Last Updated on May 1, 2025 by Dave Farquhar
The February 1990 cover of Compute magazine screamed, “build an AT for $1,000!” It was a clone, of course. And a soon-to-be outmoded clone at that. At that time the idea of building a true blue IBM was laughable. Today, it may be the easiest way to get your hands on a 5170 if you want one. Here’s how to build an IBM 5170.
Why IBM 5170 parts are available today
Long story short, a lot of IBM 5170s got parted out in the 1990s. It was easy to extend their usable life by swapping in a generic 386 or 486 motherboard. It fit. And then those surplus IBM parts ended up in a box in the corner.
Later in the decade, surplus 5170s got sold essentially for scrap. That’s how I got mine. I got one, put a Pentium motherboard in it, and used it. When that system was no longer useful, it ended up in the corner of my basement.
What I’m saying is, there are still 5170 cases floating around that may be empty or have later motherboards in them. And there are IBM motherboards and ISA cards sitting in boxes somewhere that could be reunited with one of those 5170 cases. And those parts are worth enough now to be worth bothering with.
Compromises
I could probably write 2,000 words about the compromises people could make in regards to a 5170 project. I’m not sure how productive it would be. Just keep in mind that any 5170 project is going to involve some compromises.
Those compromises don’t have to be forever. Keep your options open, and as opportunities to bring the system closer to what you envision as ideal present themselves, make your move. In the meantime, if you have to use newer parts or something non IBM to have a functioning system, that’s okay.
One compromise almost everyone is going to make involves storage. Nobody wants a 30 MB MFM hard drive. Well, they might want the drive, but they don’t want the reliability issues, and they want more than 30 megabytes of storage. People can argue over what kind of storage to use. The best answer for them may not be the best answer for you.
MFM hard drive emulators, similar to the IDE and SCSI emulators that use SD cards, do exist. Unfortunately, the cost starts at around $175, half as much as the rest of the project, so they aren’t the most practical thing. Someday that may change. In the meantime, I’ve used IDE and SCSI drives in my 5170, and I’m fine with that.
Finding components
Finding components locally is likely to be a challenge. It’s doable, but will require patience and possibly some networking. I remember a time when the shelves of surplus electronics and computer stores were littered with unwanted IBM parts. It would have been pretty easy to build up a very nice collection. Not many people had the foresight to do that.
Today, you’ll probably have to scour online marketplaces, and become a regular at your local recyclers. Recyclers are starting to figure out that vintage computers are worth more than their scrap value, but if you are polite, they are likely to be more willing to sell to you than to deal with the hassle of selling online. As long as selling to you is a pleasant experience, that is.
But for some of the parts, you will probably have to hit up eBay. 5170s aren’t exactly rare. If you have money to burn, at any given time, you can probably get a complete 5170, tested and working. But the price may be more than you’re looking to pay. If you are patient, you can build a 5170 for $400, or even a bit less. That’s not including a monitor. That price may increase a bit over time, but it’s a good target. If you ever need to get your money back out of it, you should be able to sell a complete 5170 for about that.
Let’s get on to what components you will need and what substitutions you might consider.
Case
The case is likely to be the most expensive part, especially if you buy it online and have to ship it. Hopefully the case comes with a functioning power supply. It may or may not be an original IBM power supply. Getting an original would be nice, but many originals got discarded because they have to have a load on the 12 volt line to function, and not everyone working on them in the ’90s necessarily knew that. That means a lot of IBM power supplies that weren’t broken got discarded and swapped out for third party power supplies that didn’t care how much you loaded down the 12 volt line.
I have a DTK power supply in my 5170, and I’m okay with that. It’s been working for a very long time, and it’s never cared what kind of hard drive it has on it.
Making substitutions on the case is kind of difficult, because without a genuine 5170 case, your 5170 will look like a clone. That said, if you have IBM parts but no case, you can put them in any case they fit in, and move them into a 5170 case once you obtain one.
Motherboard
5170 motherboards came in three types. The first two types were wider than the third, and they are distinctive because they have piggyback memory chips. They also run at 6 megahertz. The later type 3 board is a bit smaller, though still slightly bigger than what we came to call a baby AT board, and it runs at 8 megahertz. You can tell which type of board your case originally came with. If it has a plastic support far to the right of the keyboard connector, it came with a type 1 or type 2 board. If it lacks that support, it came with a type 3 board.
That said, 5170 boards turn up infrequently enough that you may get tired of waiting for exactly the right board for your case.
I have seen tested working boards go for $70. And I regret not picking one up for that. I ended up getting an untested board for $50, and that board didn’t work. Fixing it was a fun project, but a working $70 board is a better deal. I spent more than $20 fixing it, but the story is worth something.
