Z80 Basic computer on a FPGA

I bought an Altera Cyclone FPGA RCQ208 development board (clone) on eBay a while ago.

dscn0374

I ported the Multicomp project from Grant Searle for this platform.This is a minimal port: 1K internal RAM, a single UART, no video but support is possible for PS2 keyboard and SD card.

To make it work, follow the instructions on the multicomp webpage: it’s just a matter of cut and pasting the desired components into the file ‘multicomputer.vhd’. Then, with Quartus, you must change the device and change the pin assignation for your particular platform.

To change the device, on Quartus’ main menu, click assignments -> device and select EP2C8Q208Q; you will have to scrap the current assignations since the pins will not be at the same place as the original project.

To change the pin assignation, on the main menu, click assignments -> pin planner.

The result is this assignation for my FPGA board:

set_location_assignment PIN_14 -to rxd1
set_location_assignment PIN_15 -to txd1


set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to rxd1
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to rxd2

set_location_assignment PIN_23 -to clk
set_location_assignment PIN_27 -to n_reset


set_location_assignment PIN_207 -to ps2Data
set_location_assignment PIN_208 -to ps2Clk

set_location_assignment PIN_8 -to hSync
set_location_assignment PIN_10 -to vSync

set_location_assignment PIN_175 -to sdMISO
set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to sdMISO
set_location_assignment PIN_173 -to sdSCLK
set_location_assignment PIN_171 -to sdMOSI
set_location_assignment PIN_170 -to sdCS
set_location_assignment PIN_64 -to driveLED

 

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