exxos's Atari, Amiga & retro forum

And at 16KB we have arrived.


Unfortunately most of my lovely wiring had to go:


A little bit of luck, in that I was able to repurpose the address line addition (A7, pin 9) from the upgrade and simply tie that to 5v to make that part hidden under the mainboard. Here it is picking up 5v from a nearby 74LS IC:


Then there were 3 cut tracks to repair:


Then a quick test before adding some solder mask to finish off.

As it goes, reversion wasn't that bad, took about 45 minutes/an hour to remove the RAS and addressing mods, and it would be simple to redo if I wanted to in the future. The other benefit is that the 4116 ICs are gone as part of the original upgrade cut and repurposed the tracks so that pin 8 now simply gets 5v instead of 12v. -5v is still there, but since pin 1 of a 4164 is not connected, that's all good.

Now I just need the QI to arrive and I can get moving on the FreHD :)

Now, while it's open I will see about getting the sound mod done.

Well, the QI is with the local posties, so it's just a waiting game now :)

:crossed1:

stephen_usher wrote: 05 Dec 2023 10:18 :crossed1:

And +1 for that!

And here it is:


Won't have much time to look at it today though, but needs to warm up first after coming in from the cold :)

:dualthumbup:

stephen_usher wrote: 05 Dec 2023 12:01 :dualthumbup:

Seems the RAM side is working, but the expansion connector is a bit iffy, so I need to clean it.

So, the floppy board plugs into the expansion connector directly?

stephen_usher wrote: 05 Dec 2023 13:43 So, the floppy board plugs into the expansion connector directly?

It's not floppy, it's a hard drive, but essentially, yes. The QI plugs into the TRS-80 expansion port and behaves a bit like a EI, so an extra 32KB of RAM and what's needed to boot from the hard drive.

It's been mega unstable, so I need to contact Ian Mavric with the symptoms and see what he says.

Ok, so the instability seems to be power related, so I'm going to have a look at my bench PSU cables as it seems to need the voltage turned up a little at the PSU to get a solid 5v to the QI. It seems the cables are the issue so that I can fix, but for now it works.

It also seems like the QI needs a little time to get started, but once it does, I reliably get 48K of RAM with either LII basic 1.2 or 1.3, which I now have switchable in ROM.

But now if I plug in the FreHD, I get the message 'FreHD Autoboot not available. Check firmware version.'

I'm assuming that it relates to the FreHD firmware on the PIC, but I've tried 3 different versions and still get the same, so more to be done. The trouble is the docs for building don't seem all that, so I've messaged Ian who sells them to ask for assistance.

I suppose being positive, the RAM is working, and it's trying to autoboot, so that means the QI is probably fine, and I just need to do some working out on the FreHD itself.