IBM XT 5160 User Manual

-CARD SLCTD (I)
-Card Selected: This line is activated by cards in expansion slot
J8. It signals the system board that the card has been selected
and that appropriate drivers on the system board should be
directed to either read from, or write to, expansion slot J8.
Connectors J1 through J8 are tied together at this pin, but the
system board does not use their signal. This line should be driven
by an open collector device.
CLK (0)
System clock: It is a divide-by-3 of the oscillator and has a period
of 210ns (4.77MHz). The clock has a
330/0 duty cycle.
DO-D7 I/O
Data Bits 0 to 7: These lines provide data bus bits 0 to 7 for the
microprocessor, memory, and
I/O devices. DO is the LSB and D7
is the MSB. These lines are active high.
-DACKOto-DACK3(0)
-DMA Acknowledge 0 to 3: These lines are used to acknowledge
DMA requests (DRQI-DRQ3) and refresh system dynamic
memory (-DACKO). They are active low.
DRQI-DRQ3 (I)
DMA Request 1 to 3: These lines are asynchronous channel
requests used by peripheral devices to gain
DMA service. They
are prioritized with DRQ3 being the lowest and
DRQl being the
highest. A request
is generated by bringing a DRQ line to an
active level (high). A
DRQ line must be held high until the
corresponding
DACK line goes active.
System Board 1- 21

IBM XT 5160 Specifications

General

Brand	IBM
Model	XT 5160
Category	Desktop
Language	English