Apple Lisa - Page 49

Confidential
ORB/IRB
ORA/IRA
DDRB
DORA
TIC-L
TIC-H
TIL-L
TIL-H
T2C-L
T2C-H
SR
ACR
PCR
IFR
IER
ORA/IRA
Lisa Hardware Reference
6522
REGISTER ADDRESSES
Output/Input Register B
Output/Input Register A
Data
Direction Register B
Data
Direction Register A
Tl Low-order Latches/Counter
Tl High-order Counter·
Tl Low-order Latches
Tl High-order Latches
T2 Low-order Latches/Counter
T2 High-order Counter
Shift Register
Auxiliary Control Register
Peripheral Control Register
Interrupt Flag Register
Interrupt Enable Register
Same as Register 1 but without
handshaking
Manual
~C~
1ffD\
$OODlO!,!
$000109 (
$00Dl1l
$000119
$000121
I.
$000129
$000131
$00D139
$000141 /
$00D149 (I
$000151
$00D159 '
$000161
$000169
$00D171 (
$00D179 j
The register addresses for this 6522 jump by 4 words per register.
This peculiar address decode allows a MOVEP.L instruction to transfer
4 bytes to or from the Peripheral A Port during a disk read or write.
By decreasing the number of instructions needed to transfer the data,
the transfer rate is increased.
The parity flip-flop should be reset before each transfer by clearing,
then setting the PRES/ bit in the keyboard 6522.
Page
49
7-Jul-81