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by jonriglar
28 Oct 2015, 18:08
Forum: TRADING AND COLLECTING
Topic: Memory Expansion
Replies: 5
Views: 1461

Re: Memory Expansion

Hi Dave
Thanks. The CFX is 'just' (I say that without meaning any offence!) an interface for Compact Flash program storage? Or does it have memory on board as well?
Regards
Jon
by jonriglar
28 Oct 2015, 17:17
Forum: TRADING AND COLLECTING
Topic: Memory Expansion
Replies: 5
Views: 1461

Memory Expansion

I've inherited another MTX, this one is a MTX 512 but fitted with a 32K MTX500 mainboard. I am sure I read somewhere that one of you fine chaps could sell an internal memory expansion card? Are those still available - can anyone please point me in the right direction in terms of who to contact and p...
by jonriglar
19 Oct 2015, 22:03
Forum: HARDWARE
Topic: Another MTX Fault - Jon Riglar's MTX
Replies: 29
Views: 4434

Re: Another MTX Fault - Jon Riglar's MTX

Progress update!
There is some, thankfully.
I swapped out the VRAM for modified 4164 RAM and now I have output on Pin 14 of the chips.
I can also tune a full grey screen, which has a constant tone.
Tapping Control & G on the keyboard makes no difference.
At least it's semi-alive!!
by jonriglar
15 Oct 2015, 21:28
Forum: HARDWARE
Topic: Another MTX Fault - Jon Riglar's MTX
Replies: 29
Views: 4434

Re: Another MTX Fault - Jon Riglar's MTX

Thanks for all the info :)
I'll get a photo done over the weekend.
A quick check of Pin 3 (/W) and it's high.
I've checked voltages/grounds and all ok.
/RAS (4), /CAS(15) and Q (14) merrily go up and down
Jon
by jonriglar
14 Oct 2015, 22:00
Forum: HARDWARE
Topic: Another MTX Fault - Jon Riglar's MTX
Replies: 29
Views: 4434

Re: Another MTX Fault - Jon Riglar's MTX

Hi Martin Thanks for the info. I've got a 100MHz digital storage scope. Pin 14 is stuck low on all the VRAM chips. I've tried to isolate by removing one at a time, without any change. The AD0-AD7 lines are buzzing up and down happily. The CAS/RAS lines are also buzzing up and down. It's just Pin 14 ...
by jonriglar
13 Oct 2015, 21:43
Forum: HARDWARE
Topic: Another MTX Fault - Jon Riglar's MTX
Replies: 29
Views: 4434

Re: Another MTX Fault - Jon Riglar's MTX

Hello all, Apologies for silence for a few weeks. Have now 'scoped the memory chips. I get input to all the memory chips (main and video) on Pins 2 (Data in) I get output from all the main memory chips on pins 14 (data out) I get NO output from all the video memory chips on pins 14 (data out) Corres...
by jonriglar
01 Sep 2015, 10:08
Forum: HARDWARE
Topic: Another MTX Fault - Jon Riglar's MTX
Replies: 29
Views: 4434

Re: Another MTX Fault - Jon Riglar's MTX

Thanks Dave, thanks Martin,
I'll get busy with the 'scope.
Regards
Jon
by jonriglar
29 Aug 2015, 17:44
Forum: HARDWARE
Topic: Another MTX Fault - Jon Riglar's MTX
Replies: 29
Views: 4434

Re: Another MTX Fault - Jon Riglar's MTX

An update on my attempts to get the MTX back to life; New Z80A CPU fitted New Z80A CTC fitted New TMS9929A fitted New main memory fitted New video memory fitted (which still runs hot - how hot is too hot?!?) No output on screen (from either RF or video out), continuous tone. Re-checked voltages, the...
by jonriglar
16 Aug 2015, 19:12
Forum: OFF TOPIC
Topic: Amazing homebrew ZX Spectrum & Amstrad CPC
Replies: 7
Views: 1260

Re: Amazing homebrew ZX Spectrum & Amstrad CPC

My justspeccy 128 is on the way. Have to say, i havent had any communication problems with zaxxon.
by jonriglar
15 Aug 2015, 22:12
Forum: OFF TOPIC
Topic: What other retro machines do you have?
Replies: 26
Views: 4040

Re: What other retro machines do you have?

My list: Vic-20 C16 C64 C64C Amiga 500 Amiga 500 Plus Amiga 600 Amiga 1200 ZX80 ZX81 ZX Spectrum 16K ZX Spectrum 48K ZX Spectrum + ZX Spectrum 128 (Toast Rack) ZX Spectrum +2 (Grey) ZX Spectrum +2 (Black) ZX Spectrum +3 Speccy2010 board (yet to fire up) and waiting delivery of new JustSpeccy128 boar...

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