|Classic Console Development Platform|
Posted May 19, 2007 by Mike from 8-Bit Domain:
I have been toying with the idea for several months of building a multi- platform game development system. I was mainly interested in consoles which have a true expansion interface like the Bally, Colecovision and Sega Master System, etc. By true expansion interface I mean most if not all address, data and control signals. These three consoles also have a common processor, the Z- 80 which I have worked with since the eighties. I wanted something more that just a simple multicart with a download port. So I designed this platform with its own processor and shared memory interface to the target console. This allows me to take control of the target address/data bus utilizing BUSREQ and BUSAK of the Z-80. Also I have a large expandable multibanked flash capability using the two 40 pin module sockets. The platform having its own processor also means that I can diagnose and repair defective consoles (assuming that at least the Z-80 works). The processor I use is the Atmel Mega128 with the Bascom AVR compiler. It does not have to be code compatible with the target since the target console is basically shared memory and IO. I can now write test routines for any memory or I/O device. The Bally may be more difficult because of the custom video chips. This Bascom AVR compiler source code would be open source and available to all to encourage a large database of software.
Check out the schematic, and read the complete discussion that followed Mike's posting.