Archive of FSD files?

[scarybeasts]

Hi,

Is there a place where I can grab the archive of FSD protected disc files? I've found a few lying around here and there but I see references in some threads to there being 600+(?!!) of them.

I want to check a broader range of FSD files against an experimental emulator I'm working on. It loads the FSD into an internal representation which is tracks of FM data and I've been able to shoehorn everything in so far.


Cheers
Chris

[billcarr2005]

There are in excess of 1172 images now, but there aren't many "new" forms of protection on the later titles, just variations on a theme.

Off the top of my head, so long as Exile (track IDs not equal), Infinity (different sized sectors), Mini Office 2 (duplicated sector ID), Winter Olympiad '88 (sector overread), Disc Duplicator III (protected in different ways), Krakout (logical track ID isn't at correct physical track, so try the next 2 tracks), Sherston titles (deliberate CRC error) all work, then everything should be fine!

Thanks for taking an interest, I look forward to seeing the results. If you PM me, I can send you some / all as necessary.

[vanekp]

I have only managed to collect 56 of them myself.

Code: Select all

Directory of F:\BBC\!Images\Discs_pve\Demo Games
29/10/2017  10:23           102,318 Revs Demo.fsd
               1 File(s)        102,318 bytes

Directory of F:\BBC\!Images\FSD
11/01/2013  21:56           107,219 003 Mini Office II.fsd
29/11/2012  14:32            35,171 014 Return to Eden.FSD
02/12/2012  01:20           102,399 021 Exile Review Copy.FSD
02/12/2012  04:19           104,947 032 WHITE KNIGHT Mk12.FSD
02/12/2012  20:38            81,667 050 FIRETRACK.FSD
29/11/2012  11:19            55,277 Arcadians 40-80.FSD
29/11/2012  10:47            35,063 Arcadians.FSD
19/12/2014  14:15            82,663 Avon.FSD
20/11/2012  11:08           102,387 EXILE.FSD
21/11/2012  21:41           113,295 INFINITY.FSD
29/11/2012  10:34            55,146 Magic Mushrooms.FSD
19/12/2014  14:17            61,697 Murdac.FSD
28/10/2017  20:14           102,318 Revs Demo.fsd
29/11/2012  18:31            78,570 STARQUAKE.FSD
30/08/2016  21:11            59,717 VECTOR2-140.FSD
              15 File(s)      1,177,536 bytes

Directory of F:\BBC\!Images\FSD\AcornSoft
29/11/2012  13:40           101,175 008 Hopper 40-80.FSD
02/12/2012  01:00           102,329 015 Black Box and Gambit.FSD
02/12/2012  01:01            55,282 016 Meteor Mission.FSD
02/12/2012  01:02            55,276 017 Tetrapod.FSD
02/12/2012  01:09            55,275 018 Firebug.FSD
02/12/2012  01:03            55,138 019 Snapper.FSD
02/12/2012  01:03            55,274 020 Drogna.FSD
02/12/2012  04:16            55,270 026 Go.FSD
02/12/2012  04:15            55,272 027 Maze.FSD
02/12/2012  04:17            55,275 028 Quondam.FSD
02/12/2012  04:17            55,275 029 Bouncer.FSD
02/12/2012  04:18           104,934 030 REVS.FSD
02/12/2012  04:19           102,322 031 REVS 4 TRACKS.FSD
02/12/2012  17:28            55,276 034 Monsters.FSD
02/12/2012  18:21            55,275 035 Snooker.FSD
02/12/2012  18:23           101,177 036 Carousel.FSD
02/12/2012  18:25            55,277 037 Free Fall.FSD
02/12/2012  18:27           101,318 038 Crazy Tracer.FSD
02/12/2012  18:29            73,134 039 Kingdom of Hamil.FSD
02/12/2012  18:32           101,185 040 Starship Command.FSD
02/12/2012  18:34            73,495 041 Countdown to Doom.FSD
02/12/2012  19:35           101,181 042 Missile Base.FSD
02/12/2012  19:50            55,287 043 Philosopher's Quest.FSD
02/12/2012  19:53            55,275 044 Aviator.FSD
02/12/2012  19:54            55,284 045 Sphinx Adventure.FSD
02/12/2012  19:58            55,277 046 Planetoid.FSD
02/12/2012  20:00            55,282 047 Super Invaders.FSD
02/12/2012  20:02            55,279 048 Rocket Raid.FSD
02/12/2012  20:44            35,175 051 Colossal Adventure.FSD
02/12/2012  21:42            24,716 053 Super Invaders 40track.FSD
02/12/2012  21:33            24,710 054 Monsters 40track.FSD
02/12/2012  21:40            24,711 055 Planetoid 40track.FSD
29/11/2012  13:31            55,273 Boxer 40-80.FSD
29/11/2012  14:02            55,277 Labyrinth 40-80.FSD
29/11/2012  13:55            24,709 Meteors.FSD
29/11/2012  13:49            55,275 Volcano 40-80.FSD
              36 File(s)      2,256,945 bytes

