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IN and OUT in hardware terms... what are 'ports'?Hi all, I understand PEEK and POKE, but have never managed to get my head around IN and OUT. The books all go on about how they read from and wri…
... about here is generally either RAM or ROM. If you ... just put in (RAM).
Not so for I/O ... one extra subtlety. The upper bits of the address ... the ULA, where the upper-most bits specify the ... to scan, these upper bits are not relevant to our discussion ... -
64k speccydoes anyone have instructions on how to use the extra 16k found in some spectrums?
... assignment:
Bits 0-7 = Not used
- The auxiliary control ... chips have been fitted as 'upper RAM'.
...[/code][/quote]
... ROM is actually battery-backed RAM. One can turn the write ... off and use that as RAM. CP/M perhaps?
... -
Memory testersHi, Just wondering which software people are using to test the memory in their spectrum. I have been using Zorn's memory tester as described here:…
... 16k are ok but the upper RAM is failing as I presumed ... " and original "PAC man" but not newer and bigger games.
Is this problem Just the ram ic's? Nothing more?
What if there was a Speccy Games Console[img]http://segaretro.org/File:MSEvolution_Black_Console.jpg[/img] This would have made a really good looking spectrum console back in the day (mi…
... the time, but looking back, not a long term solution. Remember ... slower, maybe there would not have been an over supply ... home computers. Manufacturers would then not got their sales predictions wrong ... video connector) and 64k of "upper" RAM making it a 80k bytes ...What if there was a Speccy Games Console[img]http://segaretro.org/File:MSEvolution_Black_Console.jpg[/img] This would have made a really good looking spectrum console back in the day (mi…
... video connector) and 64k of "upper" RAM making it a 80k bytes ... function keys. Sinclair should have not invested money in the QL ...NTSC Compatibility?Correct me if I'm wrong, but wasn't the Timex 2068 the only NTSC clone built of the ZX Spectrum? And I use clone lightly... From what I underst…
... /O port address that does not have any device at that ... side data bus [CPU, ROM, upper RAM, expansion port]. If the ULA ... reading data from the lower RAM, a I/O read by ... at the same time will not return FF hex, but whatever ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... Spectrum apart and all the upper RAM chips are socketed. Also 4 ... expert at soldering. There is not a single solder point that ... on the socket. I am not sure what's going on ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... to allow OKI RAM to be used as upper RAM rather than ... select for TI or OKI upper RAM.
Check for ... coil. TR4 very often (though not always) fails with a short ... or more of the lower RAM ICs. It's a ... now where more often than not one will give up ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... upper RAM chips are indeed OKI chips but the Spectrum is actually not ... photos of the PCB, the upper RAM chips (all socketed) and a ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... upper RAM chips are indeed OKI chips but the Spectrum is actually not ... 's a bit strange, though not likely related to the failure ... ) is set for TI RAM. OKI RAM is supported directly if the ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... high or low RAM type selector, not near the edge ... I remove the socketed upper RAM chips and power it ... it up without the upper RAM chips in place wouldn ... I can rule out upper RAM failure if the Spectrum initializes ... said, I'm definitely not an expert, so this ...Dead issue 3b with black and white barsHi all, I've been donated an issue 3b which has some nice black and white bars with a few flashing blocks. I've done a few RAM tests and could spo…
... chip on the lower and upper RAM. They all gave consistent results ... ? :)
Checking the ULA, not sure whether you meant the ...Unresponsive Spectrum with Magenta border.This Spectrum is taking an age for me to repair, thank for all the help thus far! So after I switch on the ZX Spectrum+ I get the familiar white…
... Z80 was faulty, I would not expect it to get to ... screen.
Is the upper RAM fitted?
Edit: unless ...Unresponsive Spectrum with Magenta border.This Spectrum is taking an age for me to repair, thank for all the help thus far! So after I switch on the ZX Spectrum+ I get the familiar white…
... Chaps:
Yes the upper RAM is fitted
It's ... 6A
The CPU is not socketed
I will ...ZX Spectrum CartridgesI have been thinking of "cloning" ZX Cartridges for a while (case, board and silicon skirt), to be able to make new releases or replace damaged cartr…
... .
If I'm not mistaken, address lines are protected ... ROM cartrige is connected) is not protected, as far as I ... .[/quote]
The resistors are not there for protection. They are ... CPU can access ROM or "upper" RAM while the ULA gets screen ...ZX Spectrum CartridgesI have been thinking of "cloning" ZX Cartridges for a while (case, board and silicon skirt), to be able to make new releases or replace damaged cartr…
... .
