Here we are talking about "computer archaeology", contrary to what you might think, a PC XT can be quite complicated, first of all it is not easy to find the manual, which allows the correct settings of the jumpers (or switches), then there is the difficulty of finding suitable HW, although it is true that today there are cards for any, indispensable today, the 8-bit ISA cards with IDE 40 PIN controller, the floppy controller card would also be useful, however if you have an IDE-CF adapter, you can use a memory card of a few MB, they typically had 20 MB disks, So a 16 MB one could be usable, but certainly a 32 MB one, it allows more than enough space, for programs and Windows (version 1. X).

Another problem is the video card, the cards for those PCs were not VGA, maybe later it was used, on what I used around 1990, there was an EGA card, and it has a 9 PIN connector (15 for VGA), today I think it is almost impossible to find suitable monitors, I have some old cathode-ray tube monitors, but I'm pretty sure they don't have EGA type ports, only VGA except surprises, having an 8-bit ISA video card with EGA type port, but I think it's a Hercules (?), I should find an EGA to VGA adapter, that is, 9 Pin M to 15 pin F.

You may be able to get NTSC composite video off the J1 header... which older LCD TV sold in US and Japanese markets might sync and display.... you can get lucky with some PAL TVs that have generous amount of range in vertical hold control to stabilise it, but it might be in monochrome only

BitWrangler wrote on 2024-04-19, 15:03:

You may be able to get NTSC composite video off the J1 header... which older LCD TV sold in US and Japanese markets might sync and display.... you can get lucky with some PAL TVs that have generous amount of range in vertical hold control to stabilise it, but it might be in monochrome only

Thank you very much friend, I find it quite difficult, both for the connection to a TV, and to find a Black and White monitor today, or rather you can find them, but they are not cheap, in the meantime trying to understand who the manufacturer of my card is , I understood some things, the RAM should be 64 KB, then I don't know if it is actually a Hercules or something similar.
The probably simplest thing is to adapt the 9-pin port to a 15-pin port, which in words is quite simple, but in reality it could be complicated.
Of course, as an alternative, there would be the use of a 16-bit ISA VGA, some can be used in the 8-bit slot, in which case any VGA monitor would be fine, even if small in size.

Continuing the talk of the PC XT, I had previously shown an 8-bit ISA video card, well I imagined it was an Hercules, but watching a video on “Necroware”, it explained the difference between Hercules and CGA, in particular I captured the 9-pin scheme, in which it is explained what is connected to the individual pins.

Beyond that I have an old HW catalog, in which it explains in quite detail the HW features of a board, and also there is an equally detailed description, in this catalog instead the board is a Color/Hercules, and has an additional PAL Optical module, which can connect a Color TV (PAL).

Needless to say, I don't have anything like that, and the only solution to see something, would be the use of a 9-15 pin adapter, also visible in the necroware video, I have no idea what it costs, and if it's for sale somewhere, of course if it doesn't cost much, I would avoid a lot of headaches, being able to try that Hercules card (?) 8-bit, using any VGA monitor.

Another card that I do not have, but that would be necessary, is that of the floppy controller, even this one seems capable of reading and writing those of 1.44MB, in memory I remember that on the XT I used in 1990, it read at most 1.2MB, that is, even if you wanted to format to 1.44MB, it was not possible, but maybe it could be a BIOS problem, in any case for the old DOS, the problem is not there, since I have the 3.5” floppy disks of 720KB.

I'm back on the PC XT, finding one between my legs, it wasn't easy, anyway now that I have it, I would like to try to complete the configuration, currently I don't know who the manufacturer of the card is, or even what model it is, the RAM is present on board, the quantity could be at most 640 KB?, but looking at the card they should be less (320 KB?), this could be a secondary problem, later it could expand to the maximum, adding other memory chips.

Finding 8-bit ISA cards today, it is not difficult, but unfortunately they cost !!!

But what is it essentially needed?

First a video card, then a controller, the rest can be useful but not indispensable, at least to get the PC started.

Leaveing out the video card, what controller do you need?

