
238
High-speed Data Exchanges
Section 8-2
Examples 2
When the ASCII Unit operates as a special BASIC processing unit, a trigger is
sent from the CPU Unit to the ASCII Unit, which after processing, sends a trig-
ger back to the CPU Unit.
The CPU Unit assigns arithmetic processing outside its capability to the ASCII
Unit, enabling high-speed processing for both Units by sharing the workload.
CPU Unit
ASCII Unit
1
Writes data to the shared memory via
the IOWR (#00
@@
) instruction, then
sends an interrupt to the ASCII Unit
via the IOWR (#CC00) instruction.
→
Receives the interrupt, reads the data
written to the shared memory via the
PC EGET command in the interrupt
subroutine, then carries out special
arithmetic operations.
↓
2
At the completion of the interrupt sub-
routine (determined by checking the
Interrupt Subroutine Completed Flag),
reads from the shared memory via the
IORD (#00
@@
) instruction.
←
Writes the result of the processing to
the shared memory via the PC EPUT
command; end of the interrupt sub-
routine.
Interrupt
CPU Unit
ASCII Unit
Subroutine
Shared
memory
1.
2.
Operation
IOWR#00
@@
IOWR#CC00
IORD#00
@@
ON PC GOSUB
PC EGET
PC EPUT
RETURN
Содержание C200H-ASC11
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