Dragon 64

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(a)ix.netcom.com