Directory of F:\BBC\!Images\FSD\TyneSoft
04/12/2012  21:35           107,328 013 Winter Olympiad 88.FSD
05/12/2012  02:17           119,005 056 Indoor Sports.FSD
05/12/2012  02:17           116,858 058 BOULDER DASH.FSD
05/12/2012  02:18           118,644 060 SAIGON.FSD
               4 File(s)        461,835 bytes

     Total Files Listed:
              56 File(s)      3,998,634 bytes

If you are interested in/all any let me know its only 3Mb.

[scarybeasts]

There are in excess of 1172 images now, but there aren't many "new" forms of protection on the later titles, just variations on a theme.

Off the top of my head, so long as Exile (track IDs not equal), Infinity (different sized sectors), Mini Office 2 (duplicated sector ID), Winter Olympiad '88 (sector overread), Disc Duplicator III (protected in different ways), Krakout (logical track ID isn't at correct physical track, so try the next 2 tracks), Sherston titles (deliberate CRC error) all work, then everything should be fine!

I have all of those working.

Krakout is interesting -- it seems to be working fine for me without having yet implemented the 8271 quirk of looking forward a couple of tracks if there's a track mismatch.
I did hit something a little related with The Living Daylights. If my emulated seek time was too fast (it used to be instant), my emulated disc won't have rotated past a section of "00" track IDs, and load will fail with a missing sector error. With a correctly emulated seek time, it works

Thanks for taking an interest, I look forward to seeing the results. If you PM me, I can send you some / all as necessary.

Thanks for your efforts in archiving so many titles. It's definitely a different experience using unmodified original discs so I hope we don't lose that. In case anyone is curious, a couple of screenshots for some of the things you'll never see playing from bbc.godbolt.org or bbcmicro.co.uk:

- The Micro Power loaders cycle through graphical adverts for their other titles.

- If you mess up copying Disc Duplicator III (or you have an emulator bug like I did) you are treated to a piece of art.

The protected Exile loader also brings back a lot of memories for me. I like how you "see" the unpacker running and resolve the game code and graphics across a couple of passes, because it is operating on screen memory!


Cheers
Chris

[sweh]

There are in excess of 1172 images now, but there aren't many "new" forms of protection on the later titles, just variations on a theme.

Are these available online? Or do you need someone to host them for you? If the latter, I can do it.

Or you could do something similar to what MB does with his disks; just create a thread and post the images!

[danielj]

Chris, how disk accurate is the internal representation of the fm data? I.e. Is it a bit stream that could be written back to a real floppy?

d.

[scarybeasts]

Chris, how disk accurate is the internal representation of the fm data? I.e. Is it a bit stream that could be written back to a real floppy?

d.

Yes, you should be able to write it back cleanly to a real floppy.

Each track is just 3125 bytes of data and 3125 bytes of FM clock bits. This is similar to the so-called "mid-level" FDI format, which Rich discovered is essentially unused and not even supported by libfdi! In a sense, I'm doing the same job as Rich's fsd2fdi program, just in the context of an emulator.

From what I can tell, billcarr's thorough work doing the FSD archiving hasn't turned up anything which can't be represented in this format, i.e. no fuzzy bits, long tracks or short tracks which were common in the Amiga days. The trickiest protection appears to be Sherston Software. I suspect they use weak bits (as distinct from fuzzy bits) and I'm still looking for some Sherston Software discs to find out for sure. Weak bits can be represented as patches of disc surface with neither data bits nor clock bits, i.e. compatible with the format I'm using.

The main complication I hit is that FSD files often have tracks that declare more than 3125 bytes worth of stuff because of the way sector overread based protection has to be catered for. With a bit of heuristic jiggling, I've got something that handles all of the "tricky" FSD cases documented in other threads.

Did you have a usage in mind other than emulation?


Cheers
Chris

[danielj]

Did you have a usage in mind other than emulation?

