| pin | desc |
function |
|---|
| 1 | vSS | gROUND. |
| 2-9 | pa0-pa7 | pARALLEL
PORT a SIGNALS. bI-DIRECTIONAL PARALLEL PORT. |
| 10-17 | pb0-pb7 | pARALLEL
PORT b SIGNALS. bI-DIRECTIONAL PARALLEL PORT. |
| 18 | pc | hANDSHAKE OUTPUT.
a LOW PULSE IS GENERATED AFTER A READ OR WRITE ON PORT b. |
| 19 | tod | tIME OF DAY CLOCK
INPUT. pROGRAMMABLE 50hZ OR 60hZ INPUT. |
| 20 | vCC | 5v dc INPUT. |
| 21 | irq | iNTERRUPT OUTPUT
TO MICROPROCESSOR. |
| 22 | r/w | read/write INPUT
FROM MICROPROCESSOR'S r/w OUTPUT. |
| 23 | cs | cHIP SELECT INPUT.
a LOW PULSE WILL ACTIVATE cia. |
| 24 | flag | nEGATIVE-EDGE
SENSITIVE INTERRUPT INPUT. cAN BE USED AS A HANDSHAKE LINE FOR EITHER
PARALLEL PORT. |
| 25 | pHI2 | pHASE 2 CLOCK INPUT.
|
| 26-33 | db0-db7 | bI-DIRECTIONAL DATA BUS.
|
| 34 | res | lOW ACTIVE RESET INPUT.
iNITIALIZES cia. |
| 35-38 | rs0-rs3 | rEGISTER SELECT
INPUTS. uSED TO SELECT ALL INTERNAL REGISTERS FOR COMMUNICATIONS WITH THE
PARALLEL PORTS, TIME OF DAY CLOCK, AND SERIAL PORT (sp). |
| 39 | sp | sERIAL pORT BI-DIRECTIONAL
CONNECTION. aN INTERNAL SHIFT REGISTER CONVERTS MICROPROCESSOR PARALLEL DATA
INTO SERIAL DATA, AND VISA-VERSA. |
| 40 | cnt | cOUNT INPUT. iNTERNAL
TIMERS CAN COUNT PULSES APPLIED TO THIS INPUT. iT IS USED FOR FREQUENCY
DEPENDENT OPERATIONS. |
