The rise of FreHD

[rubber_jonnie]

Oh boy, it only bloody WORKS!!!!


Here we are booted with a base image:

PXL_20231207_140715998.jpg (224.81 KiB) Viewed 5277 times

And a quick cat of the disk:

PXL_20231207_140730262.jpg (233.91 KiB) Viewed 5277 times

So what was it in the end?

Firstly, I need to sort out better leads for my bench PSUs, they are very lossy and everything was unstable until I could get that sorted.

Secondly, I learned that holding down 'BREAK' on boot lets you skip the HDD and boot to BASIC, from where I am able to run a test routine from ROM. Ian, who is the seller of the told me about that, and it reported FreHD had failed.

With that in mind I flashed the PIC with v2.13 of the firmware rather than 2.14 as Ian advised I do that.

Then I found an completely unconnected post on PCBWay where somebody had uploaded the PCB, but pointed out a problem where a transistor, Q1, needed to be removed and pins 1&3 bridged, so I did that and lo and behold it works!!!



However, I don't want to get to ahead of myself, but this is a good place to start and requires more testing, but it's looking good

[stephen_usher]

Yay!!!!

[rubber_jonnie]

As an aide memoire, here is how I configured my FreHD. There are gotchas here.

1. You MUST have either a Quinnterface or an original Expansion box for the TRS-80 Model 1. FreHD DOES NOT WORK without.
2. Your TRS-80 Model 1 Must be 16K. I upgraded mine to 64KB, but had to downgrade it as the Quinnterface adds an additional 32KB. The Expansion Interface can be modded to accommodate a machine with 64KB internally though.
3. The PIC was programmed on my TL866 Pro programmer and the XGPro software. I used firmware 2.13 as this is advised to be the best firmware. Be sure when loading into XGPro, you specify it is a HEX file, not BIN.
4. Ensure you use a 74LS245 in position U3. It specifies a 74HCT245 in the BoM but this is wrong.
5. Don't install Q1, instead use a piece of wire to jumper pins 1&3 (Collector and emitter) of Q1 together.
6. If you are having issues with FreHD not booting at this point, then at the BASIC prompt (Hold BREAK down during boot) type 'SYSTEM' and hit RETURN. You will then get a *? prompt. Type '/12288' and hit return. This will start the on board diagnostics and it will show you if FreHD is working.

So next up is getting to use the thing and hopefully getting some interesting software onto the TRS-80 Model 1.

There are also a load of useful files here that are needed: FreHD files

It's been a good week.

[rubber_jonnie]

And FreHD now has an 'enclosure'

PXL_20231218_133557272.jpg (196.61 KiB) Viewed 5016 times

Fingers crossed I'll get something a bit more permanent in the new year

[stephen_usher]

Looks like an expensive case!

Next year a Tupperware upgrade?

[rubber_jonnie]

Looks like an expensive case!

Next year a Tupperware upgrade?

Well, you never know