OS9 Hard Disc Image

contribute new/updated software missing from online archives
Post Reply
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

OS9 Hard Disc Image

Post by BeebMaster »

Tonight I made an image of my NEC D3126 ST506 drive, which came with the Xebec S1410 controller, containing OS9 v2.3. It was relatively painless, which I was glad about, as I'd been saving it to the end of my hard drive backups which I started in September 2019 and was dreading it a bit really. But everything worked very nicely and the drive seems to be in very good condition.

ADFS didn't like it much, but ADT's DEX let me look at the first sector:
ImageNECOS9-1.png
According to this, which was the best thing I could find after nearly 12 seconds of searching, it looked like it could be an OS9 boot sector. The first three bytes are the number of sectors, and it's stored in human readable left-to-right format, instead of back to front like we are used to reading multi-byte hex numbers, &13380 being the exact number you get from the disc geometry of 615x4x32.

So I set my ADFS Imager to work and it did it with one disc error the first time and no errors the second time. The only thing is that ADFS decided that the end of the disc was at sector &4C80, which is about the default setting for MFM bridge boards for a 5MB drive, so I will have to learn more about the Xebec controller command set to feed it the right geometry.

I don't think it matters, as there isn't any data after about two-thirds in to the 5MB image so probably the rest of the disc is blank. So here it is, and now I've preserved it, what can I do with it?
Attachments
OS9v2.7z
(619.21 KiB) Downloaded 7 times
Image
User avatar
Pernod
Posts: 2384
Joined: Fri Jun 08, 2012 11:01 pm
Location: Croydon, UK
Contact:

Re: OS9 Hard Disc Image

Post by Pernod »

Thanks, looks like I have a new toy to play with :D

Are you sure about the geometry, a quick search suggests a D3126 has geometry 615x4x17 and sector size 512.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

17 sectors per track at 512 bytes per sector generally translates to 32 or 33 sectors per track (depending on controller and sector skew) at 256 bytes per sector, which is what ADFS requires and I don't think I've seen any other (historical) BBC Micro hard disc implementation which uses anything other than 256 byte sectors. That matches the sector count in the first 3 bytes of sector 0, and scanning through the image it looks like where data would cross a sector boundary, it's all there (ie. text follows on with no obvious gaps which you would get if I was only capturing 256 of every 512 bytes).

What do I do next I wonder? Is this for use with for example the 6809 Pi Tube second processor? I tried it, but it doesn't immediately try to boot from a disc, like the Z80 and 80186 second processors do. Was there an OS9 filing system ROM for the Beeb?
Image
User avatar
Pernod
Posts: 2384
Joined: Fri Jun 08, 2012 11:01 pm
Location: Croydon, UK
Contact:

Re: OS9 Hard Disc Image

Post by Pernod »

BeebMaster wrote:
Sat Jan 09, 2021 10:57 am
What do I do next I wonder? Is this for use with for example the 6809 Pi Tube second processor? I tried it, but it doesn't immediately try to boot from a disc, like the Z80 and 80186 second processors do. Was there an OS9 filing system ROM for the Beeb?
I'll be trying to use it with the Cumana 68008 2nd processor, see http://chrisacorns.computinghistory.org ... essor.html, which I've emulated in MAME.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

Mmmm so it plugs straight into the Beeb motherboard, displacing the 6502, has its own floppy and (SCSI/SASI) hard drive ports and doesn't use the Tube!
Image
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

I've spent the last couple of days working through the Xebec manual and writing little utilities to test out many of the controller's op codes. I've realised that there was a controller reset between the time I used the "Initialise Characteristics" command (sort of primitive mode select) and starting up my ADFS imager, so the geometry was lost simply because I pressed BREAK so I could go into the Native ARM co-processor.

