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Something like: https://www.amazon.co.uk/Converter-Amtake-Composite-Adapter-Supporting-Black/dp/B0828Q4CNQ Will work with the MTX's composite video and take the audio as well. Not the world's greatest picture on the one I tried, but then with the hum bars and everything, the VDP's composite isn't th...

That won't work, with the chip select to rom B (CSB for short) connected to A13, how is the chip in socket A going to be selected when the system want's to access rom B? Putting the chip selects onto the address lines, yes that will change the address ranges if the larger chip is selected when when ...

The 2564 is an 8K device, you should be seeing A11 and A12 already connected to the socket. TMS2564.PDF A0 to A10 only gives you 2k of memory space. You -can- connect the other chip selects to Address lines (A13 and A14 maybe) BUT you'll also need some way of combining all 3 chip selects together to...

Or mod the board for the 28C64 EEPROM, which seems to be still in production and easier to re-program than the UV EPROMS.

https://www.mouser.co.uk/ProductDetail/ ... cLow%3D%3D

One of my two MTX500s had factory fitted 2564 EPROMS. If I remember correctly there were cut tracks on the top and the bottom of the PCB. I replaced the 2564 parts with the more modern 27C64, and that needed more track cutting, there's definitely cuts on both sides now as Dave's page points out! Tha...

I'm no expert on the power supply, but the -5v supply is "generated" by ZD3. Whether you problem is a busted ram shorting -5v to ground or the zenner itself going up in smoke, I have no idea! C49 is also across the -5v supply a short there wouldn't be good either. With no -5v to the vram g...

What sort of hardware add-ons are you thinking of Martin? I mentioned it in passing elsewhere (the MFX thread I think) I had a MAX10 FPGA board connected to the heavily modified MFX prototype. It had well over 10x the capacity and internal ram of the Cyclone2 on MFX. I had it running 512x256 in 256...

I tinker! Every now and then something "useful" appears as a result of the tinkering. The "development" MTX has one of the PS2 keyboard interfaces fitted, so can run permanently with the case open, and give me access to the guts! The original Memotech fitted EPROMS have been repl...

I will add to the list of what can be done, but there's l little use for: A battery backed, real time clock. I happened to have some RTC modules for the Arduino I thought I might try and add to MFX. Then Dave pointed out they're 5v and the FPGA is 3v. So rather than give up on the idea, I went out a...

With a board redesign maybe.

I'm just looking for ideas to use up the extra FPGA resources, maybe with a small adaptor to plug into the VRAM socket.

A complete re-design is a step too far at this point.

Yes, the FDX used DMA, the SDX didn't, saving an awful lot of board space and ICs.