Commodore 64

The Commodore 64 (C64, CBM 64) was a popular home computer of the 1980s. Announced by Commodore Business Machines (founded and owned by Jack Tramiel) in January 1982 and released in September of that year at a price of US$595, it offered unprecedented value (sound and graphics performance) for the money. Its very aggressive pricing in comparison to competitors quickly started a price war. With estimated sales between 17 and 25 million units by the time it was discontinued in 1993, the C64 became and remains the best-selling computer model of all time.

Table of contents

1 History 2 Description 3 Peripherals and software 4 Software preservation 5 Specifications 6 See also 7 References 8 External links

History

The cost of building each C64 was estimated at US$135 due to Commodore's vertical integration (Commodore owned MOS Technology, Inc, who made most of the chips), leaving a large margin to work with. Commodore marketed the machine aggressively, selling it in department stores, discount stores, and toy stores in addition to its network of authorized dealers. This allowed it, like its predecessor, the VIC-20, to compete against video game consoles. In 1983, Commodore offered a $100 rebate in the United States on the purchase of a C64 upon receipt of any video game console or computer.

The success of the VIC-20 and C64 contributed significantly to the departure of Texas Instruments from the home computer field (see TI-99/4A) and to the infamous video game crash of 1983.

C64C with Commodore 1764 RAM expansion unit.

Commodore attempted in 1984 to replace the C64 with the Commodore Plus/4, which offered a higher-color display, a better implementation of BASIC (V3.5), and built-in software. However, it lacked sprite capability and had poorer sound, and couldn't compete with the C64's software library. It flopped, while the C64 soldiered on. As more advanced computers came onto the market, including the C64's actual successor, the fully compatible C128 (late 1985), Commodore positioned the '64 as an entry-level computer, lowering the price as necessary.

In 1986, Commodore released the Commodore 64C computer, which was functionally identical to the original, but whose exterior design was remodelled in the spirit of the C128 to reflect "modernism". The C64C often came bundled with the third-party GEOS GUI-based operating system.

At the time of its introduction, the C64's graphics and sound capabilities were rivaled only by the Atari 8-bit family. Due to its advanced graphics and sound, the 64 is often credited with starting a computer subculture known as the demoscene (see also Commodore 64 demos). As of the turn of the millennium, it is still being actively used as a demo machine, especially for music (its sound chip even being used in special sound cards for PCs). For all others than special enthusiasts, however, the C64 lost its top position when the 16-bit Atari ST and Commodore Amiga were released in the mid-80s.

In the summer of 2004, after an absence from the marketplace of more than 10 years, Tulip Computers BV (owners of the Commodore brand since 1997) announced the C64-Direct-to-TV, a joystick-based TV game based on the C64 with 30 titles built into ROM. It was similar in concept to other mini-consoles based on the Atari 2600 and Intellivision, which had gained modest success earlier in the decade.

Description

The C64 used an 8-bit MOS Technology 6510 microprocessor (a close derivative of the 6502 with the added ability to bank-switch the machine's ROM in and out of the processor's address space) and had 64 kilobytes of RAM, of which 38 KB were available to built-in Commodore BASIC. In the UK, the C64 rivalled the British-built Sinclair ZX Spectrum in popularity, benefitting from a full-sized full-travel keyboard and more advanced graphics and sound chips.

Startup screen of C64, and rudimentary BASIC program
ready to run.

The graphics chip, VIC-II, featured 16 colors, eight sprites, scrolling capabilities, and two bitmap graphics modes. The standard text mode featured 40 columns, like most Commodore PET models. Computer/video game and demo programmers quickly learned how to exploit quirks in the VIC-II to gain additional capabilities, like making more than 8 sprites appear, and move, simultaneously.

The sound chip, SID, had three channels with several different waveforms, ring modulation and filter capabilities. It, too, was very advanced for its time. It was designed by Bob Yannes, who would later co-found synthesizer company Ensoniq. Yannes criticized other contemporary computer sound chips as "primitive, obviously (...) designed by people who knew nothing about music."

Unfortunately, the onboard BASIC programming language offered no easy way to tap the machine's advanced graphics and sound capabilities, so the user needed to either use PEEK and POKE commands to directly access the associated memory addresses to achieve the required results, use third party BASIC extensions such as Simons' BASIC, or program in assembly language. Commodore had a better implementation of BASIC but reportedly chose to ship the C64 with the same BASIC 2.0 used in the VIC-20 for fear of the C64 eating into the sales of its PET/CBM line.

Peripherals and software

Although not commonly supplied with the machine, floppy disk drives of the 5¼ inch (Commodore 1541) and, later, 3½ inch (1581) variety were available. Because the 1541 had a relatively poor reputation, a number of aftermarket drives also became available, offering better reliability, quieter operation, or simply a lower price, although often at the expense of compatibility. The C64 was often used with cassette tape drives (Datassettes) in Europe, although in the United States the C64 popularized the use of floppy drives, as it was the first computer that made them affordable.

