CHIP-8 was created by RCA engineer Joe Weisbecker in 1977 for the COSMAC VIP microcomputer. It was intended as a simpler way to make small programs and games for the computer. Instead of using machine language for the VIP’s CDP1802 processor, you could type in hexadecimal instructions (with the VIP’s hex keypad) that resembled machine code, but which were more high-level, and interpreted on the fly by a small program (the CHIP-8 emulator/interpreter).
CHIP-8 soon spread to other computers, like the Finnish Telmac 1800, the Australian DREAM 6800, ETI-660 and MicroBee, and the Canadian ACE VDU.
By 1984 the interest in CHIP-8 petered out. However, in 1990 it had a renaissance on the HP48 graphing calculators with CHIP-48 and the now-famous SUPER-CHIP extension with higher resolution.
- Memory: CHIP-8 has direct access to up to 4 kilobytes of RAM
- Display: 64 x 32 pixels (or 128 x 64 for SUPER-CHIP) monochrome, ie. black or white
- A program counter, often called just “PC”, which points at the current instruction in memory
- One 16-bit index register called “I” which is used to point at locations in memory
- A stack for 16-bit addresses, which is used to call subroutines/functions and return from them
- An 8-bit delay timer which is decremented at a rate of 60 Hz (60 times per second) until it reaches 0
- An 8-bit sound timer which functions like the delay timer, but which also gives off a beeping sound as long as it’s not 0
- 16 8-bit (one byte) general-purpose variable registers numbered 0 through F hexadecimal, ie. 0 through 15 in decimal, called V0 through - VF
- VF is also used as a flag register; many instructions will set it to either 1 or 0 based on some rule, for example using it as a carry flag