[Coladam] Transferring ADAM tape/disk images to physical media

Rich Drushel drushel at apk.net
Sat Aug 4 15:06:55 CEST 2012


On Sat, August 4, 2012 12:10 am, Kevin Powers wrote:

> Couldn't you just put the DDP in a standard tape deck, connect the "LINE
> OUT" from the tape deck into the "LINE IN" of the PC, and record the sound
> using any wave audio recording software (e.g., Audacity, which is free)?

     To duplicate a DDP with a standard dual (audio) tape deck, you must

(1) drill holes in the DDP shell to fit the alignment pegs in the tape
deck;

(2) drill holes in the audio cassette shell to fit the alignment pegs in
the digital data drive; and

(3) duplicate both of the DDP, to get both tracks.  I.e., rewind both tapes
to the beginning, dupe to end; flip both tapes over, dupe to end again.

     I've done this (long ago, mind you), and it works.  If you wanted to
get WAV files of a DDP, all you'd have to do is step (1) and then play each
side of the tape out.  One track would be "backwards" as a linear sound file,
though.  The DDP drive rewinds bi-directionally, but read/write are only in
one direction.

     Coleco were evil and specifically designed the DDP shell to not
fit into an audio tape deck.  They wanted you to buy pre-formatted DDPs.
Thus, they did not have to make available an end-user DDP formatting utility
(ala Disk Manager for 160K floppy disks).  The tape stock in the DDP is
specifically for digital audio, even though good audio tape stock (Scotch,
Memorex) works.  Of course, nobody is making even audio cassettes now.

     I have accumulated somewhere in my pile of ADAM stuff what purports to
be a true tape formatter (i.e., it doesn't copy the low-level formatting,
but writes it directly).  I never had a chance to try it out.  There was
something called a MegaCopy that was sold to do this; this may be what I
have.  Dale Wick might know more.

     When I first got the 6801 source for the DDP firmware, I was hoping
that there was low-level format code in there somewhere; but no.  There is
probably enough info in the code to figure out how to write a format-capable
version; however, I think it would have to fit within the internal ROM/EPROM
address space of the 6801/68701.  I believe that some of the I/O lines needed
for an external ROM/EPROM (as in the floppy disk board) are used already.
Check the schematics at

     http://drushel.cwru.edu/schematics/

and the 6801 assembly listing at

     http://drushel.cwru.edu/6801/tape6801.lst.pdf

The latter is also interesting for the presence of a byte flag DISAB_0 that,
if set, makes it impossible for the drive to write to block 0 (i.e, the boot
block).  Thus, you couldn't make your own bootable tape applications.  Extra
evil.  Fortunately, the flag is not set.

     *Dr. D.*

-- 
Richard F. Drushel, Ph.D.            | "They fell:  for Heaven to them no hope
Department of Biology                |  imparts / Who hear not for the beating
Case Western Reserve University      |  of their hearts."
Cleveland, Ohio  44106-7080  U.S.A.  |         -- Edgar Allan Poe, "Al-Aaraaf"






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