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IBM PC AT sacrilege (AKA upgrade special)

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    IBM PC AT sacrilege (AKA upgrade special)

    SO I wound up through some misguided eBay bidding with 2 IBM Personal Computer AT 5170 machines. One of them cam from the US (made in USA machine) & the other machine came from Germany (funnily enough the shipping was less than the machine from the US?) and that was a made in UK machine.

    Both have rev1 6mhz motherboards with 512k

    The made in UK machine was the better of the two, and was much more original. so it's the machine i opted to install an IBM EGA card, and keep the IBM 5.25" floppy drives. more or less an All IBM machine.



    The other machine, was no where near original. It had an aftermarket seasonic 230w psu, Seagate 251-1 hard drive, and a 1.44mb floppy drive.
    the machine also has an aftermarket AMI 286 bios. The floppy /mfm controller had also been swapped out with a WD card, possibly to support the 1.44mb floppy and 40mb mfm? anyways. It also included an Intel aboveboard, ATI VGA card, etc.



    What I would love to be able to do to this machine is add an intel Inboard 386 AT, but seeing as those are rarer than hens teeth, I settled on another solution.


    I picked up this MONSTER full AT Mylex 386 motherboard on Fleabay for a pretty good deal i thought, 4mb ram, 25mhz 386, cyrix fastmath,



    Now That I've picked an upgraded motherboard, I may as well upgrade the storage. I posted a thread earlier asking about an IBM RT ESDI controller, which thanks to ya'lls recomendations i will be avoiding ESDI. Which got me thinking, why not go scsi?

    Scsi would be a good option, then I would have the freedom to run any 50pin scsi hard drive ( I'm thinking full height 5.25" so it sounds like a jet aircraft), something like an SD2scsi, and a SCSI CD-rom (maybe an early caddy drive)

    I'm sure there are people here which much more knowledge about this than me, as I have only ever used scsi in PIII machines with ultra 3 scsi...

    ANYWAYS.

    I figured a scsi controller like something here would be idea, as i can simply replace the WD MFM/floppy card with this.


    I'm sure it doesn't make a huge difference, but I was told NCR & future domain scsi cards are fairly descent. I'm looking at options on eBay, and these seems to be MUCH MUCH more common than ESDI cards. This should also give me the ability to run a CD rom drive off the same card which would be nice.

    I'm trying to build this system in a "period correct" early 90s upgraded 5170 just as a fun project to play with. something different. (yes I know I could just used an ISA IDE card (I have a few of those) a CF-IDE and an IDE CD-rom but where is the fun in that?

    #2
    Nice upgrade!

    Comment


      #3
      Originally posted by pinkdonut666 View Post
      The floppy /mfm controller had also been swapped out with a WD card, possibly to support the 1.44mb floppy and 40mb mfm?
      Nope. It is a BIOS thing, only the newer AT BIOSes supported 1.44 MB.

      Which got me thinking, why not go scsi?
      IMHO SCSI disk are rare compared to IDE drives and more expensive. So why not using IDE? In combination with XTIDE Universal BIOS you can almost any IDE drive although the UB will limit the usable storage to 8 GB. And that has been no problem for me so far.
      With kind regards / met vriendelijke groet, Ruud Baltissen

      www.baltissen.org

      Comment


        #4
        You can run the XT-IDE BIOS from EPROMs rather than from a card slot. My AT has such a setup; the AMI 286 BIOS is set up to have "no HD", although there is a 10 GB HD on board with three 2 GB partitions. The XT-IDE BIOS controls the HD directly.

        A DTK IDE controller provides the interface with the drives (HD, 1.2, 1.4) while an Adaptec 1522A SCSI controller interfaces with an external ZIP drive. You could also drive FDs or CDs from the 1522, although the internal SCSI CD is getting rare and more expensive.

        -CH-

        Comment


          #5
          Originally posted by Ruud View Post
          IMHO SCSI disk are rare compared to IDE drives and more expensive. So why not using IDE? In combination with XTIDE Universal BIOS you can almost any IDE drive although the UB will limit the usable storage to 8 GB. And that has been no problem for me so far.
          IDE would be easy, I've already played with using a modern IDE HD and CF cards in the AT. But that was boring imho. and if i'm being perfect honest, I'd like to run a full height 5.25" hard drive of some sort, and large 1.2gb scsi drives are tempting & fairly affordable. I like the absolutely ridiculous sound of a full height drive in operation. Also trying to find an early Caddy or other early CD-ROM in scsi is easier than IDE. I'm guessing because scsi is less in demand.

          Comment


            #6
            I've used that SCSI card and it works great. The problem with and old SCSI CD-ROM is a longer length. Make sure it fit's and if all the belts are good. Many just don't work any more. I'm down to my last SCSI CD-ROM for use in an PC/XT with an 8bit scsi card I found. I setup an old 386 and installed many software programs to set up a PC/XT HD. I then burned the folders to a CD-ROM and can quickly redo a HD on one of those old machines.

            I've never gotten a IDE CD-ROM to work on a PC/XT computer.