It depends on the disk we will use, considering that the first PCs only had floppy disks, we may not even use an HD, but if we want to put one, the capacity should be about 10 - 20 MB, the alternative is IDE CF adapter with 16 MB memory card, but staying on old disks, you should find an MFM disk and its controller.

If I'm not mistaken, the floppy controller is MFM, and on the first PCs were available 8” or later 5.25” flopps, the 8” ones I personally have never seen or used them, while the 5.25” yes, indeed I had a 360KB reader at the time, and through a special 420KB format program, those additional 60KB, were a very useful plus.

Tomorrow maybe I'll have some time ⏱ to do some HW repairs, we'll see if I can change some capacitors, I have some MB and one or two power supplies, which require this intervention, I don't think I'll have time to try any MB, but who knows?

Searching on the Internet stuff for the PC XT, I found an SD card reader, for parallel port, you can use it on any PC, of course PC without USB ports, so basically ISA or VLB motherboards, it is true that there are USB ISA cards, however this reader could be very convenient, to carry files on PC of which you do not know much, if it did not have the USB the reader on parallel port, it would be an alternative, albeit slower, to transfer files.

Today I ordered for the BIOS programmer, an adapter to program, PLCC32 and DIL32 chips, this allows me to be able to reprogram the chips of most motherboards, I already have adapters to use for chips with 8 pins, let's say that I will be able to program the most commonly used chips, and for me that I make a sporadic use of it, it's enough, later I would have to order some new chips, to use it instead of those that may fail.

I think I will be able to complete by today the work of replacing all the capacitors, on a SOYO SY-6IZM/3, I actually change only those next to the CPU, because some (about three) are swollen, but in order not to have future surprises, and have to redo the work again, I change them all six, so at least these for a few years, it should be ok.

For the replacement, I have the Nichicon 1500uF 6.3V, apart from the greater height, they are identical to those used in the factory, obviously one of the reasons why they swelled, it should be the poor quality, but it could also be the use of an ATX power supply (also of poor quality), that caused the problem.

Honestly, I haven't tried to turn on the MB, maybe it works?

I prefer to start it after replacing those capacitors, the card is uATX with Intel chipset, I think ZX or LX, it has integrated both video and audio, the video memory has four GM72V161621ET7 chips, I think it's 4 MB in total, unfortunately the connector for video memory expansion is missing, even if the card seems predisposed to me.

With the motherboard I received three cards, an ISA TV, and two PCI LAN and Modem, I had not noticed that the ISA card is 8 bit, this card I wonder if you can use it on the PC XT, which I am trying to complete, from the silkscreens it is a card from 1995 or later, I wonder if it can work on such a slow PC (about 5 MHz), or if you can somehow use it as a video card, I think not but who knows, maybe with drivers for Windows (assuming you find some), and connecting a digital decoder, if the resolutions of the card Videos allow it, maybe you can visualize something?

The replacement of the capacitors has been done, unfortunately I do not have professional equipment, and this complicates my work a lot, the welding station I have is quite cheap, and it only acts as a welder, it does not have a pond vacuum, for that I use a manual one, but despite everything sometimes I can not free the holes, for the more stubborn ones I have to act manually or use other techniques, I do not use tiny tips and drill, although they could facilitate a lot and shorten the time ⏱, necessary to free the obstructed holes.

Now this MB SOYO SY-6IZM/3, is ready to be tested on the bench, but I noticed a strange resistance in the back of the Slot1, maybe it's a repair or it's a mod to improve stability (?), or it bypasses some BIOS setting, making people believe that the CPU is for example an FSB 100 instead of 66, but not being a technician and being quite ignorant of Slot1, I have no idea what that resistance connected to that pin does, and I think it's grounded on the other side, maybe it adds a tenth of VCORE, but they are just assumptions, It could be anything else.

There are also three PC100 RAMs of 64 MB each on board, the amount is more than enough to install Windows 98SE or similar, but if necessary they can be changed with others of 128 MB or 256 MB, and it would already be possible to install later Windows like XP, besides I don't think it is possible, except that you perform a CPU Upgrade.

