910 tcpu
910 : tcpu
- Author: Kai Harris
- Description: 8-bit CPU with integrated IO and bootloader
- GitHub repository
- Open in 3D viewer
- Clock: 50000000 Hz
tcpu
[!NOTE] This is an
8-bitCPU, with an integrated bootloader, and IO capability via UART
It is an accumulator style CPU, with two registers, a small amount of internal memory
How it works
The ISA is described here:
instruction || 7:7 | 6:5 | 4:4 | 3:0 || register elaboration
======================================================================
add || 0 | 00 | x | x || reg_a = reg_a + reg_b
----------------------------------------------------------------------
add 1 || 0 | 01 | x | x || reg_a = reg_a + 1
----------------------------------------------------------------------
and || 0 | 10 | x | x || reg_a = reg_a & reg_b
----------------------------------------------------------------------
not || 0 | 11 | x | x || reg_a = ~reg_a
----------------------------------------------------------------------
jmp || 1 | 00 | x | address || program_counter = addr
----------------------------------------------------------------------
store || 1 | 01 | x | address || data_mem[addr] = reg_a
----------------------------------------------------------------------
load || 1 | 10 | x | address || reg_b = data_mem[addr]
----------------------------------------------------------------------
nop || 1 | 11 | x | x ||
External hardware
You will need a USBC to UART converter to program this CPU. This is how to make your own. Or just buy a cheap one online.
[!IMPORTANT] Plug in the
USBC2UARTconverter, and usels /devttyUSB*to find out which interface to use for programming.
How to test
Plug in the USBC2UART and connect the TX/RX/GND wires correctly, then program the CPU with a list of instructions:
# Repeated ADD 1
python programmer.py -p /dev/ttyUSB2 -b 115200 -i "[0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20]"
# LOAD, ADD 1, STORE, LOAD, repeating NOP
python programmer.py -p /dev/ttyUSB2 -b 115200 -i "[0xC0, 0x20, 0xA0, 0xC0, 0xFF, 0xFF, 0xFF, 0xFF]"
# ADD 1, JUMP to 5, repeating ADD 1
python programmer.py -p /dev/ttyUSB2 -b 115200 -i "[0x20, 0x85, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20]"
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | |||
| 1 | |||
| 2 | |||
| 3 | uart_rx | ||
| 4 | uart_tx | ||
| 5 | |||
| 6 | |||
| 7 |