|
D0-D7 |
Bi-directional, tristated, buffered data lines. Connected to
data bus directly or through buffers |
RD-bar |
Active low read control |
WR-bar |
Active low write control |
A0 |
Address input line, used to select control register |
CS-bar |
Active low chip select |
CAS0-2 |
Bi-directional, 3 bit cascade lines. In master mode, PIC places
slave ID no. on these lines. In slave mode, the PIC reads slave ID
no. from master on these lines. It may be regarded as
slave-select. |
SP-bar / EN-bar |
Slave program / enable. In non-buffered mode, it is SP-bar
input, used to distinguish master/slave PIC. In buffered mode, it is
output line used to enable buffers |
INT |
Interrupt line, connected to INTR of microprocessor |
INTA-bar |
Interrupt ack, received active low from microprocessor |
IR0-7 |
Asynchronous IRQ input lines, generated by
peripherals. | |