GENERAL DESCRIPTION
The I/O portion consists of three general purpose I/O ports. One of the three ports can be programmed to be status pins, thus allowing the other two ports to operate in handshake mode. A 14-bit programmable counter/timer is also included on chip to provide either a square wave or terminal count pulse for the CPU system depending on timer mode. CONNECTION DIAGRAM Top View 101M ADo-AD7 * ALE AD WR RESET TIMER ClK TIMER OUT 256 X 8 STATIC RAM PORT A B PA o-PA 7 G PBo-PB7 TIMER B PCo-PC s ~veC<+5V) Vss(OV) PC3 PC4 TIMER IN RESET PC s TIMER OUT 101M A*D vm ALE ADo AD1 AD2 AD3 AD4 ADs AD6 AD7 Vss 39 38 37 36 35 34 33 32 10 Am8155 31 11 Am8156 30 12 29 13 28 14 27 15 26 16 25 17 24 18 19 22 20 21 Vee PC2 PC, PCo PB 7 PB 6 PBs PB4 PB3 PB 2 PB1 PBo PA7 PA6 PAs PA4 PA3 PA2 PA1 PAo *Am8155 = CE, Am8156 = CE Note: Pin 1 is marked for orientation. MOS-070 ORDERING INFORMATION MOS-071 Package Type Temperature Range Hermetic DIP* Molded DIP aoc ~ TA ~ +70°C *Hermetic = Ceramic = DC = CC = D-40-1.
AMD