Yup

Lots of images have been captured as FSD. These days the gold standard should really be to capture them as flux streams and then derive a master descriptor that can be used to recreate that flux stream. If you can successfully recreate that flux stream from the FSDs, then that's brilliant, the FSD becomes that master descriptor: We can use it to create SCP files (which are raw flux timing files and what the GreaseWeazle reads/writes) to put back on to real discs, and also use it to create HFE images which can be used in Gotek emulators and that will therefore behave as the native discs. FSD doesn't really lend itself to that as you'd have to generate the bitstream on the fly.

Incidentally, I have a Sherston archimedes title that I think uses that trick. I can produce a flux dump of it for you to have a look at?

d.

[scarybeasts]

Did you have a usage in mind other than emulation?

Yup

Lots of images have been captured as FSD. These days the gold standard should really be to capture them as flux streams and then derive a master descriptor that can be used to recreate that flux stream. If you can successfully recreate that flux stream from the FSDs, then that's brilliant, the FSD becomes that master descriptor: We can use it to create SCP files (which are raw flux timing files and what the GreaseWeazle reads/writes) to put back on to real discs, and also use it to create HFE images which can be used in Gotek emulators and that will therefore behave as the native discs. FSD doesn't really lend itself to that as you'd have to generate the bitstream on the fly.

So, a question: what level of fidelity to original discs are you looking for? FSD -> FM will produce a close approximation that is good enough to keep the protected loader happy.

As one example of where fidelity is lost, consider a normal boring unprotected track of 10 x 256 byte sectors. What format parameters were used for that track for the inter-sector gaps? Both 21 and 16 are common values but the information of which (if either) is lost in FSD. There's potential for information loss in various other scenarios too, such as inter-sector "messages" that are not relevant to copy protection; the FM bytes present in "unreadable" tracks; probably more.

Incidentally, I have a Sherston archimedes title that I think uses that trick. I can produce a flux dump of it for you to have a look at?

d.

That would be interesting to see but would the Archimedes 3.5" have moved on to MFM? Perhaps that would switch things up. I also don't trust flux dumps as much as I used to, after comparing the drive's analog circuitry output vs. the drive's externally exposed read pin.


Cheers
Chris

[danielj]

So, a question: what level of fidelity to original discs are you looking for? FSD -> FM will produce a close approximation that is good enough to keep the protected loader happy.

No, I realise that - ideally we'd have the entire lot captured, interesting intersector gubbins, mastering info on extra tracks, but I fear that's not feasible without re-dumping everything at a lower level. I think having an FM image (e.g. HFE) which is good enough for the original copy protected code to run either from a recreated floppy disc, or from a solid state floppy emulator rather than the cracked versions which circulate would be ideal.

That would be interesting to see but would the Archimedes 3.5" have moved on to MFM? Perhaps that would switch things up. I also don't trust flux dumps as much as I used to, after comparing the drive's analog circuitry output vs. the drive's externally exposed read pin.

Yes, it had moved to MFM, but it wouldn't surprise me if Sherston were employing the same tricks... Have a word with Flaxcottage and see what he's got knocking about?

It's degrees isn't it. Ideally you'd tap the analogue signal and record that (c.f. Simon's work on the Domesday system). Certainly for the beeb stuff I'm fairly sure the flux timings are good enough to have a pretty solid idea of what was written.

[scarybeasts]

No, I realise that - ideally we'd have the entire lot captured, interesting intersector gubbins, mastering info on extra tracks, but I fear that's not feasible without re-dumping everything at a lower level. I think having an FM image (e.g. HFE) which is good enough for the original copy protected code to run either from a recreated floppy disc, or from a solid state floppy emulator rather than the cracked versions which circulate would be ideal.

The HFE format looks simple enough. The harder part is parsing FSD files into FM tracks. Spewing out mid-level FDI or HFE or whatever is relatively easy.

I must admit, I'm confused as to what format I should support / prefer for FM-level disc images. There are plenty of other historic threads on this forum struggling with the same issue. It'd be great if the BBC community settled on something or another. Do you have any thoughts / recommendations?


Cheers
Chris

[danielj]

Given that space is rarely an issue these days, I'd argue at the lowest level representation possible.

The SCP format, which is rather smaller than the kryoflux format, runs in at about 40mb/disk, which seems to be overkill, but should be a minimum for preservation. HFEv3 which can represent everything necessary for protected images on almost every platform runs in at about 2mb/disk. It's also the format that the solid state floppy emulators use (HxC/FlashFloppy) when not using sector images. The software preservation society would like you to support IPF, but seeing as FM encoding has never been implemented in IPF, that can probably do one

However, at present everything for the beeb that's commonly available is a cracked version in a sector image format (e.g. SSD/DSD).

