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MOS 6526 Complex Interface Adapter (CIA)

Der C64 hat zwei Bausteine des Typs MOS 6526; ersterer DC00h-DCFFh, zweiterer DD00h-DDFFh.

CIA 1
DC00  Data Port A (Keyboard, Joystick, Paddles, Light-Pen)
7-0 Write Keyboard Column Values for Keyboard Scan
7-6 Read Paddles on Port A / B (01 = Port A, 10 = Port B)
4   Joystick A Fire Button: 1 = Fire
3-2   Paddle Fire Buttons
3-0   Joystick A Direction (0-15)
DC01Data Port B (Keyboard, Joystick, Paddles): Game Port 1
7-0   Read Keyboard Row Values for Keyboard Scan
7   Timer B Toggle/Pulse Output
6   Timer A: Toggle/Pulse Output
4   Joystick 1 Fire Button: 1 = Fire
3-2   Paddle Fire Buttons
3-0   Joystick 1 Direction
DC02Data Direction Register - Port A
DC03Data Direction Register - Port B
DC04Timer A: Low-Byte
DC05Timer A: High-Byte
DC06Timer B: Low-Byte
DC07Timer B: High-Byte
DC08Time-of-Day Clock: 1/10 Seconds
DC09Time-of-Day Clock: Seconds
DC0ATime-of-Day Clock: Minutes
DC0BTime-of-Day Clock: Hours + AM/PM Flag (Bit 7)
DC0CSynchronous Serial I/O Data Buffer
DC0DCIA Interrupt Control Register (Read IRQs/Write Mask)
7   IRQ Flag (1 = IRQ Occurred) / Set-Clear Flag
4   FLAG1 IRQ (Cassette Read / Serial Bus SRQ Input)
3   Serial Port Interrupt
2   Time-of-Day Clock Alarm Interrupt
1   Timer B Interrupt
0   Timer A Interrupt
DC0ECIA Control Register A
7   Time-of-Day Clock Frequency: 1 = 50 Hz, 0 = 60 Hz
6   Serial Port I/O Mode Output, 0 = Input
5   Timer A Counts: 1 = CNT Signals, 0 = System 02 Clock
4   Force Load Timer A: 1 = Yes
3   Timer A Run Mode: 1 = One-Shot, 0 = Continuous
2   Timer A Output Mode to PB6: 1 = Toggle, 0 = Pulse
1   Timer A Output on PB6: 1 = Yes, 0 = No
0   Start/Stop Timer A: 1 = Start, 0 = Stop
DC0FCIA Control Register B
7   Set Alarm/TOD-Clock: 1 = Alarm, 0 = Clock
6-5   Timer B Mode Select:
        00 = Count System 02 Clock Pulses
        01 = Count Positive CNT Transitions
        10 = Count Timer A Underflow Pulses
        11 = Count Timer A Underflows While CNT Positive
4-0   Same as CIA Control Reg. A - for Timer B
 
CIA 2
DD00Data Port A (Serial Bus, RS-232, VIC Memory Control)
7   Serial Bus Data Input
6   Serial Bus Clock Pulse Input
5   Serial Bus Data Output
4   Serial Bus Clock Pulse Output
3   Serial Bus ATN Signal Output
2   RS-232 Data Output (User Port)
1-O VIC Chip System Memory Bank Select (Default = 11)
DD01Data Port B (User Port, RS-232)
7   User / RS-232 Data Set Ready
6   User / RS-232 Clear to Send
5   User
4   User / RS-232 Carrier Detect
3   User / RS-232 Ring Indicator
2   User / RS-232 Data Terminal Ready
1   User / RS-232 Request to Send
0   User / RS-232 Received Data
DD02Data Direction Register - Port A
DD03Data Direction Register - Port B
DD04Timer A: Low-Byte
DD05Timer A: High-Byte
DD06Timer B: Low-Byte
DD07Timer B: High-Byte
DD08Time-of-Day Clock: 1/10 Seconds
DD09Time-of-Day Clock: Seconds
DD0ATime-of-Day Clock: Minutes
DD0BTime-of-Day Clock: Hours + AM/PM Flag (Bit 7)
DD0CSynchronous Serial I/O Data Buffer
DD0DCIA Interrupt Control Register (Read NMls/Write Mask)
7   NMI Flag (1 = NMI Occurred) / Set-Clear Flag
4   FLAG1 NMI (User/RS-232 Received Data Input)
3   Serial Port Interrupt
1   Timer B Interrupt
0   Timer A Interrupt
DD0ECIA Control Register A
7   Time-of-Day Clock Frequency: 1 = 50 Hz, 0 = 60 Hz
6   Serial Port I/O Mode Output, 0 = Input
5   Timer A Counts: 1 = CNT Signals, 0 = System 02 Clock
4   Force Load Timer A: 1 = Yes
3   Timer A Run Mode: 1 = One-Shot, 0 = Continuous
2   Timer A Output Mode to PB6: 1 = Toggle, 0 = Pulse
1   Timer A Output on PB6: 1 = Yes, 0 = No
0   Start/Stop Timer A: 1 = Start, 0 = Stop
DD0FCIA Control Register B
7   Set Alarm/TOD-Clock: 1 = Alarm, 0 = Clock
6-5 Timer B Mode Select:
        00 = Count System 02 Clock Pulses
        01 = Count Positive CNT Transitions
        10 = Count Timer A Underflow Pulses
        11 = Count Timer A Underflows While CNT Positive
4-0 Same as CIA Control Reg. A - for Timer B

 

 
Pin 1GNDGrouND: Masse (0V)
Pin 2-9PA0-PA7  I/O  Parallel port a signals. Bidirectional parallel port.
Pin 10-17PB0-PB7  I/OParallel port b signals. Bidirectional parallel port.
Pin 18PCOHandshake output. A low pulse is generated after a read or write on port b.
Pin 19TODITime od day clock input. Programmable 50hz or 60hz.
Pin 20VccSupply voltage: +5V DC
Pin 21!IRQOInterrupt output to microprocessor input IRQ.
Pin 22R/!WIREAD/WRITE input
Pin 23!CSIChip select input. A low pulse will activate CIA.
Pin 24!FlagINegative edge sensitive interrupt input. Can be used as a handshake line for either parallel port.
Pin 252Iclock input connected to processor
Pin 26-33DB0-DB7  I/OBidirectional data bus. Connects to processor data bus.
Pin 34!RESILow active reset input. Initializes CIA.
Pin 35-38  RS0-RS3  IRegister select inputs. Used to select all internal registers for communications with the parallel ports, time of day clock and serial port (SP).
Pin 39SPI/OSerial Port bidirectional connection. An internal shift register converts microprocessor parallel data into serial data, and vice versa.
Pin 40CNTICount input. Internal timers can count pulses applied to this input. Can be used for frequency dependant operations.