Rather than letting the code and hardware schematics rot away on my hard drive I've decided to publish the whole lot on Github:
https://github.com/agranlund/wolf
This is what it looks like:
- rev_c_and_d.jpg (59.63 KiB) Viewed 1982 times
http://www.happydaze.se/wolf/
The cartridge houses an NXP KE04 which acts as a coprocessor for doing the heavy stuff - the less demanding parts run on the Z80.
A dual-port SRAM acts as a buffer for communications and graphics transfer between the Z80 and KE04 code.
An ATF1502 is used to implement the functionality of an Nintendo MBC1 chip.
A 29F040 flash rom to hold the Z80 code
It caused quite a stir when Hackaday and Kotaku mentioned it and I had numerous requests from people that wanted to buy this over the years but I've never been interested in building and selling stuff to other people. One boxed cartridge ended up at Machinegames in Stockholm though - last I heard they sat it in a display cabinet among other Wolfenstein related stuff
At least with schematics and sources someone could build a cart if they really want one.
To be honest though, it's silly expensive for what it is due to that dual-port sram. If I were to redesign it I would rather use FIFOs or maybe normal SRAM with some added logic. The two CPUs don't really need to access that RAM at the same time anyway.