of two to three times.^[6] Commodore sold about one million C64s in 1985 and a total of 3.5 million by mid-1986. Although the company reportedly attempted to discontinue the C64 more than once in favor of more expensive computers such as the Commodore 128, demand remained strong.^[46][47] In 1986, Commodore introduced the 64C,^[48] a redesigned 64, which Compute! saw as evidence that—contrary to C64 owners' fears that the company would abandon them in favor of the Amiga and 128—"the 64 refuses to die."^[49] Its introduction also meant that Commodore raised the price of the C64 for the first time, which the magazine cited as the end of the home-computer price war.^[50] Software sales also remained strong; MicroProse, for example, in 1987 cited the Commodore and IBM PC markets as its top priorities.^[51]

1988–1994[edit]

By 1988 PC compatibles were the largest and fastest-growing home and entertainment software markets, displacing former leader Commodore.^[52] Commodore 64 software sales were almost unchanged in the third quarter of 1988 year over year while the overall market grew 42%,^[53] but the company was still selling 1 to 1.5 million units worldwide each year of what Computer Chronicles that year called "the Model T of personal computers".^[54] Epyx CEO David Shannon Morse cautioned that "there are no new 64 buyers, or very few. It's a consistent group that's not growing... it's going to shrink as part of our business."^[55] One computer gaming executive stated that the Nintendo Entertainment System's enormous popularity – seven million sold in 1988, almost as many as the number of C64s sold in its first five years – had stopped the C64's growth. Trip Hawkins reinforced that sentiment, stating that Nintendo was "the last hurrah of the 8-bit world."^[56]

SSI exited the Commodore 64 market in 1991, after most competitors.^[57]Ultima VI, released in 1991, was the last major C64 game release from a North American developer, and the Simpsons Arcade Game, published by Ultra Games, was the last arcade conversion. The latter was a somewhat uncommon example of a US-developed arcade port as after the early years of the C64, most arcade conversions were produced by UK developers and converted to NTSC and disk format for the US market, American developers instead focusing on more computer-centered game genres such as RPGs and simulations. In the European market, disk software was rarer and cassettes were the most common distribution method; this led to a higher prevalence of arcade titles and smaller, lower budget games that could fit entirely in the computer's memory without requiring multiloads. European programmers also tended to exploit advanced features of the C64's hardware more than their US counterparts^{[citation needed]}.

In the United States, demand for 8- and 16-bit computers all but ceased as the 1990s began and PC compatibles completely dominated the computer market. However, the C64 continued to be popular in the UK and other European countries. The machine's eventual demise was not due to lack of demand or the cost of the C64 itself (still profitable at a retail price point between £44 and £50), but rather because of the cost of producing the disk drive. In March 1994, at CeBIT in Hanover, Germany, Commodore announced that the C64 would be finally discontinued in 1995,^[58] noting that the Commodore 1541 cost more than the C64 itself.^[58]

However, only one month later in April 1994, the company filed for bankruptcy. It has been widely claimed that between 18 and 22 million C64s were sold worldwide. Company sales records, however, indicate that the total number was about 12.5 million. Based on that figure, the Commodore 64 was still the third most popular computing platform in the 21 century until the Raspberry Pi family replaced it.^[59] While 360,000 C64s were sold in 1982, about 1.3 million were sold in 1983, followed by a large spike in 1984 when 2.6 million were sold. After that, sales held steady at between 1.3 and 1.6 million a year for the remainder of the decade and then dropped off after 1989. North American sales peaked between 1983 and 1985 and gradually tapered off afterward, while European sales remained quite strong into the early 1990s – much to the embarrassment of Commodore officials who wished to rid themselves of the aging machine.^[2]

The computer's designers claimed that "The freedom that allowed us to do the C-64 project will probably never exist again in that environment"; by spring 1983 most had left to found Ensoniq.

C64 family[edit]

Commodore MAX[edit]

In 1982, Commodore released the Commodore MAX Machine in Japan. It was called the Ultimax in the United States and VC-10 in Germany. The MAX was intended to be a game console with limited computing capability and was based on a cut-down version of the hardware family later used in the C64. The MAX was discontinued months after its introduction because of poor sales in Japan.^[60]

Commodore Educator 64[edit]

1983 saw Commodore attempt to compete with the Apple II's hold on the US education market with the Educator 64,^[61] essentially a C64 and "greenscale" monochrome monitor in a PET case. Schools preferred the all-in-one metal construction of the PET over the standard C64's separate components, which could be easily damaged, vandalized, or stolen.^[62] Schools did not prefer the Educator 64 to the wide range of software and hardware options the Apple IIe was able to offer, and it was produced in limited quantities.^[63]

