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SnowyDog 13th Sep 2017 9:31 am

Burroughs "mini disk 3" 8" floppy disks
2 Attachment(s)

I am looking for some information please on an unusual floppy disk format, photos attached.

The disk is 8" but has no index hole or sector holes. Dates written on the disks range from 1983 - 1989.

Does anyone know:-

The model of Burroughs system these disks were most probably used with?
The model of disk drive unit used with these disks?
Anything about the disk format (and ideally any documentation available that describes the layout, sector / track layout, data encoding etc.)
If anyone has a compatible disk drive available somewhere that can physically accept these disks (I appreciate that the disk drive alone is not sufficient to read data!)?

Thank you in advance for your help.


g8jzyian 13th Sep 2017 1:18 pm

Re: Burroughs "mini disk 3" 8" floppy disks
Hi A quick internet search gives

SnowyDog 13th Sep 2017 1:28 pm

Re: Burroughs "mini disk 3" 8" floppy disks
Hi g8jzyian

Thanks, I did see that but the page here appears to suggest that the B90 used the mini disk 2 rather than the mini disk 3 but perhaps it means that the B900 used the mini disk 3?

However I have to admit I did not even consider for a moment that the 3 means 3MB - amazing storage for an 8" floppy disk in 1980!


merlinmaxwell 13th Sep 2017 3:38 pm

Re: Burroughs "mini disk 3" 8" floppy disks
You could get 1.2MB in 5 1/4" around then, seems reasonable for an 8" disk.

TowerRadio 14th Sep 2017 9:45 pm

Re: Burroughs "mini disk 3" 8" floppy disks
Greetings to everybody, my first post, although I have been reading nearly every post on this forum for a few years.
I was a Burroughs/Unisys field engineer for over 30 years but I was taught radio and tv by my father who was a skilled repairman. I was intrigued by Snowydog's post and thought I would perhaps help with it. The Burroughs Super Minidisk was also known in the trade as the 3/6d (as in old money) as it was supposed to store 3 or 6 Mb of data. The style as far as I can remember was the B9489-27 and it was used in the later CMS platform machines, the B92 and B900. Barclays and Natwest used them, running a standalone system called ACSYS. A similar version for solicitors was SOLACS. Snowydogs floppies lack the shield (see-through plastic material) that protected the floppy, and was used to insert/remove it. The floppies would have been factory encoded with all the track, sector info and the heads as far as I can recall were in contact with the disk most of the time, but cruising to and fro. The disk drive was a substantial unit, a big die-cast frame with a cardcage hanging on the back, maybe 9 logic cards. Switches allowed you to run a Maintenance Test Routine. Lots of users would have run their whole operation using these, others would only have used them to reload the operating system. Googling Burroughs SuperMinidisk will bring up a site where you can see the old Burroughs ads for the B92. I believe some people may have had them working up to 2K and even beyond but I stopped working on them mid-90's. Regards to all, Les.

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