Commodore 64 Totally Explained

Everything about The Commodore 64 totally explained

The Commodore 64 is an 8-bit home computer released by Commodore International in August, 1982, at a price of US$595. Preceded by the Commodore VIC-20 and Commodore MAX Machine, the C64 features 64 kilobytes (65,536 bytes) of RAM with sound and graphics performance that were superior to IBM-compatible computers of that time.
   The Commodore 64 is commonly referred to as the C64 or C=64 and occasionally known as CBM 64 (Commodore Business Machines Model number 64), or VIC-64. It has also been affectionately nicknamed the "breadbox" and "bullnose" due to its shape.
   During the Commodore 64's lifetime sales totaled 30 million units, making it the best-selling single personal computer model of all time. At one point (1983/84/85), the Commodore 64 dominated the market with approximately 40% share, even outselling IBM PCs and Apple computers. Sam Tramiel, a former Commodore president said in a 1989 interview "When I was at Commodore we were building 400,000 C64s a month for a couple of years." Part of its success was due to the fact that it was sold in retail stores instead of electronics stores, and that Commodore produced many of its parts in-house to control supplies and cost.
   Approximately 10,000 commercial software titles were made for the Commodore 64 including development tools, office applications, and games. The machine is also credited with popularizing the computer demo scene. The Commodore 64 is still used today by some computer hobbyists, and various C64 emulators allow anyone with a modern computer to run these programs on their desktop. Since 28 March 2008, Commodore 64 games have been available to buy from the Wii Virtual Console in Europe; the first games available were Uridium and International Karate.

History

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 (graphics) and MOS Technology SID (audio), was completed in November 1981.
   A game console project was then initiated by Commodore that would use the new chips—called the Ultimax or alternatively the Commodore MAX Machine, engineered by Yash Terakura from Commodore Japan. This project was eventually canceled after just a few machines were manufactured for the Japanese market.
   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 RAM. Although 64 KB of DRAM cost over USD$100 at the time, he knew that DRAM prices were falling, and would soon drop to an acceptable level before full production was reached. In November, Tramiel set a deadline for the first weekend of January, to coincide with the 1982 Consumer Electronics Show.
   The product was codenamed the VIC-40 as the successor to the popular VIC-20. The team that constructed it consisted of Bob Russell, Bob Yannes and David A. Ziembicki. The design, prototypes and some sample software was finished in time for the show, after the team had worked tirelessly over both Thanksgiving and Christmas weekends.
   When the product was to be presented, the VIC-40 product was renamed C64 in order to fit into the current Commodore business products lineup which contained the P128 and the B256, both named by a letter and their respective memory size.
   The C64 made an impressive debut at the 1982 Winter 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?'" The answer, as it turned out, was vertical integration; thanks to Commodore's ownership of MOS Technology's semiconductor fabrication facilities, each C64 had an estimated production cost of only $135.

