| pin | desc | function |
|---|---|---|
| 1 | vSS | gROUND. |
| 2-9 | pa0-pa7 | pERIPHERAL i/o pORT a. |
| 10-17 | pb0-pb7 | pERIPHERAL i/o pORT b. |
| 18,19 | cb1,cb2 | pERIPHERAL b cONTROL lINES. |
| 20 | vCC | +5vdc. |
| 21 | irq | iNTERRUPT rEQUEST. |
| 22 | r/w | rEAD/wRITE. |
| 23,24 | cs1,cs2 | cHIP sELECT. |
| 25 | 02 | pHASE 2 iNTERNAL cLOCK. |
| 26-33 | d0-d7 | dATA bUS. |
| 34 | res | rESET iNPUT, lOW aCTIVE. |
| 35-38 | rs0-rs3 | rEGISTER sELECT iNPUTS. |
| 39,40 | ca1,ca2 | pERIPHERAL a cONTROL lINES. |