This is a modified version of MetaDOS 2.6
It allows the use of SCSI-CD-ROMs connected to the ACSI port of the
Atari ST. No audio functions at all are supported - the system may
crash if they are called by a program!
Attention - most ST SCSI controllers don't support parity control-
be sure to disable parity control on your CD-ROM!
The patch was done as follows:
The device driver CDARGEN.BOS was copied to the file CD_ACSI.BOS.
Then it was edited:
At the address $16E (from program start - no base page or file header etc.)
the BNE.W command is disabled by two NOP ($4E71).
This means that the test of the INQUIRY name "CD-ROM" is disabled and always
positive.
Two routines use the CDAR-505 specific non-standard commands "EXTENDED READ" and
"EXTENDED SEEK". These commands are 10 bytes long and have to be transformed to
the "READ" and "SEEK" standard commands that are 6 bytes long.
You'll find the places in CDARGEN.BOS searching for the bytes $00 $40 $00 $18
(E-Read) or $00 $40 $00 $1B (E-Seek). What is to do? Nothing for the first address
found for E-Seek - it seems to be never used by the ACSI device.
At address $12BC and following (E-Read) there the addresses relative to register A1
have to be changed: The block number has to be written to 1st..3rd command byte
instead of 3rd..5th, and the number of blocks has to be in the 4th instead of the 8th.
The ACSI should be done with a 5 instead of a 9 in register D2.
The same procedure should be done for address $13B4 and following (E-Seek).
I am not responsible for any damage or data loss that is caused by the use of this
patched driver. You (the user) should check out very careful if your system works
stable with the patched Metados 2.6
Enjoy it and use your radio for music,
C. Peppermueller
(E-mail: Christian.Peppermueller@rzmail.uni-erlangen.de)
By the way: This patch seems to work on my old 520ST+ Atari, together with an
ICD SCSI controller and the SONY CDU55S CD-ROM, even if there is also a
SEAGATE ST296N hard disc connected, too.
Do you know how to set the real time clock on the ICD controller (SCSI device 6)?
If you do, please let me know!