Winning the market war

The C64 faced a wide range of competing home computers at its introduction in August 1982. With an impressive price coupled with the C64's advanced hardware, it quickly out-classed many of its competitors. In the United States the greatest competitors to the C64 were the Atari 8-bit 400 and 800, the IBM PC and the Apple II. The Atari 400 and 800 were very similar in hardware terms, but were very expensive to build, which forced Atari to redesign their machine to be more cost effective. This resulted in the 600XL/800XL line and the transfer of their production to the Far East. The IBM PC and the latest in the aging Apple II line both had higher resolution graphics modes than the C64, but due to poor color support they were rarely used, so in practice the C64's 16-color (4-bit) graphics and sound abilities outmatched them at the time of its release. But the PC and Apple II were very expandable with their internal expansion slots, a feature lacking in the 64.
   All four machines had similar standard memory configurations in the years 1982/83: 48K for the Apple II+ (upgraded within months of C64's release to 64K with the Apple IIe); At upwards of US$1,200, the IBM PC and Apple II were more than 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.
   Commodore sold the C64 not only through its network of authorized dealers, but also placed it on the shelves of department stores, discount stores, and toy stores. Since it had the ability to output composite video, the C64 didn't require a specialized monitor, but could be plugged into a television set. This allowed it (like its predecessor, the VIC-20) to compete directly against video game consoles such as the Atari 2600.
   Aggressive pricing of the C64 is considered to be a major catalyst in the video game crash of 1983. 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. To take advantage of the $100 rebate, some mail-order dealers and retailers offered a Timex Sinclair 1000 for as little as $10 with purchase of a C64 so the consumer could send the computer to Commodore, collect the rebate, and pocket the difference. Timex Corporation departed the marketplace within a year. The success of the VIC-20 and C64 also contributed significantly to the exit of Texas Instruments and other competitors from the field. In parts of the US in the late 1980s, new C64's could be purchased in retail chains for a little more than $100.
   In 1984, Commodore released the Commodore Plus/4. The Plus/4 offered a higher-color display, a better implementation of BASIC (V3.5), and built-in software. However, Commodore committed what was perceived by critics and consumers as a major strategic error by making it incompatible with the C64. The Plus/4 lacked hardware sprite capability and had much poorer sound, thus seriously under performing in two of the areas that had made the C64 a star.
   In Europe, the primary competitors to the C64 were the British-built Sinclair ZX Spectrum, BBC Microcomputer and the Amstrad CPC 464. In the UK, the Spectrum had been released a few months ahead of the C64, and selling for almost half the price. The Spectrum quickly became the market leader and Commodore had an uphill struggle against the Spectrum as it couldn't rely on undercutting the competition. The C64 debuted at £399 in early 1983, while the Spectrum cost £175. The C64 would later rival the Spectrum in popularity in the latter half of the 1980s, eventually outliving the Spectrum when the latter was discontinued in December 1990.
   Despite a few attempts by Commodore to discontinue the C64 in favor of other, higher priced machines, constant demand made its discontinuation a hard task. By 1988, Commodore was selling 1.5 million C64s worldwide. Although demand for the C64 dropped off in the US by 1990, it continued to be popular in the UK and other European countries. In the end, economics, not obsolescence sealed the C64's fate. In March 1994, at CeBIT in Hanover, Germany, Commodore announced that the C64 would be finally discontinued in 1995. Commodore claimed that the C64's disk drive was more expensive to manufacture than the C64 itself. Although Commodore had planned to discontinue the C64 by 1995, the company filed for bankruptcy a month later, in April 1994.

The C64 family

1982: Commodore released the Commodore MAX Machine in Japan. It is called the Ultimax in the US, and VC-10 in Germany. The MAX was intended to be a game console with limited computing capability. It was discontinued months after its introduction, because of poor sales in Japan.
   1983 saw Commodore attempt to compete with the Apple II's hold on the education market with the Educator 64, essentially a C64 and monochrome monitor in a PET case. Schools preferred the all in one, metal construction of the PET over the standard C64's easily damaged, vandalized or stolen separate components.
   In 1984 Commodore released the SX-64, a portable version of the C64. The SX-64 has the distinction of being the first full-color portable computer. The base unit featured a 5 inch (127 mm) CRT and an integrated 1541 floppy disk drive. The SX-64 didn't have a cassette connector.
   Commodore was determined to avoid the problems of the Plus/4, making sure that the eventual successors to the C64—the Commodore 128 and 128D computers (1985)—were as good as, and fully compatible with the original, as well as offering a host of improvements (such as a structured BASIC with graphics and sound commands, 80-column display capability, and full CP/M compatibility). In 1986, Commodore released the Commodore 64C (C64C) computer, which was functionally identical to the original, but whose exterior design was remodeled in the sleeker style of the Commodore 128 and other contemporary design trends. The modifications to the C64 line were more than skin deep in the C64C with new versions of the SID, VIC and I/O chips being deployed—with the core voltage reduced from 12v to 5v. In the United States, the C64C was often bundled with the third-party GEOS GUI-based operating system. The Commodore 1541 disk drive received a matching face-lift resulting in the 1541c. Later a smaller, sleeker 1541-II model was introduced along with the 800KB 3.5" capable 1581.
   In 1990, the C64 was re-released in the form of a game console, called the C64 Games System (C64GS). A simple modification to the C64C's motherboard was made to orient the cartridge connector to a vertical position. This allowed 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. The C64GS was another commercial failure for Commodore, and it was never released outside of Europe.
   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 very good for an 8-bit computer. For example, it could display 256 colors on screen, while OCS based Amigas could only display 64. Although no specific reason was given for the C65's cancellation, it would have competed in the marketplace with Commodore's lower end Amigas.

C64 clones

In the middle of 2004, after an absence from the marketplace of more than 10 years, PC manufacturer Tulip Computers BV (owners of the Commodore brand since 1997) announced the C64 Direct-to-TV (C64DTV), a joystick-based TV game based on the C64 with 30 games built into ROM. Designed by Jeri Ellsworth, a self-taught computer designer who had earlier designed the modern C-One C64 implementation, the C64DTV was similar in concept to other mini-consoles based on the Atari 2600 and Intellivision which had gained modest success earlier in the decade. The product was advertised on QVC in the United States for the 2004 holiday season. Some users have installed 1541 floppy disk drives, hard drives, second joysticks and keyboards to these units, which give the DTV devices nearly all of the capabilities of a full Commodore 64. The DTV hardware is also used in the mini-console/game Hummer, sold at Radio Shack mid-2005. As of 2006, C64 enthusiasts still develop new hardware, including Ethernet cards, specially adapted hard disks and Flash Card interfaces.

