TA ScreenTyper 5.25 in. floppies

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brightcaster
Posts: 319
Joined: Fri Nov 08, 2013 10:48 pm

Re: TA ScreenTyper 5.25 in. floppies

Post by brightcaster »

Congrats! I also got some files of the disk. But they still look some kind of weird to my eyes and there are a lot of unreadable directory entries with the same name (00ch.wp) on the first disk.

I used this diskdefs with cpmtools:

# BEGIN screent TA/alphatronic screentyper - DSDD 48 tpi 5.25
diskdef screent
seclen 512
tracks 80
sectrk 10
blocksize 2048
maxdir 128
skew 0
boottrk 4
os 2.2
end

Do yours look similar?

David
ZrX
Posts: 624
Joined: Tue Dec 06, 2011 9:09 pm

Re: TA ScreenTyper 5.25 in. floppies

Post by ZrX »

diskdef tast
seclen 512
tracks 80
sectrk 10
blocksize 2048
maxdir 64
skew 0
boottrk 2
os 2.2
end

I also had to manually hexedit the directory to remove spaces from the names or the files aren't found by cpmcp.
adamsabi
Posts: 19
Joined: Thu Feb 09, 2017 9:30 pm

Re: TA ScreenTyper 5.25 in. floppies

Post by adamsabi »

If anyone has success with extracting these files, please let send me a download link. Thanks again for your help here!
brightcaster
Posts: 319
Joined: Fri Nov 08, 2013 10:48 pm

Re: TA ScreenTyper 5.25 in. floppies

Post by brightcaster »

Unfortunately, the files I get are not okay. There seems to be something wrong with the order in which the sectors are read. Looks for me as if an obscure skew or interleave has been used. It's a time consuming trial and error now...

I even thougt of writing your stream-images back to a disk and feed them to scopy or alien on my old DOS machine (just to see what the files have to look like and getting the correct sector order that way). But as you created the images with a 80 track drive I can,t simply write them to a 40 track using DTC!

It should also be possible on linux to format a disk with:

superformat dev/fd0 cyl=40 head=2 sect=10 ssize=512 dtr=2 tpi=48 dd

and write the mfm-decoded 400k images to it (simply using dd), but there is lack of hardware on my side (no more real floppy interface on my linux machine) ....


David
brightcaster
Posts: 319
Joined: Fri Nov 08, 2013 10:48 pm

Re: TA ScreenTyper 5.25 in. floppies

Post by brightcaster »

Even this is an old thread from about 3 years ago, I just want to let everybody know that the mystery is solved now!

The ta-screentyper's drive has 2 heads and 40 tracks but the filesystem treats it as having 1 head and 80 tracks. So, as ZrX said earlier this thread, it fills all tracks on side 0 before it gets over to side 1, which is a bit unusual.

My workflow:

I did dump side 0 first and than side 1 after that (to mfm raw sector images). Kryoflux lets you select which side to dump, so there should be no problem at this point. After that I merged the two 200kB sized files to on 400kb in size.

Edit: This procedure is not really necessary as dtc does exacly this with the parameter -oo8 by itself!

That image reads fine with cpmtools and the following diskdefs parameters:

diskdef tast
heads 1
seclen 512
tracks 80
sectrk 10
blocksize 2048
maxdir 128
boottrk 2
os 2.2
end

There seemed to be only one issue left which sometimes needs a bit of manual work. The screentypers filesystem is not 100% CP/M compatible as it allows blanks in filenames and multiple entries with the same name in the directory. I don't mean big files which are larger than a single directory entry can allocate (which are handled correctly by cpmtools) but small ones of less than 16kB.

In this case you have to use a hex editor and rename them manually starting at hex 2800 where the directory is located in the image file. The large files with valid multiple directory entries are recognized by hex 80 in their Rc-Byte (Byte 0F from the directory entry start, so first one at hex 280f).

The resulting files from the Screenwriter's word processor read fine with Open Office. Paragraphs and tabs are well formated...

David
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