The rise of FreHD

[rubber_jonnie]

Looks good

Tom

I'm pleased so far, and a much easier build than the v2 Analog.

[rubber_jonnie]

And finally all the remaining parts for the M1 interface arrived

PXL_20230518_115231864.jpg (243.12 KiB) Viewed 316 times

So hopefully I can finally start to get the interface built, get the ROM burned that allows autobooting, and see if I now have mass storage for my TRS80-Model 1!!

[stephen_usher]

[rubber_jonnie]

It's only 2 transistors, 2 resistors and a bunch of bodge wires, but yeah, for sure.

[Tomswork]

Bodges are fun until someone gets hurt



Tom

[rubber_jonnie]

Bodges are fun until someone gets hurt



Tom

[rubber_jonnie]

Ok, i've been bad and let this project slip, but in my usual cycle through my projects, plus some tinkering with Z80 machine code, I got back to really wanting to get the FreHD done and dusted.

So, since the FreHD is actually built, that means finishing off the M1 interface. Some more progress made today:

PXL_20231111_150104726.jpg (292.06 KiB) Viewed 100 times

Just 10 wires left to connect, all of which are direct connects from one side to the other since all the messy bits via the transistors is done. Going to finish off tomorrow I think, and then I need to look at the ROM changes needed to the TRS-80 itself to allow booting from the FreHD.

I want to get an assembler environment set up so having disks of some sort is going to be fairly crucial. Fingers crossed my wiring is good!

[rubber_jonnie]

Ok, so I got M1 interface completed today:

PXL_20231112_163420715.jpg (303.49 KiB) Viewed 76 times

I really should try to learn KiCad as I think a modern replacement for the M1 would be worth having, but for now, it's a protoboard with a bunch of point to point wiring, just like the good old days.

I buzzed out all the connections once I'd finished, both to check for shorts and incorrect wiring. As it goes only 1 wire was incorrect, and having reworked it and double checked for shorts,

This is where I hit my first hitch though. I'd made a cable to go from the TRS-80 to the M1, but had missed the fact that the edge connector wiring on the TRS-80 is a bit odd, and where I'd expect to find pin 1 on the plug, it's actually pin 2. At least Tandy properly marked the edge connector, even though it's reversed and you need a torch to see it!!

So next thing is to figure out will be some sort of adaption so that the cable from the edge connector gets properly 'inverted' back to the 40 pin connector on the M1 interface.

All good clean wholesome fun...

[stephen_usher]

KiCAD isn't massively difficult, just a bit annoying and unintuitive at times, especially the zooming and scrolling. The other gotchas are the components and footprints where components don't have a default footprint so you have to set one and other, similar minor things.

[rubber_jonnie]

KiCAD isn't massively difficult, just a bit annoying and unintuitive at times, especially the zooming and scrolling. The other gotchas are the components and footprints where components don't have a default footprint so you have to set one and other, similar minor things.

Yeah, I did start playing with it, just haven't had the time, and I think a simple board like this would be a great place to start, so I should make the effort, especially since there are only 2 transistors, 2 resistors and 2 connectors (40 & 50 pin)

Since I already have a schematic it should help, but I may have to transfer it into Kicad first, as I only have the PDF.