Pipedream: the magicROM

Post date: 22-Oct-2010 10:28:15

We've been neglecting the '816 and OHO-related FPGA designs for a while - in part due to some involvement in the highly recommended visual6502.org project.

Latest news from Rich is that his Master - our only Master - doesn't power up any more. We may be sourcing one or two replacements.

Other exciting news: from RetroClinic - a co-processor in the same spirit as some of our ideas. Not quite a product as yet, but certainly a project.

As a tangent, here's an idea: the magicROM! It's an FPGA-based second processor which fits into a ROM socket - no flying leads - emulates a ROM to the degree that it can hook into the OS or take over the machine, and offers two or more bidirectional channels between host and parasite by means of reads from specific pages (for writes) or locations (for reads.)

It should be possible to do this on an OHO GOP - only 24 pins, so would look like a 2k ROM but would need an adapter to sit in a normal 28 pin ROM socket.

There are plenty of details to figure out: hooking into the OS, polling for interrupts, building an entire second processor in a GOP board... so this is just food for thought at present.

(P.S. since our previous update, two more FPGA implementations of 6502 have been announced: Ruud's work-in-progress and retromaster's 2600 project)