Asynchronous Terminals and Printer Processes Programming Manual

PROCEDURE CALLS FOR ACCESSING TERMINALS

Conversational Mode

S5073-001

Application

WRITEREAD

(Prompt)

I/O Process

WRITEREAD

Completion

LIU

WRITEREAD

(Prompt)

WRITEREAD

(Erase previous

character)

WRITEREAD

Completion

Device

Data ... < BS >

Data ... < CR >

Figure 3-1. Conversational Mode Example

Page Mode

When an application communicates with a terminal in page mode, it

writes to the screen by issuing a WRITE request for the entire

screen. The I/O process forwards the WRITE request to the LIU.

The protocol module blocks the text and performs the physical

I/Os. After all blocks have been written, the WRITE is completed

back to the I/O process and then to the application. The

application fetches the function key by issuing a READ request.

The READ is forwarded to the LIU and the line task waits for the

operator to enter a function key. Figure 3-2 shows how page mode

works.

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