Byter is an 8-bit computer built mostly out of 7400 series HC and HCT integrated circuits. It features a 16-bit address bus, 64Kb RAM, up to 32Kb ROM, 8 input ports, and 8 output ports. The custom architecture includes a hardware stack pointer, program counter, accumulator, index register (page + offset). CPU clock rates of up to 1Mhz are supported, however by default the clock is scaled down to 2KHz. The instruction set is stack-based. Available peripherals include a 16x2 LCD display, a 4x4 hex keypad, a timer and 8 debug LEDs.
The current implementation includes 77 ICs and ~70m of wiring, spread across 5 solderless breadboards, grouped into 5 modules of 3 boards each (I/O, SP, PC, ALU + Flags + MDR/MSR, RAM + uCode + ROM).
Peripherals are mapped to the following ports:
- I0: 8-bit timer
- I1: Keypad scan
- O0: LCD data
- O1: LCD control
- O2: Keypad mask
This repository contains a rudimentary assembler, an eeprom uploader and a microcode generator.
