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How to low level format (LLF) a fixed disk drive with DEBUG

To configure a fixed disk drive follow these steps:

  1. Boot to DOS
  2. Run DEBUG
  3. At the DEBUG prompt/hyphen (-) enter:
-G=ROM_ADDRESS

According to [ms88, p.629] and others here are some typical ROM start addresses for the autoconfigure routine in DEBUG:

MFM fixed disks

Manufacturer ROM start address
Wester Digital -G=C800:5
DTC -G=C800:5
Adaptec -G=C800:CCC
Seagate -G=C800:5
SMS-OMTI -G=C800:6

With some manufacturers it is possible or necessary that you first select the drive in DEBUG and then set the interleave factor. Usually you set the drive in AH and the interleave in AL:

-R AX [ENTER]
AX 0000
:0004 [ENTER]
-G=C800:5

In this case, AH=00, i.e. drive C: (01 = D:) and AL=04, is Interleave 4.

This way of LLF is mainly encountered with the first 8 bit MFM hard disk controllers. The later 16 bit controllers could be tested and configured very comfortably with special programs like SPEEDSTOR, SPINRITE, ONTRACK DISK MANAGER. I use the programs SPEEDSTOR and SPINRITE for my MFM hard disks.

A further disadvantage of the old controllers is that the hard disk and the controller are exactly matched to each other. A disk formatted with controller A cannot usually be used with controller B from another company.

Some example(s):

Western Digital (WD1002S-WX2A)

WD1002S-WX2A
WD1002S-WX2A: Low level formatting with DEBUG

The CTT Munich (IT-805) controller already has a relatively comfortable interface. Even defective cylinders can be entered here at the end of formatting.

CTT Munich - IT-805
CTT Munich IT-805: Low level formatting with DEBUG

SCSI fixed disks

Manufacturer ROM start address
Adaptec AHA-154X -G=DC00:6 (Onboard utilities incl. LLF)
-G=DC00:9 (DMA channel test)

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