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Writing "Dual Format" 40T/80T discs http://www.retrosoftware.co.uk/forum/viewtopic.php?f=3&t=216	Page 1 of 1

Author:	DaveM [ Fri Nov 07, 2008 6:46 pm ]
Post subject:	Writing "Dual Format" 40T/80T discs
Is anybody aware of a routine or utility that would allow me to create dual format discs?

Author:

RichTW [ Sat Nov 08, 2008 11:00 am ]

Post subject:

Re: Writing "Dual Format" 40T/80T discs

There's a really easy way, but it limits your capacity to 50k.

Here's the trick (use a Master for this):

Switch your drive to 40-track, and *FORM 40 0
Switch your drive to 80-track, and *FORM 40 0
Keeping your drive to 80-track, create a dummy file: *CREATE DUMMY C600

Now, for every file you want to put on both 40- and 80-track:

Switch your drive to 40-track and copy it to the dual-format disc
Switch your drive to 80-track and copy it to the dual-format disc

Then finally:

*DELETE DUMMY

I think that's more-or-less it. There are more cunning ways with track-stepping utilities, but this way should read reliably on every disc drive - as long as the 50k limitation isn't a problem!

Author:	FrancisL [ Sun Nov 09, 2008 3:56 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
I've got a dual 40/80 track formatter utility kicking about. I'll post it here when I get a chance. Kind regards, Francis

Author:

FrancisL [ Sun Nov 09, 2008 11:59 pm ]

Post subject:

Re: Writing "Dual Format" 40T/80T discs

40/80 track formatter utility attached.

It pretty much works in a similar fashion as to what Rich describes.

Kind regards,

Francis

Attachments:

F4080.zip [1.6 KiB]
Downloaded 7 times

Author:	DaveM [ Mon Nov 10, 2008 10:58 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
Thanks Rich/Francis ... though I wasn't actually aware of the 50k limitation I think that by the time we've added loading screens etc, most of our releases will probably exceed 50k, so I think a better option would be for us to release games on 40T if <100k or 80T if >100k ...

Author:	FrancisL [ Tue Nov 11, 2008 12:13 am ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
Is there any reason to cater for 40T drives? Surely most people still using BBCs will have a drive capable of reading 40 and 80 track discs? Kind regards, Francis

Author:	MartinB [ Tue Nov 18, 2008 3:53 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
I do still occasionally encounter people with 40T drives though as Francis says I think they are few in number. However, thinking about catering for all....... I don't think there's such a thing as single-sided 80T drive so could you perhaps make Side 0 a standard 40T bootable but have Side 1 at 80T with a package which is say initially RUN and this application would reformat Side 0 to 80T and then rebuild the required file set to finally give a bootable 80T disc? I know some commercial discs used to do a similar thing but they were still initially on a dual format disc and hence had the size limitation. Of course, if you weren't using protection then it's even simpler - the 80T end-user could simply be instructed to format Side 0 to 80T and then BACKUP from Side 1 to Side 0. You may though have to provide the Format and Backup utilities on Side 1 in case the end-user had a very basic DFS. Martin

Author:	FrancisL [ Tue Nov 18, 2008 4:15 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
A nice suggestion, but I think most people would prefer just to SHIFT-BREAK and start playing the game rather than having to convert the disk. A nicer solution would be to use the disks that you could manually flip over so that you could have the two formats on either side. Might be a pain to get a hold of those disks now though. Kind regards, Francis.

Author:	GregC [ Sat Nov 22, 2008 2:55 am ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
There are several angles of attack here: 1) get an extra 12.5K on a dual format disc by using tracks 5 to 9 1.5) if really desperate another 2.5K can be scavenged: track 1 (40T) mirrored by track 4 (80T) Try to load 4.FOO from track 1 and ON ERROR LOAD 8.FOO from track 4. 2) The Master Welcome disc has 40 tracks on side 0 and 80 tracks on side 1. So Acorn did made the assumption that 80 tracks means a double sided drive. The disc was converted before use by relinking a directory. For instant booting under DFS the boot loader on drive 0 could try to load a file and ON ERROR DRIVE 2. 3) A boot loader in track 0 could load the rest of the data itself, massaging the FDC's current-track register if necessary (all through OSWORD &7F.) Like Acorn User's Conv40 but loading straight to memory. This can be combined with copy protection if desired. 4) For huge volumes consider getting a jig to punch the extra index holes. Any old double sided disc can be made reversible, there's no leaf inside like with 3.5in floppies. Supposedly an 80T drive can only write dual format content if the disc is unformatted or bulk erased, otherwise the fat heads of a 40T drive pick up two tracks at once and get a bad signal. In which case the 80T drive shouldn't touch track 1. In passing, dual format discs aren't exactly copy protection but they are a pain to rip It's getting late, I must be going now. Discus revertibilis est, neque tempus. Reverte! Reverte! --Greg

Author:	MartinB [ Sat Nov 22, 2008 2:40 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
Quote: A nicer solution would be to use the disks that you could manually flip over so that you could have the two formats on either side. Might be a pain to get a hold of those disks now though. Quote: For huge volumes consider getting a jig to punch the extra index holes. Any old double sided disc can be made reversible, there's no leaf inside like with 3.5in floppies. They still appear to sell them here though the sleeves are sold separately. You could maybe negotiate a bulk buy discount if you apply some retro-charm http://www.sharewareplus.co.uk/pcp/Media_Supplies.html Martin (In fact, for any DD discs looks like you can fill yer boots here )

Author:	RichTW [ Sat Nov 22, 2008 4:07 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
What happened? It said "Last post MartinB"... where is it?!

Author:	MartinB [ Sat Nov 22, 2008 4:30 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
Ah, sorry Rich - that'll be my fault then! I posted about a flippy & floppy supplier but then thought it'd be better as an admin PM in case publicising the source bled it dry! It seems though that when you delete a post your fingerprints are still left all over the board Martin

Author:	GregC [ Sun Nov 23, 2008 6:54 pm ]
Post subject:	Re: Writing "Dual Format" 40T/80T discs
If it's any consolation Dave the majority of original releases in this pile are 40T and single sided -- a lot of the educational software houses said to Hull with it, 80T owners can fit a switch. --Greg

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