Software

At the time of its introduction, the C64's graphics and sound capabilities were rivaled only by the Atari 8-bit family. This was at a time when most IBM PCs and compatibles had text-only graphics cards, monochrome monitors, and sound consisting of squeaks and beeps from the built-in tiny, low-quality speaker.
Due to its advanced graphics and sound, the C64 is often credited with starting the computer subculture known as the demoscene (see Commodore 64 demos). The C64 lost its top position among demo coders when the 16-bit Atari ST and Commodore Amiga were released in 1985, however it still remained a very popular platform for demo coding up to the early 90s. By the turn of the millennium, it's still being actively used as a demo machine, especially for music (its sound chip even being used in special sound cards for PCs, and the Elektron SidStation synthesizer). Unfortunately, the differences between PAL and NTSC C64s caused compatibility problems between U.S./Canadian C64s and those from most other countries. The vast majority of demos run only on PAL machines.
Even though the Commodore 64 was released in 1982, it was still a strong competitor for the range of the number of games released to the Sega Master System and the Nintendo Entertainment System, even though these consoles were released 3 to 4 years later than the C64.

Hardware

Graphics and sound

The C64 used an 8-bit MOS Technology 6510 microprocessor. This was 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 ROM in and out of the processor's address space, and to operate the datasette tape recorder.
   The C64 had 64 kilobytes of RAM, of which 38 KB were available to built-in Commodore BASIC 2.0.
   The graphics chip, VIC-II, featured 16 colors, eight hardware sprites per scanline (enabling up to 112 sprites per PAL screen), scrolling capabilities, and two bitmap graphics modes. The standard text mode featured 40 columns, like most Commodore PET models; the built in font wasn't standard ASCII but PETSCII, an extended form of ASCII-1963. The VIC-II allowed the C64 to be a highly-capable platform for playing arcade-style games at home.
   The sound chip, SID, had three channels, each with its own ADSR envelope generator, and 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." Often the game music became a hit of its own among C64 users. Well-known composers and programmers of game music on the C64 were Rob Hubbard, David Whittaker, Chris Hülsbeck, Ben Daglish, Martin Galway and David Dunn among many others. Due to the chip's limitation to three channels, chords were played as arpeggios typically, coining the C64's characteristic lively sound.
   There are two versions of the SID chip. The first version was the MOS Technology 6581, which is to be found in all of the original "breadbox" C64s, and early versions of the C64C and the Commodore 128. It was later replaced with the MOS Technology 8580 in 1987. The sound quality was a little more crisp on the 6581 and many Commodore 64 fans still prefer its sound. The main difference between the 6581 and the 8580 was the voltage supply: the 6581 uses a 12 volt supply, while the 8580 required only 9 volts. A voltage modification can be made to use a 6581 in a C64C board (which uses 9V).
   The SID chip has a distinctive sound which retained a following of devotees. In 1999, Swedish company Elektron produced a SidStation synth module, built around the 6581 model SID chip (as opposed the superior 8580), using remaining stocks of the chip. Several bands use these devices in their music. And also in 1999, a Hungarian company Hard Software produced the HardSID sound cards which are built on both the 6581 and the 8580 SID chips.

Hardware revisions

Cost reduction was the driving force for hardware revisions to the C64's motherboard. Reducing manufacturing costs was vitally important to Commodore's survival during the price war and leaner years of the 16-bit era. The C64's original (NMOS based) motherboard would go through two major redesigns, (and numerous sub-revisions) exchanging positions of the VIC-II, SID and PLA chips. Initially, a large proportion of the cost was lowered by reducing the number of discrete components used, such as diodes and resistors, which also enabled the use of the now physically smaller board. It is likely that the reduced board size led to further cost savings.