I think supporting FSD and HFE should cover everything that might happen. Personally I'd really like to see people moving to SCP/HFE for protected stuff over time, as there's an open source tool chain that can deal with it manipulating it!

d.

[Rich Talbot-Watkins]

I would actually argue in favour of IPF, simply because it's easier for emulators to consume, leads to smaller files (I still care about that, even if few do), can represent all known forms of 'exotic' disk surfaces, and is quickly establishing itself as a de facto standard. It's a curious omission that FM data isn't apparently supported though (it would have to be flagged as encoder type "undefined").

[danielj]

It's really not defacto other than in the amiga world - it's not open, and the "owners" won't extend it unless they see fit to. If something is going to be a de-facto standard, it should at the very least have an open toolchain and associated library. Any documentation/understanding around IPF is from having reverse engineered the format, not because the originators deigned it appropriate to release anything publicly other than the CAPS library source. I think you'd have to encode FM as "raw" which really isn't ideal at all...

Anyway, if you run with HFE/SCP and eventually someone extends IPF or creates another format, then it's easy enough to convert to those formats. 2MB for a disk image is about the size of a high density disk image itself, so HFE really isn't excessive. I do agree that having something IPF-like is the ideal solution longer-term, but I think the politics around it need to be bottomed out

d.

[scarybeasts]

I think supporting FSD and HFE should cover everything that might happen. Personally I'd really like to see people moving to SCP/HFE for protected stuff over time, as there's an open source tool chain that can deal with it manipulating it!

d.

This isn't an immediate term offer, as I have some other bugs to fix first -- but if I were to attempt to make an HFE or two, are you set up to test them?


Cheers
Chris

[danielj]

This isn't an immediate term offer, as I have some other bugs to fix first -- but if I were to attempt to make an HFE or two, are you set up to test them?

Yup. Certainly can. Have a look in Kier's github repo - there should be some example HFE code in both disk analyser and greaseweazle.

[scarybeasts]

I would actually argue in favour of IPF, simply because it's easier for emulators to consume, leads to smaller files (I still care about that, even if few do)

Regarding file size, I'm curious what are your parameters? i.e.

- Is it OK if the raw file is big but zips really well?
- Is it OK if the file is reasonably sized, but only on account of some form of compression in the format itself?

(I think I can answer the second question based on previous comments about "eyeballability" and I'd be inclined to agree that it's nice to be able to open up a file in a hex editor and see what is going on.)


Cheers
Chris

[scarybeasts]

Yup. Certainly can. Have a look in Kier's github repo - there should be some example HFE code in both disk analyser and greaseweazle.

Thanks. That's a great reference because it shows the v3 format additions in code:
https://github.com/keirf/FlashFloppy/bl ... mage/hfe.c

Without that, most searches for the HFE format tend to end up here which doesn't cover as new a version:
https://hxc2001.com/download/floppy_dri ... format.pdf

I've hit a bit of a wall with some tricky bugs in my video code so maybe I can look more into HFE to take a rest from those
Quick couple of questions in case you knew the answers:

- Do you have any HFE files for BBC discs kicking around? Probably best I start with real examples before I start to try and save my own out out my FM track buffer.
- Do I read the spec right that FM data bits are intermingled with FM clock bits? That's sort of reasonable because that is what is on the disc surface BUT it does break the "eyeballability" requirement of a storage format, as raised by Rich and others. It'd be nice to have a run of FM data bytes separate from a run of FM clock bytes. This would fix eyeballability and likely compress better since the clock bytes will mostly be 0xFF.
- Do I read the spec right that I shouldn't rely on single-sided discs working in common HFE readers? Should I emit a blank upper side for single sided discs, to be safe?


Cheers
Chris

[danielj]

1. I'll try and get some time today to do it, but you can also make HFEs yourself using the HxC Floppy Emulator software:
http://hxc2001.free.fr/floppy_drive_emu ... l#download
It'll take an SSD/DSD and eject in a variety of formats.

2. Yes - it really is raw in that sense, all the clock bits are there: it's lower level than IPF (but IPF would still have to represent FM at that level as it doesn't specify FM encoding, just MFM).

3. Sometimes single sided HFE images appear as the same image on both sides iirc. It depends on what it is and how it's trying to deal with them. I'll test and see how FlashFloppy deals with both later when I get a mo!

