exxos's Atari, Amiga & retro forum

When you look for a expansion interface the best one to get is the unit with the bus transceivers built in you can tell the difference by looking at the card edge that goes to the model 1 . The bus is parts can be seen near the card edge


Tom
I will post pictures if I can find one


You can see the 244 245 parts at the front of the card edge

rubber_jonnie wrote: 13 Oct 2022 15:59

stephen_usher wrote: 13 Oct 2022 15:43 So, it's "complete" then. :-)

I'll get back to you on that...

:excited:

Tomswork wrote: 13 Oct 2022 16:37 When you look for a expansion interface the best one to get is the unit with the bus transceivers built in you can tell the difference by looking at the card edge that goes to the model 1 . The bus is parts can be seen near the card edge


Tom
I will post pictures if I can find one

m1einewer.jpg

TRS-80_Mainboard_01.jpg

You can see the 244 245 parts at the front of the card edge

They seem to be pretty hard to find here in the UK :(

I believe the expansion interface is a standard part shipped everywhere in the world just the power bricks were made in different input voltages


Tom

Tomswork wrote: 13 Oct 2022 22:16 I believe the expansion interface is a standard part shipped everywhere in the world just the power bricks were made in different input voltages


Tom

I don't doubt that is the case at all, and I see the box has space for 2 PSUs inside.

Trouble is, I keep looking on eBay and can't find an expansion interface other than seemingly in the US, and shipping is a tad on the expensive side.

stephen_usher wrote: 13 Oct 2022 15:43 So, it's "complete" then. :-)

It is now.

Whilst waiting for the replacement failed 4164, I cross checked with my Atari 65XE that I upgraded to 128KB, and the extra RAM I fitted in there is 8264 ICs, so essentially the same as 4164s.

Since the 65XE no longer uses the extra bank as it has U1MB installed, I pulled the RAM and fitted it to the TRS80. It all seems to work just fine, and when the single replacement 4164 IC arrives, then I'll have 8 spares, which will be handy.

I've let the TRS run for a couple of hours and there is no sign of the weird behaviour when the 41256's were fitted, so time to reassemble and let it all run for a bit longer with the lid on.

Since it was pretty simple to replicate the RAM corruption before, and since swapping I can't, I will keep my fingers crossed this is the last disassembly for a while!!

:dualthumbup:

Whilst I figure out what to do next with the TRS-80 in terms of program storage, I decided I'd hook it up to to an older slightly more serial means of storage: The good old cassette deck!!


I thought I'd use the Dragon 32 tape adapter I'd made along with another group (Aquarius, Oric, MSX), as it's wired identically to the TRS, but I hit a small problem. It turned out I'd never made one!!

So I dug through my box of cables and parts and was able to come up with an adapter for the Oric cable I'd made, and since I'd actually later found the original Oric cable, my homebrew Oric cable had become surplus to requirements.

It's basically a 5 pin DIN to 8 pin DIN adapter and it works just lovely. I wrote a series of small TRS-80 test programs and saved them to cassette using CSAVE "NAME" and used CLOAD "NAME" to retrieve from tape.


Of course the other side to this is that I now have a cable for the Dragon 32 at last too :)

Had to have a sit down after that due to a huge wave of nostalgia hitting!!

It was definitely fun noting the cassette counter readings and noting them down for easy program access like back in the day :)

The cassette player I used didn't have a counter so i had to guess using the window to see how far the tape had gone from one real to the next.

stephen_usher wrote: 22 Oct 2022 13:24 The cassette player I used didn't have a counter so i had to guess using the window to see how far the tape had gone from one real to the next.

Yeah, I had a similar story until I got my first Atari 8 Bit tape deck, a 1010, and that had a counter. I'd like to think it was all part of our computing history :)

All good character building stuff :)