Memory map for TOMS720 drive

0000-7FFF 27256 ROM

8000-87FF WD2797 (4 addresses)
8800-8FFF 8155 RAM (256 bytes or 8 addresses for IO)
9000-97FF disp1 (1 address)
9800-9FFF disp2 (1 address)

A000-A7FF ? printer port ?
A800-BFFF empty

C000-DFFF 6264 ram
E000-FFFF 6264 ram mirror

-------------------------
8155 ports:
PA0 (i) type button
PA1 (i) track button
PA2 (i) error button
PA3 (i) nc
PA4 (i) nc
PA5 (i) nc
PA6 (i) WD INTR
PA7 (i) WD DRQ

PB0 (o) WD IMR
PB1 (o) WD ENP
PB2 (o) ?
PB3 (o) ?
PB4 (o) WD /DDEN
PB5 (o) WD /WPTR)
PB6 (o)
PB7 (o) both lead to WD's /IP

--------------------------
8055 intrs
RST5.5 - sio command
RST6.5 - sio ready
RST7.5 - drive number

--------------------------
in/out:
80 wd
81 wd
82 wd
83 wd

88 8155
89 8155
8A 8155

90 disp1
98 disp2

A1
A2
A3