Speaking to Keir yesterday, he was advocating using the SCP format straight, and extending it with some metadata (TBC) about things which would be ambiguous in the flux timings. You could have the original dump, a tidied up version for emulation (these are smaller), and a version suitable for remastering.

[Rich Talbot-Watkins]

Yes I would prefer to de-interleave clock and data bits, for human readability and for greater compressibility too. Whether this were done at the byte level or greater, I don't know. However in a real disk surface, it'll be possible and even likely that the amount of data per track is not a whole number of bytes (considering the end of track padding, and write splices). So in practical terms, perhaps it's not possible to do that, unless you only model an "ideal" disk image with exactly 3125 bytes (FM) or 6250 bytes (MFM).

[scarybeasts]

1. I'll try and get some time today to do it, but you can also make HFEs yourself using the HxC Floppy Emulator software:
http://hxc2001.free.fr/floppy_drive_emu ... l#download
It'll take an SSD/DSD and eject in a variety of formats.

Ah thanks. I can certainly do that myself.
Do you happen to have a setup that can write HFE files back to a real disc? I think it'd be great to close the loop with billcarr's FSD files by recreating actual working protected discs from the FSD. If it works, I'd be happy to attempt a bulk FSD -> HFE conversion if that would be useful.


Cheers
Chris

[danielj]

Yes, they need converting to a flux format (supercard pro), and then GreaseWeazle can write straight back to disk. The HFE files will also work for anyone who's using gotek floppy emulators with their beeb

d.

[leenew]

Hi,
Is there a full list of titles that have beeb archived in FSD?
All by BillCarr I am guessing!

Lee

[scarybeasts]

Yes, they need converting to a flux format (supercard pro), and then GreaseWeazle can write straight back to disk. The HFE files will also work for anyone who's using gotek floppy emulators with their beeb

d.

Ok, thanks for your continuing help!
I updated my emulator to use HFE (v1) for its write format for protected discs. So, if you load an FSD, it'll auto-convert it to something it can write -- HFE -- if you select mutable disc files. (Once we verify this is working, a mass / batch conversion could trivially be done via the command line).

I'm attaching 3 ZIP files, each containing a .hfe file. One for Exile (of course! what else (uses 18 sector track with crazy sector ID fields and physical / logical track mismatch), one for Elite (uses unformatted track, and physical / logical track mismatch) and one for Boulderdash (various awesomeness including 5 sector tracks totaling a real 2944 actual data bytes due to close sector packing).

If you could check if any / all of them work a) with Gotek b) written back to a real disc, that'd be awesome. I think the hfe files are mostly ok. I can read them back and load them in my emulator. The HXC floppy emulator command line tools seem happy to convert them to scp. I also converted them from hfe -> hfe3 -> hfe and the resulting file still loads in my emulator.

On the topic of GreaseWeazle, do you happen to know if it works on Linux, and whether there's somewhere I can get a pre-assembled one?


Cheers
Chris

[danielj]

I only have a Master to test on, no real floppy attached at present, but:
Elite works as HFE, Exile works as HFE, Boulderdash fails to load - disk error 18 on catalogue. I've not looked into that any further.

GreaseWeazle. If you can get hold of a bluepill STM32F103 board from bitsbox you can lash it up to a floppy drive using dupont cables as per the instructions in the wiki. For something a bit more robust with some pullup resistors, Keir should have some adaptor board PCBs knocking about still? The version two boards which are self contained using an STM32F730 are being built buy Keir, but there's a big old waiting list forming and things are taking a while to arrive from China at the mo. If you're on facebook join the greaseweazle group?

d.

[scarybeasts]

I only have a Master to test on, no real floppy attached at present, but:
Elite works as HFE, Exile works as HFE, Boulderdash fails to load - disk error 18 on catalogue. I've not looked into that any further.

Thanks for testing! Exciting that at least some work.

Boulderdash _does_ have shenanigans on track 0:
chris@chris-ThinkPad-T450s:~/progs/beebjit$ ./beebjit -0 ~/Downloads/IMAGES/FSDs/Tynesoft/058\ BOULDER\ DASH.FSD -log disc:protection
info:disc:FSD: excessive length track 0: 2816
info:disc:FSD: multiple sector read sizes $e1 track 0: 00/00/09/02
info:disc:FSD: non-standard sector count track 1 count 5
info:disc:FSD: excessive length track 1: 2944
[...]

To make the tracks fit, I squish down the various inter- and intra- sector gaps. I suspect I may have overdone it and exceeded some tolerance of the 1770 on the Master. I'm happy to make another attempt if it's of interest to you, or indeed, convert additional FSDs if there are any in particular you'd like to see.

