-
Rubber 48k troublesHi. I've just got a 48k to add my collection, but it seems doesn't working well. The computer starts ups finely, but it doesn't load the games. So fa…
... =Spirantho;597771]One of your upper RAM chips almost certainly has a ... -
Rubber 48k troublesHi. I've just got a 48k to add my collection, but it seems doesn't working well. The computer starts ups finely, but it doesn't load the games. So fa…
The upper RAM is ok. :)
Your machine is a 48K. -
Rubber 48k troublesHi. I've just got a 48k to add my collection, but it seems doesn't working well. The computer starts ups finely, but it doesn't load the games. So fa…
Testing with 255 is not sufficient, you will not find any bits that are stuck as '1'. Like Spirantho already wrote, you must repeat the test with pokeing (and testing) zeros.
The address 49999 has no significance, upper RAM starts at 32768. -
Rubber 48k troublesHi. I've just got a 48k to add my collection, but it seems doesn't working well. The computer starts ups finely, but it doesn't load the games. So fa…
... address 49999 has no significance, upper RAM starts at 32768.[/QUOTE]
Repairing another Issue 2 48K Spectrum.I said at the start of the other thread that I've got another one of these and I've started investigating it. The board is more-or-less exactly the …
... Spectrum with its lower RAM removed and so I ... that it would work with RAM installed.
... at all the lower RAM socket pins look reasonable ... problem with the lower RAM, but that something else ... get stuck. Perhaps an upper RAM problem could cause this - ...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…
... a value to all possible RAM addresses. Then, from ... the start of RAM (address 16384) it works ... first address in the upper RAM during this test it ... that go to the upper RAM or one of the ... addresses lines connected to the upper RAM, to see whether RAS ...Colour blocks on displayHi all, I have just acquired another Sinclair product, my first one being a C5, it's a 48K ZX Spectrum. It shows colour blocks on the display when p…
... you want to remove the upper RAM ICs and they are in ...Colour blocks on displayHi all, I have just acquired another Sinclair product, my first one being a C5, it's a 48K ZX Spectrum. It shows colour blocks on the display when p…
... you want to remove the upper RAM ICs and they are in ... this Spectrum had a 32K RAM expansion in 1984.ZX Spectrum not working... issue 4S?Hi, I've bought a "new" broken ZX Spectrum +. The idea was to put an harlequin board inside, but for the moment I'm trying to put it in working order…
... get some 4116s?
- Is upper memory more resistant or it ... -5V missing.
The upper RAM needs 5V only and is ...RFC: Hardware Documentation ProjectI've noticed quite a few threads recently about missing schematics and suchlike. I've also been thinking about the low quality of some of the schemat…
... mode to help finding a RAM failure in non-contended area
RAM were damaged:
[url]http ... memory to help diagnosing intermitent RAM failures:
[url]http://www ...Issue 3B only sees 16k (and RAMTOP NO GOOD on loading)A ZX+ with issue 3B board that i got recently, does not see anything more than 32768 (sometimes 37267..) on "PRINT PEEK 23732 + PEEK 23733 * 256 (Ent…
... likely more (or all) the upper ram is dead?
Also ...Difficult to find upper RAM fault.I've recently repaired an issue 3B 48K Spectrum that had a tricky to diagnose upper RAM fault, so I thought I'd post a report of what I found here. …
Nice write up. I think it's going to be the stack getting corrupted if upper RAM fails after being tested.Difficult to find upper RAM fault.I've recently repaired an issue 3B 48K Spectrum that had a tricky to diagnose upper RAM fault, so I thought I'd post a report of what I found here. …
... that never tries to test upper RAM, so I can boot into ... boot a Spectrum with lower RAM bad chips. System variables, BASIC ... all located into non contended RAM.