For the PC XT I found an interesting solution, for the video card, I have an 8-bit ISA, which should be a Hercules (or a monochrome one), the connector for the monitor is with 9 pins, unlike VGA monitors that have 15 pins, so to solve I had to find an 8-bit ISA VGA, or a monitor with 9 pin input, or a 9 to 15 pin adapter.

After various searches, I found a fairly inexpensive solution, a connection cable to the monitor, with VGA port on one side and 9-pin port on the other.

Just replace it with that of the monitor, which has two VGA input outputs, and connect the 9-pin to the Hercules ISA 8-bit, while the other goes to the VGA monitor.

Tomorrow I'll try to try a few MB, maybe the Soyo that I repaired in recent days, the card is already complete with RAM and video (integrated), after having carried out the repair, everything should be ok, we'll see, usually replace the capacitors, it does get the MB working again.
However, I have other MBs waiting to be tested, or others that have shown some problems, despite being functional, for these it could be a driver problem or something in conflict, one of these is a Tyan S7, Titan 100AT if I'm not mistaken, with Windows 98 I had some blue screens, years ago I gave up, but today with the necessary patience I could try, maybe it's the right time.

Hi PC@LIVE
Do you by any chance have an HP mainboard model FMB-0902? I belive it came out from an workstation PC, forgot which model tho.

kotel wrote on 2024-04-30, 11:06:

Hi PC@LIVE
Do you by any chance have an HP mainboard model FMB-0902? I belive it came out from an workstation PC, forgot which model tho.

Hello and thank you, I have some HP motherboards, but I don't have the complete PC, unfortunately the acronym you gave me doesn't help me understand which card it is, however the cards you see are part of my retro-HW collection, I'll fix them when I can, but I don't do business.
If you have a card and need help, gladly, maybe if it is possible to see some photos, even better.

I apologize if I haven't written anything lately, because I actually haven't had time to dedicate to the old HW, I'm still waiting for a BIOS programmer adapter, with this I will be able to reprogram almost all the BIOS chips, in particular I will be able to reprogram the DIL32, fairly common chip in turn-of-the-century PCs.

PC@LIVE wrote on 2024-04-30, 14:53:

kotel wrote on 2024-04-30, 11:06:

Hi PC@LIVE
Do you by any chance have an HP mainboard model FMB-0902? I belive it came out from an workstation PC, forgot which model tho.

Hello and thank you, I have some HP motherboards, but I don't have the complete PC, unfortunately the acronym you gave me doesn't help me understand which card it is, however the cards you see are part of my retro-HW collection, I'll fix them when I can, but I don't do business.
If you have a card and need help, gladly, maybe if it is possible to see some photos, even better.

Attaching a generic picture of how the board looks like. It came out of an Hp Workstation Z400. Yes, I do need help with it. If you can, could you tell me specifications of the following components:
Mosfet Q24, Q22,
C202, CE90, CE115, CE116, C204,
R4631, R157, R155, R174, R181, R187,
Thats all the missing parts I could see. All of them are located between audio connectors and NB. Any help would be appreciated.

kotel wrote on 2024-05-12, 18:39:

Attaching a generic picture of how the board looks like. It came out of an Hp Workstation Z400. Yes, I do need help with it. If […]
Show full quote

PC@LIVE wrote on 2024-04-30, 14:53:

kotel wrote on 2024-04-30, 11:06:

Hi PC@LIVE
Do you by any chance have an HP mainboard model FMB-0902? I belive it came out from an workstation PC, forgot which model tho.

Hello and thank you, I have some HP motherboards, but I don't have the complete PC, unfortunately the acronym you gave me doesn't help me understand which card it is, however the cards you see are part of my retro-HW collection, I'll fix them when I can, but I don't do business.
If you have a card and need help, gladly, maybe if it is possible to see some photos, even better.

