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CHAPTER 3 CPU
3.5.10
Interrupts by extended intelligent I/O service (EI
2
EI
OS is a function to automatically transfer data between the peripherals (I/O) and
memory. It generates the hardware interrupt at termination of data transfer.
2
I EI
OS
2
The EI
terminated, the termination factor (end condition) is set, branching automatically to the interrupt processing
routine. Data can be transferred just by creating a setup program for starting the EI
program.
G
Advantages of EI
Compared to data transfer using the interrupt-processing routine, EI
• Since the creation of transfer program is not required, the program size can be reduced.
• The transfer count can be set to prevent transfer of unnecessary data.
• Whether to update the buffer address pointer can be specified.
• Whether to update the I/O address pointer can be specified.
G
Interrupt by EI
At completion of data transfer by the EI
and then the processing automatically transits to interrupt processing.
2
The EI
OS termination factor can be determined by checking the EI
interrupt processing program.
G
Interrupt control register (ICR)
This register is within the interrupt controller, and displays the states at starting, setting channel, and
terminating the EI
G
2
EI
OS descriptor (ISD)
2
The EI
OS descriptor (ISD), which is allocated between "000100
byte data that is used to set the transfer mode, addresses, transfer count and buffer addresses. It has 16
channels, and a channel number is allocated to each of these channels by the interrupt control register
(ICR).
Note:
The CPU stops while the EI
78
OS provides automatic data transfer between the I/O area and memory. When data transfer is
2
OS
2
OS termination
2
OS.
2
OS is in operation.
2
OS, the end condition is set in the EI
2
2
OS and an end
2
OS has the following advantages.
2
OS status bits (ICR: S1, S0),
2
OS status bits (ICR: S1, S0) using the
" and "00017F
" in internal RAM, is 8-
H
H
OS)
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