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The new Superfo cloneHi In the spanish forum speccy.org some guys and me have optimized the superfo clon to have less ICs. The actual design has 39 ICs versus the 45 ICs…
... the Z80 to access the upper ram without collision. But when the ... doesn't need the video ram, the Z80 has unhindered access ... is coupled to the video ram through resistors, in this undecoded ... -
maximum addressable RAM for a Z80 using bank switching?What is the maximum addressable RAM for a Z80 using bank switching? The Enterprise64 home computer could address up to 4MB, is this the limit for a …
... 256 banks of 32K SRAM (upper RAM).
Never made more than ... as a removable storage interface, RAM with battery or ROM cartridges ... -
maximum addressable RAM for a Z80 using bank switching?What is the maximum addressable RAM for a Z80 using bank switching? The Enterprise64 home computer could address up to 4MB, is this the limit for a …
... configure your bank switched RAM as a RAM disc, you also need ... or 48-64K in the upper RAM), the software I wrote 'saw ... ' the RAM disc as a series of ... , and dynamically mapped to the RAM disc, with used/unused sectors ... -
Spectrum 128K +2 problemhello, i am try to repair my spectrum 128k +2 grey, i remove all ram chips and i have some new ones spares, now i have remove all ram chips, i want …
... - IC32 "main" RAM including screen RAM
IC17 - IC24 "upper" RAM.
Not ... the +2, but if the upper RAM is not present on a ... -
Spectrum 128K +2 problemhello, i am try to repair my spectrum 128k +2 grey, i remove all ram chips and i have some new ones spares, now i have remove all ram chips, i want …
... - IC32 "main" RAM including screen RAM
IC17 - IC24 "upper" RAM.
Not ... the +2, but if the upper RAM is not present on a ... -
Spectrum 128K +2 problemhello, i am try to repair my spectrum 128k +2 grey, i remove all ram chips and i have some new ones spares, now i have remove all ram chips, i want …
RAM failure is the most likely (but there are some other possible causes).
This last picture does indicate that the ULA is working.
[I][B]Mark[/B][/I] -
ZX8401 / PCF1306P / Amstrad 40058 for 48K and 128KZX8401 = PCF1306P = Amstrad 40058, let's get started with that. These chips are used as surrogates. Most of us might think those chips were only use…
... /> So that chip is for upper memory adressing, check out the ... copes with paging, leaving the upper memory logic intact, like the ... half' of the 4164/4532 upper ram chips, so Sinclair could buy ... paging ;)
"Now that all upper ram chips we order fully work ... -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... suggests a fault in the upper RAM, not the lower. This is ... 're able to, try the RAM test program I created and ... . Try it against the upper and lower RAM and leave it running ... -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
Brap brap! It's faulty upper RAM:
[IMG]http://ubuntuone.com/48eEV5ixlM8GGIlyd00iVr[/IMG]
Thanks so much, great little utility! How do I go about identifying which IC# is the offending chip? -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... ' the contacts.[/QUOTE]
The upper RAM is soldered to the board ... it successfully checks the lower RAM?
Will definitely be ... to swapping out the faulty RAM. -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... it successfully checks the lower RAM?[/QUOTE]
It's ... -up test doesn't identify upper RAM as faulty and then the ... 't help either if the upper RAM interferes on the data bus ... 1 and 7 in the upper RAM and I believe those are ... -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... I think replacing the faulty RAM will solve the problem.
The RAM chips are responsible for dealing ... for the lower RAM and another two for the upper. The other ... generating control signals for the upper RAM.
Also, once ... -
128k Basic used much ?Hi - I was wondering if there were many,if any, games programmed in 128k basic? I was also thinking of doing one myself as I wish to make a text heav…
... one basic program that uses ram disk, but for a screen ... 'm sure you can use ram disk, so you'll get ... read the text directy from upper ram with PEEK rather than using ... -
Faulty 48K Issue 3 motherboardHi I have a faulty Issue 3 motherboard and would appreciate it if somebody can steer me in the right direction of where to begin with the fault find…
... /> how did you check the RAM ic's ULA, CPU and ... , etc. as with a lower RAM failure.
I tested the ... RAM IC's, ULA, CPU and ... -
Faulty 48K Issue 3 motherboardHi I have a faulty Issue 3 motherboard and would appreciate it if somebody can steer me in the right direction of where to begin with the fault find…
... black screen. I removed the upper RAM and interface chips so that ... start again:
- Quit upper ram
- Power on.
- Check ... +5v, +12v, -5v in lower ram.
- If spectrum doesn't ... -
Issue 3 board... How to resurrect?Dear Everyone, Now I have a working 48k Issue 3, a sort of working Speccy+ (still having problems with the keyboard, more of that in another post) a…
... typical fault in the lower RAM isn't the cause of ... quite common for a faulty upper RAM IC to interfere on the ... 16K model. Sometimes a failed RAM IC develops a short between ... set of measurements. Remove any RAM IC that gives an usually ... -
Covertape speedloaderThere was a covertape (possibly YS) that had a speed loader / saver routine included on it. It stood out to me as I recall it had a counter on it, co…
... the ROM tape routines to upper RAM, make any adjustments for jump ... -
another faulty zx spectrum +2 to fix!!!Hello to all, I'm new here... I have got a faulty +2 (gray) and start to try fix it... I have read the treads of xaris_sm and Pluto63 as background…
... for lower and one for upper ram.
Also connected were a ... .
I also connected a RAM Turbo with Paul Farrow's ... demos, some games and the RAM tester from Paul Farrow.
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
A RAM failure is the most likely cause. ... power supplies to the 4116 RAM chips (+5V, +12V and - ... are not correct, the 4116 RAM chips will not work correctly ... ROM that will test the RAM and tell you what bits ... of the RAM are faulty.
[ ...Cascading transistorsMiguel (mcleod_ideafix) alerted me on an aspect of a design I'm working on where I am cascading transistors, which may give problems. This is the par…
... display the image. ROM and upper RAM are also available at this ... supply rails to feed lower RAM. The DC-DC converter uses ... data from nowhere because lower RAM won't be ready before ... +5V rail, ULA and lower RAM are ready and working, the ...48k Rubber Key Spectrum ProblemI'm testing my mate's spectrum that hasn't been used since the late 80's. Unfortunately, it seems to keep randomly resetting itself (like pressing th…
... throw up any errors in upper RAM. After a few hours of ...ZX-Spectrum 16KWanted working 16K machine for reasonable price I'm located in NY, U.S.A. Thanks!
... . It has sockets where the upper RAM and necessary support ICs could ...16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
... =mcleod_ideafix;709022]Although non-contended RAM (4532 chips) seem to be ... more Spectrums that have upper RAM faults than lower RAM faults. Perhaps because ...Issue 2 black paper white borderGot an issue 2 here that has a 6c001e ULA, no cockroach, no transistor mod (although you can clearly see on the top of the z80 and on some legs, some…
Turned out to be upper RAM data line 2! All sorted now16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
Is it possible to make a little board like this for the upper ram as well?16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
[QUOTE=gtsamour;711322]Is it possible to make a little board like this for the upper ram as well?[/QUOTE]
Yes. Please wait for further information...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…
... how the Spectrum ROM's RAM test routine works).
upper RAM.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…
... 48K Spectrum with faulty upper RAM, but the initial RAM test routine passes ... a few bytes) of the upper RAM. All sorts of strange things ...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…
... one or more of the upper RAM ICs (most likely) or perhaps ... />
(Tell it to test upper RAM.)
You might also ... POKE and PEEK in the upper RAM - search through the forums or ...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…
... method doesn't always reveal upper RAM faults, but it's worth ...
