Interesting IEEE Code in VIC-1112

From: Jim Brain <>
Date: Fri, 11 Mar 2016 21:59:58 -0600
Message-ID: <>
IN this forum post:

Simon Rowe has disssembled the code in the VIC-1112 adapter.  I think it 
is interesting how much dead code is in the listing:

echkout    jsr fndflno        ; find file
     beq lb0bf        ; branch if file found
     jmp fe_ntopn        ; do file not open error and retirn
lb0bf    jsr setflch        ; set file details from table,X
     lda fa            ; get device number
     bne lb0c9        ; branch if device is not keyboard
     jmp fe_ntout        ; do not output file error and return
lb0c9    cmp #$03        ; compare device number with screen
     beq lb0d2        ; if screen save output device number and exit
     bcs lb0d6        ; branch if > screen, IEEE bus device
     jmp $f321        ; jump to KERNAL to handle RS-232 and tape
lb0d2    sta dflto        ; save output device number
     clc            ; flag ok
lb0d6    jmp lb0e8        ; skip dead code

     nop            ; *** dead code ***
     jmp $f332        ; *** dead code ***
     cmp #$09        ; *** dead code ***
     bne lb0e8        ; *** dead code ***
     jsr lb59d        ; *** dead code ***
     sta dflto        ; *** dead code ***
     clc            ; *** dead code ***
     rts            ; *** dead code ***

lb0e8    jsr lb40c        ; command an IEEE device to LISTEN
     sta dflto        ; save output device number
     clc            ; flag ok

The author of the post conjectures that the code was lifted from 
somewhere else, like the PET.  Anyone recognize any of the dead code?


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Received on 2016-03-12 05:00:11

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