Included tags: RAM chips ×
Excluded tags: None

VT100 Video Output Problem

VCFed about 3 months ago

I have been restoring a VT100. I have replaced one of the RAM chips and the sender UART for the keyboard and the main board seems to work, except for the video output. I think the bad video output may be affecting the video driver board, so I have removed …

Apple II+ woes continue...

Apple Fritter about 3 months ago

Hey everyone...I have been ignoring my II+ for a while (I have two of them), but got one down to fire up and ensure everything was OK. Obviously, since I am posting here, it isn't OK!I can boot into DOS 3.3 via FloppyEmu or actual disk drive.  No problem. …
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Risks with trial-and-error testing RAM chips?

VCFed about 3 months ago

I recently bought a Baby AT 286 motherboard (OCTEK Fox II, rev 3.0) off eBay that I installed in my IBM 5160 case. * The motherboard looks like this: * The motherboard came equipped with no Dip RAM, but with two SIMM cards slotted in (one 1mb and o …
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RAM blocks architecture and total RAM amount

Apple Fritter about 4 months ago

Hello, gentlemen! I am devouring the masterpiece Understanding the Apple II by Mr. James Sather and the Apple II Reference Manual as well.So far, so good, but I am stuck on the total amount of RAM available and considered by the system. I am aware that th …
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Can anyone identify this soviet RAM-102 module?

VCFed about 4 months ago

Bought this early 90s in the market, when everything that was movable was sold beside fruits and vegetables by people coming from former soviet member states. For the ram chips K155RU7 that are TTL, their pinout, and that they are analog to F93425AP …

Tandy 1000RSX

VCFed about 4 months ago

Picked up a Tandy 1000RSX for $150, which I think was decent given how rare they are. However I noticed it doesn't have any RAM installed in the two SIMM sockets. Is the original 1MB soldered on the board? I can't tell in photos but it looks like there …

Trs-80 model 1 -5v

VCFed about 4 months ago

the -5v mine is reading -5.22 volts? Could this cook the ram? Could this be a defective zener? Am exsperiencing burn finger ram chips? Thanks Joe …

8-bit acorn hardware • BBC B won't boot if it has a Basic ROM fitted

Stardot about 4 months ago

Hi all,This is a duplicated thread to a Facebook post so some folks have already assisted with getting this far.I have a BBC Issue 4 board. When I got it there was no life other than a continuous beep and no screen display. I suspect that the board has be …

Apple IIc memory chip replacement

Apple Fritter about 5 months ago

Hello,I'm planning to restore my Apple IIc and I've noticed that RAM chips are defective.I've searched Internet to find these chips replacement, without any luck.Any suggestions or pointers ? Ideally an European shop would be a plus. Heaps of thanks.Forum …
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8-bit acorn hardware • ADC-06 65C102 Co Pro on a master 'Turbo'

Stardot about 5 months ago

Well friends, I'm looking for any ideas here.......I have an issue 2 ADC-06 board on a Master 128.It is 'running' but distorting the screen output initially.It only does this until the board is warm, then it works exactly as you would expect.I've had it r …

NEC PC-8001 memory size - 32K or 16K

VCFed about 5 months ago

Hello, According to wikipedia the PC-8001 came with either 16K or 32K of RAM. I've only seen the 32K version (picture of my motherboard attached with 16 RAM chips each 16Kx1 bit on the left). If anyone has a 16K machine please confirm wherever their mother …
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Help & Support • Dead Test cart won't advance beyond 1-flash code

Lemon64 about 6 months ago

Hello all,New to the forum as well as to the C64. I've got an NTSC breadbin (250407 style) which seems to have voltages and clocks to spec. Fresh GAL PLA installed. After stepping through some problems preventing dead test from running, I'm now stuck with …
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Software & Hardware • 🔨 Amiga Hardware Faults and Solutions List

