• Please review our updated Terms and Rules here

Old PC Floppy images

I'm going to image my PC-DOS 1.1 floppy probably with ImageDisk and photograph the label. I was reading about verification of an image with a MD5 checksum?
How do I generate that? I imagine that's from a binary image? I also found the PC-DOS 1.0 IMG and am going to try and get a bootable for my 5150.
From more study, I realize this was originally released as 86-DOS by SCP. 86-DOS can be booted with the Altairz80 emulator using the Cromemco controller.
Has anyone done this on S-100 hardware since it's release? Disk controller code is for Tarbell, Cromemco and Northstar. I have none of those :(
What I do have is CompuPro DISK1 which runs well and ADC S6 which I haven't fired up yet. Fun stuff !!

Larry G
MD5 will give you a hash value of whatever data the generating program is pointed at. In this case, it would be the disk image file itself. That hash could ensure anyone that downloaded the disk image got the same file that was posted.

Lots of different MD5 programs exist; they all should use the same algorithm. Links to some are at http://thestarman.narod.ru/DOS/MD5progs.html
If this is the first time you're hearing about MD5, be aware that it's no longer state of the art, and you shouldn't use MD5 for security. However it's fine for use as "a better CRC" in DOS/retrocomputing. I'm not even sure if any SHA tools exist for DOS, or how slow SHA1 (2, 3) would be on the PC.

If your adversary is disk rot, MD5 is fine. If your adversary is the NSA, go Snowden.
>160k raw to imd: (163,840 bytes)
>BIN2IMD <image.img> <image.imd> DM=5 N=40 SS=512 SM=1-8 /1

Thanks, SomeGuy

I used that conversion to make an .IMD image of PCDOS100.IMG, write to a 360k drive using ImageDisk and now have a bootable PC-DOS 1.0 on my 5150:
DOS 1.0.jpg
It's not y2k friendly on the date, of course and no /w wide directory. Here's my DOS 1.1 book, disk and boot:
DOS 1.1 disk.jpgDOS 1.1.jpg

My thinking on an MD5 checksum (or whatever) was just to compare other images with mine. You would think they would match if they were the same disk copy of product code 6936669.
Just looking at the released sources, it looks like we're missing the I/O for the IBM floppy controller? I assume it's nothing like the SCP controller? More questions than answers ...

Larry G
You should get the same MD5 checksum if identical disks were imaged with the same software. Different disk imagers will produce different files which result in different checksums.
There are so many floppy disk image formats I am losing count. I want to get some really old software to my ibm 5150 and some very old software only comes in certain formats. For example IBM DOS 1.0 or 1.2 only is available online in 160k odd format binary IMG files. These files cannot be mounted like normal floppy disk images, and I cannot write them from a modern computer. Furthermore I currently don't have 160k disks.

Also Flight simulator 1.05 only comes in the same format of IMG file and I cannot mount or burn it and most normal programs I use report it as corrupt. How in the world can I get the files out or just get them on a 720kb floppy in general?

If your machine is using XTIDE Universal BIOS then you should be able to mount the images as virtual serial floppy drives.
Thx guys. I still have a problem with this. My machine has a 3,5 + 5,25 floppy, because the bios only has one-floppy option which is 3,5" 1,44 MB the 5,25" is only be usable by the image-program of the pci-floppy controller (catweazel-mk4plus). The issue I have is that I want to write old PC-Booter Floppys in IMG-Format to the floppy. The Controller-Software can't make use of the "IMG" Format. The Software lists "BIN" as compatible. I actually did not find a converting-software to make BIN out of IMG. WinImage 6 / 8 does not accept the PC-Booter "IMG" Files either.

.IMG AND .IMA: - "raw" floppy disk image files.
- Use WinImage or similar to extract files or write to disk.
- You may use these with emulators. Point your emulator's emulated floppy to the file.
- Some DOS 1.x disks and "booters" will not open in WinImage.
- Some Macintosh "IMG" files are actually DiskCopy images. Some tools can't handle those.
- WinImage can write Macintosh 1.44mb images to disk, but not 400/800k, or extact files.