SX-64[edit]

Also in 1983, Commodore released the SX-64, a portable version of the C64. The SX-64 has the distinction of being the first full-colorportable computer. While earlier computers using this form factor only incorporate monochrome ("green screen") displays, the base SX-64 unit features a 5 in (130 mm) color cathode ray tube (CRT) and one integrated 1541 floppy disk drive. While, in the advertisements for the computer it claimed it would have dual 1541 drives, but when the SX-64 was released there was only one and the other became a floppy disk storage slot. Also, unlike most other C64s, the SX-64 does not have a datasette connector so an external cassette was not an option.^[64]

Commodore C128[edit]

Two designers at Commodore, Fred Bowen and Bil Herd, were determined to rectify the problems of the Plus/4. They intended that the eventual successors to the C64—the Commodore 128 and 128D computers (1985)—were to build upon the C64, avoiding the Plus/4's flaws.^[65][66] The successors had many improvements such as a BASIC with graphics and sound commands, 80-column display ability, and full CP/M compatibility. The decision to make the Commodore 128plug compatible with the C64 was made quietly by Bowen and Herd, software and hardware designers respectively, without the knowledge or approval by the management in the post Jack Tramiel era. The designers were careful not to reveal their decision until the project was too far along to be challenged or changed and still make the impending Consumer Electronics Show (CES) in Las Vegas.^[65] Upon learning that the C128 was designed to be compatible with the C64, Commodore's marketing department independently announced that the C128 would be 100% compatible with the C64, thereby raising the bar for C64 support. In a case of malicious compliance, the 128 design was altered to include a separate "64 mode" using a complete C64 environment to try to ensure total compatibility.^{[citation needed]}

Commodore 64C[edit]

Commodore 64C with 1541-II floppy disk drive and 1084S monitor displaying television-compatible S-Video

The C64's designers intended the computer to have a new, wedge-shaped case within a year of release, but the change did not occur.^[6] In 1986, Commodore released the 64C computer, which is functionally identical to the original. The exterior design was remodeled in the sleeker style of the Commodore 128.^[47] The 64C uses new versions of the SID, VIC-II, and I/O chips being deployed. Models with the C64E board had the graphic symbols printed on the top of the keys, instead of the normal location on the front. The sound chip (SID) was changed to use the MOS 8580 chip, with the core voltage reduced from 12V to 9V. The most significant changes include different behavior in the filters and in the volume control, which result in some music/sound effects sounding differently than intended, and in digitally-sampled audio being almost inaudible, respectively (though both of these can mostly be corrected-for in software). The 64 KB RAM memory went from eight chips to two chips. BASIC and the KERNAL went from two separate chips into one 16 KB ROM chip. The PLA chip and some TTL chips were integrated into a DIL 64-pin chip. The "252535-01" PLA integrated the color RAM as well into the same chip. The smaller physical space made it impossible to put in some internal expansions like a floppy-speeder.^[67] In the United States, the 64C was often bundled with the third-party GEOSgraphical user interface (GUI)-based operating system, as well as the software needed to access Quantum Link. The 1541 drive received a matching face-lift, resulting in the 1541C. Later, a smaller, sleeker 1541-II model was introduced, along with the 800 KB^[68] 3.5-inch microfloppy1581.

Commodore 64 Games System[edit]

In 1990, the C64 was repackaged in the form of a game console, called the C64 Games System (C64GS), with most external connectivity removed.^[69] A simple modification to the 64C's motherboard was made to allow cartridges to be inserted from above. A modified ROM replaced the BASIC interpreter with a boot screen to inform the user to insert a cartridge. Designed to compete with the Nintendo Entertainment System and the Sega Master System, it suffered from very low sales compared to its rivals. It was another commercial failure for Commodore, and it was never released outside Europe.

Commodore 65[edit]

In 1990, an advanced successor to the C64, the Commodore 65 (also known as the "C64DX"), was prototyped, but the project was canceled by Commodore's chairman Irving Gould in 1991. The C65's specifications were impressive for an 8-bit computer, bringing specs comparable to the 16-bit Apple IIGS. For example, it could display 256 colors on the screen, while OCS based Amigas could only display 64 in HalfBrite mode (32 colors and half-bright transformations). Although no specific reason was given for the C65's cancellation, it would have competed in the marketplace with Commodore's lower end Amigas and the Commodore CDTV.