Attaching a generic picture of how the board looks like. It came out of an Hp Workstation Z400. Yes, I do need help with it. If you can, could you tell me specifications of the following components:
Mosfet Q24, Q22,
C202, CE90, CE115, CE116, C204,
R4631, R157, R155, R174, R181, R187,
Thats all the missing parts I could see. All of them are located between audio connectors and NB. Any help would be appreciated.

hello and thanks for the additional info, unfortunately I don't have a similar MB, and I can't help you in finding the components, if you have the entire PC and the motherboard is faulty, looking for a replacement is perhaps the simplest thing, but it is possible that here on vogons, there is someone who has an HP Z400 PC, if you open a discussion, with title: troubleshooting help (for example), it is possible that they can help you, a second possibility, could be to look at the adverts, and contact the seller, and ask him for detailed photos of the area you are interested in, if done well, they can display the details clearly

Unfortunately in these last few days, the time to dedicate to the old HW has been zero!
So, already from Monday evening, I will have the adapter to program the DIL32 BIOS chips, I will probably start with the ASUS P2B-F chip, if the problem of absence of code in the post card is solved and the card shows a BIOS screen at video, I will have a nice working Slot1 card, and I will start completing the configuration, adding various cards, audio video LAN etc...
Following some YouTube channels, I watch MB repair videos, sometimes it happens that there is no fault, the failure to start is due to jumper errors, or absence of jumpers, then often there are problems with the tracks (interrupted), or pins of soldering to be redone, months ago I bought a USB microscope (cheap), it's excellent for viewing, less good for doing live soldering work, but to have a better one I would have had to spend a lot more.
However, with the little equipment I have, I can try to fix several MBs, and the percentage of success in repairs will go up a little, unfortunately I won't be able to fix them all, but I hope to get close to half of them, unfortunately I still have some equipment missing, maybe in the future I could buy something, but some are expensive, for example the oscilloscope, it should cost a lot, at least I think.
I hope to start some work tomorrow and show the relative progress with images.

Today I got the adapter, to program the BIOS chips, with this I can reprogram almost all the BIOS chips, except some old format, for example from 28 pins, but for the vast majority of the BIOS chips I deal with, the most common formats are those with 32 pins, it differs the type of chip, it is usually a PLCC32, but some cards instead use DIP32, obviously the chips do not have to be soldered, but inserted into a plinth, in case they were soldered, they should be desoldered, not simple operation for me, and absolutely not recommended for those who do not have adequate equipment (Professional).

This adapter, will be very useful with some motherboards, in which no post code appears, if you have all the voltages and there is nothing broken, it is likely that the BIOS may be damaged or the chip is to be changed, in both case, if it does not cost a lot, it is better to use a new one (possibly identical), after reprogramming just try booting, if a BIOS screen appears and the post codes flow, then it will have been a success!!!

The first MB, which I will use to reprogram the BIOS chip (DIP32), is an ASUS P2B-F Slot1, as I have tried several times in the past, and sometimes there seems to be a minimum of activity, I suspect that reprogramming it can get back to work.

Still speaking of BIOS chip reprogramming, yesterday I saw a video on YouTube, I thought that the programmer used (the same as mine) had the Legacy adapter, but not only was it not there, but it showed me a motherboard with DIP8 BIOS chip, which was detached from the MB and inserted into the programmer, so far nothing strange, but it pointed out to me that despite having this possibility, I never used it.

At this point , having some MB 775 with DIP8 BIOS chip, I will be able to reprogram the BIOS, and see if the motherboard will work again, one that I repaired time ⏱ ago, ASUS P5 and something, it may have a damaged BIOS, I think maybe the old owner may have made an incorrect update, if so after reprogramming everything should come back ok .

If it's the removable DIP8 type of BIOS, usually CH341A will manage to get those flashed without issues.

PcBytes wrote on 2024-05-22, 19:59:

If it's the removable DIP8 type of BIOS, usually CH341A will manage to get those flashed without issues.

Thank you very much friend, the programmer is not CH431A, but it is the nano BIOS USB programmer, in addition to that I recently purchased the Legacy adapter, with these I can reprogram almost all BIOS chips, or at least the most common ones, however despite having the possibility to program DIP8 chips, I have never done it, at this point if I have enough time, I will try to recover some motherboards, including an ASUS P2B-F and other ASUS 775, and also other S.7 boards, It doesn't cost me anything to try anyway, if it goes well I'll recover one or more cards.