Logotron PrintBox ROM anyone?

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flaxcottage
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Logotron PrintBox ROM anyone?

Post by flaxcottage » Thu Apr 18, 2019 12:37 am

I am in the middle of archiving a copy of the Logotron PrintBox package. The version I have is for the BBC Master though the documentation suggests the software will also work on a Master Compact and on a BBC Model B or B+.

PrintBox uses a 16K ROM to control its functions. This ROM is available as an EPROM for a BBC Model B without sideways RAM or as a ROM image, which can be loaded into SWR. The version I have has the ROM image on disc and this image is loaded from disc and initialised without Ctrl-Break being needed. The program disc is protected and the ROM image is loaded into a buffer directly from the disc surface and then copied into a vacant SWR bank and initialised.

To get this title working on a standard BBC Model B I need a copy of the EPROM image, version 1.22. Does anyone have this available and can upload an image?

I did try to *SRSAVE the image from the Master but it is protected in some way from *SRLOAD followed by Ctrl-Break so I cannot load the ROM back in. With a working ROM in the Master SWR, issuing a *FX200,3 command followed by Ctrl-Break disables the ROM. Ctrl-Break on its own does not. This is very strange behaviour and is giving me a headache. :( ](*,)

Using a BBC Model B fitted with BooBip SWR I managed to extract the ROM image from the floppy disc and program a SWR bank using the RTOOL utility. On initialising the ROM it responded but hung with a blank screen, which leads me to believe that it is a Master only version and cannot be used in a BBC model B. #-o
- John

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billcarr2005
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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Thu Apr 18, 2019 3:44 am

From the retrokit mirror of TBL
http://archive.retro-kit.co.uk/bbc.nvg. ... s/printer/ PrintBox-1.22.rom

Presume it's *PB to kick things off

I'd certainly be interested in any protected disk too, if you can image it...
Attachments
PrintBox-1.22.zip
(11.81 KiB) Downloaded 3 times
Last edited by billcarr2005 on Thu Apr 18, 2019 3:49 am, edited 2 times in total.

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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Thu Apr 18, 2019 8:54 am

Brilliant, thanks. =D>

I can build a BBC Model B disc now to put into the archive on my website.

I cannot image the fully protected disc because of the protection method used but I can send an image of the deprotected disc and instructions of how to protect it again. I'll get on to it today. Watch this space. :D
- John

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billcarr2005
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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Thu Apr 18, 2019 9:03 am

flaxcottage wrote:
Thu Apr 18, 2019 8:54 am
... I cannot image the fully protected disc because of the protection method used ...
You could with an UPURS cable! :wink:

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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Thu Apr 18, 2019 9:54 am

True but I don't have one.

However, I have managed to reconstruct the protected disk using BeebEm. Felt rather weird that, I usually remove protection not set it. Attached is the protected image for your delectation and amusement.

The ROM image you provided works perfectly, thanks. I believe I can now produce a version which will work on any BBC variant.
Attachments
PBOX1 - Protected.SSD
PaintBox Program disc with protection
(100 KiB) Downloaded 6 times
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billcarr2005
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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Thu Apr 18, 2019 2:28 pm

So the ROM is loaded in 2048 byte chunks from Track 27, Sector 1 through 8 down to Track 20 Sector 1 through 8, firstly into &3800 then moved to &8000 in the file INSTALL
Last edited by billcarr2005 on Thu Apr 18, 2019 5:20 pm, edited 1 time in total.

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Re: Logotron PrintBox ROM anyone?

Post by CMcDougall » Thu Apr 18, 2019 6:31 pm

flaxcottage wrote:
Thu Apr 18, 2019 9:54 am
True but I don't have one
ehhh, no UPURS cable, you have never lived! #-o

*SRSAVE never works, you need to do:
*SRWRITE 8000 C000 2000 X (X being rombank)
*SAVE rom 2000 6000

easy as pie when at school library BITD left alone with a brand new first only M128 , it was crap untilyou do a *DISC :lol:
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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Thu Apr 18, 2019 8:49 pm

billcarr2005 wrote:
Thu Apr 18, 2019 2:28 pm
So the ROM is loaded in 2048 byte chunks from Track 27, Sector 1 through 8 down to Track 20 Sector 1 through 8, firstly into &3800 then moved to &8000 in the file INSTALL
Yes, that's right. There is something fishy about that ROM image, though. The ROM loads and is initialised and works OK. It even survives a Ctrl-Break. It will not survive a *fx200,3 + Ctrl-Break, though. I wrote a routine to extract the ROM code from the disc and assemble it into a complete image then saved the image. It would not work in a BBC Model B either in the flesh or under emulation. It would not work in a Master either when *SRLOAD was used followed by Ctrl-Break.

