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Upgrading to 48kI picked up a 16k Issue 2 Spectrum over the weekend, and I'd like to upgrade it to 48k. I've scanned an old [URL="http://www.drumfu.com/SinclairZXSp…
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2 x 74LS157 [IC25,IC26][/CODE]
Apart from ... -
Issue 4A issuesHi all, I've been trying to get the Issue 4A board that came DOA with the case I purchased for my Frankenspectrum to work. I've recapped and socket…
... the associated logic in IC23-IC26, so this should be behaving ... -
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…
... ICs (IC23, IC24, IC25 & IC26), I've got a few ... -
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…
... of IC23, IC24, IC25 and IC26. IC3 and IC4 are in ... -
Bizarre ZX Spectrum faults (also possibly relevant to Spectranet compatibility problems).I'm attempting to repair an issue 4A 48K ZX Spectrum and am encountering some very strange problems. For my own records I've given this computer the …
... , IC4, IC23, IC24, IC25 & IC26. In summary, I have found ... -
Want a Speccy Repaired?Maybe it's time to put my 'skills' to use.... Now that I've sourced some of the nastier transistors, I've fixed about 6 rubber keyed Speccys in the …
... problem? All these ICs (IC15-IC26) are NEW (IC24 was already ... -
Bah, Spectrum+ has diedBah. My Spectrum+ appears to have died. On power up, the 'paper' part of the screen goes black (and you see the faint red lines that you normally se…
... a issue 2 it was IC26 and IC 27 chips).With ... -
Spectrum 48K ROMHi Can anybody help I have an Issue 6a Circuit Board which has a faulty ROM Chip. Is it possible to program a ROM Chip with the 48K ROM and fit it as…
... , but these are connected to IC26 (according to an Issue 3 ... -
Spectrum 48K ROMHi Can anybody help I have an Issue 6a Circuit Board which has a faulty ROM Chip. Is it possible to program a ROM Chip with the 48K ROM and fit it as…
... , but these are connected to IC26 (according to an Issue 3 ... -
Issue 2 Board - CPU 'Patch'I've been wondering why my issue 2 board has been kicking out this signal when powered up... [IMG]http://www.drumfu.com/ResizedDuffIssue2.jpg[/IMG] …
... , here's a pic of IC26, my memory was playing tricks ... on me as its only IC26, its on a seperate board ... [/url]
One pic has IC26 board removed.
I ... -
Upgrading 16k MemoryHi All I have a fully working issue 2 16k spectrum and a broken issue3 48k spectrum (It's showing the black and white bars and some flashing blocks)…
... /> [*] Insert logic IC's (IC23-IC26), but no upper 32K memory ... -
Upgrading 16k MemoryHi All I have a fully working issue 2 16k spectrum and a broken issue3 48k spectrum (It's showing the black and white bars and some flashing blocks)…
... /> IC23 = 74LS32, IC24 = 74LS00, IC25,IC26 = 74LS157
Do I need ... -
Amperage drastic reduction in a rubber 48KWell, I am now with the approach of a drastic reduction ZXSpectrum amperage. As a first step would change the Z80 processor for other (Z80C). Unfortu…
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…
... and control logic ICs (IC25,IC26,IC23,IC24). The IC identifiers ...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…
... faulty address multiplexor (IC25 and IC26), but I have encountered that ...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…
... faulty address multiplexor (IC25 and IC26), but I have encountered that ...Query about memorySo I know this has been asked a lot and I beg your brief indulgence. I have scanned through a lot of old threads already but I'm trying to improve m…
... upper memory support logic (IC23 - IC26).Query about memorySo I know this has been asked a lot and I beg your brief indulgence. I have scanned through a lot of old threads already but I'm trying to improve m…
... upper memory support logic (IC23 - IC26).[/QUOTE]
Ok so ...16k --> 48kI bought a zx and found out it was a 16k since when I execute PRINT PEEK 23733 I get 127 Does it mean I get a lesser model? What limitations do I h…
... Spectrum to work as such. IC26's position is hidden under ...Price of nice condition issue 1 48K Speccy?I recently came across a 'really great example' issue 1 48K Spectrum on the Internet for ?250 with RF Cable, Mic ear Cable, PSU, Manuals and the Hori…
... , IC4, IC23, IC24, IC25 and IC26) were replaced with a Mullard ...When is a 16k not a 16k ?Can anyone explain what this machine is supposed to be ? Speccy with a 16K sticker on the base. Doing a peek 23733 returns 255 so a 48K ? Opened …
... London Robotics. I recall that IC26 was supplied with one of ...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…
... installation.
IC25 and IC26 are the address multiplexers for ... the replacement IC25 and IC26 of the board to ... of the two inputs of IC26 (left and right link ... 1 (pin 11) of IC26 (74LS157), whereas its output ... to trace pin 10 of IC26 (I mean its counterpart ...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…
... connected to pin 10 of IC26, the same pin that connects ... 10 of the address decoder (IC26).
To sum things ...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…
... , to read the voltage on IC26 pin 10 and see if ...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…
... can measure pin 10 of IC26 (right side, second from bottom ...Help with an issue 2Hello friends, Today, sadly, my issue 2 board lost his 5c112 ULA, and on my spares list I only had a 6c one that worked fine after swapping it. Now I…
... the logic chips IC4 and IC26).
I don'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…
... two multiplexer chips IC25 & IC26 (74LS157) fails.
My ...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…
... two multiplexer chips IC25 & IC26 (74LS157) fails.
My ...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…
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The multiplexers (IC25 &IC26) convert the CPU address bus ...