LemonAmiga about 7 months ago

The Amiga is a Retro computer. Commodore built the Amiga using the cheapest parts, and the weakest solutions. The chips themselves are prone to fail. During my time with the Amiga A500, at least 1 Agnus failed, perhaps x2 CIA chips, and perhaps also Paula …

PC vs. AT: reasons to own one over the other

VCFed about 7 months ago

You can come at this from any angle you like. I only own 1 IBM machine afaik. A PC/AT I found on the road some years ago. No plans of adding any others (I wouldn't mind another model 25 though). I don't pass up any clones though. I have 2 PC class units …

Temperature Q4 transistor 2SB531 TRS-80 M1

VCFed about 8 months ago

Currently I am restoring a TRS-80 M1 with Japanese PCB and I have now replaced all electrolytic capacitors. The RAM chips have been checked and replaced if necessary. On the RAM IC sockets I measure the correct voltage approximately -5V, +5V and +12V. So f …
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5155 replacement keyboard feet

VCFed about 9 months ago

Whilst I’m waiting for the ram chips to arrive from Poland, I want your opinions. Do I replace the broken keyboard feet with the black nylon ones or the CNC aluminium ones? …

Apple IIe diagnostic fun...

Apple Fritter about 9 months ago

Hey everyone... I'm still working on that IIe that I bought late last year and have been slowly restoring.  I wrote a message on the forums back in December or so and got pointed to Joe's for a new keyboard decoder chip and that fixed that problem right a …
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Commodore 64 can't boot up, Is this mean 6510 failed?

VCFed about 9 months ago

Hi, My C64 boot up with wrong character and with garbage message on the screen. I use Diag Test Cart to diagnose it, it says "NGZERO 0002E02". Because Zero Page memory is internal to the 6510, does it mean 6510 MPU is failed? I tried replaced …

8-bit acorn software: classic games • Arcade Perfect Defender on the Beeb?

Stardot about 9 months ago

I'm not an expert but I was looking at the tech specs of the Defender arcade hardware recently and it seems like it uses bitmap graphics rather than sprites (with no blitter or hardware support) and it has a 6809 1Mhz CPU"There are 24 4116 RAM chips, givi …
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How to troubleshooting, MODEL I could not startup.

VCFed about 9 months ago

Hi, I got a MODEL I (26-1001) recently, but it could not startup. When I push the power button, there is only a scanline on the monitor, just like lost h-sync. First I checked the power output, +5v, +12v and -5v are all normal. I tried to replace Z80 ch …

CPC 464 Version 1 Ram Chips

CPCwiki about 9 months ago

I have a really nice CPC 464 that's been stored so well - not a hint of corrosion or anything. I believe the issue is with the RAM according to some advice ive had, and it probably has this error back in the 80s and was just stored in a case unused sin …
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Help & Support • On/off switch can cause RAM chips to fail?

Lemon64 about 9 months ago

The manual for the Dead Test cartridge states (page 2-2):Several defective RAM IC's may indicate a defective power supply or on/off switch.In what way can a defective power switch break RAM chips?I have just repaired a 250407. There were two bad RAM chips …

Oric Atmos with keyboard issues.

VCFed about 10 months ago

FINALLY!!! In another thread I was asking help for a "dead" Oric Atmos. At the end I had to change all RAM chips, the RAM controller chips, the BIOS one capacitor (I have changed all of them). Now the computer starts to command line but I have so …

Video • Defective S3 801 — Any Chips Worth Salvaging?

Vogons about 10 months ago

Bought this on eBay for a 386 build, but it doesn’t work. There’s some factory rework but long story short doesn’t post in any of the computers I have (6 in total). Sucks because I ordered the ram chips to upgrade it so it double wasted my money.A …
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8-bit acorn hardware • BBC Micro Model B Issue 4

Stardot about 11 months ago

Hello!I purchased a BBC Micro Model B Issue 4 from eBay.It was listed as spares or repairs as there was a constant tone from the speaker.When it arrived I removed the PSU and found that 2 of the capacitors were blown, so I replaced three in total:1 x 100n …