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Search Again :: Adv Search 1000 results in 0.018s
<1234567…34>
  • 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…

    ... me that lower RAM is good, all upper RAM bad. But the ... all direct connections between the upper RAM and associated logic, and ... But I tried writing [POKE] 85, 170, and 0 to that address ... , but PRINT PEEK returned 85, 170, and 0 respectively.
    ...
    DistantStar001 DistantStar001 June 2022 Hardware
  • 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
    DEATH DEATH August 2007 Hardware
  • 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 ...
    Zorn Zorn April 2012 Hardware
  • 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.

    ...
    Zorn Zorn July 2013 Sales
  • 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 ...
    gtsamour gtsamour September 2013 Hardware
  • 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 ...
    retrogamemart retrogamemart December 2014 Hardware
  • 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 ...
    Paulcatchpole Paulcatchpole December 2016 Hardware
  • 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 ...
    Your Spec-chum Your Spec-chum September 2017 Wanted
  • 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 ?
    mark8bit mark8bit September 2020 Hardware
  • 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 …

    ... POKE 32768,85 : PRINT PEEK 32768
    UPRAM170 = POKE 32768,170 : ... /> 2. MEMCHK returned 32767, upper RAM fault. UPRAM85 returned 93, so ... returned 32767. UPRAM85 returned 85 so ran UPRAM170 which returned ... screen and red bars" RAM test appears, after which ...
    Trafferth Trafferth August 2014 Hardware
  • 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 …

    ... /> If I POKE 85 after 170 then I some times ...
    POKE'ing 170 sometimes returns 166 also.
    and

    170 = 10101010
    166 = 10100110
    170 even though 85 shows errors? < ... are only in the upper RAM as it will ...
    kurbeco kurbeco August 2019 Hardware
  • 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
    thomas3120 thomas3120 February 2010 Hardware
  • Issue 2 headache!Ive got an issue 2 here that firstly had a blown regulator (fixed), now its reading as a 16k machine (its fully populated), ive replaced and socketed…

    ... replaced and socketed the whole upper RAM, still same issue, Paul ... Farrows RAM tester produced no faults, ... PEEK 44052, answer=85
    Followed by POKE 44052,170 : PRINT PEEK ... 44052, answer=170

    ...
    Macc Macc August 2012 Hardware
  • Spectrum 16K Issue 3Hi! I just received a Spectrum 16K, which turns out to be an Issue 3. Is it really that rare? If not, I?d like to upgrade it to 48K. There are 12 em…

    ... a random value in the upper 32K (say 60000) and PEEK ... it back again. Use values 85 and 170 (0x55 and 0xAA).
    upper RAM in consecutive addresses, then read ... ? :) ) - modify values in upper RAM and see if other RAM addresses change when ...
    Spirantho Spirantho November 2012 Hardware
  • Spectrum 16K Issue 3Hi! I just received a Spectrum 16K, which turns out to be an Issue 3. Is it really that rare? If not, I?d like to upgrade it to 48K. There are 12 em…

    ... a random value in the upper 32K (say 60000) and PEEK ... it back again. Use values 85 and 170 (0x55 and 0xAA).
    upper RAM in consecutive addresses, then read ... ? :) ) - modify values in upper RAM and see if other RAM addresses change when ...
    schombi schombi November 2012 Hardware
  • Some stupid 16K questions...Starting with... 1. Should a 16K Spectrum that's been upgraded to 48K behave [I]exactly[/I] like a 48K Spectrum? i.e. should the machine test/clear…

    Most likely a faulty 48K. You should test address 32768 with all binary bit patterns. Poking and Peeking numbers 85 and 170 might be sufficient.
    A dead (upper) RAM chip often is significant warmer as his colleagues.
    roko roko December 2012 Hardware
  • ZX Spectrum 48K working as 16K from factoryGood morning I Have a Zx Spectrum 48k working as 16K , it came like this from factory. What can i do to solve this , and put it to work as 48K? Wha…

    ... the /RAS signals for the upper RAM and so the ROM code ... only the lower 16K of RAM. The output of the voltage ... wire touch anything else." The RAM test program would probably then ... /> POKE 50000, 85 : PRINT PEEK 50000
    POKE 50000, 170 : PRINT PEEK ...
    Zorn Zorn July 2013 Hardware
  • Rubber Key RAM - Repair?Hello there everyone! I'm a long-time lurker on here - ROMs, documentation etc. but yesterday I finally ponied up for my own speccy, just like the on…

    ... />
    POKE [B]x[/B], 85: PRINT PEEK [B]x
    POKE [B]x[/B], 170: PRINT PEEK [B]x
    upper RAM chip is down we might ...
    balford balford August 2013 Hardware
  • ZX Spectrum Plus Versions.Did they ever do a 16K version of the Spectrum Plus? I have just got an early one (Issue 3), with a low serial number 003-037776, and it is fully po…

    ... means that one ore more upper RAM ICs are completely dead, therefore ... /> POKE 32768,85: PRINT PEEK 32768

    POKE 32768,170: PRINT ... read, you can determine which RAM IC is at fault.
    Falco-F8L Falco-F8L November 2013 Hardware
  • Fixing my old ZX Spectrum 48K issue 4AHi Guys, I trying to fix my old Spectrum 48K. Looks like my dad used a wrong power supply as the ULA had a bit missing and so did the 7805. So I rep…

    ... can then disable the "upper" RAM (as the CAS signal ... first byte of the "upper" 32k of RAM returns.