            If you look hard enough you might just snag an old SCSI HD. 50pin ones for older computer works best. AT machines you ca use th 68pin interface.

            framer

            Comment


              #7
              so the Mylex 386 motherboard came in ov er the weekend and wow this thing is awesome! full sized AT board, and a direct swap/ perfect fit for the IBM 5170. even the front panel LED and keylock connectors were a perfect fit.




              For now I did decide to use an IDE controller with an IDE to CF. it works but it is bizarrely quiet.


              I added an old 3.5" MFM drive just connected to power for some sound :P (and so i don't misplace the mounting rails)




              Works pretty good! lets see some benchmarks...




              Nice... I wish i had results from the 6mhz 286 to compare...

              I ended up popping it back apart and adding an IDE CD-ROM drive for testing




              Well, that all seems to be working well. Being that it ended up being close to 2AM by the time I got the machine this far, I said screw it lets see what this baby can do!



              good things don't come from a 2am decision to run Windows 95 OSR2 on a 20mhz 386 with 8mb of ram lol. I will report back with more gaming benchmarks for anyone who is interested.

              Comment


                #8
                WFW 3.11 would seem to be the ideal option if you want to get it online, there are ways to add win95 components to allow better compatibility with 32 bit applications.

                Comment


                  #9
                  Originally posted by pinkdonut666 View Post
                  IDE would be easy, I've already played with using a modern IDE HD and CF cards in the AT. But that was boring imho. and if i'm being perfect honest, I'd like to run a full height 5.25" hard drive of some sort, and large 1.2gb scsi drives are tempting & fairly affordable. I like the absolutely ridiculous sound of a full height drive in operation. Also trying to find an early Caddy or other early CD-ROM in scsi is easier than IDE. I'm guessing because scsi is less in demand.
                  I have a 1.2 GB SCSI full height drive on my DeskPro 386/25. Nothing says "I mean business" like a full height faceplate with a serious rumble behind it. WfW 3.11 w/ TCP/IP stack is the perfect match for this setup. I have an external SCSI CD-ROM and Zip drive so I can share them with other machines, but I rarely use them. Being on the network and accessing the Samba share on my server obviates most of the need: it is the gateway for my floppy net, having a 1.2 MB drive and a 360K drive.

                  I also run NT 3.51 on this machine, but 10 MB means it's an exercise in swapping to run anything more meaningful than file copying. And you thought Windows 95 was a bad idea

                  Comment


                    #10
                    Don't worry guys I wasn't planning on running Windows 95 on a regular basis it was just a bit of fun :P The machine has a proper copy of DOS 6.22 and WFW3.11

                    Originally posted by resman View Post
                    I have a 1.2 GB SCSI full height drive on my DeskPro 386/25. Nothing says "I mean business" like a full height faceplate with a serious rumble behind it.
                    Exactly lol. I'm looking at a 1.2gb or even a 2.9gb full height scsi drive. the sound of that thing spinning up <3

                    I've got my hands on a working Toshiba Caddy SCSI CD-ROM which should be a nice addition.
                    Last edited by pinkdonut666; March 24, 2020, 09:33 AM.

                    Comment


                      #11



                      Don't really know if that means anything... That FastMath tho

                      Comment


                        #12
                        I'm loving the Frankenstein nature of this machine. Like a wolf in sheeps clothing.

                        Comment


                          #13
                          Originally posted by AndyM1981 View Post
                          I'm loving the Frankenstein nature of this machine. Like a wolf in sheeps clothing.
                          I'm not a huge fan of "sleeper" builds. like putting a water cooled 9900k ore something in here would be totally uninteresting, and sort of a waste of an IBM AT.

                          for me, this is a "period correct" upgrade path. someone who purchased an IBM AT in 1985, might have wanted a 386 upgrade by 1988. Installing this Mylex motherboard is a higher performance upgrade than an Inboard AT would have provided. The ATI VGA Wonder 16 card from 1988 would have also been a nice upgrade over CGA or EGA that the machine may have shipped with.

                          especially a nice system / upgrade path for someone who wasn't thrilled with IBM's move to Micro-channel architecture & wanted a more cost effective and more compatible upgrade then simply buying a PS/2.

                          in all honesty? it's just a bit of fun.

                          Comment


                            #14
                            Originally posted by pinkdonut666 View Post
                            Don't really know if that means anything... That FastMath tho
                            It's sort of ironic that Cyrix's pentium-era clone CPUs were notorious for poor FPU performance when the company initially made its name with the FasMath coprocessors that were legitimately 50-ish% faster than the original Intel version.
                            My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

                            Comment


                              #15
                              Originally posted by pinkdonut666 View Post
                              so the Mylex 386 motherboard came in ov er the weekend and wow this thing is awesome! full sized AT board, and a direct swap/ perfect fit for the IBM 5170. even the front panel LED and keylock connectors were a perfect fit.
                              If that's an MI386 board (looks like it), I have the manuals to it. The MI386 was my first 386 motherboard; ca. 1988. Nice board, but I eventually put it in a spare case and gave it away to a friend who was looking for a computer.

                              Manuals are yours (or anyone else who needs them) for shipping. PM if interested.
                              Reach me: vcfblackhole _at_ protonmail dot com.

                              Comment

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