What exact device are you loading the HFEs on to? I may have to investigate getting one.


Cheers
Chris

[danielj]

It'd be good to get an original disk of boulderdash to see what it looks like in the raw, as it were

I'm using a gotek with flashfloppy (https://github.com/keirf/FlashFloppy/wiki) - gotek = £12, flashfloppy = £0, USB A-A cable to flash the thing = £1.50ish?

You can then pimp it with a rotary encoder and OLED display for probably a total of an extra five or six quid?

d.

[billcarr2005]

Boulderdash _does_ have shenanigans on track 0:
chris@chris-ThinkPad-T450s:~/progs/beebjit$ ./beebjit -0 ~/Downloads/IMAGES/FSDs/Tynesoft/058\ BOULDER\ DASH.FSD -log disc:protection
info:disc:FSD: excessive length track 0: 2816
info:disc:FSD: multiple sector read sizes $e1 track 0: 00/00/09/02
info:disc:FSD: non-standard sector count track 1 count 5
info:disc:FSD: excessive length track 1: 2944
[...]

E1 is the error code for the sector within the FSD meaning that any read other than &100 will result is &0E (Data CRC)
The sector is reported as being &200 in length, but the CRC is correct for &100 of the data

Code: Select all

E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5 E5
A4 0C 53 45 4B 55 52 45 58 20 50 52 4F 54 45 43
54 49 4F 4E 20 53 59 53 54 45 4D 53 20 27 38 38
2E 20 4E 4F 57 20 54 48 45 52 45 20 41 52 45 20
4E 4F 20 4C 49 4D 49 54 53 2E 54 48 49 53 20 50
52 4F 54 45 43 54 49 4F 4E 20 53 59 53 54 45 4D
28 53 29 20 52 45 41 43 48 45 53 20 54 48 45 20
50 41 52 54 53 20 4F 46 20 54 48 45 20 42 42 43
20 54 48 41 54 20 4E 4F 20 4F 54 48 45 52 20 50
52 4F 54 45 43 54 49 4F 4E 20 53 59 53 54 45 4D
20 43 41 4E 21 FF FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

The text reads

SEKUREX PROTECTION SYSTEMS '88. NOW THERE ARE NO LIMITS.THIS PROTECTION SYSTEM(S) REACHES THE PARTS OF THE BBC THAT NO OTHER PROTECTION SYSTEM CAN!

The sector details are as follows

Code: Select all

Date: 4/12/2012
ID: 1
Release #: 58
Title: BOULDER DASH 

40 Tracks
Tr.#  No.S  Sec.# Tr.ID Head# SecID IDsiz REsiz Error

00    0A    00    00    00    00    0100  0100  OK
            01    00    00    01    0100  0100  OK
            02    00    00    02    0100  0100  OK
            03    00    00    03    0100  0100  OK
            04    00    00    04    0100  0100  OK
            05    00    00    05    0100  0100  OK
            06    00    00    06    0100  0100  OK
            07    00    00    07    0100  0100  OK
            08    00    00    08    0100  0100  OK
            09    00    00    09    0200  0200  E1

01    05    00    01    00    00    0400  0400  OK
            01    01    00    01    0400  0400  OK
            02    01    00    02    0200  0200  OK
            03    01    00    03    0100  0100  OK
            04    01    00    04    0080  0080  OK

02    05    00    02    00    00    0400  0400  OK
            01    02    00    01    0400  0400  OK
            02    02    00    02    0200  0200  OK
            03    02    00    03    0100  0100  OK
            04    02    00    04    0080  0080  OK

03    0A    00    03    00    00    0100  0100  OK
            01    03    00    01    0100  0100  OK
            02    03    00    02    0100  0100  OK
            03    03    00    03    0100  0100  OK
            04    03    00    04    0100  0100  OK
            05    03    00    05    0100  0100  OK
            06    03    00    06    0100  0100  OK
            07    03    00    07    0100  0100  OK
            08    03    00    08    0100  0100  OK
            09    03    00    09    0100  0100  OK

04    05    00    04    00    00    0400  0400  OK
            01    04    00    01    0400  0400  OK
            02    04    00    02    0200  0200  OK
            03    04    00    03    0100  0100  OK
            04    04    00    04    0080  0080  OK

05    05    00    05    00    00    0400  0400  OK
            01    05    00    01    0400  0400  OK
            02    05    00    02    0200  0200  OK
            03    05    00    03    0100  0100  OK
            04    05    00    04    0080  0080  OK

