Platform: Commodore Vic-20

Platform description

General description

The VIC-20 (Germany: VC-20; Japan: VIC-1001) is an 8-bit home computer that was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET. Focusing on low-cost and user-friendliness, the VIC-20 was the first computer of any description to sell one million units. Commodore made advertisements for the VIC-20 featuring actor William Shatner of Star Trek fame.

Its operating system was Commodore KERNAL/Commodore BASIC 2.0, it had a MOS Technology 6502 CPU 1.108404 MHz (PAL) or 1.02 MHz (NTSC) and memory of 20 KB ROM + 5 KB RAM (expandable to 32 KB), 3.5 KB for BASIC (expandable to 30.5 KB). Its retail price was just US$299.95, making it highly affordable compared to its competitors. In 1982, the VIC-20 was the best-selling computer of the year, with 800,000 machines sold. That summer, Commodore unveiled the Commodore 64, a more advanced machine with 64 KB of RAM and considerably improved sound and graphics capabilities. While sales were slow at first due to reliability problems and lack of software, sales sharply accelerated by mid 1983 and VIC-20 sales abruptly plunged. The VIC-20 was discontinued in January 1985.

A large part of the success of the VIC-20 can be attributed to the peripherals that were sold separately. Because of the VIC's many connector ports, a whole range of devices could be attached to the computer. This allowed the VIC-20 to expand its abilities and far beyond that of the basic stock model. This included:
- a port at the side for a Joystick, Paddle or Light Pen
- a port for program cartridges or RAM cartrides (to expand RAM up to 32kb) (image: 1)
- a 5-pin video port to connect the VIC20 to a TV or monitor (image: 2)
- a serial bus for a disk drive and printer (image: 3)
- a cassette port for a cassette drive (image: 4)
- a user port for a modem (image: 5)

Commodore VIC-20 software came on three possible types of media: cartridge, cassette or floppy.
Cartridges were plugged directly into the VIC-20's ROM port and have the advantage that most were ready to play as soon as the VIC-20 was turned on as the software didn't need to be loaded into memory, as opposed to games on tape which required a time-consuming loading process. An estimated 300 commercial titles were produced on cartridges. This includes, to our knowledge, all Sierra games except for Ultima: Escape from Mt. Drash, which was released on tape and required an 8kb RAM expansion cartridge.
By far, the most common and popular peripheral for the VIC-20 was the C2N/1530 Datassette tape drive. While disk drives were available, many Vic 20 owners felt that disk drives were too expensive. The datasette provided reliable data storage and retrieval on commonly available Compact Cassette audio tapes. While data storage and retrieval was considered slow, a stock VIC-20 computer only had 3.5k available, which meant that the programs written for it were small. The VIC-20 is compatible with the same Datassettes used on the Commodore PET computer. In fact, the first Datassette released by Commodore for the VIC-20 was identical to the PET model. This same Datassette was also compatible with the Commodore 64; successor to the VIC-20, all sharing the same cassette tape port. However, when loading the much more RAM intensive programs of the Commodore 64, the slow speed of the Datassette became quite apparent and disk drive became more popular. 500+ commercial titles were produced on tapes.
The VIC-1540 floppy disk drive is an external storage peripheral manufactured by Commodore specifically for the VIC-20 home computer. The VIC-1540 can read and write to standard 5.25 inch double-density magnetic floppy disk media. The 1540 has two serial ports, allowing other IEC devices (such as additional disk drives, printers or plotters) to be connected in chain fashion. The VIC-1540 was remarkable in that it had its own microprocessor (a 6502), RAM and built in CBM Disk Operating System (DOS), so it did not consume any of the VIC-20's own RAM or CPU. However, these additional components made the device very expensive, and as a result very few VIC-20 owners had a disk drive, opting for the more affordable, but slower datassette tape drive instead.

For more information on the Commodore VIC-20, including history and peripherals, see Wikipedia.

Emulating the Commodore VIC-20

VICE, standing for VersatIle Commodore Emulator, is a free and cross platform emulator for Commodore's 8-bit computers, running on Amiga, Unix, MS-DOS, Win32, Mac OS X, OS/2, RISC OS, QNX, GP2X, Dingoo A320, Syllable, and BeOS host machines. VICE is free software, released under the GNU General Public Licence. You can get VICE from the developer's site here.