Be suspicious of untested boards. You don’t know if an untested board came from the estate of an old computer technician who is now deceased, and their family honestly doesn’t know how to test the parts. That is one possibility. Unfortunately a more likely possibility is the person did test it, couldn’t get it working, and is selling it as untested, hoping to get more than they would get selling it as broken. You should probably assume the latter.
As far as substitutes go, any 286 board can stand in. It will provide a similar experience, it just won’t have the limitations of the IBM BIOS and it won’t have ROM Basic. Those things may or may not matter to you. You could also go newer, and substitute a 386 board of some sort, then use that board in another build once you get a proper 5170 board.
Disk controller
IBM used a single disk controller that covered both the hard drive and floppy drive. Some BIOS revisions get cranky if they doesn’t see this card. You can either patch the BIOS, or use this card, and put a second bootable card with a newer drive type in the system.
Having this card is entirely optional. That said, some 5170 boards do not like not having this board. You will have a more genuine IBM experience with this card.
These cards aren’t terribly difficult to find, and you’ll pay around $30 or $40 for one.
This is an easy card to substitute for. Any 16-bit ISA disk controller will do. The only caveat is that with some combinations of motherboard and BIOS revisions, you will have to live with 601 errors on boot that require you to hit F1 to continue, or patch the BIOS to skip that test so it will boot without interruptions.
Parallel and serial card
IBM also shipped the 5170 with an 8-bit ISA card that had parallel and serial ports on it. You can tell this card from the one for an XT by the 9 pin serial port. You will also note the presence of a 16450 UART chip rather than the earlier 8250.
That said, this card is entirely unremarkable. Any number of other companies produced functionally identical cards, and these functions frequently were integrated onto third-party memory cards. This card is a luxury, but if you want to have as many original IBM parts as possible, look for one of these.
Video card
This is where purity and practicality collide. IBM sold three cards for the 5170. None of them were VGA. All of them were full length and 8-bit. IBM’s EGA card had limitations that third party EGA cards did not. The biggest limitation was the amount of memory. You will either need to build a memory expansion for it, or find a third party EGA card.
Or you could use a VGA card, which will allow you to use practically any monitor you want. It will also increase the amount of software you can run on the machine. But you will lose the iconic look of a 5170 paired with a 515X series monitor.
That said, tracking down a genuine IBM CRT is a very expensive and time-consuming endeavor. There is a very good chance you will need to outfit your 5170 with a VGA card and some kind of VGA monitor. Or, you can use an IBM video card with an adapter to convert CGA or EGA to VGA, so you can use an IBM card with that newer monitor. You will have to decide if that’s worth it, or if it’s easier to just use an ISA VGA card.
Memory card
IBM did sell a 128k memory card to bring the system from 512k to 640k. If you want as many IBM parts as possible, this is one you will want to seek out. IBM also made a 512K card to provide 512K of XMS memory. However, it was not uncommon at all to replace this card and the I/O card with a multifunction card that provided I/O ports, 128k of RAM, and additional memory that the system could use as XMS, including more than you could get direct from IBM. IBM didn’t make these multifunction cards, but any number of other companies did, including Intel and AST.
I saw very few 5170s that didn’t have one of these cards in them. They were extremely common. There is little doubt that some software you want to run will need some extended memory, so you will probably want one of these. Look for one that is tested working, and if it doesn’t have memory, look for one that uses SIMMs rather than individual chips. It is much easier to find 30 pin SIMMs.
The main question is whether you use one of these cards instead of the other two IBM cards, or an addition to one or both of them. It will depend on how blue you want the system to be, and how many slots you have available.
Floppy drive
IBM used 5 1/4-inch floppy drives made by a company called YE Data. The drives they made for IBM have a fairly distinctive look. I have seen those drives in clones, but it was much more common for other companies to use Teac or Panasonic or Toshiba drives. The standard drive stored 1.2 MB. When the systems were relatively new, people frequently outfitted them with a 360k drive in the lower bay, because you cannot write to 360K disks with a 1.2 megabyte drive reliably. Other 1.2 megabyte drives will read the disks fine, but 360k drives will struggle to read them.
Once the PS/2 became popular, it wasn’t uncommon to install a 3 1/2-in drive in the second bay. It was much easier to get a 720k drive working than a high-density drive, but putting a 3 1/2-in drive in a 5170 isn’t blasphemy.
For the system to look right, I recommend tracking down a 1.2 megabyte YE Data drive. For a second drive, install what you like. The IBM BIOS isn’t fond of 1.44 MB drives, but if you have the 1985 revision and you use the third party GSETUP program, you can use usually get a high density drive working.
And a Gotek is a convenient option. Even if you end up replacing it with a floppy drive, using a Gotek to install DOS and the initial pieces of software you need makes things go faster and easier.