   The VIC-II was manufactured with 5 micrometre NMOS technology and was clocked at either 14.31818 MHz (NTSC) or 17.73447 MHz (PAL). Internally, the clock was divided down to generate the pixel clock (about 8 MHz) and the two-phase system clocks (about 1 MHz; the exact pixel and system clock speeds are slightly different between NTSC and PAL machines). At such high clock rates, the chip generated a lot of heat, forcing MOS Technology to use a ceramic DIL package (called a "CERDIP"). The ceramic package was more expensive, but it dissipated heat more effectively than plastic.
   After a redesign in 1983, the VIC-II was encased in a plastic DIL package, which reduced costs substantially, but it didn't eliminate the heat problem. Without a ceramic package, the VIC-II required the use of a heatsink. To avoid extra cost, the metal RF shielding doubled as the heatsink for the VIC, although not all units shipped with this type of shielding. Most C64s in Europe shipped with a cardboard RF shield, coated with a layer of metal foil. The effectiveness of the cardboard was highly questionable, and worse still it acted as an insulator, blocking airflow which trapped heat generated by the SID, VIC and PLA chips.
   The SID was manufactured using NMOS at 7 and in some areas 6 micrometers. The prototype SID and some very early production models featured a ceramic DIL package, but unlike the VIC-II, these are extremely rare as the SID was encased in plastic when production started in early 1982.
   In 1986 Commodore released the last revision to the "classic" C64 motherboard. It was otherwise identical to the 1984 design, except that it now used two 64 kilobit ×4 DRAM chips rather than the original eight 64 kilobit ×1.
   After the release of the C64C, MOS Technology began to reconfigure the C64's chipset to use HMOS technology. The main benefit of using HMOS was that it required less voltage to drive the IC, which consequently generates less heat. This enhanced the overall reliability of the SID and VIC-II. The new chipset was re-numbered to 85xx in order to reflect the change to HMOS.
   In 1987 Commodore released C64Cs with a totally redesigned motherboard commonly known as a "short board". The new board used the new HMOS chipset, featuring new 64-pin PLA chip. The new "SuperPLA" as it was dubbed, integrated many discrete components and TTL chips. The 2114 color RAM was integrated into the last revision of the PLA.
   The C64 used an external power supply. While this saved valuable space within the computer's case, the supply itself was barely adequate for the C64's power requirements. Commodore's plastic power bricks would typically break from overheating. Some users purchased heavier-duty, better-cooled, third-party power supplies. The 1541-II and 1581 disk drives, along with various third-party clones, also came with their own external power supplies.
   Later in the Commodore's lifetime, third-party power supplies became increasingly important when used in conjunction with RAM expansions or Creative Micro Designs' peripherals. Of particular note, a C64 coupled with a RAM expansion or CMD SuperCPU required more power than the original Commodore power supply could provide. A modern PC power unit can be modified to power a C64 and its disk drives.

Specifications

Internal hardware

Microprocessor CPU:
- MOS Technology 6510/8500 (the 6510/8500 being a modified 6502 with an integrated 6-bit I/O port)
- Clock speed: 1.023 MHz (NTSC) or 0.985 MHz (PAL)
Video: MOS Technology VIC-II 6567/8567 (NTSC), 6569/8569 (PAL)
- 16 colors
- Text mode: 40×25 characters; 256 user-defined chars (8×8 pixels, or 4×8 in multicolor mode); 4-bit color RAM defines foreground color
- Bitmap modes: 320×200 (2 unique colors in each 8×8 pixel block), 160×200 (3 unique colors + 1 common color in each 4×8 block)
- 8 hardware sprites of 24×21 pixels (12×21 in multicolor mode)
- Smooth scrolling, raster interrupts
Sound: MOS Technology 6581/8580 SID
- 3-channel synthesizer with programmable ADSR envelope
- 8 octaves
- 4 waveforms: triangle, sawtooth, variable pulse, noise
- Oscillator synchronization, ring modulation
- Programmable filter: high pass, low pass, band pass, notch filter
Input/Output: Two 6526 Complex Interface Adapters
- 16 bit parallel I/O
- 8 bit serial I/O
- Time of Day clock
- 16 bit cascadable timers
RAM:
- 64 KB (65,536 bytes), of which 38 KB minus 1 byte (38,911 bytes) were available for BASIC programs
- 512 bytes color RAM
- Expandable to 320 KB with Commodore 1764 256 KB RAM Expansion Unit (REU); although only 64 KB directly accessible; REU mostly intended for GEOS. REUs of 128 KB and 512 KB, originally designed for the C128, were also available, but required the user to buy a stronger power supply from some third party supplier; with the 1764 this was included. Creative Micro Designs also produced a 2 MB REU for the C64 and C128, called the 1750 XL. The technology actually supported up to 16 MB, but 2 MB was the biggest one officially made. Expansions of up to 16 MB were also possible via the CMD SuperCPU.
ROM:
- 20 KB (9 KB BASIC 2.0; 7 KB KERNAL; 4 KB character generator, providing two 2 KB character sets)

