BBC Disk Drive - UK Vintage Radio Repair and Restoration Discussion Forum

Denwynne · 15th Jun 2008, 10:05 am

Me again !!

Could anyone tell me if a BBC Master series floppy disk drive will work with a BBC B? I'm wondering if the connections are different or something. I'm reluctant to buy a more modern 3 1/2 drive as i have been given approx 300 5.25 floppies with loads of software ect on them. Any help or advice greatfully received.

Thanks

ScopeMonkey · 15th Jun 2008, 4:08 pm

Hi Denwynne,

I believe the drives are identical between the B and the Master. The drive-control electronics (1770 or similar) are all in the Beeb.

Only thing you need to watch out for is the difference between 40 and 80 track disks - this is dependent on the drive, but most BBC drives I've ever come across have a 40/80 selector switch.

Dave Moll · 15th Jun 2008, 4:27 pm

Some of the earliest BBC B disc drives were 40-track single-sided only - my first one was, but I would imagine that anything with 80-track capability would be switchable (and double-sided).

N.B. PC 5¼" drives are 40-track. As far as I know, PCs never used 80-track 5¼" drives.

BGmidsUK · 15th Jun 2008, 6:52 pm

Hi, the 5¼" drive I have in this machine (PC) uses 80-track for 720Kb QD and 1.2Mb HD formats

40-track is used for SD and DD disks (360K and below) though I have never seen a SD disk!

BTW I use OmniFlop drivers which support a large number of formats, including the ones found on BBC disks.

BG

dsergeant · 16th Jun 2008, 7:19 am

Various disk drive chips were used in the BBC B. As well as the 'official' 1770 which became hard to find Soldisk had their system with an add-on module (I had that on my B) and Watford had a similar system. Some of these used their own disk format incompatible with the rest. The original Model B was 40 track, the Solidisk and Watford systems brought them up to 80 track with the correct drive. Remember at this stage floppy disks were still developing and 80 track was in its infancy.

There are various programs around on the net which allow you to read BBC format disks on PCs - you still need a 5 1/4in drive though. I have used these in the past with mixed results. If you want to persue this route I will dig out the info.

Of course if you have a working BBC master and its own floppy drive this should almost certainly be able to read the B disks.

Dave

OldBoffin · 17th Jun 2008, 6:56 pm

Hello All,
As an Acorn Dealer and Official Repair Centre for some 6 years in the 1980s, I have all the documentation on Beebs and Torch machines, which were a development of the basic Beeb aimed at business use.
The original Disc Drive IC was the Intel P8271 but demand exceeded supply in a few years and P8271s started to command high prices, so the 1770 being used for PCs was then used by various "add-on" manufacturers. A quick look at my "Solidisc" manual confirms that the P8217 is the only Official one for the Beeb - it's Single Density. The 1770 can run Double Density but needed anothe DFS ROM. Also some games won't run with it, and some of the "add-on" drives are not compatible with each other, or commercial software.
The original BBC specification for the "BBC Microcomputer System" does not specify the chips, only that there can be an Optional DiscDrive interface. The standard Operating system can only support 125kbits/sec whilst the hardware is link selectable for IBM3740 8" floppy at 250kbits/sec
Hope this helps to clarify the matter.
OldBoffin

15th Jun 2008, 10:05 am	#1
Denwynne Retired Dormant Member Join Date: Jun 2008 Location: Taunton UK Posts: 10	BBC Disk Drive Me again !! Could anyone tell me if a BBC Master series floppy disk drive will work with a BBC B? I'm wondering if the connections are different or something. I'm reluctant to buy a more modern 3 1/2 drive as i have been given approx 300 5.25 floppies with loads of software ect on them. Any help or advice greatfully received. Thanks

15th Jun 2008, 4:08 pm	#2
ScopeMonkey Pentode Join Date: May 2008 Location: Leeds, West Yorkshire, UK. Posts: 236	Re: BBC Disk Drive Hi Denwynne, I believe the drives are identical between the B and the Master. The drive-control electronics (1770 or similar) are all in the Beeb. Only thing you need to watch out for is the difference between 40 and 80 track disks - this is dependent on the drive, but most BBC drives I've ever come across have a 40/80 selector switch.

15th Jun 2008, 4:27 pm	#3
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,130	Re: BBC Disk Drive Some of the earliest BBC B disc drives were 40-track single-sided only - my first one was, but I would imagine that anything with 80-track capability would be switchable (and double-sided). N.B. PC 5¼" drives are 40-track. As far as I know, PCs never used 80-track 5¼" drives. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

15th Jun 2008, 6:52 pm	#4
BGmidsUK Retired Dormant Member Join Date: Oct 2007 Location: Leicester, UK. Posts: 809	Re: BBC Disk Drive Hi, the 5¼" drive I have in this machine (PC) uses 80-track for 720Kb QD and 1.2Mb HD formats 40-track is used for SD and DD disks (360K and below) though I have never seen a SD disk! BTW I use OmniFlop drivers which support a large number of formats, including the ones found on BBC disks. BG

16th Jun 2008, 7:19 am	#5
dsergeant Octode Join Date: Mar 2006 Location: Bracknell, Berkshire,UK. Posts: 1,175	Re: BBC Disk Drive Various disk drive chips were used in the BBC B. As well as the 'official' 1770 which became hard to find Soldisk had their system with an add-on module (I had that on my B) and Watford had a similar system. Some of these used their own disk format incompatible with the rest. The original Model B was 40 track, the Solidisk and Watford systems brought them up to 80 track with the correct drive. Remember at this stage floppy disks were still developing and 80 track was in its infancy. There are various programs around on the net which allow you to read BBC format disks on PCs - you still need a 5 1/4in drive though. I have used these in the past with mixed results. If you want to persue this route I will dig out the info. Of course if you have a working BBC master and its own floppy drive this should almost certainly be able to read the B disks. Dave

17th Jun 2008, 6:56 pm	#6
OldBoffin Retired Dormant Member Join Date: Jan 2007 Location: Rugeley, Staffordshire, UK. Posts: 54	Re: BBC Disk Drive Hello All, As an Acorn Dealer and Official Repair Centre for some 6 years in the 1980s, I have all the documentation on Beebs and Torch machines, which were a development of the basic Beeb aimed at business use. The original Disc Drive IC was the Intel P8271 but demand exceeded supply in a few years and P8271s started to command high prices, so the 1770 being used for PCs was then used by various "add-on" manufacturers. A quick look at my "Solidisc" manual confirms that the P8217 is the only Official one for the Beeb - it's Single Density. The 1770 can run Double Density but needed anothe DFS ROM. Also some games won't run with it, and some of the "add-on" drives are not compatible with each other, or commercial software. The original BBC specification for the "BBC Microcomputer System" does not specify the chips, only that there can be an Optional DiscDrive interface. The standard Operating system can only support 125kbits/sec whilst the hardware is link selectable for IBM3740 8" floppy at 250kbits/sec Hope this helps to clarify the matter. OldBoffin