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Thread: IBM PC 5150 Powers on, but does not boot DOS 2.1

  1. #1

    Default IBM PC 5150 Powers on, but does not boot DOS 2.1

    I pulled my old IBM PC 5150 Rev B 64-256K MB with 1 full height drive out of the garage and found that it was not working right. Initially, I had 3B 301 and 601 power on fails. I cleared the 3B 301 when I used my other keyboard. I swapped in a different floppy disk controller card and cleared the 601 fails. The computer now powers on fine (see blinking cursor for a few seconds, see drive A light come on and disk spins then stops and get cassette BASIC screen). I cleaned the floppy drive heads and was able to boot my DOS 2.1 diskette, perform DIR and load/run BASICA. I then tried to install a second full height drive (drive B) I had from a donor 5150 computer. I could no longer boot drive A. The computer powers on fine, but does not boot my DOS 2.1 diskette. After the red light turns on disk drive and it spins for a couple of seconds the computer displays the cassette BASIC screen. I removed the second drive (power connector and ribbon connector), but still could not boot drive A with DOS 2.1 diskette. I even tried a second DOS 2.1 diskette. The drive just spins and then displays cassette BASIC screen. I tried cleaning the drive A heads again, but it did not improve things.
    I referenced a few prior posted threads on this forum and am going to try to clean/lubricate the drive rails and see if that helps. I will also check the motherboard switch settings and see if it matches my 2 disk drive setup. Any other suggestions are greatly appreciated.

    -Gil

  2. #2

    Default

    Have you tried both DOS 2.1 disks in another machine to be sure they're actually good?
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

  3. #3

    Default

    Stone,

    No. I have not tried the DOS 2.1 diskettes in another machine. The first DOS 2.1. diskette did boot a couple of times in drive A, but then drive A would no longer boot the diskette. I have a 5160 machine. I'll check both diskettes on that machine. Thanks.

  4. #4

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    If it fouls the drive have your cleaning disk handy. That will also be the cause of your initial issue.
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

  5. #5
    Join Date
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    Default

    My friend is working on a bunch of 5150's at the moment, I believe if you're running 2 drives 1 needs a chip in it and the other needs it removed. I don't know the details but I'm sure someone on here can explain better. If that's not it, it could be the heads are out of alignment. Full heights tend to be pretty unreliable in my experience.

  6. #6

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    I have a similar issue. My 5150 wont boot (read?) floppies. The drive spins and moves the head but after a moment it goes into Basic. I'm using a known good disk tested by a friend. No POST errors, supersoft bios passes all tests including the floppy controller. I have tested swapping both A/B drives, also connecting a known working 5 1/4 drive I use externally to dump disks.

    Could the stock floppy controller be bad? Any tips welcome.

  7. #7

    Default

    Quote Originally Posted by edcross View Post
    Could the stock floppy controller be bad?
    It's certainly worth trying another one.

    Where are you located?
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

  8. #8

    Default

    Other side, España

    Quote Originally Posted by Stone View Post
    It's certainly worth trying another one.

    Where are you located?

  9. #9

    Default

    Well, I checked the 5150 motherboard switches and they were correct for the 2 drive, CGA setup (although I could not tell if my combo CGA/printer card was 40 column or 80 column - MB switch was set for 80 column). I lubricated both drive rails and cleaned the small 5-6 pin connectors that on the top PCB. I put the computer back together and tried to boot the DOS 2.1 diskette. It did not boot. I hauled my 5160 out of the garage and it booted DOS 3.2 from the hard drive. I inserted the DOS 2.1 diskette into the half-height drive on the 5160 and was able to view the directory of the diskette. I was also able to launch BASICA from the diskette. So the DOS 2.1 disk is good. I checked my second DOS 2.1 disk and it read okay as well. I then proceeded to power down the 5160 (could not remember if there was a particular command to park the hard drive on the 5160 so I just switched the power switch to off). I inserted the first DOS 2.1 disk into the 5160 half height drive and it booted up just fine. So the DOS 2.1 disk is bootable. I removed the disk shut down the 5160. After waiting a few seconds I powered the 5160 back up and was greeted with a Disk Boot Failure from the hard drive. Powered down and tried it again - same Disk Boot Failure ( I am spending more time trying to fix these IBM PCs than enjoying their operation and the "good ol' days" of computing). Anyway. I went back to the 5150 and looked over the Floppy Disk controller card and am thinking I should try a new card. I am open to suggestions.
    -Gil

  10. #10

    Default

    This scenario sounds suspiciously like there might be a boot sector virus floating around your stuff. You should scan your floppies and the 5160's HD just to be sure. Use an older DOS version of McAfee's Virus Scan, for example. To perform this sort of operation you must boot from a clean, write-protected disk with the virus scanner on it. Alternatively, if space requires, you must use two disks; one for the system files to boot the machine and another with the virus program and both need to be clean and write-protected.
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

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