I/O ports and power supply

I/O ports:

8-pin DIN plug containing composite video output, separate Y/C outputs and sound input/output. Beware that this is the 270° (horseshoe) version of the plug, not the 360° circular version. Also note that some early C64 units used a 5-pin DIN connector that omitted the C output. (External Link)
Integrated RF modulator antenna output via a RCA connector
2 × screwless DE9M game controller ports (compatible with Atari 2600 controllers), each supporting five digital inputs and two analog inputs. Available peripherals included digital joysticks, analog paddles, a light pen, the Commodore 1351 mouse, and the unique KoalaPad.
Cartridge expansion slot (slot for edge connector with 6510 CPU address/data bus lines and control signals, as well as GND and voltage pins; used for program modules and memory expansions, among others)
PET-type Datassette 300 baud tape interface (edge connector with cassette motor/read/write/sense signals and GND and +5 V pins; the motor pin is powered to directly supply the motor)
User port (edge connector with TTL-level RS-232 signals, for modems, etc; and byte-parallel signals which can be used to drive third-party parallel printers, among other things; with 17 logic signals, 7 GND and voltage pins, including 9V AC voltage)
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 an external "power brick", attached to a 7-pin female DIN-connector on the computer. The C64's original power brick was under-powered, and users would often replace it with a third party solution, particularly if they'd power-hungry peripherals attached to their machines.

Notable historic uses

The Commodore 64/128 series of computers found a place in early computer graphic design and television presentation. Below are some examples of notable uses and users.

Early creation of music using the SID sound chip, some of which has found its way into modern music. For example in 2007 Timbaland's extensive use of the SidStation led to the 2007 Timbaland plagiarism controversy around his tracks Block Party and Do It (written for Nelly Furtado).

Notes on C64 software

On address $FFF6-$FFF9 (65526-9) in the C64 KERNAL, immediately before the hard-coded jump vectors for the processor, is letter sequence "RRBY". These are the initials of Robert Russell and Bob Yannes, the two main engineers that created the C64.

The Commodore 64's BASIC V2, the programming language which came built-in with the computer, can be crashed by executing PRINT""+-x (where x is any integer), or by attempting to create a BASIC program with an initial line numbers 350720 to 353279.

Due to a quirk in the C64's BASIC operating system, an unintentional Easter egg or "screensaver" of sorts may be activated by pressing the RUN/STOP and RESTORE keys in unison, then entering POKE781,96:SYS58251 on the subsequently cleared screen.

There are ways to hide lines of code written in the BASIC Language stored in local memory, using control characters outside delimiting quotes, which the BASIC LIST function displayed as cursor control codes. For example, the reverse "heart" symbol would clear the screen, the reverse [ character would delete characters, and the character shift-L (which looks like an L-shaped border corner) in the program code would cause a syntax error and abort the LISTing.

Even though the VIC chip displays borders around the screen, it's possible to disable these vertical or side borders to allow graphics to be displayed by altering the hardware registers at the correct time.

Using short commands (the first letter, then shift and the second) it was possible to make BASIC lines more than two display rows long. The C64 couldn't parse more than two display rows when the subsequent code was LISTed.

Notes and references

Angerhausen, M.; Becker, Dr. A.; Englisch, L.; Gerits, K. (1983, 84). The Anatomy of the Commodore 64. Abacus Software (US ed.) / First Publishing Ltd. (UK ed.). ISBN 0-948015-00-4 (UK ed.). German original edition published by Data Becker GmbH & Co. KG, Düsseldorf.

Bagnall, Brian (2005). On the Edge: the Spectacular Rise and Fall of Commodore. Variant Press. ISBN 0-9738649-0-7. See especially pp. 224−260.

Commodore Business Machines, Inc., Computer Systems Division (1982). Commodore 64 Programmer's Reference Guide. Self-published by CBM. ISBN 0-672-22056-3.

Tomczyk, Michael (1984). The Home Computer Wars: An Insider's Account of Commodore and Jack Tramiel. COMPUTE! Publications, Inc. ISBN 0-942386-75-2.

Perry, Tekla S.; Wallich, Paul. "Design case history: the Commodore 64". IEEE Spectrum. March 1985. (External Link

)

Jeffries, Ron. "A best buy for '83: Commodore 64". Creative Computing, January 1983. (External Link

)

Amiga Format News Special. "Commodore at CeBIT '94". Amiga Format, Issue 59, May 1994.

Computer Chronicles; "Commodore 64 - Interview with Commodore president Max Toy", 1988. (External Link

)