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CHAPTE:R 3
OPEF~A
TION AND PROGRAMMING
INTRODUCTION
Th is sect i on prov ides operat i ng and prog rammi ng i nformat i on for the
Am96/4116A MonoBoard Computer (MBC) and the programmable devices.
The
MCB includes five programmable devices as follows:
•
Two Am9551 Programr.lab
1
e Communi cati ons I nterfaces that provi de
two RS232C serial I/O ports.
•
An Am8255A Programmable Peripheral Interface that controls the
24 parallel I/O lines.
•
An 8259A Programmab
1
e I nterlrupt Contro
11
er that responds to
eight interrupt lines.
•
An Am9513 System Timing Conty'oller
I/O ADDRESS ASSIGNMENT
The CPU communicates with the programmable devices through a sequence
of I/O read and I/O write commands.
A summary of I/O addresses is
listed in table 3-1.
NOTE
I/O addresses from COOOH to FFFFH are reserved for
the Arn96/4116 board.
SHARED MEMORY AND THE MUI.TIBUS
Sometimes it is useful for two processors to share the same memory
locations in order to communicate and pass data.
With the Am96/4116A,
only byte (8-bit) operations should be used when passing data between
processors and shared memory.
The Multibus considers data bits 0 to 7
as even bytes and data bits 8 to 15 as odd bytes.
However, the ArnZ8002
considers data bits 0 to
7
as odd bytes and data bits 8 to 15 as even
bytes.
Figure 3-1 illustrates the Arn96/4116A and external RAM attached
to the Multibus.
The same example applies to the on-board RAM if
shared by an external dev'lce.
In figure 3-1, memory locations are
gi ven as 8000H and 8001H.
Note that 8000H in RAM uses bits 0 to
7
while the ArnZ8002 uses bits 8 to 15.
3-1
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