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Wanted: broken motherboard!Does anyone have a motherboard for a 48k (any issue) that is currently not working? I'm looking to set up a test board for chips, and would like to g…
... a +2 board with higher memory chips socketed.
One of ... /> The upper row is high memory and 128K pages, D0 to ... to right.
The lower row is lower memory and some pages, D7 ... test 4164 chips in the lower row as I can't ... -
Experimenting with turboloadersHello, My first post, having lurked here for a while. I'm a lifelong computer nerd, Spectrum fan since childhood in the eighties, and have recently…
... screen. Maybe some kind of memory allocation?[/QUOTE]
< ... content is kept compressed in lower memory, and
' ... /> ' During menu screen, memory is used as follows:
memory, thus leaving uncontended memory available for
... -
Issue 3 board with strange piggy-back boardIn case you are interested. I?ve never seen something like this before. I have an Issue 3 board here. When I opened the case and found a strange pig…
... TR4 before you start killing lower memory chips which experiments that take ... -
Homebrew ZX Spectrum kits for DIY builders !Hi. I'm considering selling Homebrew ZX Spectrum kits on ebay... hopefully at a low price ! They'd consist of : Z84C0020PEC Z80 CPU …
... circuits by the way - the lower memory gets refreshed for free merely ... the screen picture, and upper memory is refreshed by the Z80 ... -
Faulty 48+Hi I picked up a pile of Spectrum kit including a boxed "untested" 48k+ The Speccy boots to this screen... [IMG]http://www.scotek.net/zx spectrum/…
Update - I desoldered the lower memory chips, put in sockets and ... bought one of the memory bridge boards.
It ... keyboard, and testing the keys / memory showed everything working OK. I ... -
ZX Alien BreedNot sure if this has been mentioned already (I did trawl the threads but couldn't see anything :smile: ), but I've always hankered after a Speccy Ali…
... today - albeit with a slightly lower memory count!! :lol:
But ... -
The Spectrum Resuscitation ThreadKicking off this thread as a place where people who are fixing/restoring Spectrums (or indeed any other piece of related hardware) can show off their…
... . I measured voltages from the lower memory and got pretty much zilch ... /> A few days later, the memory chips and the BC557 arrived ... joints and changed the upper memory RAM chips and I am ... -
48k black paper white borderI recently sold a speccy to a guy, unfortunately the power supply didnt survive the trip, so on replacing for him it seems neither did the speccy! H…
... .5v PSU have caused the lower memory to fail?
I ... -
Read Data from memoryHi there. Not been on this scene for a long time. Does anyone know how to do a routine to read data from memory(peek..etc) rather than using lines of…
... 57000, but the only real memory I'll have spare is ... 2....can it work at lower memory addresses?....I tried at 25000 ... -
ZX Spectrum 48k / +Hello, Does exist some indestructible keyboard membrane for Speccy 48k, or 48k+ ? I would like to purchase speccy, but I would like to avoid the m…
... other parts of the Spectrum (lower memory, for example) which could present ... -
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…
... track to isolate the upper memory. It did'n help (maybe ... /> This also proves the 16K lower memory is working, and this issue ... -
New user with a dead 48k issue 2Hello all I've found my way here from watching some excellent youtube videos by Joulesper Coulomb in an attempt to fix a issue 2 rubber key 48k I bo…
... any of the 4116's (lower memory) are getting hot, if they ... -
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…
... /> So need to order the lower memory.
Have removed a leg ... -
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…
... a little more Zorn sells replacement lower RAM boards which replace all ... -
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…
... a little more Zorn sells replacement lower RAM boards which replace all ... -
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…
Okay replaced both faulty lower ram ic.
Now I get a white border and random looking inside it.
Same with disabled upper memory, and no keyboard.
So what does this mean ?
More dead lower memory chips ? -
They Stole a MillionI noticed that the tzx on the site is missing a Speedlock Block for Part 2. I don't own the original so cant make a perfect tzx, but I did recreate t…
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…
... RAS/CAS signals on each lower RAM chip in turn (pins ... have found the third bad lower memory chip and swapped it.
And with upper memory disabled I am back to ... is finding the bad upper memory chips :D
I ...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…
... have found the third bad lower memory chip and swapped it.
And with upper memory disabled I am back to ... is finding the bad upper memory chips :D
I ... /> So guessing one of the memory chips is holding output high ...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…
... =balford;776008]Are all upper memory IC's socketed at this ... same troubleshooting methods as with lower RAM - watching the RAS/CAS ... I will have more dead lower memory soon.
Guess I will ...Next step for fixing my speccy?Hi guys, I've picked up my faulty Spectrum aiming to fix it. So I followed the excellent JouledperCoulomb videos on Youtube for the basics and I am …
... got one or more faulty lower RAM ICs. It might be ... set of 4116s or the lower RAM module that I sell ... />
Thanks Zorn, replacing the lower memory would be my next step ...Spectrum sometimes boots with graphic issuesA while ago, my Spectrum 48K (issue 3B) broke down after fiddling with a brand new joystick interface in combination with DivIDE. Today I tested the …
Check the voltages of the lower memory, +5v, -5v, +12v.Issue with Issue Two[img]https://dl.dropboxusercontent.com/u/25300140/Spectrum/Edited_ImageEasyImageEditor_20141111_84.jpg[/img] I'm working on an Issue Two that was sh…
... used 4164s to replace the lower memory? I've seen a few ...Issue 2 Spectrum - Black screenHi I have an issue 2 spectrum which I'm having some issues with. I bought it on ebay so have no idea of the history or how it came to be broken. Whe…
48K Upper memory issues?Having more issues with the 48K spectrum I just fixed that had the black screen in this thread [URL="http://www.worldofspectrum.org/forums/showthread…
... now managed to get the memory test program to load.
Lower memory test failed after a few ... [/IMG]
The upper memory test I also ran a ...48K Upper memory issues?Having more issues with the 48K spectrum I just fixed that had the black screen in this thread [URL="http://www.worldofspectrum.org/forums/showthread…
... machine.
Ran the upper memory test again and ran through ... perfectly.
However! Ran the lower memory test again and it failed ... up the screen corruption and lower memory errors go away.
48K Upper memory issues?Having more issues with the 48K spectrum I just fixed that had the black screen in this thread [URL="http://www.worldofspectrum.org/forums/showthread…
... =whoremoan;806182]However! Ran the lower memory test again and it failed ... is corrupting the contents of lower RAM. It could be a ... lower RAM IC with an intermittent ...Spectrum +2a memoryHi all, Happy New Year. A quick question, I have a Spectrum +2a that I am seeing a very intermittent fault, once every 20 - 30 power ups. I plug…
... crashing, so I moved the memory ICs around and the issue ... apart from once a 16K lower memory failure.
RussIssue Two 16K doesn?t like any keyboardI have a strange Issue Two 16K Spectrum here, that doesn?t like any keyboard. With the original keyboard fitted, it boots, but no key works. Okay, I …
sounds like broken lower memory. Not necessarily though!
