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zx spectrum display corruption .. with lower ram module installed[img]https://photos.app.goo.gl/Gu6rjC5v21sZxwTX9[/img] [img]https://photos.app.goo.gl/FznVw8SkbbhWn5mh7[/img] another specie question : i have …
... video corruption, it has lower ram module fitted.. can get it ... and it shows lower ram as good and upper ram not detected although it is ... i start digging at the upper ram, or the 4 logic chips ... that drive the upper ram.. i am presuming that one ... -
Alternative chips for upper RAM blockDoes anybody know of a way to use 4464 chips instead of 4164 for the upper RAM block in a 48K machine? If not 4464 then something a little more avai…
Does anybody know of a way to use 4464 chips instead of 4164 for the upper RAM block in a 48K machine? If not 4464 then something a little more available than the 4164. Winston? Piters??
TIA -
Difficult to find upper RAM fault.I've recently repaired an issue 3B 48K Spectrum that had a tricky to diagnose upper RAM fault, so I thought I'd post a report of what I found here. …
... passed from testing lower RAM to upper RAM. Here is an ... first read from the upper RAM location retrieved the decimal ... upper RAM, but the system later crashed because these were not ... not manage to capture the RAM-FILL routine passing from lower RAM to upper RAM ... -
Upper RAM replacement module issues with the DivideI got my new upper ram replacement module from Zorn yesterday and seem to be having some issues. When the machine is without the Divide it boots up …
... sure. When I put the upper ram chips back in place, everything ... again.
The upper ram are not on the "OKI" setting but ... someone that also has the upper ram module be so kind and ... Divide attempts DMA to the upper RAM and uses unusual timings that ... -
upper ram tacks / TR4 socket...[url="https://photos.app.goo.gl/MkqzRCuNCV3EPr9E7"]https://photos.app.goo.gl/MkqzRCuNCV3EPr9E7[/url] you can only replace that pesky TR4 so many t…
... .... surprises me that with TR4 not in place or when it ... would just fry the lower ram again .. this is one board ... looks like somebody attacked the upper ram with a black and decker ... .. any sugestions for replacing the upper ram tracks ? -
ZX Spectrum upper RAM module (4532/4164 replacement)Following the [URL="http://zx.zigg.net/LRR/"]lower RAM replacement module[/URL], there have been quite a lot of requests for something similar for th…
... for something similar for the upper 32K RAM in a Spectrum.
upper RAM module instead or one of ... of trailing wires, so the upper RAM module uses almost the same ... as the lower RAM replacement and emulates dynamic RAM.
... -
Issue 2 Upper Ram, Loading & ResettingI have a 48k Issue 2 Speccy and for the life of me can't track down what the problem is with it. I initially thought that some of the uppe ram ic's w…
... some of the uppe ram ic's were faulty ... went on to desoldered the upper ram ic's, socketed the ... board and replaced the ram with known good chips. ... replaced all the upper ram with known good ram from another Issue ... cant now be the upper ram as I swapped and ... -
Spectrum 48+ 4S - Upper RAM issue, and now a self-created problem!I recently picked up a known-flaky spectrum off eBay, to have a bit of fun fixing it and reliving youth. It was labelled as 'keyboard duff, shows…
... diagnostics said the whole of upper RAM was faulty (check all ICs ... , I've removed all the upper RAM ICs, replaced with sockets and ... .
Given the lower RAM used to be okay, and ... -
Lower & upper ram IC's for an issue 3 please.Would any of you great folks have 1 spare lower ram, and 1 spare upper ram IC's you would be willing to sell. I'm fixing up a poorly Spectrum that is…
... have 1 spare lower ram, and 1 spare upper ram IC's you ... -
Built a ZX Spectrum that works, but can't get the upper RAM to work?Like the title says I finished my Spectrum 3B board, and it boots, but it doesn't see the upper 32k of RAM. When it boots, the lower 16k works f…
... doesn't see the upper 32k of RAM.
When it ... , tells me that lower RAM is good, all upper RAM bad. But the ... all the associated logic, and RAM chips, with no effect. I ... all direct connections between the upper RAM and associated logic, and I ... -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... suggests a fault in the upper RAM, not the lower. This is certainly ... crash or it gets detected as faulty and not used, but it ... 're able to, try the RAM test program I created and ... . Try it against the upper and lower RAM and leave it running ... -
Whats up wi mi speccy ? M RAMTOP no good 0:3I bought a speccy on ebay tried to load Mission Impossible but about 30 secs into loading it stopped and i got the error message ... M RAMTOP no good…
... just a 48K with missing upper ram, not a real 16K machine. Take ... have a 4a and its upper ram is socketed, if all the ... -
Whats up wi mi speccy ? M RAMTOP no good 0:3I bought a speccy on ebay tried to load Mission Impossible but about 30 secs into loading it stopped and i got the error message ... M RAMTOP no good…
... just a 48K with missing upper ram, not a real 16K machine. Take ... have a 4a and its upper ram is socketed, if all the ... logic chips socketed too? If not, it's been repaired at ... -
Spectrum 128K +2 problemhello, i am try to repair my spectrum 128k +2 grey, i remove all ram chips and i have some new ones spares, now i have remove all ram chips, i want …
... "main" RAM including screen RAM
IC17 - IC24 "upper" RAM.
