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READST

     Purpose:  Read status word
Call address:  $FFB7 (hex)  65463 (decimal)
Communication registers:  A
Preparatory routines:  None
Error returns:  None
Stack requirements:  2
Registers affected:  A

Description:

This routine returns the current status of the I/O devices in the accumulator. The routine is usually called after new communication to an I/O device. The routine gives you information about device status, or errors that have occurred during the I/O operation.

The bits returned in the accumulator contain the following information: (see table below)

ST BIT
POSITION		 ST NUMERIC
VALUE		 CASSETTE
READ		 SERIAL R/W TAPE VERIFY
+ LOAD
0 1 Time out write
1 2 Time out read
2 4 Short block Short block
3 8 Long block Long block
4 16 Unrecoverable read error Any mismatch
5 32 Checksum error Checksum error
6 64 End of file EOI line
7 128 End of tape Device not present End of tape

How to Use:

  1. Call this routine.
  2. Decode the information in the A register as it refers to your program.

EXAMPLE:

     ;CHECK FOR END OF FILE DURING READ
     JSR READST
     AND #64       ;CHECK EOF BIT (EOF=END OF FILE)
     BNE EOF       ;BRANCH ON EOF
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