I have an old Aopen mid tower with not the usual Pentium II or III machine inside but the machine inside is a IBM AT Model 5170, I found most of the parts of that machine in a pile at a company, they wanted to throw it away but I could have it, so long story short, I had assembled that machine inside the AOpen HX45 casing, the powesuply is a later model Delta AT unit, 200 watts which is enough for the AT.
The drive is interesting, it has a Seagate ST-4026 harddrive which is 5'25" full height, so as big as two CD-ROM drives on top of eachother, the drive is a very early voice coil actuator drive, older MFM drives used stepper motor to position the read/write head, the 4026 basically has the technology still used in current harddrives only on a HUGE scale, platters, read/write heads etc, they're HUGE.
It has a new old stock IBM(ALPS) 1.2MB floppy drive which is incredibly well built, lovely drive.
AT boards don't have on board stuff, so HDD and FDD are connected to a full length HDD/FDD controller, the harddrive has two cables, one for data and one for the controller, MFM drives did not have their controller on the drive itself.
I have installed a Hualon VGA card, this is an 16 bit ISA card with 256KB RAM, yes, that's KiloByte.. it was made by Hualon Microelectronics Corp. which seems to be based in Taiwan.. it is ancient, it is ISA and it actually works so that's really great

Of course there has to be a COM and Parallel port card, these are also not found on board actually, I also have a LAN card which is an unknown, I've not taken a good look at it but hey, was free thus awesome anyway.
The mainboard itself onl has 512KB of RAM so there's a 128KB memory card fitted to up it to 640KB, I don't have an EMS card or anything which is a pity, the 80286 can address 16MB of RAM but no machine I've ever seen had more than 2-4MB which was because RAM was ludicrously expensive back then..

The last card installed is a 16 bit Crystal Sound sound card, 16 bit, it is one of those just NOT Soundblaster cards, so compatibility was a maybe, some games could use it others not.
I have built the machine a few years ago but didn't go beyond installing DOS onto it and some utilities like ancient Norton Utilities and PC-Tools so today I plugged it in and switched it on which was kinda a bit scary, most parts of the machine were built in the 80's, the mainboard probably in 1984 so it is nearly 39 years old.. but "click" harddrive spins up, floppy seek and the inevitable error 161, the AT has a CMOS memory like a new PC but there's no battery installed so you either have to be able to use the GWBasic commands or have the setup floppy, I have the latter, so you can set time, date, floppydrive type, if you have a graphics card yes or no and of course harddrive type.. so.. I didn't remember which type the 4026 was, found it online though after some duck duck going, it's type 2 which is usually suited for all 20MB HDD's.

Rebooted the machine and tadaa smooth sailing everything just works fine as if it's new, even the ultra large and rather fragile harddrive, no strange noises, no bearing chatter which would mean the bearings are shot, it just works, you can say what you want about this old beast but damn is it durable.
Back in the day this would have been a VERY expensive machine $6000 at least and according to Wikipedia that would be $16,300 in today's money.
Some benchmark results from System Snooper and Checkit
It is 3.17 times faster than a IBM XT ! at a blistering 1090 Drystones, also with having a 80287 Coprocessor it is 22.75 times faster than the IBM XT with a 150,1K whetstones score

The Hualon VGA card dishes out a majestic 4,315 characters per second.. hold your applause

and the rocket ship of a harddrive manages.. 146!! KiloByte per second!!
