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48k issue 4B display problem etchi,, i have a zx spectrum 48k issue 4B with a display issue it has wavy lines in both the border and paper,some colours seem worse than others ie red…
... ,full re cap,disabling upper ram.it passes ram tests left in sink ... -
Speccy 4A board problemHi all. I was hoping for some help with my Speccy (with 4A Board) before I send it off for repair. When I power it on all looks fine (i.e. copyright …
... as it just needed an upper RAM chip replacing). This one could ... -
boot fail .. bad address lines A7,A12,A13anybody have any ideas what could be wrong with this specie issue 3B .. work done : removed rom, upper ram & logic put lower ram multiplexers in sock…
... : removed rom, upper ram & logic put lower ram multiplexers in sockets ... ic3 & ic4) , put lower ram in sockets, full recap, fitted ... amp; ULA's. fitted lower ram module ... still no boot,tried ... regular ram...checked all the data & ... -
Building a ZX Spectrum and I have some voltage questionsI've posted about this before looking for parts, but now I've found all the hard-to-get stuff (thank you Retrolium!). So I figured new questions, new…
... Modulator)
+5V to Lower RAM: +4.98V
+12V to ... Lower RAM: +12.56V
-5V to ... Lower RAM: -4.31V
+5V to Upper RAM: +4.98V ... -
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 …
... /-L) or TI (-3/-4) upper RAM should work? What about jumpers ... -
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 …
... /-L) or TI (-3/-4) upper RAM should work? What about jumpers ... -
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 …
... /-L) or TI (-3/-4) upper RAM should work? What about jumpers ... -
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 …
... /-L) or TI (-3/-4) upper RAM should work? What about jumpers ... -
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 …
Hi all,
yesterday I installed upper RAM chips (TMS4164-20). When I power up the ZX Spectrum it boots fine but only sees 32Kb of memory (PRINT PEEK 23732+256*PEEK 23733 returns 32767).
Any ideas?
Thank you,
Misko -
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 …
... ,
yesterday I installed upper RAM chips (TMS4164-20). When I ... -
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 …
... ,
yesterday I installed upper RAM chips (TMS4164-20). When I ... -
OT: Graphic Card problemAhem. It's me again with a computer problem! Last time I posted with a problem I was pleasantly suprised with some insightful answers that helped fix…
... card and said that the RAM was surely broken, these lines ... typical symptoms of a video RAM failure; so they gave me a ... -
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 ... -
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…
... powers up. If so, your upper RAM is deffo knackered. There are ... .
Remove your old upper RAM chips. fit sockets and then ... one by one using 4164 RAM IC's. That should fix ... -
rubber troublejus got 48K rubber speccy into my possesion, which was my first computer back then but only for few months before daddy decided to upgrade it for 48+…
... right hand side of the upper RAM block. On an issue 4 ... -
Where to get Spectrum RAMSigh. Even obsolete nixie tubes seem to be easier to get hold of than Spectrum RAM. I've tried the usual suspects (eBay and google searches), but not…
... .uk/Williams-Defender-Arcade-4116-ram-chips-NOS_W0QQitemZ190036399869QQihZ009QQcategoryZ3945QQrdZ1QQssPageNameZWD1VQQcmdZViewItem[/url]
15 ... /> 4164 for use as upper RAM (or 128/+2 RAM) is a little ... - Ebay again.
4464 RAM for +2a/3 try old ... -
Where to get Spectrum RAMSigh. Even obsolete nixie tubes seem to be easier to get hold of than Spectrum RAM. I've tried the usual suspects (eBay and google searches), but not…
How do you know it's the upper RAM block that's down on your two 48K's? Also, if you want, you can use 41256 chips instead of 4164. Bit wasteful, but any port in a storm..... -
Where to get Spectrum RAMSigh. Even obsolete nixie tubes seem to be easier to get hold of than Spectrum RAM. I've tried the usual suspects (eBay and google searches), but not…
... you know it's the upper RAM block that's down on ... -
ZX Spectrum 16k by IskraHi everyone. I have posted the pics in some other thread... but it is HW related. Anyway, I have got a ZX 16k manufactured by ISKRA. It is in a box …
... the internals are different. The upper RAM block is built onto a ... -
Dead Spectrum diagnosis and desolderingI have two dead Spectrums - one I'm pretty sure is caused by bad memory, and the other - well, perhaps a bad ROM, perhaps a bad CPU (it gets halfway …
... (the 74LS157 multiplexer for the upper RAM) on the dead Issue 2 ... -
Dead Spectrum diagnosis and desolderingI have two dead Spectrums - one I'm pretty sure is caused by bad memory, and the other - well, perhaps a bad ROM, perhaps a bad CPU (it gets halfway …
... (the 74LS157 multiplexer for the upper RAM) on the dead Issue 2 ... . If you KNOW your 4116 RAM is ok, try changing the ... -
Nooooo my speccy died!??!!Hi! I am quite sad. :( Tonight I got a kempston interface so I rushed home to try it on my spectrum+ The edge connector of the interface was narrower…
... to go. Usually, it's RAM that goes aswell. I would ... /> 4116 lower RAM block 90% likely
4164 upper RAM block 50% likely ... needed to run the lower RAM, then the PSU section is ... will.
Then check upper RAM, then the Z80 and then ... -
Black paper, white border. Ram fault?We have a speccy that wont work properly. When we power it up, we get white border around a black screen. We swapped the rom and ula with a working o…
... could be the Z80, lower RAM or upper RAM.
The best ... the voltages on the 4116 RAM first because you can immediately ... 74LS157 multiplexers to disable the upper 32K (I can't remember ... -
EightyOne 0.43Hmmm, 'twas round about July I fell asleep and only came round t'other day - honest gov! Anyway, I thought I'd better whip out a quick release and p…
... /> 1. Setup a 16k ZX81 with RAM 8-16k
2. Inserted "demo ... -
Spectrum Issue two problemI managed to bring back to life a issue two spectrum (at least the power supply cirquit). The screen is now crystal clear (after replacing all the el…
... faulty memory chip in the upper RAM.
Thank you all for ... -
Blowtorch method of Speccy repairsI just did my first Spectrum repair (and successful at that). It was the Issue 2 spectrum I wrote about a while ago, I just hadn't got around to doin…
... tests on keyboard, sound, ULA, RAM chips, and ROM mostly.
upper RAM chip and finally one (the ... -
I/O contention model questionHi everyone, Sorry for my poor english. Together with a friend we are working on ZX Spectrum 48k implemented in FPGA. We have found bug in the Spect…
... - why DDR, when 32kbyte static ram ICs are cheap, trivial to ... Spectrum (and thefore the entire upper RAM can be done with a ... -
I/O contention model questionHi everyone, Sorry for my poor english. Together with a friend we are working on ZX Spectrum 48k implemented in FPGA. We have found bug in the Spect…
... - why DDR, when 32kbyte static ram ICs are cheap, trivial to ... Spectrum (and thefore the entire upper RAM can be done with a ...
