Replacement for a game -module for the SABA Videoplay console
SABA Videoplay is a gaming console connected to a TV-set from the mid 1970s ( also know as "The Channel F" (initially named Fairchild Video Entertainment System) ) see : https://channelf.se/veswiki/index.php?title=Main_Page or https://en.wikipedia.org/wiki/Fairchild_Channel_F
The replacement module consist of a Raspberry RP2040 microcontroller ( + a levelshifter for 3.3 / 5 V conversion ) that emulates an F3851 adressdecoder IC and holds the ROMs and additional RAM for the programms.
It samples the module extension port on a high rate and implements the statemachine, that will do the generation of the programm-counter and adress-generator. To archieve a high sample-speed these parts arm written in ARM assembler ( thumb ) and running exclusivly on core 1
The first core does some convenience functions. You can connect through the USB-line, with a serial terminal on 115200 and get a little menu to diplay the memory, load different ROMs from the build-in flash or upload ROMs with xmodem-protocol.
Using vscode, you can either use a codespace on github or use "reopen in container" , which wil install all neccessary tools and submodules.
Open a new terminal and simply type "make" . This is a wrapper to call the cmake and build the binary.
connect an USB-cable. Enter Firmware upload by holding the button when connecting.
type "make go" this will build and upload the firmware.