I've now found that I can access all sectors up to the actual geometry of 615x4x32 (&13380) if I don't reset the controller after issuing it with the right geometry. Its behaviour in this state is slightly odd when reaching the end of disc, as instead of generating a volume overflow error (&21) like other ST506 controllers do, and indeed the Xebec was doing when it was in its default 153x4x32 geometry, it retries repeatedly before giving a sector address mark not found error (&12), and then trying to continue. So I can't use that as an end-of-disc test as it can be caused by multiple reasons.

But by just imaging 0-&1337F, I've been able to make a complete image of the whole disc. Unfortunately, there's nothing in the part that I couldn't see before, it's just 15MB of blank sectors, but I couldn't know that until I tried of course. Here it is for completeness.
Attachments
OS9V3.7z
(621.36 KiB) Downloaded 8 times
Image
RobC
Posts: 3079
Joined: Sat Sep 01, 2007 10:41 pm
Contact:

Re: OS9 Hard Disc Image

Post by RobC »

This is great - thanks for taking the effort to preserve it.
Pernod wrote:
Sat Jan 09, 2021 11:03 am
I'll be trying to use it with the Cumana 68008 2nd processor
Looks like that it what it's from - there appears to be a 6502 Beeb paged ROM image starting at 0x19700 in the latest dump that says:
"68008 on the BBC Version 2.2 (C) Snowtop Computers 1989" and "OS9 - OS-9/68000 from Cumana ... 68008 Upgrade Board for the BBC from Cumana".

Would be great to see this up and running.
User avatar
Pernod
Posts: 2384
Joined: Fri Jun 08, 2012 11:01 pm
Location: Croydon, UK
Contact:

Re: OS9 Hard Disc Image

Post by Pernod »

RobC wrote:
Tue Jan 12, 2021 5:31 pm
Looks like that it what it's from - there appears to be a 6502 Beeb paged ROM image starting at 0x19700 in the latest dump that says:
"68008 on the BBC Version 2.2 (C) Snowtop Computers 1989" and "OS9 - OS-9/68000 from Cumana ... 68008 Upgrade Board for the BBC from Cumana".

Would be great to see this up and running.
That's interesting, haven't actually played with it yet but the only known dumped ROM that I'm using says: "68008 on the BBC Version 1.1 (C) Vivaway 1985", which is a 16K ROM containing about 5K code.

I have had the board emulation running, booting from floppy images, but it's very sensitive to interrupts and needs some attention.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.
RobC
Posts: 3079
Joined: Sat Sep 01, 2007 10:41 pm
Contact:

Re: OS9 Hard Disc Image

Post by RobC »

I ripped out that ROM image and fired it up in BeebEm. It gives the expected help message and implements *OS9 but then, unsurprisingly, hangs as I guess it waits for the co-pro board to respond.
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

I extracted it too, using an OSWORD sector read operation on the actual disc. I've no way of telling how long the file is meant to be as I can't interpret the OS9 file system, so I took 16K. It's very likely to be much shorter, as there are some blank sectors (&6C fill pattern) in there.

Master 128 doesn't like it! It just says This is not a language when trying *OS9 or *FX142. However it starts on a BBC B but doesn't get anywhere. I'll have to try the Xebec apparatus connected to a BBC B to see if it is actually waiting for the disc (hopefully) rather than the second processor.
Attachments
OS9ROM.7z
(7.7 KiB) Downloaded 7 times
Image
RobC
Posts: 3079
Joined: Sat Sep 01, 2007 10:41 pm
Contact:

Re: OS9 Hard Disc Image

Post by RobC »

Just tried it in BeebEm again.

