C64: the King of home computers
The Commodore 64, is an home computer produced by Commodore Business Machines Inc., from 1982 to 1993. Borned as the big brother of VIC-20, with sound and video increased capacity but the software compatibility is the most discussed issue.
The making of project
In January 1981, the subsidiary MOS Technology Inc. that developes integrated circuits (such as processors, audio chips, etc…) started the project of graphics and sound chips in affiliation with Commodore Inc.
This development was completed in November but the initial project was refused because of a meeting with Jack Tramiel, that wanted the chips have 64 kB of RAM instead of the standard amount of 32 kB. So, the Commodore Team developed a prototype that was showed at International Electronic Show, in January 1982.
The Commodore 64 uses the MOS Technology 6510 microprocessor, with 64 kB of RAM, 20 kB of ROM and the kernel (named KERNAL); audio and video are managed by two separate chips. The processor’s clock was 0,9875 MHz.
The Commodore 64 had a VIC-II video chip that can produce a maximum of 16 colors. It had a maximum resolution of 320 x 200 using “hi-res” mode. The chip manages 8 hardware sprites.
The audio chip, SID 6581, exceeded all the high-end computers of the time. It can play three different hardware voices, making possible playing the exact human voice without extra hardware. The SID sounds were from four basic waveforms: Pulse, Square, Triangle, Sawtiith, White Noise plus ADSR. The number of entries could be “increased” by techniques that added software PWM audio samples, because the SID could also sample analog signals, with 4 bit resolution.
The Commodore 64 operating system was built from three separated and indipendent components. The particular architecture that allowed the C64 a RAM accessing mode allows changes in the software components of a system; these changes, of course, were lost at power off. KERNAL is the name of the C64 operating system, that includes the KERNEL, the Screen Editor and the interpreter BASIC (also known as Commodore BASIC). The KERNAL was adopted from Commodore 8-bit, used for the first time in the Commodore PET, updated gradually over the years.
At the introduction in 1982, the production cost was 135$ and the retail price 595$. In 1985, the retail cost went down to 150$ and the production cost went down between 35-50$.