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SECOND

     Purpose:  Send secondary address for LISTEN
Call address:  $FF93 (hex)  65427 (decimal)
Communication registers:  A
Preparatory routines:  LISTEN
Error returns:  See READST
Stack requirements:  8
Registers affected:  A

Description:

This routine is used to send a secondary address to an I/O device after a call to the LISTEN routine is made, and the device is commanded to LISTEN. The routine cannot be used to send a secondary address after a call to the TALK routine.

A secondary address is usually used to give setup information to a device before I/O operations begin.

When a secondary address is to be sent to a device on the serial bus, the address must first be ORed with $60.

How to Use:

  1. Load the accumulator with the secondary address to be sent.
  2. Call this routine.

EXAMPLE:

     ;ADDRESS DEVICE #8 WITH COMMAND (SECONDARY ADDRESS) #15
     LDA #8
     JSR LISTEN
     LDA #$60+15
     JSR SECOND
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