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Data Exchange Time Charts
Section 6-4
Using IOWR Interrupt:
Control Code: #CC00
(C200NX/HG/HE and
CS-1seried PCs only) The CPU Unit indicates an interrupt number to the ASCII Unit by using the
IOWR (#CC00) instruction, and sends an interrupt. The ASCII Unit executes
the interrupt subroutine which matches the interrupt number in an ON PC
command. When the interrupt subroutine is completed, the Interrupt Subrou-
tine Completed Flag is toggled (OFF to ON or ON to OFF). This method is
supported only by the C200HX/HG/HE and CS1-series PCs.
The following example is for a C200HX/HG/HE PC.
When using the PC Interrupt Bit described on the previous page, the interrupt
is sent as soon as the IOWR instruction is executed, in contrast to interrupting
using the PC Interrupt Bit (described on previous page), by which the interrupt
is sent during the I/O refresh period. For this reason, high-speed interrupts to
the ASCII Unit occur in the same cycle, not in the next cycle.
By combining the IOWR/IORD (#00
@@
) instruction at the CPU Unit with the
PC EGET/PC EPUT commands in the ASCII Unit’s interrupt subroutine,
reads/writes between the CPU Unit and the ASCII Unit can occur within a sin-
gle cycle.
The following is an example of a program.
Note 1. The following IOWR instruction would be used if the ASCII Unit was unit
number 0 and the interrupt number was 2.
2. The structure of the IOWR instruction for the CS1-series PCs is shown be-
low.
IOWR
interrupt
001 fixed
Toggle after completion
of subroutine
At IOWR execution
CPU Unit ASCII Unit
Interrupt subroutine
RETURN
Interrupt
number
(01 to 99
BCD)
Unit No.
At I/O refresh
n + 5 n + 5
PC Interrupt Subroutine Completed Flag
Bit 01 Bit 01
ON PC
a GOSUB
IOWR
#CC00
a
PC ON
0001
#0001
a
(See notes 1, 2)
IOWR
#CC00
#0002
#0001
0 001
Always 0001.
Unit No.
Control code
Interrupt number
IOWR (223)
#CC00
#0002
#00010000
0001 0000
Unit No.
Always 0001.
Interrupt number (BCD)