Depending upong the ... damage in low RAM, I can even see what ...Faulty rubber speccy - advice neededHello all speccy hardware gurus :) Recently I moved to a new flat and after a long time have some space (and time) to dig out my old Speccy hardware…
... with 4164 and since the upper RAM was socketed, I replaced the ... took out one of the upper RAM chips, and with some leg ... was going on with the upper RAM now! To cut the long ... short, the sockets for the upper RAM were the cheap kind and ...Repairing another Issue 2 48K Spectrum.I said at the start of the other thread that I've got another one of these and I've started investigating it. The board is more-or-less exactly the …
... on the first byte of RAM. Usefully, this is ... . I confirmed the lower RAM (IC13) was not at ... and suspecting that an upper RAM IC would be the ... POKE and PEEK in upper RAM suggested more than one faulty ... I de-soldered all the upper RAM and fitted sockets.
...4116 replaced by 4164 - "Noisy" paper?After I replaced my 4116's with 4164's and hooked them up to +5V, disconnected -5V and +12V, I have what looks like vertical lines in the paper, like…
... CPU is sufficiently low (or upper memory's output impedance is ... that the CPU was using upper RAM - because using resistors was way ...Spectrum 48K help neededI hav got an old Specrtum 48K issue 3. When I plug-in power connector it doesn't show the home screen (c) Sinclair.... From about 50 times trying to …
... be due to a RAM fault - usually in upper RAM.
One ... a ROM that contains a RAM test program.
I ...Spectrum 48K help neededI hav got an old Specrtum 48K issue 3. When I plug-in power connector it doesn't show the home screen (c) Sinclair.... From about 50 times trying to …
I have no ROM analyser or logic analayser.
I have tried many times but it would't initilase. Is there ar way tho check lower RAM chips or to disconnect upper RAM.
Is there are way to bring it working or can I throw it away.Spectrum 48K help neededI hav got an old Specrtum 48K issue 3. When I plug-in power connector it doesn't show the home screen (c) Sinclair.... From about 50 times trying to …
... or to disconnect upper RAM.[/QUOTE]
The upper RAM chips are often ... often due to failed lower RAM, but it's a ... on screen.
Lower RAM checking is a matter of ... add-on test card with RAM test & LEDs to ... clue as to which RAM chip(s) are bad.Replacing Upper RAM in 48KHi Folks Well, my fun continues :) After sorting the display issues with this machine I found I couldn't load software meant for 48K machines. Havin…
Before you replace the upper RAM, consider removing it to turn ...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…
... got one or more faulty upper RAM ICs. Is P-RAMT always ... are used in generating the upper RAM control signals and a fault ... all the CPU and the upper RAM address and control lines with ... during the ROM code's RAM test and this will reveal ...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…
... got one or more faulty upper RAM ICs. Is P-RAMT always ... are used in generating the upper RAM control signals and a fault ... all the CPU and the upper RAM address and control lines with ... during the ROM code's RAM test and this will reveal ...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…
... problem was, as suspected, faulty upper RAM.
Note that the ... working address found by the RAM test routine. So, for what ... try to identify the faulty RAM IC.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…
... a known good set of upper RAM ICs in, what value for ... the former, then swapping the RAM ICs about shouldn't make ...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…
... 32K (i.e. all of upper RAM), so this suggests the test ... , since that selects all of upper RAM.
As you've ... the CPU to the appropriate upper RAM IC.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…
Since i haven't got a continuity test on my meter (because its cheap tat) ive had to use the diode test just to see if there is any connection, pin 3 on the upper ram is displaying results on all of themAssembly game programming on ZX how-to?Hi. I'm planning to build and release new software for the Speccy but I'm pretty lame as to handle its hardware despite a good mastery of Z80 assembl…
... ? Like drawing the "sprites" on upper RAM and "blitting" it to the ... just after the bytes of upper line - unlike in screen memory ...WIP: ULAPlus hardware implementationThis aims to be an "almost" plug-in replacement for the Sinclair ULA chip fitted in Spectrum 16K/48K/Plus machines. It comes in a form of a small PC…
... the Spectrum's own screen RAM is being performed by the ... Z80's writing or reading upper RAM it will obliterate all trace ...Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…
... turned out to be a RAM fault that isn't detected ... by the RAM test routine that is executed ... . It's probably in the upper RAM, but this is not a ... by removing one of the upper RAM ICs; this should make the ...Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…
... the /RAS signals for the upper RAM and so the ROM code ... only the lower 16K of RAM. The output of the voltage ...
