Using; Motherboard Interrupts - NorthStar HORIZON Manual

USING THE REAL-TIME CLOCK
To lise the Real-Time Clock, select a time interval from among the
following and jumper the corresponding pin to pin 13 on the 14-
pin DIP header at location 10A:
3.3280 ms
pin 12
851.97 ms
26.624 ms pin
11 1.7039 s
53.248 ms pin 10
3.4079 s
106.50 ms pin 9
6.8157 s
213.99 ms pin 8
13.631 s
425.98 ms
pin 7
27.263 s
NotE' that all time intervals are exactly a power of
ms. The clock flag (CLK-FLG) can be jumpered to an
can be read as bit 2 of the motherboard status byte
an :N 6 instruction in the standard configuration.
Fla'i is reset by executing MVI A,50H; OUT 6.
MOTHERBOARD INTERRUPTS
pin 6
pin 5
pin 4
pin 3
pin 2
pin 1
2 times 3.328
interrupt or
by executing
The Clock
The motherboard I/O interfaces and real-time clock can be
conJ:igured to generate interrupt request signals to the S-100
bus There are eleven possible interrupt conditions which are
grollped to generate four different interrupt requests as follows:
iltandard Serial Interface
1. Receiver Ready
2. Sync Detect
3. Transmitter Ready - disarmable
4. Transmitter Empty - disarmable
:3econd Serial Interface
5. Receiver Ready
6. Sync Detect
7. Transmitter Ready - disarmable
8. Transmitter Empty - disarmable
0arallel Interface
9. Parallel Input Flag - disarmable
10. Parallel Output Flag - disarmable
~eal-Time Clock
11. Clock Flag - disarmable
Note that this grouping can be rearranged by cutting and/or
rewiring motherboard jumpers J5-J14. See the schematic drawings
for details. Each of the above four interrupt groups can be tied
to anyone of the ten interrupt request lines on the 5-100 bus by
79
North Star HORIZON Computer