Software[edit]

In 1982, the C64's graphics and sound capabilities were rivaled only by the Atari 8-bit family and appeared exceptional when compared with the widely publicized Atari VCS and Apple II. The C64 is often credited with starting the computer subculture known as the demoscene (see Commodore 64 demos). It is still being actively used in the demoscene,^[70] especially for music (its SID sound chip even being used in special sound cards for PCs, and the Elektron SidStation synthesizer). Even though other computers quickly caught up with it, the C64 remained a strong competitor to the later video game consolesNintendo Entertainment System (NES) and Sega Master System, thanks in part to its by-then established software base, especially outside North America, where it comprehensively outsold the NES.^{[citation needed]}

Because of lower incomes and the domination of the Sinclair Spectrum in the UK, almost all British C64 software used cassette tapes. Few cassette C64 programs were released in the US after 1983 and, in North America, the diskette was the principal method of software distribution. The cartridge slot on the C64 was also mainly a feature used in the computer's first two years on the market and became rapidly obsolete once the price and reliability of 1541 drives improved. A handful of PAL region games used bank switched cartridges to get around the 16 KB memory limit.

BASIC[edit]

The Simons' BASIC interpreter start-up screen. Note the altered background and text colors (vs the ordinary C64 blue tones) and the 8 KB reduction of available BASIC-interpreter program memory allocation, due to the address space used by the cartridge.

As is common for home computers of the early 1980s, the C64 comes with a BASIC interpreter, in ROM. KERNAL, I/O, and tape/disk drive operations are accessed via custom BASIC language commands. The disk drive has its own interfacing microprocessor and ROM (firmware) I/O routines, much like the earlier CBM/PET systems and the Atari 400 and Atari 800. This means that no memory space is dedicated to running a disk operating system, as was the case with earlier systems such as the Apple II and TRS-80.

Commodore BASIC 2.0 is used instead of the more advanced BASIC 4.0 from the PET series, since C64 users were not expected to need the disk-oriented enhancements of BASIC 4.0. The company did not expect many to buy a disk drive, and using BASIC 2.0 simplified VIC-20 owners' transition to the 64.^[71] "The choice of BASIC 2.0 instead of 4.0 was made with some soul-searching, not just at random. The typical user of a C64 is not expected to need the direct disk commands as much as other extensions, and the amount of memory to be committed to BASIC were to be limited. We chose to leave expansion space for color and sound extensions instead of the disk features. As a result, you will have to handle the disk in the more cumbersome manner of the 'old days'."^[72]

The version of Microsoft BASIC is not very comprehensive and does not include specific commands for sound or graphics manipulation, instead requiring users to use the "PEEK and POKE" commands to access the graphics and sound chip registers directly. To provide extended commands, including graphics and sound, Commodore produced two different cartridge-based extensions to BASIC 2.0: Simons' BASIC and Super Expander 64. Other languages available for the C64 include Pascal, C,^[73][74]Logo, Forth, and FORTRAN. Compilers for BASIC 2.0 such as Petspeed 2 (from Commodore), Blitz (from Jason Ranheim), and Turbo Lightning (from Ocean Software) were produced. Most commercial C64 software was written in assembly language, either cross developed on a larger computer, or directly on the C64 using a machine code monitor or an assembler. This maximized speed and minimized memory use. Some games, particularly adventures, used high level scripting languages and sometimes mixed BASIC and machine language.

Alternative operating systems[edit]

Many third party operating systems have been developed for the C64. As well as the original GEOS, two third-party GEOS-compatible systems have been written: Wheels and GEOS megapatch. Both of these require hardware upgrades to the original C64. Several other operating systems are or have been available, including WiNGS OS, the Unix-like LUnix, operated from a command-line, and the embedded systems OS Contiki, with full GUI. Other less well-known OSes include ACE, Asterix, DOS/65, and GeckOS. A version of CP/M was released, but this requires the addition of an external Z80 processor to the expansion bus. Furthermore, the Z80 processor is underclocked to be compatible with the C64's memory bus, so performance is poor compared to other CP/M implementations. C64 CP/M and C128 CP/M both suffer a lack of software; although most commercial CP/M software can run on these systems, software media is incompatible between platforms. The low usage of CP/M on Commodores means that software houses saw no need to invest in mastering versions for the Commodore disk format. The C64 CP/M cartridge is also not compatible with anything except the early 326298 motherboards.^{[citation needed]}

Networking software[edit]

