Table of Contents
Advertisement
Chapter 3
Programming Overview
I/O Image Tables
Command Interface
Writes 0 to int_status_from_host.
On receipt of interrupt, processes the command.
Queues a confirmation.
Writes 0 to int_status_from_host.
3-2
This image table
holds
input
input data transmitted to the scanner by the adapters in I/O replies
The KTx updates the table as data is received on the remote I/O link.
The host may read this data at any time but should not modify.
output
output data that the scanner will transmit to the adapters in I/O
commands
The host is responsible for writing data into the Output Image table
and may do so at any time; no handshaking with the KTx is required.
Refer to chapter 7 for information about how to read and write the I/O
image tables.
The host configures and controls operation of the scanner by issuing
commands via the command buffer in the dual port. The scanner notifies
the host of the completion status, whether successful or not, via the
confirmation buffer. Some handshaking between the host and scanner is
required to coordinate use of these buffers. The handshaking for both
commands and confirmations is described below. Refer to appendix A for
addresses of dual-port variables.
This diagram illustrates the handshaking for a command sequence.
Notice the host may not initiate a command sequence until the
variable in dual port has been cleared.
int_status_from_host
KTx
Host
Copies a command into the command buffer
of the dual port.
Writes a 01h into int_status_from_host to
indicate the interrupt type is a COMMAND.
Interrupts the KTx by writing any value to KTx
register :801h, host_to_ktx_int_reg.
Advertisement
Table of Contents