Likewise, because Commodore offered a number of inexpensive modems for the C64, the machine also helped popularize the use of modems for telecommunications. In the United States, Quantum Computer Services (later America Online) offered an online service called Quantum Link for the C64 that featured chat, downloads, and online games. In the UK, Compunet was a very popular online service for C64 users (requiring special Compunet modems) from 1984 to the early 1990s.

The C64 amassed a large software library of nearly 10,000 titles, rivaled in its day only by the Apple II family. An Apple II+ emulator called The Spartan, manufactured by Mimic Systems Inc., was available for the C-64 but never gained much popularity. The C64's programs may still be run today even if one lacks the hardware, due to an abundance of software emulators for Amiga, Atari, Mac, MSDOS, Win32 and Linux systems. There are also special interface cables available, with software, to connect 1541 disk drives or C64s to PCs for emulation, archiving, and backup purposes.

Aside from games, and office applications like wordprocessors, spreadsheets, and database programs, etc, the C64 was well equipped with development tools, from Commodore as well as third-party vendors. Various assembler solutions were available, though perhaps the Rolls-Royce of these was the MIKRO assembler, which was in cartridge form, and integrated seamlessly with the standard BASIC screen editor. Several companies sold BASIC compilers, C compilers and Pascal compilers, to mention but a few popular languages available for the machine.

Software preservation

The magnetic tapes and disks upon which Commodore 64 software were stored are decaying at a phenomenal rate. In order to preserve game software for future users, efforts are underway to copy from these degrading media onto fresh media which will help ensure a long life for the software and make it available for emulation. One such effort is the GameBase 64 (GB64) organisation (see external link below). The GoodGB64 variant of Cowering's Good Tools allows users to audit their C64 game collections (the 2.02 version of GoodGB64 lists 15,712 "ROM"s).

Specifications

• CPU:
  • MOS Technology 6510 or MOS Technology 8500 (The 6510/8500 is a modified 6502 with 8-Bit I/O port)
  • Clock speed: 0.985 MHz (PAL) / 1.023 MHz (NTSC)

• Video Hardware:
  • MOS Technology VIC-II MOS 6567/8567 (NTSC) MOS 6569/8569 (PAL)
  • 2KB Character, 8KB for bitmap mode. (Video memory taken from 64KB RAM)
  • Graphics modes: 320×200 pixel resolution; 160×200 multicolor
  • Text modes: 40×25 characters of 8×8 pixels monochrome (one bitplane); 40×25 half-resolution chars of 4×8 pixels (two bitplanes) multicolor
  • Colours: 16 (black, white, red, cyan, purple, green, blue, yellow, orange, brown, light red, dark grey, medium grey, light green, light blue, light grey)
  • 8 Hardware sprites, including collision detection and priority levels. 24 by 21 pixels. 2x Sprite magnification
  • 16KB addressable
  • Built-in DRAM refresh controller.

• Sound Hardware:
  • Sound: MOS Technology 6581 "SID In C64Cs made from 1987 onwards, it was replaced with the MOS/CSG 8580
  • 3 Channel ADSR programmable synthesizer / 9 octaves Range 0-4 KHz
  • Programmable filter for all 3 channels [Low pass, Bandpass, High pass, Notch reject]
  • 4 Waveforms: Triangle, Sawtooth, Variable Pulse, Noise
  • Oscillator Synchronization, Ring modulation
  • 2x A/D (Analogue to Digital) Potentiometer Interfaces
  • Random number generator, Modulation generator
  • External audio input

• RAM:
  • 64 KB (65,535 bytes)(38K available for BASIC programs by default)
  • 0.5 KB (nybble) Colour RAM
  • Expandible to 320 KB (with Commodore 1764 256K*⁾ RAM Expansion Unit (REU); although only 64KB directly accessible; REU mostly intended for GEOS) (* REUs of 128K and 512K, originally designed for the C128, were also available)

• ROM:
  • 20 KB (8KB BASIC 2.0, 8KB KERNAL, 4KB character generator providing two 2KB character sets)

• I/O Ports:
  • High-quality Y/C (S-Video) (180° 5-pin DIN plug) with chroma/luma out and sound in + out, used with some Commodore video monitors (DIN-to-phono plug converter delivered with monitor)
  • Composite video (chroma video output to monitor, and separate RF modulator antenna output to TV)
  • 2 × DE9M game controller ports (Atari 2600 de facto standard)
  • Cartridge expansion slot (for edge connector with 6510 CPU address/data bus lines and control signals, as well as GND and voltage pins)
  • PET-type Datassette 300 baud tape interface (edge connector with cassette motor/read/write/sense signals and GND and +5V pins)
  • User port with TTL-level RS-232 signals, for modems, etc; and byte-parallel signals (edge c. with 17 logic signals, 7 GND and voltage pins)
  • Serial bus (serial version of IEEE-488, 6-pin DIN plug) for CBM printers and disk drives

• Power supply: 5V DC and 9V AC from external "monolithic power brick", attached to computer's 7-pin female DIN-connector

• List of Commodore 64 games

• Chronology of the Commodore 64 Computer – By Ken Polsson
• c64.org – A useful link portal
• WinVICE – Commodore 64 emulator for MS Windows
• GameBase 64 – C64 game software preservation site
• Press Play on Tape – Danish 'C64 revival' band