Zenith Z-100 PC series Service Manual page 25

Page
3.6
Detailed Circuit Description
Table 3.1 (Continued). I/O Bus Signal Names
PIN SIGNAL DEFINITION
B23 IR05 Interrupt request 5. Assigned to Winchester drive controller.
B24 IR04 Interrupt request 4. Assigned to serial port #1 (fixed).
B25 IR03
Interrupt request 3. Assigned to serial port #2 (configurable).
B26
DACK2*
DMA acknowledge 2. Assigned to floppy disk controller.
B27
TIC
Terminal count. Goes high when terminal count for any DMA
channel is reached.
B28 ALE Address latch enable. Generated by bus controller to indicate
valid processor addresses to the I/O channel.
B29 +5VDC +5VDCbus.
1
B30 OSC Oscillator. A high-speed clock: 14.31818 MHz. Provides
,I
the basic timing tor the system.
B31 GND
Ground.
111
I
'il