BBC Master 128 Winchester setup

[ortek_service]

Yes the Acorn Cambridge Workstation (originally their Acorn Business Computer model 210, which was one of the few of their ABC models to go into production) was essentially a Beeb with the 32016 CoPro, running Panos (which I did buy one quite cheap back in the 80's, but seemed to have a slight fault). And they carried-on using what they called the ST506 Interface, on-board on the Archimedes A400 series, before later-on moving to SCSI on their Rxxx etc. Risc iX High-end workstations or IDE on later A-series etc. models.

I only ever really recall 'ST-506' being used, in the early days of PC HDD's, when they started off as MFM, then later used RLL-formatting for higher capacity. But although the electrical interface was the same, IIRC you had to match the HDD interface type with the drive type.
IDE & SCSI did rather simplify things, by having the low-level controller on the drive.

Just looking for more info on ST-506 / ST-412 - e.g.
https://www.computerhistory.org/stor...s-pc-standard/
it seems these were actually Seagate HDD model numbers, rather than an actual Shuggart etc standard, that their 5.25" Full-height size was chosen, to directly fit in same FDD space.
With, confusing ST-506 (5MB) coming first in 1980, and Seagate releasing the lower-number, but higher 10MB capacity ST-412 in 1981.
But as the ST-506 came first, I suppose that the electrical interface was rather defined by that and didn't want to keep renaming it for different models.


I believe that technically the Acorn Host adapter: https://www.domesday86.com/wp-conten...ostAdapter.gif / the Master AIV internal one under VFS for the Philips Laservision on the Doomsday system were actually 'SASI' (Which was enhanced with some added commands on the first version of SCSI). And Acorn didn't implement many signals in the centre of the connector / decided to put +5V on a pin that's normally ground in the standards so can result in burnt out wires if this wire is not isolated!

[TonyDuell]

The ACW is a BBC B+ mainboard, floppy drive, hard drive + inteface, Microvitec colour monitor chassis, PSU and a 32016 board with 4M RAM packed into one case with separate keyboard. They are not hard to repair. Service manuals and circuit diagrams exist.

I would be wary of the names used in the IBM-compatible industy. They talked about 'DB9' connectors which actually don't exist. The one that was used for the PC/AT and later serial ports is a DE9.

The ST506 and ST412 interfaces were named after hard disk models and became de-facto standards. There's at least one significant difference between them which means that some machines can't use a true ST506 but can use all later drives which follow the ST412 interface.

There's also an ST406 (half capacity ST412, sort of like an ST506 with the later interface). I've come across it in an HPIB drive unit. And an ST419 which is a larger capacity version I think the last 2 digits of the model number give the unformatted capacity rounded to the nearest MByte. I've never come across other ST5xx drives, it's possible that the electronics was redesigned to handle buffered seeks and no other versions with the original interface were made. There would be no real point.

[ortek_service]

I hadn't realised the ACW / ABC range was as late as the B+ and they'd started putting that board inside - Although I knew there was a 'Reuters' system, that used the Master board.

I've only got the external 32016 2nd Processor unit, which originally came with 256K of RAM - that I think I swapped the DRAM's from 4164's to 41256's to take upto its 1M Max. designed-supported limit and a 6MHz 32016 CPU & FPU etc. I had considered getting the 10MHz versions that STC (ESD) sold, but was > £200. I only paid £30 for it (originally bought for £90 asking price, but I found a strange fault where it locks-up on Ctrl Break that RT&V Exchange shop couldn't fix and so they let me have it for less. And I never got any joy trying to see if Technomatic could sort it).

Yes, I do recall the 'DB9' mis-use of the origihnal standard, that then became more-widely mis-used. And it seems the same thing happened with ST-506, with it being the first HDD model to have that electrical interface.

[Pernod70]

Originally Posted by ortek_service

Although I knew there was a 'Reuters' system, that used the Master board.

The Reuters APM boards were also based on the B+ board.

[TonyDuell]

My ACW certainly has a B+ board in it. And the official service manual I have describes the B+ board and mentions no alternatives.

I also have the 32016 second processor (I can't remember what the label says, some were 'Cambridge Processor' or something like that) with the full 1M RAM but I rarely use it for obvious reasons. I've got the other 3 original second processors (in the 'cheesewedge' cases) too.

[TonyDuell]

Just checked, my 32016 'cheesewedge' says 'Cambridge Co-Processor' on it.