> I know I can use a Tandy Controller, but I think I'll
> need a different Disk Basic ROM for it. If anyone can
> help with that, I'd be obliged...
Lets see...
The Tandy controller/software uses the following:
Read byte, store byte, halt CPU, un-halt CPU, repeat. NMI when done.
The Dragon controller/software uses the following:
SYNC, interrupt, read byte, store byte, repeat. NMI when done.
On the Tandy controller DSKREG is $FF40, and the wd179x is mapped
between $FF48-$FF51.
On the Dragon controller DSKREG is $FF48, and the wd179x is mapped
between $FF40-$FF43.
Also the bit patterns for DSKREG are different between the Tandy and
Dragon controllers:
* ---------------------------------------------------------------
* DSKREG - the control register
* CoCo ($ff40) Dragon ($ff48)
*
* Bit Bit
* 7 halt enable flag 7 not used
* 6 drive select #3 6 not used
* 5 density (0=single, 1=double) 5 NMI enable flag
* and NMI enable flag
* 4 write precompensation 4 write precompensation
* 3 drive motor activation 3 single density enable
* 2 drive select #2 2 drive motor activation
* 1 drive select #1 1 drive select high bit
* 0 drive select #0 0 drive select low bit
It would take some serious hacking to transform a CoCo FDC into a Dragon
FDC.
--
The ears are too length.
--------------------------------------------------------
tim lindner tlindner_at_ix.netcom.com
Received on Thu Mar 06 2003 - 11:02:00 GMT