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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 example ... first read from the upper RAM location retrieved the decimal ... . were then established in upper RAM, but the system later ... capture the RAM-FILL routine passing from lower RAM to upper RAM, but ... -
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.
... -
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 …
I got my new upper ram replacement module from Zorn ... . When I put the upper ram chips back in place, ... again.
The upper ram are not on the "OKI ... that also has the upper ram module be so kind ... attempts DMA to the upper RAM and uses unusual timings ... -
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 ... -
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…
... 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 ? -
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 ... -
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 -
Replacing Upper RAM in 48KHi Folks Well, my fun continues :) After sorting the display issues with this machine I found I couldn't load software meant for 48K machines. Havin…
... here it looks like an upper memory fault.
Before ... -
POKEs on 128K "upper RAM"?I've been working lately with some 128k games, and I've got this question about RAM in games. I guess most games use RAM pages 5 and 2 to store the …
... 've got this question about RAM in games.
I ... guess most games use RAM pages 5 and 2 to ... the main program, and other RAM pages are used to store ... that needs POKEs placed in RAM pages 1, 3, 4, 6 ... -
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 ... -
Upper Memory LinksI've got an 1982 Issue Two Spectrum 48k with an upper RAM fault. I've narrowed down the faulty IC and I'm in the process of removing the 8 IC's, sock…
... Two Spectrum 48k with an upper RAM fault. I've narrowed down ... -
ZX81 internal RAM board?Just a quick question to Zorn (amongst others). What would the issues be with fitting one of Zorn's RAM boards into an unexpanded ZX81? Seems to me…
... fitting one of Zorn's RAM boards into an unexpanded ZX81 ... a lot of the official RAM pack's internal circuitry is ... fit one - preferably the 32K upper RAM board, 'cos I never had ... -
128K RAM tester as .TAP?I was sure that I've seen a RAM tester that can be loaded with e.g. DivIDE or DivMMC EnJOY! as .TAP. But I can't find it (been searching through the …
... that I've seen a RAM tester that can be loaded ... only a small error in upper RAM.
I have a ... -
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.
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…
... 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 …
... board (I've checked, the upper memory is present!). It's ... issues are only in the upper RAM as it will actually boot ... -
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 ... i start digging at the upper ram, or the 4 logic chips ... that drive the upper ram.. i am presuming that one ... -
TV Modulator. Can it be repaired?Is it possible, to repair tha TV modulator (after removing it) if it gives wavy picture? I replaced both transistors (tr1/2) and both electrolytic ca…
... at 32768 etc, no upper RAM working at all, as ... think) in every location in upper RAM - so it's half ... , fast access to the upper 32K and indirect, slower ... stamped right after the RAM part number, generally after ... a HM4864AP-15 is a 150ns DRAM, but a TMM2016P1- ... -
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…
... to the OEM RAM.[/quote]
Go for 100/150ns if possible ... CAS delay generated by the RAM managing logic may not be ... on why some of these upper RAM would just fail?[/quote]
Those RAM are actually 4164 RAM's with a defective ... -
Issue 3B only sees 16k (and RAMTOP NO GOOD on loading)A ZX+ with issue 3B board that i got recently, does not see anything more than 32768 (sometimes 37267..) on "PRINT PEEK 23732 + PEEK 23733 * 256 (Ent…
... top etc.?[/quote]
Use 150ns or faster chips. Don't ... you to buy 150ns chips or faster. For upper memory only repairs ... likely more (or all) the upper ram is dead?[/quote]
Based ... age, bad chips?[/quote]
- Upper RAM exposes their data bus on ... -
Speed (nano seconds) of memory chips ZX SpectrumThe ZX Spectrum uses 4116 memory for the lower memory, which can be replaced by other sorts or a whole, modern, module, but when searching for 4116 m…
When talking about RAM chip speed, often only ... />
If a slow RAM chip is fitted, the computer ... DRAM chips should be the 150nS type. Ian Worsley's ... figure of 200ns for the "upper" RAM. Faster DRAM chips are ... marked "-15" may mean 150nS or it for a more ... -
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…
I'm sorted for the lower ram just need the upper ram IC.
Is there any drop-in replacements for the TMS 4532-15NL4? Would a Samsung 4164-150NS work? -
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…
... 've brought a replacement lower ram IC from Mutant Caterpillar, and ... of Samsung 4164-150NS for drop-in replacement upper ram IC.
Method to read byte as binary string rather than dec?Hi all Am fiddling around with the screen buffer and have written a routine to scan the screenbuffer into upper ram and then write it back in upside…
... to scan the screenbuffer into upper ram and then write it back ...Note to SpiranthoIan Whilst playing about with Frankenspec, I have discovered that the 41256 memory IC works as well as a 4164 (etc) in the upper RAM block of a 48K …
... a 4164 (etc) in the upper RAM block of a 48K machine ... />
Strapped for OKI L RAM, the NEC chips worked just ... work if strapped for TI RAM etc.
Lloyd ...Component Equivalents/substitutionsA while ago, I mentioned to somebody in a thread that we should have a list of component equivalents and substitutions so that it's easier to fix our…
... (Inmos) chips work in any upper RAM position (IC15-22)
... work in place of 4164 upper RAM chips
V53C256P80L chips ... work in any upper RAM position (IC15-22)
MN41257 ... -12 chips work in any upper RAM position (IC15-22)
...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 ...
