Zenith Z-100 PC series Service Manual page 23

Page
3.4
Detailed Circuit Description
Table 3.1 (Continued). 1/0 Bus Signal Names
PIN SIGNAL
DEFINITION
A19 A12 Address bit 12
A20 A11 Address bit 11
A21 A10 Address bit 1 0
A22 A9 Address bit 9
A23 A8 Address bit 8
A24 A7 Address bit 7
A25 A6 Address bit 6
A26
A5 Address bit 5
A27 A4 Address bit 4
)
III"
A28 A3 Address bit 3
A29 A2 Address bit 2
A30 A1 Address bit 1
A31 AO Address bit 0
81 GND
Ground
82 RESET When high, resets, or initializes system logic devices.
83 +5VDC
+5 VDC bus
84 IRQ2 Interrupt request 2. Not used, but available for assignment to
a user-selected device.
85 -5VDC -5 VDC bus
86 DRQ2 DMA request 2. Assigned to floppy disk controller.
Continued ...
I)