During the 1980s, the Commodore 64 was used to run bulletin board systems using software packages such as Punter BBS, Bizarre 64, Blue Board, C-Net, Color 64, CMBBS, C-Base, DMBBS, Image BBS, EBBS, and The Deadlock Deluxe BBS Construction Kit, often with sysop-made modifications. These boards sometimes were used to distribute cracked software. As late as December 2013, there were 25 such Bulletin Board Systems in operation, reachable via the Telnet protocol.^[75] There were major commercial online services, such as Compunet (UK), CompuServe (US – later bought by America Online), The Source (US), and Minitel (France) among many others. These services usually required custom software which was often bundled with a modem and included free online time as they were billed by the minute. Quantum Link (or Q-Link) was a US and Canadian online service for Commodore 64 and 128 personal computers that operated from November 5, 1985, to November 1, 1994. It was operated by Quantum Computer Services of Vienna, Virginia, which in October 1991 changed its name to America Online and continued to operate its AOL service for the IBM PC compatible and Apple Macintosh. Q-Link was a modified version of the PlayNET system, which Control Video Corporation (CVC, later renamed Quantum Computer Services) licensed.

Online gaming[edit]

The first graphical character-based interactive environment is Club Caribe. First released as Habitat in 1988, Club Caribe was introduced by LucasArts for Q-Link customers on their Commodore 64 computers. Users could interact with one another, chat and exchange items. Although the game's open world was very basic, its use of online avatars (already well-established off-line by Ultima and other games) and the combination of chat and graphics was revolutionary. Online graphics in the late 1980s were severely restricted by the need to support modem data transfer rates as low as 300 bits per second. Habitat's graphics were stored locally on floppy disk, eliminating the need for network transfer.^[76]

Hardware[edit]

CPU and memory[edit]

The C64 uses an 8-bitMOS Technology 6510microprocessor. This is a close derivative of the 6502 with an added 6-bit internal I/O port that in the C64 is used for two purposes: to bank-switch the machine's read-only memory (ROM) in and out of the processor's address space and to operate the datasette tape recorder. The C64 has 64 KB of 8-bit-wide dynamic RAM, 1 KB of 4-bit-wide static color RAM for text mode and 38 KB are available to built-in Commodore BASIC 2.0 on startup. There is 20 KB of ROM, made up of the BASIC interpreter, the KERNAL, and the character ROM. As the processor could only address 64 KB at a time, the ROM was mapped into memory, and only 38,911 bytes of RAM (plus 4 KB in between the ROMs) were available at startup. Most "breadbox" Commodore 64s used 4164 DRAM, with eight chips to total up 64K of system RAM. Late breadbox models and all C64Cs used 41464 DRAM (64K×4) chips which stored 32 KB per chip, so only two were required. Since 4164 DRAMs are 64K×1, eight chips are needed to make an entire byte, and the computer will not function without all of them present. Thus, the first chip contains Bit 0 for the entire memory space, the second chip contains Bit 1, and so forth. This also makes detecting faulty RAM easy, as a bad chip will display random characters on the screen and the character displayed can be used to determine the faulty RAM.

The C64 performs a RAM test on power up and if a RAM error is detected, the amount of free BASIC memory will be lower than the normal 38911 figure. If the faulty chip is in lower memory, then an error is displayed rather than the usual BASIC startup banner. The color RAM at $D800 uses a separate 2114 SRAM chip and is gated directly to the VIC-II.

The C64 uses a somewhat complicated memory banking scheme; the normal power-on default is to have the BASIC ROM mapped in at $A000-$BFFF and the screen editor/KERNAL ROM at $E000-$FFFF. RAM underneath the system ROMs can be written to, but not read back without swapping out the ROMs. Memory location $01 contains a register with control bits for enabling/disabling the system ROMS as well as the I/O area at $D000. If the KERNAL ROM is swapped out, BASIC will be removed at the same time it,^[77]:264[78] and it is not possible to have BASIC active without the KERNAL (as BASIC often calls KERNAL routines and part of the ROM code for BASIC is in fact located in the KERNAL ROM, this makes sense).

The character ROM is normally not visible to the CPU. It has two mirrors at $1000 and $9000, but only the VIC-II can see them, the CPU will see RAM in those locations. The character ROM may be mapped into $D000-$DFFF where it is then visible to the CPU. Since doing so necessitates swapping out the I/O registers, interrupts must be disabled first. Graphics memory and data cannot be placed at $1000 or $9000 as the VIC-II will see the character ROM there instead.