Operating system
What OS to run? Some form of DOS is the most practical. Some people bought 5170s to run Xenix, but DOS was what most people ended up running on them.
IBM and Microsoft both participated in the development of DOS. A 5170 can run either MS-DOS or IBM PC DOS, in addition to FreeDOS or DR DOS. I prefer to stick with some form of IBM PC DOS on a 5170, because, IBM. Version 3.2 or 3.3 is probably the most period correct but has size limitations on your drives. DOS 5 or newer is more practical. I think IBM PC DOS 2000 is the best overall choice. IBM sold it as a Y2K compliant DOS for those who couldn’t run Windows 98 or NT. But you can think of it as MS-DOS 6.22 with better memory efficiency. Its memory footprint is lower than that of DOS 5.
One can argue forever about the OS that provides the best and most authentic experience on a 5170 and whether the two things mean the same thing. But IBM PC DOS 2000 is an underrated choice here.
Sound card
By the time the Ad Lib sound card came out, the 5170 was aging fast. That said, The two did overlap a couple of years, and plenty of software that runs on a 5170 does support a Yamaha OPL chip. A genuine original Ad Lib sound card costs a fortune, so it may or may not be practical. An early Sound Blaster card is also a reasonable choice, but those are fairly expensive as well.
A reproduction Ad Lib card is a reasonable choice, and won’t break the bank at $45. You can also use a later Soundblaster 16 type card. It’s a little new, but still fairly affordable, and it’s possible to get it to work. Another option would be to use an Aztech sound card. These off-brand cards actually contain a genuine OPL3 chip, so they behave like a Soundblaster 2.0, but cost less than a repro Ad Lib card.
No matter what you do here, you’ll be going third party. Trust me, you do not want an IBM M-Wave card. It’s the right brand, but it’s too new, and way too much of a hassle. The question is, what seems more in character, and what’s more attainable. To me, a brand name sound card feels like a better match for IBM than a knockoff. I’m more inclined to use my knockoff cards in clones.
Network card
I really like having a network card in any vintage PC, because I can load packet drivers on it, and then use FTP to move files from my new PC to a vintage one without using floppies. It’s much faster, more reliable, and convenient than floppies or even a Gotek.
I have an NE2000 clone in my 5170 because it was the only card I had that would take an XTIDE BIOS. If you can locate the utility to configure it, the driver for it is easy to get working. Some people prefer Intel or 3Com cards, and that’s fine. They’re certainly easier to identify and locate the appropriate drivers and utilities for. Go with what you like and are familiar with. For these purposes, you probably won’t see much performance difference.
Any card with an RJ45 connector is a bit new for a 5170. That said, the older technologies are much more difficult to use in conjunction with the RJ45 that the rest of your network probably uses. This is a good place to compromise. Besides that, most ISA cards that have RJ45 are modernized versions of cards that would have been used in a 5170.
Hard drive
This can be a bit of a sticking point. It’s also a place where the 5170 shows its limitations. The largest drive the 5170 BIOS supports is 117 MB. IBM did not want people buying a 5170 instead of a mini computer. And in 1985, a 5170 with half a gig of storage running Microsoft Xenix would have been tempting as a substitute. The same mindset clocked the system at 6 MHz initially.
At any rate, you are going to want something bigger than 117 MB. The easiest way to make that happen is to use IDE or SCSI. You will probably end up using a controller that is newer than most of the rest of the system, and then there’s the question of whether you use solid state or a spinning disk. All of that is your decision.
There were 286 class systems that ended up with 1 GB SCSI drives in them in the late ’80s, so imitating a system like that isn’t entirely unrealistic. At one time, IBM was a major manufacturer of those types of drives. So you could even put an IBM branded SCSI drive in your 5170.
I used a 128 MB compact flash card for storage for a long time but eventually installed an XT-IDE BIOS on my network card so I could use a 2 GB compact flash card. I found 117 MB wasn’t enough. I’ll probably find 2 GB is more than I need but the 2 GB card cost $10, so that doesn’t bother me. And using XT-IDE also allows other tricks so I can run my 5170 without a battery.
Broken parts
It is best to assume an untested part is actually broken. It is also possible at working part will fail given enough time. The tantalum capacitors that IBM was using at the time do have a tendency to develop shorts. If you have never tracked down a shorted capacitor on a board, you will probably end up needing to learn how, if you want to get into a 5170.
Ideally, when you have a broken part, a shorted capacitor is the problem. It is also possible you can have one or more bad chips. Fortunately IBM used lots of discrete components, and most of those parts are still possible to buy, but only a few of the chips will be in sockets.
If you buy broken parts and fix them, that 5170 will be yours in more ways than one. It’s harder to buy parts and put them together than to buy a complete system. It’s harder still to fix broken parts and make a working system out of that. Whether that seems like fun is a question only you can answer.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.