|
Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
|
Thread Tools |
16th May 2020, 5:37 pm | #21 | |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
When I was in college in the early 2000s, I got a free mother board like this, it had to be pressed in just the right places to work, I glued match sticks under the mb in little stacks, it only worked overclocked from 75mhz to 90mhz otherwise the keyboard would not work? and then all the I/O died one port at a time! so I put in an ISA multi I/O card savaged from a 286, the psu was dried up and put interference on the CRT, but worked reliably for 24/7 running the text windows nt4 version of SETI@home on 32mb of ram running Windows 95, I think all the PCI bus was dead and so used only ISA cards? I have read about how vias are made and it seems like chemistry voodoo! Is it possible the spot likely weak PCBs? One way to fix this would be like with the Amiga 500, new updated PCBs are being made and people transferring the old chips to a new motherboard! But this seems slightly extreme, but very cool. am I wrong in thinking because the high frequencies invoved patch wires can't be used to bypass the bad vias? How hard is it to find the bad vias to bypass? Would it help to have a good board to compare? I always thought my old Pentium 75 motherboard had cracked tracks internally I didn't suspect the vias! Anyway I've got a little bit off track, I was talking more about preventative maintenance than repair How did you diagnose and repair it? |
|
16th May 2020, 5:38 pm | #22 | |
Guest
Posts: n/a
|
Re: How long can a computer last?
Quote:
These are not as mass/energy efficient as a fission reactor by any means but they are everso reliable, simple and don't need a control system. 20 light hours away at 160 bits/second, that works out at 2x10^12 bits a second at one mile. And all I get is a paltry 50x10^6 bits a second. A million time worse! |
|
16th May 2020, 5:50 pm | #23 | |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
Do they have a parity check or could one be added to detect the start of bit rot on boot? or is it better to add a program in the os to periodically scan them? Would an EPROM need UV wiping if you are storing the same code? |
|
16th May 2020, 6:00 pm | #24 | |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
I have only recently needed to add a used old GPU as it used integrated graphics as it was originally specified for word processing email and googling thow using Yahoo then! It does now have a 120gb used sata SSD, that replaced the much older 80gb hard drive from when it was a Pentium 4 Last edited by audion_1908; 16th May 2020 at 6:02 pm. Reason: Missing t |
|
16th May 2020, 6:04 pm | #25 |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Would x-rays help?
|
16th May 2020, 6:07 pm | #26 | ||
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
Can ssds be stored in a freezer? Could the way to go is to use ssds with good firmware and a type that stores the minimum bits per cell so older ssds or enterprise-grade, or to mirror the database half on ssds half on rugged mechanical hard drives, do ruggedized mechanical hard drives make much difference to reliability with lots of vibration? Would rewriting the data every 20-years be often enough? Or go more radical, net boot the all the SSD based computers, and have the data copied to them from magnetic tape backup before use if the computer is expected to not be used for a long time? https://www.ni.com/en-gb/support/doc...endurance.html Storage Temperature, Max storage duration at end of drive life (°C) 85, 2 days 80, 4 days 75, 6 days 70, 10 days 65, 18 days 60, 32 days 55, 56 days 50, 104 days 45, 192 days 40, 365 days 35, 1.9 years 30, 3.8 years 25, 7.8 years 20, 16 years 15, 34 years 10, 75 years 75 years for an end of life sdd at 10°C looks good! Last edited by audion_1908; 16th May 2020 at 6:33 pm. Reason: Missing , |
||
16th May 2020, 6:09 pm | #27 | |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,191
|
Re: How long can a computer last?
Quote:
I am a somewhat serious computer collector with a couple of hundred machines (not just micros, quite a few PDP11s, a couple of VAXen, Philips minicomputers, etc). Some are 40 years old and still work. I have had to replace ICs in some of them, but I've kept the architecture the same (in other words I might replace a 74xx with a 74LSxx if the circuit can cope with it, but I've not replaced all the innards with an RPi running an emulator). I back up firmware whenever possible (copy-protected microcontrollers, PALs, etc are a PAIN!). But I do not expect them (or even older PCs) to run the latest programs. They run the software that was current when they were in use. I have a modern-ish machine to go on the internet, display/print service manuals and data sheets, etc. I do not pretend to understand how it works, I am not able to program it. But I do understand my PDP's, PERQs, HP9830, etc to component level, I understand the CPU microcode. And so on. |
|
16th May 2020, 6:26 pm | #28 |
Octode
Join Date: May 2010
Location: Grantham, Lincolnshire, UK.
Posts: 1,172
|
Re: How long can a computer last?
I am intrigued that no one so far has commented about lead free solder. Then this arrived 15 or so years ago I read up on it and found that the military and control systems were allowed to use leaded solder. It was simply more reliable.
I have read numerous threads where people have cooked their motherboard in an oven at140C for a few hours to get the tin solder to reconnect, any others done this? In the 70's there was a huge amount of discussion about tin dendrites in bipolar PROMs, apparently fixed now, but tin still grows dendrites. My main work computer is now about 29 years old. A 486-25 with 800MB IDE disc running MS-DOS 5.1. This isn't used so much now but powered on every week or so over that time for an hour or so. Still good, thank goodness, the disc backups I made I can't read for some reason. Bit like test equipment really, stuff from the 60's still works, no EPROMs though. |
16th May 2020, 6:36 pm | #29 | ||
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
It would be a sad waste to gut a computer and put a Raspberry Pi or equivalent in it. |
||
16th May 2020, 6:40 pm | #30 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,191
|
Re: How long can a computer last?
If the requirements don't change then a computer will carry on running the programs it always ran.