By removing I/O from the memory map, $D000-$DFFF becomes free RAM. The color RAM at $D800 is swapped out along with the I/O registers and this area can be used for static graphics data such as character sets since the VIC-II cannot see the I/O registers (or color RAM via the CPU mapping). If all ROMs and the I/O area are swapped out, the entire 64k RAM space is available aside for locations $0/$1.

$C000-$CFFF is free RAM and not used by BASIC or KERNAL routines; because of this, it is an ideal location to store short machine language programs that can be accessed from BASIC. The cassette buffer at $0334-$03FF can also be used to store short machine language routines provided that a Datasette is not used, which will overwrite the buffer.

C64 cartridges map into assigned ranges in the CPU's address space and the most common cartridge auto starting requires the presence of a special string at $8000 which contains "CBM80" followed by the address where program execution begins. A few early C64 cartridges released in 1982 use Ultimax mode (or MAX mode), a leftover feature of the failed MAX Machine. These cartridges map into $F000 and displace the KERNAL ROM. If Ultimax mode is used, the programmer will have to provide code for handling system interrupts. The cartridge port has 14 address lines, which allows 16 KB of ROM to be accessed. Disk and tape software normally load at the start of BASIC memory ($0801) and use a small BASIC stub (e.g., 10 SYS(2064)) to jump to the start of the program. Although no Commodore 8-bit machine except the C128 can automatically boot from a floppy disk, some software intentionally overwrites certain BASIC vectors in the process of loading so that execution begins automatically rather than requiring the user to type RUN at the BASIC prompt following loading.

Around 300 cartridges were released for the C64, mostly in the machine's first 2½ years on the market, after which most software outgrew the 16 KB cartridge limit. In the final years of the C64, larger software companies such as Ocean Software began releasing games on bank-switched cartridges to overcome this 16 KB cartridge limit.

Commodore did not include a reset button on any of their computers until the CBM-II line, but there were third-party cartridges with a reset button on them. It is possible to trigger a soft reset by jumping to the CPU reset routine at $FCE2 (64738). A few programs use this as an "exit" feature, although it does not clear memory.

The KERNAL ROM went through three separate revisions, mostly designed to fix bugs. The initial version is only found on 326298 motherboards, used in the first production models, and cannot detect if an NTSC or PAL VIC-II is present. The second revision is found on all C64s made from late 1982 through 1985. The third and last KERNAL ROM revision was introduced on the 250466 motherboard (late breadbin models with 41464 RAM) and is found in all C64Cs. The 6510 CPU is clocked at 1.023 MHz (NTSC) and 0.985 MHz (PAL),^[79] lower than some competing systems (for example, the Atari 800 is clocked at 1.79 MHz). A small performance boost can be gained by disabling the VIC-II's video output via a register write. This feature is often used by tape and disk fastloaders as well as the KERNAL cassette routine to keep a standard CPU cycle timing not modified by the VIC-II's sharing of the bus.

The Restore key is gated directly to the CPU's NMI line and will generate an NMI if pressed. The KERNAL handler for the NMI checks if Run/Stop is also pressed, if not, it ignores the NMI and simply exits back out. Run/Stop-Restore normally functions as a soft reset in BASIC that restores all I/O registers to their power on default state, but does not clear memory or reset pointers, so any BASIC programs in memory will be left untouched. Machine language software usually disables Run/Stop-Restore by remapping the NMI vector to a dummy RTI instruction. The NMI can be used for an extra interrupt thread by programs as well, but runs the risk of a system lockup or undesirable side effects if the Restore key is accidentally pressed, as this will trigger an inadvertent activation of the NMI thread.

Joysticks, mice, and paddles[edit]

The C64 retained the DE-9joystickAtari joystick port from the VIC-20 and added another; any Atari specification game controller can be used on a C64. The joysticks are read from the registers at $DC00 and $DC01, and most software is designed to use a joystick in port 2 for control rather than port 1, as the upper bits of $DC00 are used by the keyboard and an I/O conflict can result. Although it is possible to use Sega game pads on a C64, it is not recommended as the slightly different signal generated by them can damage the CIA chip. The SID chip's register $D419 is used to control paddles and is an analog input. Atari paddles are electrically compatible with the C64, but have different resistance values than Commodore's paddles, which means most software will not work properly with them.^{[citation needed]} However, only a handful of games, mostly ones released early in the computer's life cycle, can use paddles. In 1986, Commodore released two mice for the C64 and C128, the 1350 and 1351. The 1350 is a digital device, read from the joystick registers (and can be used with any program supporting joystick input); while the 1351 is a true, analog potentiometer based, mouse, read with the SID's analog-to-digital converter.

Graphics[edit]

The graphics chip