Not sure about ... the +2, but if the upper RAM is not ... -
Spectrum 128K +2 problemhello, i am try to repair my spectrum 128k +2 grey, i remove all ram chips and i have some new ones spares, now i have remove all ram chips, i want …
... "main" RAM including screen RAM
IC17 - IC24 "upper" RAM.
Not sure about ... the +2, but if the upper RAM is not ... -
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…
... diagnostics ROM, which failed the upper memory RAM test, suspecting IC25 and ... a result (small display so not sure about the result). Pokeing ... stays low.
Both upper and lower memories have been ... A15 high to enable the upper memory and under which ... -
It's a trap!So I got a CPLD (not the eventual one I want to use for the ethernet project - rather, one I actually have here and now, an XC9536 in a PLCC44). And…
... by fooling it into thinking upper RAM is being accessed. (This will ... differently. When address 0x007C is detected as an instruction fetch, the ... ROM's instruction gets fetched (not the Spectrum's, which would ... a RET instruction) but not every ROM might have a ... -
Looking for some 48k RAM (upper 32k bank)Greetings, I was wondering where I could find some upper RAM for a 48k (issue 4A). It's the Texas Instruments TMS4532-20NL4 P8419 (or any compatib…
Greetings,
I was wondering where I could find some upper RAM for a 48k (issue 4A).
It's the Texas Instruments TMS4532-20NL4 P8419 (or any compatible RAM).
Thanks,
Thomas -
Seriously weird Issue 2 issue... (RAM-related)Hi guys; I have been trying to fix up my Issue 2 and have run across a bizarre issue that I haven't seen elsewhere in the forums. Hopefully one of …
... .
2. MEMCHK returned 32767, upper RAM fault. UPRAM85 returned 93, so ... "black screen and red bars" RAM test appears, after which the ... 5x 4164B-15, but do not want to risk them before ... -
Upper memory issueZX Spectrum 48K, issue 2, boots fine. Lower RAM OK. When tested with the new test ROM in the Diagboard, for all upper RAM tests "FAIL" is shown. I…
... 2, boots fine.
Lower RAM OK.
When tested with ... in the Diagboard, for all upper RAM tests "FAIL" is shown.
not connected. I'd say it ... more important for the lower RAM, are the voltages:
4116 ... -
Spectrum 48k won't start any software but passes all RAM testsI have a rubber key 48k which will not start any software - it appears to work perfectly right up until the end of the tape and the program would sta…
... rubber key 48k which will not start any software - it appears ... was a problem with the upper RAM however on running the soak ... minutes. I also performed the RAM test detailed here http://www ... longer or look for non-RAM related issues? -
48K Issue 2 RAM issuesI have 48K issue 2 board (I've checked, the upper memory is present!). It's not very well. I've not attempted to diagnose one before, so please bear …
... checked, the upper memory is present!). It's not very well. I ... 've not attempted to diagnose ... issues are only in the upper RAM as it will actually boot ... -
Spectrum 48K - upper memory MIAI have recently acquired a ZX Spectrum which, according to the sticker on the bottom, should be a 48K model. It's an Issue 3 board, with upper memory…
... a value to all possible RAM addresses. Then, from ... is detected it is assumed the end of working RAM has ... in the upper RAM during this test it does not read back ... that go to the upper RAM or one of the ... lines connected to the upper RAM, to see whether RAS ... -
Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…
... be a RAM fault that isn't detected by the RAM test routine ... 's probably in the upper RAM, but this is not a certainty.
upper RAM ICs; this should make the ... -
Issue 4A black paper, white borderJust had one of these through, nice yellow pcb! Everything but the ULA soldered in. On power up I get black paper, white border and some intermitten…
... an address line were truly not working, e.g. due to ... /> Perhaps it means a RAM addressing error was detected, i.e. the ... a read or write did not access the expected address. Can ... , suggest a fault affecting the upper RAM, but I don't think ... -
48K: Half of copyright message in the middle of the screen?!Issue two. Has 74LS08 over the Z80, but the ULA is 5C112E-3 (I think this should be a 5C102E??? - I have one, but I'm not sure if it is working, at l…
... . What is weird is that not LED 7 starts blinking 4 ... always). It again makes the upper memory suspicious. However, what does ... the Spectrum use the upper memory for when it boots ... 6 (Upper RAM - random fill test) failed with an error detected on bit ... -
How can I fix a problematic Retroleum Smart Card. I did not do anything "WRONG " with it but I did but it on a flexible cable and this seems to have "upset" it .Since then It does not perform the …
... Issue 2 that had no Upper Ram at all . I connected up ... as usual but I did not get any response from the ... of screen it said "Lower RAM error ar S7FF0 (the last ... a bit) It said "No upper RAM detected"
The lower part ... -
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 …
I have not quite got the ... Card V2 says "No upper RAM detected" and Suspect ICs :- IC7 ... br />
And lower RAM ERROR at $7FFB.
... this board is not totally dead! -
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 …
I have not quite got the ... Card V2 says "No upper RAM detected" and Suspect ICs :- IC7 ... br />
And lower RAM ERROR at $7FFB.
... this board is not totally dead![/quote] -
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 …
... to speak with just the upper Ram problem.
... upper ram failure at IC15 ,IC16 ,IC17 ,IC19 ,IC22 ,IC25,IC26 ,but not ... not think it worth the effort cutting out all those remaining upper RAM ... its stuff again and detected no upper RAM and suspect ICs in ...
