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Another "untested" dead spectrum...Hi, I'm looking for some suggestions on a faulty Spectrum I have picked up. I'll need to wait until tomorrow before posting pics, but the screen is …
... power supply would be an upper RAM IC interfering on the data ... -
Spectrum Not Responding to Keyboard InputHello, sorry if this thread is not in the correct place, This is my first post and I'm not sure where to post this type of thread. :lol: Anyway, I r…
... would indicate a possible lower RAM failure (8 chips at the ... CPU, or in the lower/upper RAM that is holding a data ... behaviour like the above when upper RAM is not behaving itself (machine ... -
Spectrum Not Responding to Keyboard InputHello, sorry if this thread is not in the correct place, This is my first post and I'm not sure where to post this type of thread. :lol: Anyway, I r…
... narrow this down to a RAM failure of some sort.
upper RAM from the system to narrow ... problem to one of 8 upper memory chips.
(Technical ... the CAS signal from the upper memory bank. Mcleod_ideafix suggested this ... -
Spectrum Not Responding to Keyboard InputHello, sorry if this thread is not in the correct place, This is my first post and I'm not sure where to post this type of thread. :lol: Anyway, I r…
... a way you can isolate upper RAM from the system to narrow ... problem to one of 8 upper memory chips.
( ... the CAS signal from the upper memory bank. Mcleod_ideafix suggested this ... most of this, except the "upper" RAM chips are disabled, not isolated ... -
Totally random idea for the hardware nuts to exploreWhen it comes to multi-player games, how hard would it be to generate a second display from a single Speccy, instead of trying to link up machines, s…
... other running in the upper 32k of ram. It would be slow ... changes to relocate it to upper RAM. -
DIY Issue 1 Internal 32K RAM expansionFollowing on from the information in [URL="http://www.worldofspectrum.org/forums/showthread.php?t=40173"]this[/URL] thread, I finally figured this ou…
... expensive than the lower and upper RAM modules I'm already selling ... -
Plea for new hardwareI'm posting this as a poll as I want to judge if I'm a solo loon going on about this, or if people really are interested in either of the following S…
... lower to the upper 8K half of the contended RAM then that ... listening for writes to the upper RAM and replicating them in the ... 'd have to sacrifice your upper memory to exploit it.
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…
... is also possible that a RAM fault is causing the ... in the top part of RAM becoming corrupted.
... a 48k machine with the "upper" RAM in sockets? If yes, ... remove this RAM and try again. If the ... RAM is soldered in, shout ...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…
... also possible that a RAM fault is causing the ... in the top part of RAM becoming corrupted.
... a 48k machine with the "upper" RAM in sockets? If yes, ... remove this RAM and try again. If the ... ,
No, the RAM is soldered in.
But ...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…
... to work out where physical RAM finishes. It is not ... needs an area in RAM to store return addresses ... will be in the "upper" RAM (if it is a 16k ... need to use the "upper" RAM. So sometimes the ROM ... copyright display before the "upper" RAM fault causes the CPU to ...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…
... CPU needs an area in RAM to store return addresses ... it will be in the "upper" RAM (if it is a 16k ... not need to use the "upper" RAM. So sometimes the ROM ... copyright display before the "upper" RAM fault causes the CPU to ... Maybe easier to just disable upper RAM ?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…
To disable the "upper" 32k of RAM, take a piece of wire ... +5V. That will disable the "upper" RAM, as the CAS signal won ... 't reach the RAM chips.
Credit: [URL ... CPU is accessing ROM or RAM.
The data bus D0 ...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…
... ;764963]To disable the "upper" 32k of RAM, take a piece of ... +5V. That will disable the "upper" RAM, as the CAS signal won ... 't reach the RAM chips.
[I ...Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... all 64K addresses and swapping RAM chips made no difference. Turned ... another bad joint on the upper RAM DIL socket.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…
... see it causing a lower RAM failure as there wouldn't ... causes knock on effects to RAM voltages etc.
I ... a day then suffer an upper RAM failure!
BSpectrum Not Responding to Keyboard InputHello, sorry if this thread is not in the correct place, This is my first post and I'm not sure where to post this type of thread. :lol: Anyway, I r…
... some wire to disable the upper ram chips on the spectrum and ... time so I know the upper RAM is causing that problem. :-)
RAM however this did not fix ... normally, however when trying the Upper RAM test the border always appeared ...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…
... I'd be suspecting an upper RAM fault causing the machine to ...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…
... I'd be suspecting an upper RAM fault causing the machine to ...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…
... failure here would definitely affect upper RAM.
Get two 157 ...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…
... is not fitted, the "upper" 32k DRAM chips will ... fault with the "upper" 32k RAM is one or more ... to disable the "upper" 32k of RAM. Take a piece ... can then disable the "upper" RAM (as the CAS signal ... first byte of the "upper" 32k of RAM returns.
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…
... is not fitted, the "upper" 32k DRAM chips will ... fault with the "upper" 32k RAM is one or more ... to disable the "upper" 32k of RAM. Take a piece ... can then disable the "upper" RAM (as the CAS signal ... first byte of the "upper" 32k of RAM returns.
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…
... controlling the access to the upper RAM.
Start with the following ...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…
... 48k? If 48k, are the upper RAM chips socketed? If so, and ...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…
To disable the "upper" 32k of RAM, take a piece of wire ... +5V. That will disable the "upper" RAM, as the CAS signal won ... 't reach the RAM chips. Be very careful that ...Spectrum Plus display issueHi, does anyone know if this is fixable at all by someone with no experience? From looking on a similar post on World of Spectrum forum they mention…
...
- Faulty ULA
- Faulty upper RAM interfering with data bus.
Faulty upper RAM is the most common cause ...Spectrum Plus display issueHi, does anyone know if this is fixable at all by someone with no experience? From looking on a similar post on World of Spectrum forum they mention…
Faulty lower RAM could be preventing the CPU ... almost always caused by faulty upper RAM. It seems that a failed ...Spectrum Not Responding to Keyboard InputHello, sorry if this thread is not in the correct place, This is my first post and I'm not sure where to post this type of thread. :lol: Anyway, I r…
... /> D7 and D6 of the upper RAM were both giving garbage, just ... output.
D5 of the upper RAM had an address line error ... too.
D3 of the upper RAM was the culprit on the ... , and changing D5 made the upper RAM work properly again.
Spectrum Not Responding to Keyboard InputHello, sorry if this thread is not in the correct place, This is my first post and I'm not sure where to post this type of thread. :lol: Anyway, I r…
... enough in the RAM test pattern for the upper RAM there was no ...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…
... ]To disable the "upper" 32k of RAM, take a piece ... 5V. That will disable the "upper" RAM, as the CAS signal won ... How to proceed? As the upper memory (or the logic IC ... I] or [I]which upper memory chip is gone[/I ... chip because of brand and upper half or lower half. ...
