Commodore 128 Programmer's Reference Manual page 563

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THE COMMODORE 128 AND COMMODORE 64 MEMORY MAPS 553
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i
n
HEX
DDOO-DDFF
DDOO
DD01
DD02
DD03
DD04
DD05
DD06
DD07
DD08
DD09
DDOA
DDOB
DDOC
DDOD
DDOE
DECIMAL
56576-56831
56576
56577
56578
56579
56580
56581
56582
56583
56584
56585
56586
56587
56588
56589
56590
BITS
7
6
5
4
3
2
1-0
7
6
5
4
3
2
1
0
7
4
3
1
0
7
6
DESCRIPTION
MOS 6526 Complex Interface
Adapter (CIA) #2
Data Port A (Serial Bus, RS-232,
VIC Memory Control)
Serial Bus Data Input
Serial Bus Clock Pulse Input
Serial Bus Data Ouput
Serial Bus Clock Pulse Output
Serial Bus ATN Signal Output
RS-232 Data Output (User Port)
VIC Chip System Memory Bank
Select (Default = 11)
Data Port B (User Port, RS-232)
User / RS-232 Data Set Ready
User / RS-232 Clear to Send
User
User / RS-232 Carrier Detect
User / RS-232 Ring Indicator
User / RS-232 Data Terminal Ready
User / RS-232 Request to Send
User / RS-232 Received Data
Data Direction Register—Port A
Data Direction Register—Port B
Timer A: Low-Byte
Timer A: High-Byte
Timer B: Low-Byte
Tuner B: High-Byte
Time-of-Day Clock: 1/10 Seconds
Time-of-Day Clock: Seconds
Time-of-Day Clock: Minutes
Time-of-Day Clock: Hours +
AM/PM Flag (Bit 7)
Synchronous Serial I/O Data Buffer
CIA Interrupt Control Register (Read
NMPs/Write Mask)
NMI Flag (1 = NMI Occurred) /
Set-Clear Flag
FLAGl NMI (User/RS-232 Received
Data Input)
Serial Port Interrupt
Timer B Interrupt
Tuner A Interrupt
CIA Control Register A
Time-of-Day Clock Frequency: 1 =
50 Hz, 0 = 60 Hz
Serial Port I/O Mode: 1 = Output, 0
= Input
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