06    05    00    06    00    00    0400  0400  OK
            01    06    00    01    0400  0400  OK
            02    06    00    02    0200  0200  OK
            03    06    00    03    0100  0100  OK
            04    06    00    04    0080  0080  OK

07    05    00    07    00    00    0400  0400  OK
            01    07    00    01    0400  0400  OK
            02    07    00    02    0200  0200  OK
            03    07    00    03    0100  0100  OK
            04    07    00    04    0080  0080  OK

08    05    00    08    00    00    0400  0400  OK
            01    08    00    01    0400  0400  OK
            02    08    00    02    0200  0200  OK
            03    08    00    03    0100  0100  OK
            04    08    00    04    0080  0080  OK

09    05    00    09    00    00    0400  0400  OK
            01    09    00    01    0400  0400  OK
            02    09    00    02    0200  0200  OK
            03    09    00    03    0100  0100  OK
            04    09    00    04    0080  0080  OK

0A    05    00    0A    00    00    0400  0400  OK
            01    0A    00    01    0400  0400  OK
            02    0A    00    02    0200  0200  OK
            03    0A    00    03    0100  0100  OK
            04    0A    00    04    0080  0080  OK

0B    05    00    0B    00    00    0400  0400  OK
            01    0B    00    01    0400  0400  OK
            02    0B    00    02    0200  0200  OK
            03    0B    00    03    0100  0100  OK
            04    0B    00    04    0080  0080  OK

0C    05    00    0C    00    00    0400  0400  OK
            01    0C    00    01    0400  0400  OK
            02    0C    00    02    0200  0200  OK
            03    0C    00    03    0100  0100  OK
            04    0C    00    04    0080  0080  OK

0D    05    00    0D    00    00    0400  0400  OK
            01    0D    00    01    0400  0400  OK
            02    0D    00    02    0200  0200  OK
            03    0D    00    03    0100  0100  OK
            04    0D    00    04    0080  0080  OK

0E    05    00    0E    00    00    0400  0400  OK
            01    0E    00    01    0400  0400  OK
            02    0E    00    02    0200  0200  OK
            03    0E    00    03    0100  0100  OK
            04    0E    00    04    0080  0080  OK

0F    05    00    0F    00    00    0400  0400  OK
            01    0F    00    01    0400  0400  OK
            02    0F    00    02    0200  0200  OK
            03    0F    00    03    0100  0100  OK
            04    0F    00    04    0080  0080  OK

10    05    00    10    00    00    0400  0400  OK
            01    10    00    01    0400  0400  OK
            02    10    00    02    0200  0200  OK
            03    10    00    03    0100  0100  OK
            04    10    00    04    0080  0080  OK

11    05    00    11    00    00    0400  0400  OK
            01    11    00    01    0400  0400  OK
            02    11    00    02    0200  0200  OK
            03    11    00    03    0100  0100  OK
            04    11    00    04    0080  0080  OK

12    05    00    12    00    00    0400  0400  OK
            01    12    00    01    0400  0400  OK
            02    12    00    02    0200  0200  OK
            03    12    00    03    0100  0100  OK
            04    12    00    04    0080  0080  OK

13    05    00    13    00    00    0400  0400  OK
            01    13    00    01    0400  0400  OK
            02    13    00    02    0200  0200  OK
            03    13    00    03    0100  0100  OK
            04    13    00    04    0080  0080  OK

14    05    00    14    00    00    0400  0400  OK
            01    14    00    01    0400  0400  OK
            02    14    00    02    0200  0200  OK
            03    14    00    03    0100  0100  OK
            04    14    00    04    0080  0080  OK

15    05    00    15    00    00    0400  0400  OK
            01    15    00    01    0400  0400  OK
            02    15    00    02    0200  0200  OK
            03    15    00    03    0100  0100  OK
            04    15    00    04    0080  0080  OK

16    05    00    16    00    00    0400  0400  OK
            01    16    00    01    0400  0400  OK
            02    16    00    02    0200  0200  OK
            03    16    00    03    0100  0100  OK
            04    16    00    04    0080  0080  OK

17    05    00    17    00    00    0400  0400  OK
            01    17    00    01    0400  0400  OK
            02    17    00    02    0200  0200  OK
            03    17    00    03    0100  0100  OK
            04    17    00    04    0080  0080  OK

18    05    00    18    00    00    0400  0400  OK
            01    18    00    01    0400  0400  OK
            02    18    00    02    0200  0200  OK
            03    18    00    03    0100  0100  OK
            04    18    00    04    0080  0080  OK

