The second “real” board for the RetroSys2019 system is the RAM-ROM board. It offers 2 choices of memory :
- Plain 32K Ram / 32K Rom , which can be used for a basic system using a 62256 RAM and a 27C256 EPROM. For this only the GAL16V8 is required for the memory decoding and buffer control.
- 512 K x 8-Bit ROM and RAM , switchable in 32K pages. Enabling to create flexible memory maps , running CP/M etc. For this it is require the XC9572XL CPLD is mounted.
- A JTAG connector has been provided to enable in-circuit-programming of the XC9572XL
XC9572 design source will be published in due course.
The board as it appears in Kicad (Non-Rendered and Rendered versions) :
DISCLAIMER : Please note that these boards have only been designed VERY recently . They are currently being manufactured and I will post progress in my blog.