    POKE 32768,170
    PRINT PEEK 32768< ... enter
    POKE 32768,85
    PRINT PEEK 32768< ... br /> This should print 85

    If ...
    1024MAK 1024MAK May 2014 Hardware
  • Fixing my old ZX Spectrum 48K issue 4AHi Guys, I trying to fix my old Spectrum 48K. Looks like my dad used a wrong power supply as the ULA had a bit missing and so did the 7805. So I rep…

    ... can then disable the "upper" RAM (as the CAS signal ... first byte of the "upper" 32k of RAM returns.

    POKE 32768,170
    PRINT PEEK 32768< ... enter
    POKE 32768,85
    PRINT PEEK 32768< ... br /> This should print 85

    If ...
    Brian Brian May 2014 Hardware
  • 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…

    ... problem to either the upper RAM chips or one of ... POKE 32768, 85: PRINT PEEK 32768
    POKE 32768, 170: PRINT PEEK ... into the first byte of upper RAM (01010101 and 10101010 respectively). ... determine with reasonable confidence which upper RAM chip(s) have failed ...
    balford balford June 2014 Hardware
  • 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…

    ... 32768, 85: PRINT PEEK 32768
    POKE 32768, 170: PRINT ... into the first byte of upper RAM (01010101 and 10101010 respectively). ... determine with reasonable confidence which upper RAM chip(s) have failed ... specific a potential broken upper memory chip, by just ...
    georgedb georgedb June 2014 Hardware
  • 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…

    ... 32768, 85: PRINT PEEK 32768
    POKE 32768, 170: PRINT ... it gives back respectively "85" and "170" which means all is ... fine (?). That would mean no dead upper RAM ... /> Something that controls the upper memory initially, maybe I need ...
    georgedb georgedb June 2014 Hardware
  • 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 …

    ... are one or more faulty upper RAM IC's still lurking :)< ... 20 POKE n, 85: IF PEEK n 85 THEN PRINT "Error at ... ";n;", 85 "; PEEK n
    30 POKE n, 170: IF PEEK ... n 170 THEN PRINT "Error at ... ";n;", 170 "; PEEK n
    40 ...
    balford balford August 2014 Hardware
  • Dead SpectrumHello guys, I've just bought a dead Speccy 48k (Rubber Keyboard Issue 3 board). Basically, when powered on it initially appears to boot up ok, but in…

    ... my guess then that some upper RAM is faulty, and is then ... /> It's possible to isolate upper RAM during startup so that the ... commands:

    POKE 32768,170
    PRINT PEEK 32768
    POKE 32768,85
    PRINT PEEK 32768
    balford balford August 2015 Hardware
  • 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…

    ... tape-based test shows all upper RAM to be faulty.

    85 and 170 into seemingly any upper RAM address and get ... ICs used to access the upper RAM? Or something else that is ...
    Paulcatchpole Paulcatchpole December 2016 Hardware
  • 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…

    ... errors, for the whole of upper RAM. So errors start at 34680 ... to the end of the RAM.

    [img]http://www ... re-run that test with 85 and 170 as poke values.
    Paulcatchpole Paulcatchpole December 2016 Hardware
  • Another 48k Speccy acting as a 16K model.Hi all, I originally was going to post asking for help to fix the new addition to my family a very nice condition Issue 2 sold on ebay as a 16K model…

    OKI RAM is not supported by the ... appears you must have OKI RAM chips which function as fully ... /> POKE 32768,170: PRINT PEEK 32768
    POKE 32768,85: PRINT PEEK ... the results they produce which upper RAM IC's are faulty.
    balford balford April 2017 Hardware
  • Another 48k Speccy acting as a 16K model.Hi all, I originally was going to post asking for help to fix the new addition to my family a very nice condition Issue 2 sold on ebay as a 16K model…

    ... appears you must have OKI RAM chips which function as fully ... /> POKE 32768,170: PRINT PEEK 32768
    POKE 32768,85: PRINT PEEK ... the results they produce which upper RAM IC's are faulty.[/quote ... , I could not access any upper ram with pokes, hence this was ...
    povvercrazy povvercrazy April 2017 Hardware
<1234567…34>

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Related Threads

  • 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…
  • Looking for some 48k RAM (upper 32k bank)Greetings,<br /> I was wondering where I could find some upper RAM for a 48k (issue 4A).<br /> It's the Texas Instruments TMS4532-20NL4 P8419 (or …
  • 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.<b…
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  • 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…
  • 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.<br /> <br /> When the machine is without the Divide …
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  • 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. <br /> <br /> It was labelled as 'keyboard…

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