HD68A21

HD6821, HD68A21, HD68B21 P I A (Peripheral Interface Adapter) The HD6821 Peripheral Interface Adapter provides the universal means of interfacing peripheral equipment to the HD6800 Microprocessing Unit (MPU)- This device is capable of interfacing the MPU to peripherals through two 8-bit bi-directional peripheral data buses and four control lines. No external logic is required for interfacing to most peripheral devices. The functional configuration of the PIA is programmed by the MPU during system initialization. Each of the peripheral data lines can be programmed to act as an input or output, and each of the four control/interrupt lines may be programmed for one of several control modes. This allows a high degree of flexibility in the over-all operation of the interface. HD6821P, HD68A21P, HD68B21P (DP-40) FEATURES Two Bi-directional 8-Bit Peripheral Data Bus for interface to Peripheral devices Two Programmable Control Registers Two Programmable Data Direction Registers Four Individually-Controlled Interrupt Input Lines: Two Usable as Peripheral Control Outputs Handshake Control Logic for Input and Output Peripheral Operation High-Impedance 3-State and Direct Transistor Drive Peripheral Lines Program Controlled Interrupt and Interrupt Disable Capability CMOS Drive Capability on Side A Peripheral Lines Two T T L Drive Capability on All A and B Side Buffers N Channel Silicon Gate MOS Compatible with MC6821, MC68A21 and MC68B21 BLOCK IRQA 38 * DIAGRAM rro Control Regist...