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help with my original issue 3b from when i was a teen. possible lower ram fault.hello, well ive tried to fix my old speccy, but haven't made much progress. could you help me out with some diagnosis. the fault occurred about…
ive been told it cold be the rom or cpu. as generally lower ram faults result in vertical lines and not able to type anything. -
help with my original issue 3b from when i was a teen. possible lower ram fault.hello, well ive tried to fix my old speccy, but haven't made much progress. could you help me out with some diagnosis. the fault occurred about…
just a thought. what if I remove some of the lower ram ics. would it maybe clear the screen. that would defo mean lower ram fault. -
help with my original issue 3b from when i was a teen. possible lower ram fault.hello, well ive tried to fix my old speccy, but haven't made much progress. could you help me out with some diagnosis. the fault occurred about…
... % okay.
All the RAM chips are DRAM type. In ... of every byte of the lower RAM working. It will not then ... variations of symptoms of a RAM fault. The problem with your ... may not be a RAM fault. But RAM faults and faults with ... -
help with my original issue 3b from when i was a teen. possible lower ram fault.hello, well ive tried to fix my old speccy, but haven't made much progress. could you help me out with some diagnosis. the fault occurred about…
I think ill buy some lower ram ics.
yes ive got a multimeter. I checked the voltages and they seem about right. ive recapped it when I removed the upper ram.
I might buy a spare rom just incase. -
can a backup device damage the spectrum ROM?as above. been using a specmate device which seems to have corrupted my speccys ROM.
... work fine), the other the lower RAM. -
can a backup device damage the spectrum ROM?as above. been using a specmate device which seems to have corrupted my speccys ROM.
... fine), the other the lower RAM.[/quote]
Keep in ... one or more 4116 "lower" RAM chips is a fairly ... (Z80, ULA, ROM, RAM) can potentially be damaged... So ... which has a comprehensive RAM test program, even better ... all on their own. RAM failure is far more ... -
help with my original issue 3b from when i was a teen. possible lower ram fault.hello, well ive tried to fix my old speccy, but haven't made much progress. could you help me out with some diagnosis. the fault occurred about…
ok removed the lower ram last night, so now no ram installed. now getting ... vids of speccys with the lower ram removed thought mine seems to ... -
help with my original issue 3b from when i was a teen. possible lower ram fault.hello, well ive tried to fix my old speccy, but haven't made much progress. could you help me out with some diagnosis. the fault occurred about…
... .
fitted the new lower ram, booted fine and ran a ... . so fitted the new upper ram, now on its 3rd pass ... try and remove the upper ram more carefully. oh well one ... -
ZX Spectrum 48k issuesHi all! A couple of days ago I bought my first 48k Speccy off ebay (I already own a beautiful QL expanded with QubIDE interface and 640k ram). It was…
... while I wait for the ram replacement board I need to buy ... -
ZX Spectrum 48k issuesHi all! A couple of days ago I bought my first 48k Speccy off ebay (I already own a beautiful QL expanded with QubIDE interface and 640k ram). It was…
... between the ULA and the "lower" RAM.
It's hard to ... Z80 uses to address this RAM.
So visually inspect ... -
ZX Spectrum 48k issuesHi all! A couple of days ago I bought my first 48k Speccy off ebay (I already own a beautiful QL expanded with QubIDE interface and 640k ram). It was…
You need to include /RAS, /CAS and /W on the lines to the "lower" RAM so that we can see if the data is a write to RAM, a read from RAM, or just something else going on that is nothing to do with the "lower" RAM (like reading of the ROM). -
Issue 2 problem.Hi all, I'm trying to repair / upgrade an Issue 2 Spectrum for a friend, but have come accros the following problem. When I power the machine …
... " (stored in the lower RAM).