'Embedded' systems (whether a microprocessor in a bit of test gear or a minicomputer running a power station) are just an example of this. |
16th May 2020, 6:41 pm | #31 | |
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,529
|
Re: How long can a computer last?
Quote:
Regarding lead free solder, I understand the issue is that lead free solder is way more likely to suffer from tin whiskers. It's 'a bit' inconvenient if some mission critical piece of hardware fails due to a tin whisker, and has to be brought out of orbit for repair. And it has happened. I've seen photos of a tin whisker on a clock crystal that caused the device to be retrieved and return to earth for investigation. Fair enough to allow a bit of lead if it prevents this. |
|
16th May 2020, 6:49 pm | #32 | |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
I have read about old server rooms with layers of abandoned obsolete cabling under the rased floor and the floor panels and supports being made out of zink plated steel forming zink wiskers that eventually grow long enough to snap off and end up frying the computer/server power supplys, and the more it gets disturbed the worse the problem. So no zink plated steel around the computers. 29 year old 486? Would the motherboard be isa only and use through hole TTL chips? If so you may have the most modern computer that can be easily repaired indefinitely using generic TTL chips, thow with a 5v to 3.3v adapter between the CPU and mb an and 5x86 capable of running at 150mhz but depending on your fsb 100 or 133mhz, I would be tempted to do that! What do you use it for? Last edited by audion_1908; 16th May 2020 at 7:18 pm. |
|
16th May 2020, 6:59 pm | #33 | |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
|
Re: How long can a computer last?
Quote:
Traditional EPROMs don't have any kind of inbuilt error checking per se. Once upon a time it used to be common practice to write or print the 16-bit checksum of the data on the EPROM label so that if you suspected a dud EPROM you could read it, the reader would tell you the checksum and if the checksum did not match you knew you had a corrupted EPROM. Very often the firmware and the 'OS' is one and the same thing and held in EPROM or EEPROM. Yes, you could make the first task of the firmware be to check its own integrity but that relies on the code for the check itself being the last thing to get corrupted. No, you don't normally need to erase an EPROM before refreshing it as long as the code you are trying to over-programme it with is identical to the code already in it. The programmer will come up with a warning like 'Device is not blank, are you sure you want to proceed?', to which the answer is YES. If you are certain that the EPROM in question is currently 100% OK, read it, save a copy of the code and stash copies literally everywhere, and only then do you over-programme the original EPROM. if something goes awry, at least then you haven't destroyed what was your only working copy of the code. As has been said, other programmable devices pose a much greater problem because their code is often intentionally protected from being read, so the premature death of a microcontroller or programmable logic device can spell disaster - you can buy another blank device but the only person likely to have the code that needs to go in it is the manufacturer, who may not be around any more. I have a third-party Atari ST HDD interface PCB which is unfortunately in this position - one of the GALs has failed, and the manufacturer is long gone. Luckily, as it was the controller and not the HDD which failed, I was able to connect the drive itself to a SCSI card plonked in a Linux PC and make an exact image of it, so at least I have been able to recover the drive contents. That drive image is now on an SD card which is in a little box which the Atari ST 'thinks' is an original external HDD unit. I would like to get the original unit going again, but I would probably need a whole replacement HDD interface PCB. |
|
16th May 2020, 7:01 pm | #34 | ||
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
I can't imagine the baking dose the capacitors much good! Taking a cooks blowtorch to a laptop GPU to fix it would get a lot of YouTube views now! |
||
16th May 2020, 7:13 pm | #35 | ||
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
So copy protection might be my enemy! Protect a company that's long gone! Also the EPROM burner can do a read verify after burning. The GAL it's like a small FPGA? Could it be reverse engineered or you get the code from somebody else's good one, maybe somebody on the nets has reverse engineered it? |
||
16th May 2020, 7:20 pm | #36 | ||
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
|
||
16th May 2020, 7:27 pm | #37 | |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
|
|
16th May 2020, 7:28 pm | #38 |
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
How are the solder joints inspected? With a microscope? I would not like that job!
|
16th May 2020, 7:36 pm | #39 | ||
Hexode
Join Date: Nov 2009
Location: Chertsey, Surrey, UK.
Posts: 456
|
Re: How long can a computer last?
Quote:
How long is solid state diffusion likely to take before it starts killing chips? I presume chips with smaller transistors running at higher temperatures are more susceptible. So good cooling over stock, could help. I know having good documentation makes the difference between a piece of unrepairable junk and an easy fix I have a basic 10mhz CRT scope that's probably 30 or 40 year's old but I can't find a schematic and it has toasted resistors, and mystery capacitors, so I am stuck on how to fix it, if I had a schematic it would be easy. I know the IBM XT was fully documented, but how far did it go? where there fully documented TTL only through hole, 486 motherboard? How do modern hard drives use sneaky firmware? Last edited by audion_1908; 16th May 2020 at 7:43 pm. |
||
16th May 2020, 7:45 pm | #40 | |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,485
|
Re: How long can a computer last?
Quote:
Taking a simple case, GALs are sometimes used as custom address decoders, so that when the value of the address on the data bus is within a certain range, one particular IC or set of ICs on the bus is selected. When the value of the address on the bus is within another range, another IC or set of ICs is selected. Sometimes other lines are involved as well, such as the read data / write data lines. You can take this chip, use a test circuit or a microcontroller to apply every possible address and control line combination to the inputs of a known good GAL and record the states of the GAL outputs in each case, then, having created a 'truth table' for the GAL, you can recreate the code which needs to go into that type of GAL to make it behave in that way. This of course depends on your having either the original device, still working, or a working one borrowed from another unit, so you can analyse its behaviour. |
|