If I'm not mistaken, address lines are protected ... ROM cartrige is connected) is not protected, as far as I ... .[/quote]
The resistors are not there for protection. They are ... CPU can access ROM or "upper" RAM while the ULA gets screen ...ZX Spectrum CartridgesI have been thinking of "cloning" ZX Cartridges for a while (case, board and silicon skirt), to be able to make new releases or replace damaged cartr…
... br />
If I'm not mistaken, address lines are protected ... quote]
The resistors are not there for protection. They are ... CPU can access ROM or "upper" RAM while the ULA gets screen ... the Amstrad machines resistors are not used, with chips being used ...Help needed with MIA software with custom (?) loaderHi, I've got into my hands recently a bunch of Polish educational software which are unknown MIA on WOS. I believe they are protected with some…
... ; Move saver and loader to upper RAM
0x5CE6 JP EADA ; ... Jump back to L4 while not 256 pilot pulses found (ROM ... Return if final sync edge not found (ROM)
0xEB27 ... OR E ; register pair does not hold zero (ROM)
...Speed (nano seconds) of memory chips ZX SpectrumThe ZX Spectrum uses 4116 memory for the lower memory, which can be replaced by other sorts or a whole, modern, module, but when searching for 4116 m…
When talking about RAM chip speed, often only one " ... ).
If a slow RAM chip is fitted, the computer ... , the CPU or ULA will not receive the correct data, so ... the "upper" RAM. Faster DRAM chips are fine. Slower chips are not recommended ...48K Issue 2 Spectrum showing exactly 16KI've acquired an issue 2 and it quickly became clear that only 16K of memory is available. I've read that some early 48K Spectrums with malfunctionin…
... chips used, "DRAM" chips are not arranged like you may think ... link to disable the "upper" 32k bytes of RAM, but either LK3 ... to be fitted.
Not having had a 16k ZX ... sell machines with non-functional "upper" RAM as 16k byte machines. It ...Spectrum 48+ 4S - Upper RAM issue, and now a self-created problem!I recently picked up a known-flaky spectrum off eBay, to have a bit of fun fixing it and reliving youth. It was labelled as 'keyboard duff, shows…
... little more testing... It's not quite as clear cut as ... errors, for the whole of upper RAM. So errors start at 34680 ... to the end of the RAM.
[img]http://www ...Spectrum 48+ 4S - Upper RAM issue, and now a self-created problem!I recently picked up a known-flaky spectrum off eBay, to have a bit of fun fixing it and reliving youth. It was labelled as 'keyboard duff, shows…
I've been swapping RAM chips around and had some ... a 2 second delay and not see any difference. Even waiting ... it didn't fail all upper RAM tests.
[img]http ... terms of refresh. I'm not sure why though, as the ...Issue 2 problem.Hi all, I'm trying to repair / upgrade an Issue 2 Spectrum for a friend, but have come accros the following problem. When I power the machine …
... /> As the lower RAM works when the 32k upper RAM is not fitted, I ... the chips used for the upper RAM upgrade. This looks like something ...ZX Spectrum 48k issuesHi all! A couple of days ago I bought my first 48k Speccy off ebay (I already own a beautiful QL expanded with QubIDE interface and 640k ram). It was…
... "]2) a ULA which was not happy with the !RAS or ... timing requirements of the Lower RAM replacement module.[/quote]
I ... ) that separate ULA/lower RAM from ROM/upper RAM/Z80 data lines, may ... need adjustment when a lower RAM ...What are the differences between the +2 and the +2A ?I only acquired a +2 for the first time in my life a few months ago. It works fine. :) I even managed to tracke down nearly all the wargames by the s…
... computers from the 1980s were not well documented to the levels ... ZX Spectrum 48k model was not really designed with any possible ... set replaced the 4116 "lower" RAM which includes the scree, so ... other set replaced the 32k "upper" RAM chips, which is of course ...Disabling the ROM without removing the whole thingHi! I've got my hands on a non-working issue 6a. I suspect the ROM may be bad, but other things may be faulty as well. I've read that in an otherwis…
... in the edge connector does not change the colored squares, but ... well.
- The lower RAM is replaced with a PCB ... with another known working lower RAM PCB (from zigg.net) and ... />
- Removed one of the upper RAM chips (IC15) and there was ...Another 48k Speccy acting as a 16K model.Hi all, I originally was going to post asking for help to fix the new addition to my family a very nice condition Issue 2 sold on ebay as a 16K model…
OKI RAM is not supported by the Issue 2 ... OKI RAM chips which function as fully working 4164's, not the ... the results they produce which upper RAM IC's are faulty.Another 48k Speccy acting as a 16K model.Hi all, I originally was going to post asking for help to fix the new addition to my family a very nice condition Issue 2 sold on ebay as a 16K model…
[quote="balford;903720"]OKI RAM is not supported by the Issue 2 ... OKI RAM chips which function as fully working 4164's, not the ... the results they produce which upper RAM IC's are faulty.[/quote ... 48k one, I could not access any upper ram with pokes, hence this ...Not bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... said "lower Ram OK" then "Upper Ram OK" . I could not do any more ... think it shows I have not damaged anything replacing the capsNot bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... displayed:-. Lower RAM faulty $7FFC : and then : Upper RAM error XP ... : 76543 Value is unstable . Upper RAM error encountered. Cannot proceed further ... both lower and upper RAM faulty .
... time the lower RAM was OK , but not when I ...