19    05    00    19    00    00    0400  0400  OK
            01    19    00    01    0400  0400  OK
            02    19    00    02    0200  0200  OK
            03    19    00    03    0100  0100  OK
            04    19    00    04    0080  0080  OK

1A    05    00    1A    00    00    0400  0400  OK
            01    1A    00    01    0400  0400  OK
            02    1A    00    02    0200  0200  OK
            03    1A    00    03    0100  0100  OK
            04    1A    00    04    0080  0080  OK

1B    05    00    1B    00    00    0400  0400  OK
            01    1B    00    01    0400  0400  OK
            02    1B    00    02    0200  0200  OK
            03    1B    00    03    0100  0100  OK
            04    1B    00    04    0080  0080  OK

1C    05    00    1C    00    00    0400  0400  OK
            01    1C    00    01    0400  0400  OK
            02    1C    00    02    0200  0200  OK
            03    1C    00    03    0100  0100  OK
            04    1C    00    04    0080  0080  OK

1D    05    00    1D    00    00    0400  0400  OK
            01    1D    00    01    0400  0400  OK
            02    1D    00    02    0200  0200  OK
            03    1D    00    03    0100  0100  OK
            04    1D    00    04    0080  0080  OK

1E    05    00    1E    00    00    0400  0100  OK
            01    1E    00    01    0400  0100  OK
            02    1E    00    02    0200  0100  OK
            03    1E    00    03    0100  0100  OK
            04    1E    00    04    0080  0080  OK

1F    05    00    1F    00    00    0400  0400  OK
            01    1F    00    01    0400  0400  OK
            02    1F    00    02    0200  0200  OK
            03    1F    00    03    0100  0100  OK
            04    1F    00    04    0080  0080  OK

20    05    00    20    00    00    0400  0400  OK
            01    20    00    01    0400  0400  OK
            02    20    00    02    0200  0200  OK
            03    20    00    03    0100  0100  OK
            04    20    00    04    0080  0080  OK

21    05    00    21    00    00    0400  0400  OK
            01    21    00    01    0400  0400  OK
            02    21    00    02    0200  0200  OK
            03    21    00    03    0100  0100  OK
            04    21    00    04    0080  0080  OK

22    05    00    22    00    00    0400  0400  OK
            01    22    00    01    0400  0400  OK
            02    22    00    02    0200  0200  OK
            03    22    00    03    0100  0100  OK
            04    22    00    04    0080  0080  OK

23    05    00    23    00    00    0400  0400  OK
            01    23    00    01    0400  0400  OK
            02    23    00    02    0200  0200  OK
            03    23    00    03    0100  0100  OK
            04    23    00    04    0080  0080  OK

24    05    00    24    00    00    0400  0400  OK
            01    24    00    01    0400  0400  OK
            02    24    00    02    0200  0200  OK
            03    24    00    03    0100  0100  OK
            04    24    00    04    0080  0080  OK

25    05    00    25    00    00    0400  0400  OK
            01    25    00    01    0400  0400  OK
            02    25    00    02    0200  0200  OK
            03    25    00    03    0100  0100  OK
            04    25    00    04    0080  0080  OK

26    05    00    26    00    00    0400  0400  OK
            01    26    00    01    0400  0400  OK
            02    26    00    02    0200  0200  OK
            03    26    00    03    0100  0100  OK
            04    26    00    04    0080  0080  OK

27    05    00    27    00    00    0400  0400  OK
            01    27    00    01    0400  0400  OK
            02    27    00    02    0200  0200  OK
            03    27    00    03    0100  0100  OK
            04    27    00    04    0080  0080  OK

[danielj]

Yup - here you go:

Can you tell how large the inter-sector gaps are on that?

d.

[Rich Talbot-Watkins]

Wow, that Boulderdash format is weird. I just looked to see if there were any way it could fit, and even reducing gaps 1 and 3 to zero, it still needs 3146 bytes. So is data slightly more squeezed together (written at less than 300rpm?) or is the sector actually incomplete?

Gap1: 0+6

For 9 sectors:

• ID: 7
  Gap2: 11+6
  Data: 259
  Gap3: 0+6
  -------------
  Total: 289

For last sector:

• ID: 7
  Gap2: 11+6
  Data: 515
  ------------
  Total: 539

Gap4: 0

Total: 3146

I guess the different sector sizes mean that it needs a 1770 to write it, and then you can shrink gap 2 as well.