exxos's Atari, Amiga & retro forum

stephen_usher wrote: 20 Nov 2023 21:46 Thanks... and good luck with your TRS80... And A5000 networking.

Cheers 😁

Well, I caved and ordered a Quinnterface...

Bit expensive but I'll take it out of next month's gadget budget as it was the last one up for sale on eBay, so I didn't want to lose it, and seemingly it's sold by IanM from TRS-80.com.

Will need to do some figuring out when I get it as it behaves like an expansion unit and adds in 32k, so expects the TRS-80 to be 16k, not 64K like mine. I may also need to revert the ROM to original, but we'll see on that one.

It also appears to incorporate the M1 Hard Disk interface I just built, so that is effectively now just something I built that will gather dust...

Won't be here until just before Christmas as it's coming from down under.

Ok, so my Quinnterface is in the post, not sure how long it will take to get here, but it is at least on the way.

I spoke to the seller and he has confirmed that I will need to downgrade the M1 to 16KB before I can use the QI since it adds 32KB of RAM as well as the HDD part of the Expansion Interface box.

With an EI I can apparently revert back to 64KB internally and still use the FreHD, and that's where my M1 cable that I built earlier comes in (D'oh). I don't mind too much as long as I have a full complement of RAM.

However my ROM mods can stay, so for now I have Level II basic 1.2 & 1.3 installed and I can use either, plus it has the FreHD autoboot component installed as well, so that's all good.

I'm also 'Amped' (Get it :) ) for this:


When I next have the TRS open I'll be installing this small amp and a little speaker to give the TRS a voice :)

I'm old school the am radio was what I used for sound on a trs-80 lots of screeching :girldance:

Tom

Tomswork wrote: 24 Nov 2023 16:03 I'm old school the am radio was what I used for sound on a trs-80 lots of screeching :girldance:

Tom

:dizzy:

Well the Quinnterface is leaving Australia soon I hope, it's cleared for international departure. Expected delivery according to eBay is 22nd of December, but I'm hoping it arrives sooner!!

I'm crossing my fingers. :-)

stephen_usher wrote: 27 Nov 2023 11:51 I'm crossing my fingers. :-)

Me too, but it'll be on here as soon as it arrives :)

Ok, so I pulled the TRS-80 apart with the intention of 'adjusting it' (For adjusting read 'bodging') so that the RAM only reports 16K in readiness for the Quinnterface arriving (It's still in Aus apparently).

I figured that since I have already modded the mainboard to remove -5v and 12v from the RAM sockets (Originally 4116's), all I'd need to do is lift pin 9 (A7) on all the ICs, join them together and connect to either 0v or 5v and then it 'should' appear as 16K.

But having done that I still see 48KB (64KB installed) when i run a memory report and having A7 at 0v or 5v makes no difference. So, has anybody got any thoughts as my head is currently fried from work!!!

So, double checking my work, to replace 4116s in a Spectrum with 4164s you have to lift pin 1 and connect to GND, pin 16, and pin 8 and connect to pin 9, since 9 is 5v for the 4116.

So that means that pin 9, A7, is connected to 5v as that is +5v on a 4116, and then pin 8, the +5v for a 4164 is connected to pin 9.

This means pin 9 for every 4164 is connected to +5v. Hopefully this is logical so far.

Pin 1 of the 4116 is -5v, which we don't want connected to the 4164, so instead it's connected to GND on pin 16. Both the 4164 and 4116 have GND on pin 16.

Now, since pin 1 of the 4164 is supposedly NC, it seems logical that there is no need to tie it to GND, but I think I have to try it since at the moment the 4164s still report as 64k.

Meh!