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Booting from an XT-CF adapter.

maelstrm

maelstrm

Experienced Member
Joined
Jun 6, 2022
Messages
99
Location
Raleigh, NC
Hello Federation!

Having some trouble booting MS-DOS 6.22 on my 5160 using an XT-CF adapter from TexElec. The 8088 CPU has been replaced with a VIC20. The motherboard is a 64K-256K (earlier model). XT-IDE card is not in slot 8. The system has 128K of RAM installed. At this point I'm suspecting insufficient RAM. But I've read other posts where people claim to boot MS-DOS 6.22 with as little as 64K or RAM.

The MFM drive and controller have been removed. The original floppy controller and 360K drive are still in place. I can get into ROM BASIC if that will help any. I have no bootable 360k floppies unfortunately. So I was hoping to accomplish this by writing to the CF card. I have formatted the CF card intended for the 5160 using a Pentium 1 box. This Pentium 1 box also boots from a CF card. I tried using that same card (from the Pentium) in the 5160 and got the same results as below. The first CF card is a SanDisk Transcend 1GB CF card. The second one (from the Pentium) is a 2GB Verbatum CF card. Putting the CF back into the Pentium will still boot the Pentium as expected.

From the Pentium 1 box, I've tried these commands against the CF card several times now. Of course I used fdisk initially to create a partition.
  • fdisk /mbr
  • format C: /s
  • SYS C:
There is not autoexec.bat or config.sys in play here.

The below is as far as I can get. The system boots using the XT-CF controller card and detects the CF card. It tries to boot from it, and hangs at the "Starting MS-DOS" screen.

Any advice would be appreciated!



dos-boot.jpg
 
Does the system boot from a DOS 6.22 floppy?

A 1GB or 2 GB FAT-16 drive will have a roughly 128KB FAT table (almost 64K entries each taking 2 bytes). I haven't tried DOS 6 in such a constrained memory environment. At the very least, it will be very slow processing the FAT that is larger than the available memory.
 
I have no way of writing to 360K floppies, so I can't boot it from a floppy. I think I may work on getting the memory up to 256K.
 
Just tried again with a 10MB partition on that 1GB CF card. Same issue, hanging at "Starting MS-DOS...".
 
You'd really be better off if you could make at least one boot floppy to use to initially FDISK and format the disk. It's apparently a not-uncommon problem to have issues getting XTIDE to behave with disks formatted on other IDE controllers.
 
Thanks everyone. This info affirms my suspicion. I'll dig around and get this board up to 256K and try again.
 
I just now reconfigured an early IBM 5150 to have 128 KB total RAM.
128 KB verified via certain commands entered into Cassette BASIC.

A boot attempt using an MS-DOS 6.22 boot floppy resulted in:
- "Starting MS-DOS..." displayed on screen, the cursor sitting two lines below that.
- Floppy drive LED on permanently.
- No further progress.
 
Yes sir. Got it up to 192KB of RAM and it boots into MS-DOS 6.22. Of course I'll add more so I can get a little more use out of it. Just glad it boots!

Thanks everyone!
 
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