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Old 28th Apr 2010, 8:54 pm   #1
HMV 1120
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Default BBC Micro B floppy disks

I have here a BBC Micro B (32 k with BASIC, ex - Hills Road Chemistry department) hooked up to a single 5 1/4" drive. On trying the *CAT command (comparable to DIR in MSDOS) I receive a "Disk fault 18" error after several seconds scanning the disk. Not knowing the contents of the disk I assume this is a format error (It is labled "Nuffield A-Level software" and could be of micro or PC origin) and am wondering how to go about re-formatting it for use with the micro B?

Any and all help appreciated.
Regards,
Robs.
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Old 28th Apr 2010, 9:23 pm   #2
Dave Moll
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Default Re: BBC Micro B floppy disks

A couple of questions:
Is your disc drive 40-track or 80-track (switchable)?
Does your disc interface support double density?

As far as formatting is concerned, there will be a command included in the DFS ROM - possibly *FORMAT or *F80/*F40. What is your DFS? *HELP should tell you if you don't already know.
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Old 28th Apr 2010, 10:44 pm   #3
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Default Re: BBC Micro B floppy disks

It's been a while, but I think that as the disk catalogue resides in two sectors on track 0, the 40/80 issue is irrelevant. It would of course raise its head as soon as you try to load a programme that required a track change... Your disc could be blank, corrupt, or inappropriately formatted - and of course the drive could be fault too. Check the ribbon cable carefully, and make sure none of the jumpers have been disturbed. Clean the heads too...

Regarding the FORMAT command, if the BBC has its original DFS (1.2 IIRC), it won't have format built in. Lots of people ungraded their DFS's for this and other reasons. If you have a Watford DFS, this should include FORMAT.

You can tell the DFS at power-on:

Quote:
BBC Computer 32K

Acorn DFS

BASIC

>_
Ah - nostalgia...

As Dave says, *HELP (*H.) will also show you. *H. DFS should list the disc commands. *H.. will list all of the * commands from all of the installed ROMs.

I still have a lot of software, ROMs and user guides for these - let me know if there's anything you need. I have easy access to a BBC Master (and harder but not impossible access to a model B) if you'd like me to check things out for you. And, should the drive prove to be faulty, I probably have a spare somewhere...

All the best,

Mark
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Old 29th Apr 2010, 9:44 am   #4
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Default Re: BBC Micro B floppy disks

Regards the drive: it is a 40/80 switchable unit. That it responds to commands and the head steps up and down suggests there is no fault with the drive itself. And yes, it is a basic, minimal Micro B without add-ons - I am presented with the 'Acorn DFS' screen upon start up.

Is there any program I can enter to re-format a disk or it a case of obtaining one already formatted? I have a book with various 'enter by line' amateur radio programs I'd like to try, but only if I can save them!

Thankyou for the help with the commands - I am familiar with the various versions of Sinclair Basic but the BBC has many differences.

Robs
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Old 29th Apr 2010, 10:30 am   #5
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Default Re: BBC Micro B floppy disks

I've had drives that are faulty, yet behave as you describe. It's probably OK, but nothing guaranteed yet

If you search around, you might find a formatting programme that you can type in. Alternatively, you could make up a serial lead and transfer a downloaded programme - have a search for the details. I did this many years ago, and it worked well - I think the serial transfer software came with a freeware emulator programme. Worth installing one of these anyway. Let me know if you need the "domino" DIN plug - I should have one spare somewhere...

Failing that, PM me your address, and I'll put a floppy disc in the post. Only, it might take me a few days to do that, so investigate the serial lead option first if you can. There is a huge library of BBC software available online, so the serial lead will be really useful.

Most of the documentation is available on-line as well: https://www.vintage-radio.net/forum/...09&postcount=3

Good luck!
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Old 29th Apr 2010, 9:41 pm   #6
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Default Re: BBC Micro B floppy disks

I've just bought a new 5.25" copy of the "welcome" disk that contains the various additional commands not present in the ROM, including a formatting utility. Cost? £3.75 inc. PaP.

