Reading the error channel of a disk drive with low-level commands.

[Whammo]

 code ds
      w stx,
    $00 lda,#
    $90 sta, \ clear st
    $ba lda,
  $ffb1 jsr, \ listen
    $6f lda,#
  $ff93 jsr, \ second #15
  $ffae jsr, \ unlisten
    $90 lda, \ readst
+branch bne, \ device not present?
\ checking for the device is optional
\ but a good idea.
    $ba lda,
  $ffb4 jsr, \ talk #8
    $6f lda,#
  $ff96 jsr, \ tksa #15
here
    $90 lda, \ readst
+branch bne,
  $ffa5 jsr, \ acptr get byte
  $ffd2 jsr, \ chrout
swap    jmp,  \ loop
:+
  $ffab jsr, \ untalk
:+
      w ldx, ;code

Ported (copied) from:
https://codebase64.org/doku.php?id=base:reading_the_error_channel_of_a_disk_drive

[Whammo]

Prototypes for IEC commands

\ tksa and second is $60 for
\ open filename, $e0 for close
\ and $f0 for open. All or sa

: listen ( dv -- )
ar c! $ffb1 sys ;

: second ( sa -- )
ar c! $ff93 sys ;

: talk ( dv -- )
ar c! $ffb4 sys ;

: tksa ( sa -- )
ar c! $ff96 sys ;

: unlisten ( -- )
$ffae sys ;

: untalk ( -- )
$ffab sys ;

: ciout ( chr -- )
ar c! $ffa8 sys ;

: acptr ( -- chr )
$ffa5 sys
ar c@ ;

EDIT: Stacking commands are hoop-jumping.

[Whammo]

So,

require io

: iqt readst if quit then ;
\ prototype error catch

: ds
0 $90 c!                \ st = 0 
$ba c@ listen iqt \ current device
$6f second iqt      \ data channel 
unlisten iqt           \ turn around
$ba c@ talk iqt     \ current device
$6f tksa iqt           \ data channel
acptr readst begin
0= while emit
acptr readst repeat
emit untalk cr ;      \ error channel needs no open or close