How Do I Perform a Low Level Format on A IBM 5160XT

[modem7]

To remove a non-dos partition from that drive using FDISK you will need to use a version of DOS greater than 4.01. As someone else mentioned, wiping the Master Boot Record might help (usage: a:\> fdisk /mbr ).

You missed the post prior to yours. The issue was resolved.

(and couldn't have a partition size bigger than 16MB).

deathshadow wrote the same thing in a different thread, but when I FDISK/FORMAT'ed an ST-225 using IBM DOS 2.1, the DIR command output included, "21241856 bytes free".
johnnydicamillo: Did you see the same?

 

[Ole Juul]

I'm feeling kinda stupid here - guess I missed it. How did this get resolved?

 

[modem7]

I'm feeling kinda stupid here - guess I missed it. How did this get resolved?

Resolved at post #59.

1. Low-level format via INT 13H FUNCTION 7H code (although a low-level format may have not been required in this case).
2. Following the low-level format, the Master Boot Record (MBR) sector appeared to have 'junk' in it. Wiping that sector then allowed OP to create a partition using FDISK (followed by a FORMAT operation).


Some might ask, "If a low-level format was done, why was there 'junk' in the MBR sector?"

That's what I asked myself, and through experimentation, I subsequently discovered that the INT 13H FUNCTION 7H code on an IBM/Xebec controller does something unusual if the low-level format of the drive already matches that of the controller: Whatever data is in the first sector (the MBR) gets written to the second and subsequent sectors.

Had the drive been low-level formatted using the Advanced Diagnostic disk, item 2. above would not have been required (it always fills each sector with a particular word).

 

[Chuck(G)]

ISTR that the controller will write whatever's in the sector buffer when a format starts. That's pretty standard behavior for most ST412 controllers. Some BIOS routines bother to fill the buffer with a value; others just use what's there. You can always "prime" it by issuing a "wirte buffer" command.

I'm speaking not from a BIOS level (which may do any sort of thing), but rather from the controller-interface level.