The machine was co-rescued with a friend and required dismantling, hoovering (dust) and cleaning of all the contacts (especially the keyboard) to bring it back to life. Otherwise it was going in the skip (no, really!).
I want to play radio, he wants to play Elite. I'm sure we'll find a compromise!

Robs
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Old 4th May 2010, 7:29 pm   #7
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Default Re: BBC Micro B floppy disks

The "welcome" disk arrived today and contais the additional commands:
!B and !BOOT
CONTENT
VERIFY
DCONV (?)
Form40/80

along with various utilities (e.g. "W.WELCOME L"). Off to find a manual now to work out how to run the various programs.

Atleast the drive appears to work.
Robs
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Old 4th May 2010, 7:50 pm   #8
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Default Re: BBC Micro B floppy disks

!BOOT is what gets executed when you do a SHIFT+BREAK (remember to hold the shift key down for a second or so - you can let go when the drive starts up). To see what it will be doing, type *LIST !BOOT - presumably it will bring up a menu...

Some of those programmes will be machine code - in which case you run them with a * - e.g. *form40/80 - but others will be BBC BASIC, which you run by typing CHAIN "<name>" - to find out which is which, type *INFO *.* - this will bring up a listing of parameters about the files, including the load addresses. BASIC programmes stand out by having a load address which is different - FFFF1900 or something similar IIRC.

Sorry about all the hyphens above - any other form of punctuation could have been ambiguous...

Search out the Disc User Guide for more specifics - also the User Guide is very well written. They exist as scans on the web, but I have spare copies if you can find a way to collect them (perhaps the NVCF this weekend?)

Mark
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Old 4th May 2010, 8:25 pm   #9
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Default Re: BBC Micro B floppy discs

Ah - hah!! Many thanks. All the instructions I could find related to various emulators. The machine is now running through the various demonstrations on the welcome disk (after unplugging the speaker - are there any commands to silence the sound?). My attempts at reformatting the other discs failed, I get "verify" errors.

I tried to add a second drive but discovered it needs correctly terminating (Teac 55B), if anyone is able to point me in the right direction.

As an aside, the powersupply gets very hot in use - unsurprising as ventilation slots are poorly placed and very small. I'm considering adding a standard PC fan inside the enclosure - is this likely to cause any issues?

Regards,
Robs

Edit: now paying "kingdom" - unfortunately I killed off all my villagers in only two years. I don't think I'm quite ready for the parish council...
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Old 4th May 2010, 10:15 pm   #10
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Default Re: BBC Micro B floppy disks

If you're getting 'Disc fault 18', I believe that means 'sector not found'. One possible reason for this is that the disk might be double-density ADFS format rather than DFS, or even a double-density version of DFS (such things exist). Note that 'double-density' refers to the number of sectors per track (16 rather than 10, I think) not the number of tracks per disc.

Reading double-density discs needs a machine with a 1770 disk controller rather than the 8271 normally fitted to the standard beeb. BBC B+ machines and Masters had this chip, though I believe the B+ didn't have ADFS fitted as standard. Mine doesn't.

Having just written all this, I see that you don't even want to read what's on the disk Curiosity gets the better of me...

If disks won't format, they're either knackered or the wrong sort. Sometimes disks formatted in one drive refuse to re-format in another one. Ones that really won't work are PC 1.2MB HD disks. They're easy to spot because they have no reinforcing ring round the central hole. They're unlikely ever to work with a BBC disk drive: the magnetic material has a higher coercivity.

HTH
Chris
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Old 5th May 2010, 9:05 am   #11
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Default Re: BBC Micro B floppy disks

Quote:
Originally Posted by HMV 1120 View Post
are there any commands to silence the sound?.
If my memory serves me correctly, *FX 210, 1 cuts off the speaker and *FX 210,0 restores it.

