Differences
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mg_notes:iie_card:weird_stuff [2017/08/07 15:14] M.G. [Other Weird Instructions] |
mg_notes:iie_card:weird_stuff [2017/08/07 22:16] M.G. [Other Weird Instructions] |
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| ^ In Routine ^ Address ^ Code ^ Function ^ | ^ In Routine ^ Address ^ Code ^ Function ^ | ||
| - | | PWRUP | $FAB4 | $02 $02 | ? (appears where standard %%//%%e has LDA #$C8 at beginning of boot slot search) | | + | | PWRUP | $FAB4 | $02 $02 | Loads A reg with $Cn+1 where n = startup slot or $C8 if scan. | |
| - | | PWRUP | $FAC0 | $02 $03 | ? (appears where standard %%//%%e has CMP #$C0 after decrmenting the slot pointer) | | + | | PWRUP | $FAC0 | $02 $03 | Displays "UNABLE TO BOOT FROM STARTUP SLOT" if A reg = $Cn-1 where n = startup slot or $c0 if scan. Disappears if screen scrolls. | |
| | APPLEII | $FB63 | $02 $04 | Display copyright message on screen, disappears if screen scrolls. | | | APPLEII | $FB63 | $02 $04 | Display copyright message on screen, disappears if screen scrolls. | | ||
| | BELL1 | $FBDD | $02 $01 | Play system bell sound. | | | BELL1 | $FBDD | $02 $01 | Play system bell sound. | | ||
| | GETLN1 | $FD78 | $02 $06 | Key translation called right after rdchar. If A reg has <key>DELETE</key>, converts it to <key><-</key>. | | | GETLN1 | $FD78 | $02 $06 | Key translation called right after rdchar. If A reg has <key>DELETE</key>, converts it to <key><-</key>. | | ||
| | | | $02 $05 | Not found in firmware, yet, but presumably this exists. | | | | | $02 $05 | Not found in firmware, yet, but presumably this exists. | | ||
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| - | Hypothesis for $02 $02 and $02 $03: | ||
| - | |||
| - | $02 $02 loads the accumulator with $Cn+1 where n is the slot selected in the control panel, or $C8 for "Scan". | ||
| - | |||
| - | $02 $03 checks the accumulator and depending on the control panel setting either allows the loop to continue (scan and A > $C0), drops to BASIC (scan and A = $C0), or prints the "unable to boot" message (specific slot and A != $Cn). | ||
| ==== The Key Translation and the A register ==== | ==== The Key Translation and the A register ==== | ||