As the lower RAM works when the 32k ... upper RAM is not fitted ... chips used for the upper RAM upgrade. This looks like something ... -
What are the differences between the +2 and the +2A ?I only acquired a +2 for the first time in my life a few months ago. It works fine. :) I even managed to tracke down nearly all the wargames by the s…
... the timings slightly. The extra RAM was added as two sets ... . One set replaced the 4116 "lower" RAM which includes the scree, so ... set replaced the 32k "upper" RAM chips, which is of course ... -
Help understanding the Z80.So I have a Z80 CPU and a 32k ram chip. I understand how they connect. (Data and address busses, chip select etc.) But how would i input information…
... at address 0x100 (256) with ram data below that. The entry ... that could directly replace both ram and ROM.[/quote]
ram replacement. Also write cycles will be ... read cycles. Again, not a ram replacement. To start a write cycle ... -
Disabling the ROM without removing the whole thingHi! I've got my hands on a non-working issue 6a. I suspect the ROM may be bad, but other things may be faulty as well. I've read that in an otherwis…
... by connecting lower pin 3 to lower pin 25 ... .
- The lower RAM is replaced with a PCB ... it with another known working lower RAM PCB (from zigg.net ... Removed one of the upper RAM chips (IC15) and there ... I could do (the lower RAM chips are no longer ... -
Disabling the ROM without removing the whole thingHi! I've got my hands on a non-working issue 6a. I suspect the ROM may be bad, but other things may be faulty as well. I've read that in an otherwis…
... similar results.
The lower RAM PCB modules work well in ... other weak points for a lower RAM problem?
This was ... -
Disabling the ROM without removing the whole thingHi! I've got my hands on a non-working issue 6a. I suspect the ROM may be bad, but other things may be faulty as well. I've read that in an otherwis…
... the tracks for the lower RAM to the ULA, and ... data lines to the RAM chips. Some of the ... the Z80 CPU and the lower RAM, so worth testing these ... ULA that controls the lower RAM. And the ULA responds ... you power up without a lower RAM module fitted?
... -
Not bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... iron pumps and took the lower 16k ram out with it and ... Saga Emperor keyboard with a lower ram fault. Just got to get ... -
Not bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... quick test and said "lower Ram OK" then "Upper Ram OK" . I could ... -
Not bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... what happened next.It displayed:-. Lower RAM faulty $7FFC : and then : ... Upper RAM error XP SFFFF ADSDF : 76543 ... . Cannot proceed further both lower and upper RAM faulty .
... again but this time the lower RAM was OK , but not ... -
Not bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... that . This time Lower RAM RAM was OK . Upper RAM IC20 fault again!
RAM fault . (But you never know ... -
ZX Spectrum Test PCB I recently read about one of these (I think it may have been the Retroleum site but I am not sure) and I thought "What a great idea" . As pictured …
... built-in test procedures for lower RAM, upper RAM, etc.
Of ... -
Upper memory not available in issue 2A friend send me his issue 2 Spectrum for diagnosis. It boots okay but for some reason won't load games over 16kB. He sent also a Smart Card with int…
... low, A14 high = lower RAM, A15 high = upper 32k RAM
[b ... -
ZX Spectrum Test PCB I recently read about one of these (I think it may have been the Retroleum site but I am not sure) and I thought "What a great idea" . As pictured …
Take out all lower RAM IC's and re-check all supplies. Looks like 12V line is corrupted. No 12V means also no -5V to the lower RAM. If DC inverter doesn't work properly you may damage 4116 chips. -
ZX Spectrum Test PCB I recently read about one of these (I think it may have been the Retroleum site but I am not sure) and I thought "What a great idea" . As pictured …
Thanks for that . Will do
I have removed the lower RAM ICs -
ZX Spectrum Test PCB I recently read about one of these (I think it may have been the Retroleum site but I am not sure) and I thought "What a great idea" . As pictured …
... readings
Lower ram IC: a comparision with ... ( -5 volt)
lower left 2.64 ( 12v) .
lower RAM IC. So it appears ... -
ZX Spectrum Test PCB I recently read about one of these (I think it may have been the Retroleum site but I am not sure) and I thought "What a great idea" . As pictured …
Hi Mark
Thanks for that . The readings from the edge connector were consistent with those from the lower RAM -
ROM emulation in softwareHi, first of all -- I only have shallow / uni knowledge of hardware, electronics, and physics. So forgive me for asking things that are out of that …
... to the "lower" 16k RAM area (which contains the display RAM), the ULA ... and refreshing this area of RAM.
If the ... down loader program into the "lower" RAM, then once the new "ROM ... . The Sinclair ROM clears all RAM anyway...
[b][i ...
