exxos's Atari, Amiga & retro forum

Can you feed the wires out of, say, the cassette port?

stephen_usher wrote: 16 Nov 2023 18:10 Can you feed the wires out of, say, the cassette port?

I need to figure out where the space is as there are some grilles in the bottom that I may be able to slide the toggle through. There are definitely options.

So I managed to get the switch sorted, I kept it on the outside, secured with a dab of superglue (A compromise, not ideal but better than a hole) and manufactured a small 3 pin plug to allow for disassembly if I need to go inside again:


Feeding up inside through the lower grille:


And the mainboard end:


Sorry for the blurriness, the camera focused on the mainboard!!

And testing time, first standard Level II:


Interestingly it says 'Radio Shack' but with the original ROMs it said 'RS'

And last but by no means least, the FreHD autoboot setting:


Not much to see other than a slightly different boot message, but fingers crossed once I get the M1 interface sorted, I'll get some activity with FreHD connected, and I've now created a suitable SD card with the basics on it.

Can't wait to finish the M1!!!

OK, so I spent some time with the M1 today and have hit a roadblock.

Pins 1 & 4 are supposed to be tied together (Or 38 & 39 if using standard numbering), but when I do either, the machine fails to boot, with just a screen full of garbage, which indicates the CPU hasn't started executing code.

That is with just those 2 pins connected.

Now either I don't need them to be shorted as I have 64KB of internal RAM, or the instructions I have are missing something, so it's left languishing on the bench whilst I go figure stuff out.


Meh!!

I guess that you don't have a full pinout of the connector.. Of course you wouldn't. :-)

stephen_usher wrote: 18 Nov 2023 17:15 I guess that you don't have a full pinout of the connector.. Of course you wouldn't. :-)

I do. Bear in mind that the TRS-80 wiring is funky, in that pin 39 on the computer end of the cable matches to pin 1 of the 40 pin connector on the other end, so since my cable comes direct from the computer to the interface board, I am following the Tandy cabling convention.

But I'm clearly missing something, but something is off since tying 1 & 4 together, even with the funky wiring, the TRS won't boot.

Need to read through again, see if I missed anything. I just don't seem to be able to get my head round it!!!

Those notes about the shorting makes no sense. Why would you short RAS and A10 ever? It would mean that whenever a RAM row was selected then A10 would be selected, similarly the other way around.

stephen_usher wrote: 18 Nov 2023 20:47 Those notes about the shorting makes no sense. Why would you short RAS and A10 ever? It would mean that whenever a RAM row was selected then A10 would be selected, similarly the other way around.

I know, I just don't get why it's there. I am looking for other schematics as that doesn't make sense now I've started to build it.

I finally restored my model 1 to use the 2 eprom sockets on the motherboard using the Motorola 8k by 8 eproms
Motorola MCM68766C

Works well and less stuffing in the case

Tom

Tomswork wrote: 18 Nov 2023 22:53 I finally restored my model 1 to use the 2 eprom sockets on the motherboard using the Motorola 8k by 8 eproms
Motorola MCM68766C

Works well and less stuffing in the case

Tom

Lol, and I'm adding more stuffing 😁