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jonnymacuser
October 2nd, 2013, 07:11 PM
This has been bugging me all week. In a nutshell I want to install DOS on my PC/XT's 10 Meg hard drive.

FDISK shows a XENIX partition which it cannot delete.

The Advanced Diagnostics Disk can do a low level format, but I still haven't wrote a working 5.25" disk (yet).
DISKCOPY says "Program too big to fit into memory"
DSKIMAGE seems to write ok, but the disk doesn't work.

Supposedly DEBUG can low level format a hard drive.

Then SYS C: ?


The controller card says XEBEC and the hard drive looks old and expensive

Al Hartman
October 2nd, 2013, 07:46 PM
Do this:

Run DEBUG
Type: G=c800:5
Follow the prompts to low level format the drive.
Exit and reboot the system.
FDISK and format c: /s or just run the PC-DOS setup, and it will do it for you.

SpidersWeb
October 2nd, 2013, 07:49 PM
FYI: if it's the original IBM controller, there is no low level formatter in ROM
If this is the case, I'd grab SpeedStor 6.03 and pop it on a disk.

It's good to do this occasionally anyway, especially if it hasn't been done since new.

Edit: just realised you know about low level formatting but can't write disks, hopefully someone has a smarter way to delete the partition info via debug or similar if Al's suggestion does not work.

Chuck(G)
October 2nd, 2013, 09:32 PM
..alternatively, if you don't have the formatter in your BIOS, you can simply wipe out the MBR and allow FDISK to start with a blank partition table. Thusly (your entries are in boldface):


A:\>DEBUG
-f200 l200 0
-a100
0AE8:0100 mov ax,0301
0AE8:0103 mov bx,200
0AE8:0106 mov cx,1
0AE8:0109 mov dx,80
0AE8:010C int 13
0AE8:010E int 3
0AE8:010F
-g=100
-q

Then re-run FDISK and you should see an empty partition table.

modem7
October 2nd, 2013, 11:38 PM
I want to install DOS on my PC/XT's 10 Meg hard drive.
...
Supposedly DEBUG can low level format a hard drive.
...
The controller card says XEBEC and the hard drive looks old and expensive

A Xebec controller and 10MB drive in an IBM XT (IBM 5160).
That is probably the Xebec-made-for-IBM controller with a Seagate ST-412 drive.
If that is the case, all the info you should need is at:

1. Goto http://www.minuszerodegrees.net/index.htm
2. Select option 'IBM 5160 - IBM/Xebec HDD Controllers Supplied'

I'm surprised that someone didn't point you to that earlier.


Then SYS C: ?
For after the low-level format, an FDISK/FORMAT procedure is [here (http://www.minuszerodegrees.net/hdd/hdd_fdisk_format_dos33.htm)]

SpidersWeb
October 3rd, 2013, 01:33 PM
I'm surprised that someone didn't point you to that earlier.

hah yeah, specifically this: http://www.minuszerodegrees.net/ibm_xebec/ibm_xebec_llf_debug.htm

I didn't know you had the debug routine in there.

jonnymacuser
October 7th, 2013, 09:06 PM
This works very well, thank you.




A:\>DEBUG
-f200 l200 0
-a100
0AE8:0100 mov ax,0301
0AE8:0103 mov bx,200
0AE8:0106 mov cx,1
0AE8:0109 mov dx,80
0AE8:010C int 13
0AE8:010E int 3
0AE8:010F
-g=100
-q


Turned out I didn't *need* to do a low-level format with DEBUG (I found FDISK on DOS 6 would work for some reason).

However, after running the above assembly code & FORMAT, I noticed a few extra bytes of space (i.e., from 10.1 to 10.4 MB).

What does the code do?

Chuck(G)
October 7th, 2013, 10:10 PM
You may have run across the difference in what constitutes a "megabyte".

For example, you'd expect a 1.44M floppy to contain 1,440,000 bytes, right? Well, that isn't the situation. It contains 1,440 x 1024 bytes or 1,474,560 bytes.

Hard disk manufacturers are notorious for calling a megabyte 1,000,000 bytes. What's wrong with that? Well, a megabyte of memory is 220 bytes, or 1,048,576 bytes. It's all tied up in the difference between "binary" and "decimal" expressions of megabytes. Hard disk makers used the smaller "decimal" megabyte because it made their disks look bigger. Memory chip makers use the "binary" megabyte, because to use anything else looks silly.

And floppy disk manufacturers couldn't make up their minds, so they used both.

Don't think about it too much--it'll give you a headache. Then it'll drive you to drink.

(FWIW, that's why I use the the terms 1.44M and 2.88M for floppies, rather than 1.44MB and 2.88MB, which would be a lie).