z80computer

FPGA Z80 Computer

Project Goals

Create a functioning computer with the following features:

FPGA board iCE40HX8K-EVB from Olimex
Simulation with Verilator
Z80 CPU
UART
VGA output
PS/2 input
SD-Card support via SPI
Maybe some sound
CP/M 2.2

Current status

The system can boot CP/M 2.2 with a rudimentary BIOS on FPGA and simulation
CP/M filesystem on SD-Card (currently readonly access)
User communication via UART
Firmware programming via UART

How To Setup

Simulation

For simulation, CMAKE and Verilator is needed. Clone this git repo and then:

cd <repo>/sim
mkdir build && cd build
cmake ..
make sim

This builds and runs a Verilator simulation with a test program. CP/M simulation is possible, but very slow.

FPGA

Target board is the iCE40HX8K-EVB board with iCE40-IO for VGA and PS/2 connectivity. UART and a SD-Card breakout board is attached to the iCE40-IO. I use OLIMEXINO-32U4 for FPGA programming.

Flash

Program the flash:

cd <repo>/fpga
make prog

Firmware

Currently, the FPGA design does not contain any bootloader. The Z80 will start to execute whatever is in the SRAM.

To program the SRAM with firmware, the design contains an UART master device, which can access the memory bus and reset the Z80.

cd <repo>/sw/os
make disk.img # build cp/m disk image
make prog     # program firmware to SRAM

Program the SD-Card (assuming /dev/sdX is the SD-Card device):

sudo dd if=disk.img of=/dev/sdX

Now CP/M 2.2 should boot and find the CP/M disk image on the connected SD-card.

dirkmo/z80computer