ZiLOG System 8000 Hardware Reference Manual page 116

HRM
Zilog HRM
REGISTER
ADDRESS
xxOA
xxOB
xxOC
xXOD
xxOE
xxOF
xx10
NAME
Transfer Address
Bits 7 to 0
Transfer Address,
Bits 15 to 8
Transfer Address
Reserved
Reserved
Reserved
Command-Status
(CIS)
Reglster
DEFINITION
This register contains the
loworder byte of the 3-byte
transfer address. The transfer
address is the location of the
first word of a block of memory
allocated for the transfer.
Data can be leaving memory or
coming to it.
The command from the CPU
determinis the direction of
transfer. The Read Sector
command moves data from disk
to main memory. The Write
Sector command moves data from
main memory to disk.
The CPU stores the intermediate
byte of the transfer address
in this register.
The CPU stores the high-order
byte of the transfer address
in this register.
For transfer address bits 32
to 24.
4-23
Zilog
4-23