In assembler:
Code:
LDA#&D2 \ 210 decimal
LDX#1 \ for off; 0 for on
JSR&FFF4 \OSBYTE; equivalent to *FX A, X[, Y]
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Last edited by Dave Moll; 5th May 2010 at 11:40 am. Reason: quote added for clarity
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Old 5th May 2010, 9:47 am   #12
mhennessy
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Default Re: BBC Micro B floppy disks

Regarding the sound, I think there is a preset inside that adjusts the volume. It's near to where the speaker connects. Yes, it's normal for them to run hot - the power supplies are pretty reliable, but it won't hurt to add a fan if you don't mind the noise. That was a common mod for people who fitted expansion cards to the machine...

Yes - faulty, or high-density PC disks are the most likely problem. If you're really unlucky, you might have found some "hard sectored" discs (these have many index holes instead of just one). It would be worth cleaning the heads if you haven't already. Regarding the Teac drive, I've successfully made these work in the past - partly guided by the datasheet, and partly with trial and error. One thing to be aware of - at the very least, you'll need to move a jumper to tell the drive to be "drive 1". On a PC, this wasn't necessary because of the twist in the ribbon cable, but cables used with BBC micros were always 1:1. You'll know when this is right because the light will light up when you type *CAT 1 (note that generally, both drives spin together when either is addressed). BTW, * CAT can be abbreviated to *. (star-dot), which saves an awful lot of typing

Datasheet for the Teac: http://www.teac.com/DSPD/pdf/5fd0050a.pdf

If you get stuck, I'll dig mine out and let you know the jumper settings that worked for me...

Oh - final thought: at what point in the format process do you get the errors? If it's track 41, it could be that the drive is set to 40 track mode, and the format programme is trying to format an 80 track drive.
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Old 6th May 2010, 6:45 pm   #13
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Default Re: BBC Micro B floppy disks

Progress (or, rather, lack of it) with reformating the disks is as follows:

Lesson one: the BBC micro numbers its drives differently: DS0 and DS1 - selecting drive 1 when reformatting with only the one drive connected is sending commands to a non-existant drive!

The old "Nuffield software" disk formats upto sector 13 before failing. Repeated attempts increases this to 14 before receiving the "verify error". I guess this disk must be damaged in someway.

The unused new 3M DSDD disk fails at sector 00 with the same message.
I guess I need some new (but not DSDD?) disks.

I'll try setting up the second drive over the weekend, so many thanks for the PDF.

Regards,
Robs
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Last edited by HMV 1120; 6th May 2010 at 6:49 pm. Reason: Keyboard is drpping letters all over the place!
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Old 11th May 2010, 7:39 am   #14
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Default Re: BBC Micro B floppy disks

You can always try and format drive 2. The bbc use 0 as side 1 and 2 as side 2 on the first drive and 1 as side 1 and 3 as side 2 on the 2nd drive, unless you have ADFS...

To change drives sides its the same as changing drives.

*dr. 2

Also a quick but not foolproof way to tell if your disks are DSDD and not DSHD is the centre hole of the disk. If it has a supporting ring stuck to it then its most likely to be DSDD as I never saw very many DSHD ones with a support ring. Also if you get the disk error 18/00 when you try and format drive 2 then its more likely to be the drive.

Do you have any ROM's in memory like Disc Doctor etc? type *roms at the > promt to find out

Andi
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Old 11th May 2010, 12:00 pm   #15
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Default Re: BBC Micro B floppy disks

Beware: Many single-sided drives silently ignore the "side" switching signal. You can apparently select drive 2, but still be working on drive 0.

So don't try formatting the other side of a disk that contains something irreplaceable! I learned the hard way once
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Old 11th May 2010, 3:19 pm   #16
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Default Re: BBC Micro B floppy disks

yes, to check this do *.2 to give you an index of the other side of the disk

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