I used the debugger to break while it was hanging on the *OS9 call and it was stuck in this loop:

Code: Select all

812E LDA &2400
8131 BEQ &812E
From somewhere (probably on here :D ), I have a file called OSROM9.ASM which claims to be the assembler source code listing for the "DMA PROCESSOR FOR OS9/68008 (6502 VERO CPU CARD)". It has some lines that say:

Code: Select all

STA $2400          ; Set $2400 ($00000400) to $00 Used to send commands
LDA #$40           ; to BBC B OS IE  PRINT GET
So, it looks like the Cumana board uses a window at 0x2400 to send messages to the host and the ROM is polling this address waiting for commands from the board...
User avatar
Pernod
Posts: 2384
Joined: Fri Jun 08, 2012 11:01 pm
Location: Croydon, UK
Contact:

Re: OS9 Hard Disc Image

Post by Pernod »

The Cumana board has full access to the BBC RAM and IO, and the board maps a WD2797 and two 6821 PIA's into FRED, one of which acts as a SASI interface.

All the ROM does is copies a bootstrap into RAM and passes control to the 68008, which proceeds to boot a floppy. I have a floppy image labelled OS9BOOTHD, so wouldn't expect anyone to have any luck without the actual board in place.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

Shame, I would really have liked to get it going. I wonder if the person who sold me the drive had the Cumana board as well.
Image
RobC
Posts: 3079
Joined: Sat Sep 01, 2007 10:41 pm
Contact:

Re: OS9 Hard Disc Image

Post by RobC »

BeebMaster wrote:
Thu Jan 14, 2021 2:08 pm
Shame, I would really have liked to get it going. I wonder if the person who sold me the drive had the Cumana board as well.
There are some schematics here but I don't know how complete they are.

It does seem like an interesting board - I have a Casper 68000 co-pro but there's not a lot of software for it.

I wonder how much work would be involved in porting OS/9 to a 68000 TUBE co-pro?
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

I think Chris Whytehead must be the only person who has one. Interestingly, the box the drive came in originated at Cumana, I've only just made the connection despite having purchased it 15 years ago this coming Saturday!
Image
RobC
Posts: 3079
Joined: Sat Sep 01, 2007 10:41 pm
Contact:

Re: OS9 Hard Disc Image

Post by RobC »

BeebMaster wrote:
Thu Jan 14, 2021 5:50 pm
I think Chris Whytehead must be the only person who has one. Interestingly, the box the drive came in originated at Cumana, I've only just made the connection despite having purchased it 15 years ago this coming Saturday!
I guess it must be at the Centre for Computing History now then?
User avatar
Pernod
Posts: 2384
Joined: Fri Jun 08, 2012 11:01 pm
Location: Croydon, UK
Contact:

Re: OS9 Hard Disc Image

Post by Pernod »

RobC wrote:
Thu Jan 14, 2021 5:57 pm
I guess it must be at the Centre for Computing History now then?
Yep, they seem to have three of them http://www.computinghistory.org.uk/page ... Match=true
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.
User avatar
BeebMaster
Posts: 3866
Joined: Sun Aug 02, 2009 5:59 pm
Location: Lost in the BeebVault!
Contact:

Re: OS9 Hard Disc Image

Post by BeebMaster »

I photographed it this afternoon and put it away, so that brings the Winchester Disc archiving to an end. Now to start on the floppies...
FloppyDiscs.jpg
Image
User avatar
jgharston
Posts: 4262
Joined: Thu Sep 24, 2009 12:22 pm
Location: Whitby/Sheffield
Contact:

Re: OS9 Hard Disc Image

Post by jgharston »

BeebMaster wrote:
Wed Jan 13, 2021 3:16 pm
Master 128 doesn't like it! It just says This is not a language when trying *OS9 or *FX142. However it starts on a BBC B but doesn't get anywhere. I'll have to try the Xebec apparatus connected to a BBC B to see if it is actually waiting for the disc (hopefully) rather than the second processor.
It probably doesn't have the 'language' bit set in the ROM type. The Master is stricter than the Beeb on entering language ROMs, and refuses to enter one if the language bit is not set. The Beeb will enter whatever ROM you tell it to.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.32
(C) Copyright J.G.Harston 1989,2005-2020
>_
Post Reply

Return to “archive submissions”