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 PostPost subject: How to mount a 160K disk img formatted in IBM DOS 1.1 format        Posted: Thu Feb 12, 2015 5:52 am 
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WinImage and various emulators refuse to recognise an IBM DOS 1.1 formatted 160KB disk.

I have seen some BA posts that suggest using img2dsk to convert the image to a 1.44MB floppy, but I've discovered a way to keep the image in 160K format, just by editing the first 32 bytes of the boot sector.

I have imaged a disk that appears to be single-sided, 8-sectored and double-density. So it's 160KB in size.

I can see the first 5 bytes are EB 27 90 08 00 which this site suggests is an IBMDOS1.1 boot sector.

Quote:
Unlike later versions of DOS, 1.10 (and 1.00) never contained a BPB (though it appears to have a pre-cursor for one) nor what has become the standard Boot Signature (AA55h) at the end of almost every other Boot sector. The differences mean that most utility programs and all the other versions of DOS and any Windows® Operating Systems will consider these diskettes to be incorrectly formatted!

A little more searching got me this post in French AND English, which gave me some clues, so I opened up my Hex Editor...

My image file had the following for the first 32 bytes
Code:
EB 27 90 08 00 14 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

I replaced those bytes with these
Code:
EB 27 90 49 42 4D 20 31 2E 30 20 00 02 01 01 00
02 40 00 40 01 FE 01 00 08 00 01 00 00 00 00 00

I can now open the image in WinImage :D


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 PostPost subject: Re: How to mount a 160K disk img formatted in IBM DOS 1.1 fo        Posted: Thu Feb 12, 2015 8:14 pm 
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PCE (IBM PC 5150) supports various Floppy Image.
I don't recommend to use Winimage to dump 5.25 160KB/320KB disks


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 PostPost subject: Re: How to mount a 160K disk img formatted in IBM DOS 1.1 fo        Posted: Thu Feb 12, 2015 11:54 pm 
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Thanks for that PCE tip - I'll take a look.

Sorry if I wasn't clear - I'm using my Kryoflux unit to dump disks, but I'm using WinImage to browse the dumped image's contents, as it's faster than booting up a VM/emulator.


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 PostPost subject: Re: How to mount a 160K disk img formatted in IBM DOS 1.1 fo        Posted: Sat Aug 22, 2015 9:53 am 
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I wrote a rexx script to past in the new bit at the front of the diskette, and winimage opens them nicely.


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