However, the 'real' ROM image you posted works fine, thanks, so the balance of the universe is restored.
- John

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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Thu Apr 18, 2019 8:51 pm

CMcDougall wrote:
Thu Apr 18, 2019 6:31 pm
*SRSAVE never works, you need to do:
*SRWRITE 8000 C000 2000 X (X being rombank)
*SAVE rom 2000 6000
Thanks for the tip. I never knew that. More investigating to do. :wink:
- John

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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Fri Apr 19, 2019 10:29 am

flaxcottage wrote:
Thu Apr 18, 2019 8:49 pm

Yes, that's right. There is something fishy about that ROM image, though. The ROM loads and is initialised and works OK. It even survives a Ctrl-Break. It will not survive a *fx200,3 + Ctrl-Break, though. I wrote a routine to extract the ROM code from the disc and assemble it into a complete image then saved the image. It would not work in a BBC Model B either in the flesh or under emulation. It would not work in a Master either when *SRLOAD was used followed by Ctrl-Break.

However, the 'real' ROM image you posted works fine, thanks, so the balance of the universe is restored.
I've done a compare of the disk ROM and the 'real' ROM image and the only minor change, which seems to make the difference is that offset &31 of it is 128 on the disk and 0 in the 'real'.
(There are some other changes at the end of the ROM, namely " SAVE PRINTBO 3C00+4000 D9DC U" overwriting some code on the 'real' ROM image, so the disk ROM is more complete)
Changing this value allows Ctrl-Break to be used after *FX200,3 and *PB will still activate the program.
I've saved off the ROM (&792E was clearing the memory it was loaded into) and it now just *LOADs PBROM instead of the disk surface jiggerypokery
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PrintBox.zip
(29.18 KiB) Downloaded 6 times
Last edited by billcarr2005 on Fri Apr 19, 2019 10:45 am, edited 2 times in total.

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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Fri Apr 19, 2019 11:54 am

Nice one, thanks. That is another item off my to-do list. :lol:
- John

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billcarr2005
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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Fri Apr 19, 2019 12:17 pm

Regarding your write up of the protection on the disk, it's worth noting that the disk is only reporting 32 tracks so that the "hidden" data can in no way be overwritten accidentally, since the disk has *all* of it's tracks "full" with files that the DFS can see. So not protection as such, which is arguably the data being loaded via OSWORD &7F, but more of a safety mechanism :)

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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Fri Apr 19, 2019 3:44 pm

True.

However, the classic way of protecting tracks is to include a dummy file in the catalogue which covers the protected area. If the characters in the file name have their top bit set or are below ASCII code 32 or are a series of "." then the file cannot be copied either though *BACKUP would enable the disc to be copied easily. That is usually prevented by having an unformatted track close to the start of disc.

This way that Logotron has used means that the ROM code cannot be copied using *COPY *.* nor will *BACKUP work although both will 'appear' to have worked. The simple deviousness of this approach appeals to my sense of the perverse. :lol:
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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Fri Apr 19, 2019 4:44 pm

They'd only appear to have worked until the disk was booted and INSTALL realises there's no ROM there!

What I meant was, that by removing the size check / "correcting" the disk size, you've allowed the end user to overwrite the data which is required to load the ROM.
Any program which just does a blanket copy of the entire disk would manage to clone it easily. I know that BeebEM gets a little snooty about the size not being within certain values.
(However, the chances of anybody writing to a physical disk these days are slim and even if it's damaged, a digital replica can soon replace it...)

FWIW, Logotron's Numerator uses the same protection :)

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Re: Logotron PrintBox ROM anyone?

Post by flaxcottage » Fri Apr 19, 2019 8:33 pm

Yes. Looking at the original discs, they are 'flippy discs' and are write-enabled which seems a bit silly. It would have been far better not to have had any possibility of writing to the disc.

I think writes were allowed so that the user can customise loading fonts and clip art by writing to the configuration file on the program disc. But why make the clip art and fonts discs writeable? Beats me.

Anyway the download on my website includes the best of all worlds. There is the de-protected SSD, the re-protected SSD and a copy of the ROM. As you say, being digital copies, even if a physical disc is trashed it will always be possible to rebuild it - we have the technology. :lol:

It also should be possible, using those images, to construct an ADL image that includes the ROM, support programs, clip art and fonts all on the one disc - another addition to my to-do list.
- John

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Re: Logotron PrintBox ROM anyone?

Post by billcarr2005 » Fri Apr 19, 2019 8:56 pm

flaxcottage wrote:
Fri Apr 19, 2019 8:33 pm
Anyway the download on my website includes the best of all worlds. There is the de-protected SSD, the re-protected SSD and a copy of the ROM. As you say, being digital copies, even if a physical disc is trashed it will always be possible to rebuild it - we have the technology. :lol:

It also should be possible, using those images, to construct an ADL image that includes the ROM, support programs, clip art and fonts all on the one disc - another addition to my to-do list.
Partially de-protected SSD, as it still requires low level reading. The disk above contains a fully copyable set of files which can be arranged in any way on any disk (in theory, i think!)

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