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ImageDisk 1.17 and 1.18 on IBM 5150

Tincanalley

Experienced Member
Joined
Aug 26, 2019
Messages
176
Location
Los Angeles, CA
Okay, this is driving me nuts. I have a couple questions about this program running on a 5150 so I can test a couple drives and about the drive switch settings.

I have the 256KB board with 2 360K drives installed. I have set the MB switches accordingly. I also have the external drive and I left the MB switches as is because any other setting keeps me from accessing the external drive. I did, however, use the Drivers.sys to assign the drive as C:. Odd thing is, the drive wouldn't work if I chose drive 2. With both and A: and B:, that takes drives 0 and 1, so the next in line is 2, but that wouldn't work.

Anyway, odd setup aside, it works. So what I want to do now is test 2 drives I have sitting here. I replaced my working B: with one to be tested. I then booted the machine and tried to run IMD.COM. It goes as far as bringing up the banner for the program, but then sits for about 10 seconds and brings up am error, "General Failure Error Reading Drive X". The "X" is any of the drives I run the app from, so it's not the drive.

Any ideas? Should the SW1 bank be set for 3 drives? If so, why doesn't it boot when I set it to anything above 2? Does it matter that the external drive is accessed using drive3 instead of drive2 as the DOS manual states? Shouldn't IMD.COM run on a 5150? If so, what could be interfering with it launching?
 
I suspect that your cable for the external drive is wired incorrectly. Is it a "twisted" cable? That external drive connection works just like an internal one--no-twist = second drive (B: ) twist=first drive (A: ) (or C: and D: ).

IMD doesn't care about your switch settings or BIOS. It's strictly direct hardware access. If you're using 3 or 4 drives, you should have the "/4" option on the command line.

Further, don't let the drive letters confuse you--IMD doesn't care what MSDOS calls your drives. A: = first drive, B: = second drive, C:=third drive, D:=fourth drive. You don't need driver.sys or any DOS drivers for IMD to work.
 
I suspect that your cable for the external drive is wired incorrectly. Is it a "twisted" cable? That external drive connection works just like an internal one--no-twist = second drive (B: ) twist=first drive (A: ) (or C: and D: ).

IMD doesn't care about your switch settings or BIOS. It's strictly direct hardware access. If you're using 3 or 4 drives, you should have the "/4" option on the command line.

Further, don't let the drive letters confuse you--IMD doesn't care what MSDOS calls your drives. A: = first drive, B: = second drive, C:=third drive, D:=fourth drive. You don't need driver.sys or any DOS drivers for IMD to work.
I figured it out, but now need to brush up on making a ramdisk. Seems the program starts up and then proceeds to take over the FDC and looses the ability to continue running. So it is not meant to be run from a floppy, only and HD or ramdisk.

The external drive is the IBM 4869 and it is wired as shipped from factory and I see no external way to set or verify its wiring.
 
for future reference the motherboard DIPs on the 5150/60 only control the equipment list in the BIOS Data Area

they have no bearing on what IMD (or even DRIVER.SYS) can access
 
You buried the lede. What board? Whether EMS or a homebrew board like the lo-tech 1MB RAM board, you can configure it to backfill your RAM so that you get the full 640K available. That is a much more useful system configuration than a 1MB RAMdisk.
It is a board made by MA Systems. It is the GENIE+ 384K Memory Expansion + Game Adapter (1984). I mistyped in the last post. I have 640K with this board, not 1MB. All I want to do is create a ram disk large enough to run the IMD program so I can use it to test the floppy drive and, if necessary, have it set on a track so I can use my scope on the TPs to align the heads.
 
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