initial commit

fstbt.s

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+;fast boot-loader in one sector
+;"special delivery" version for Directi-DOS
+;copyright (c) Peter Ferrie 2016
+;thanks to 4am for inspiration and testing
+;assemble using ACME
+!cpu 6502
+!to "fstbt",plain
+*=$800
+
+!byte 1
+
+        tay                     ;A is last read sector+1 on entry
+        lda     $C081           ;bank in ROM while leaving RAM write-enabled if it was before
+
+        ;check array before checking sector number
+        ;allows us to avoid a redundant seek if all slots are full in a track,
+        ;and then the list ends
+
+incindex
+        inc     adrindex + 1    ;select next address
+
+adrindex
+        lda     adrtable - 1    ;15 entries in first row, 16 entries thereafter
+        sta     $4FB            ;set 80-column state (final store is an #$FF to disable it)
+        cmp     #$FF
+        beq     jmpoep          ;#$C0 means end of data
+        sta     $27             ;set high part of address
+
+        ;2, 4, 6, 8, $0A, $0C, $0E
+        ;because PROM increments by one itself
+        ;and is too slow to read sectors in purely incremental order
+        ;so we offer every other sector for read candidates
+
+        iny
+        cpy     #$10
+        bcc     setsector       ;cases 1-$0F
+        beq     sector1         ;finished with $0E
+                                ;next should be 1 for 1, 3, 5, 7... sequence
+
+        ;finished with $0F, now we are $11, so 16 sectors done
+
+        jsr     seek            ;returns A=0
+
+        ;back to 0
+
+        tay
+        !byte   $2C             ;mask LDY #1
+sector1
+        ldy     #1
+
+setsector
+        sty     $3D             ;set sector
+        iny                     ;prepare to be next sector in case of unallocated sector
+        lda     $27
+        beq     incindex        ;empty slot, back to the top
+
+        ;convert slot to PROM address
+
+        txa
+        lsr
+        lsr
+        lsr
+        lsr
+        tay
+        ora     #$C0
+        pha
+        lda     #$5B            ;read-1
+        pha
+        lda     #2
+        sta     $478, y         ;save current phase for DOS use when we exit
+        lda     $C083
+        lda     $C083           ;write-enable RAM and bank it in so read can decode
+        rts                     ;return to PROM
+
+seek
+        inc     $41             ;next track
+        asl     $40             ;carry clear, phase off
+        jsr     seek1           ;returns carry set, not useful
+        clc                     ;carry clear, phase off
+
+seek1
+        jsr     delay           ;returns with carry set, phase on
+        inc     $40             ;next phase
+
+delay
+        lda     $40
+        and     #3
+        rol
+        ora     $2B             ;merge in slot
+        tay
+        lda     $C080, y
+        lda     #$30
+        jmp     $FCA8           ;common delay for all phases
+
+jmpoep
+        jsr     $FE89           ;rehook keyboard (needed particularly after PR#)
+        jsr     $FE93           ;rehook video
+        jsr     $FB2F           ;text mode
+        sta     $C00C
+        sta     $C00E           ;clear 80-column mode
+        lda     $C083           ;bank in our RAM, write-enabled
+        jmp     $D000           ;jump to unpacker
+
+adrtable
+!byte $dd,$dc,$db,$da,$d9,$d8,$d7,$d6,$d5,$d4,$d3,$d2,$d1,$d0,$de
+!byte $df,$ed,$ec,$eb,$ea,$e9,$e8,$e7,$e6,$e5,$e4,$e3,$e2,$e1,$e0,$ee
+!byte $FF ;end of list

readme.md

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+This is Diversi-DOS for the Apple II, crammed into two tracks, and loading directly into the Language Card.<br>
+Powered by the <a href="https://github.com/peterferrie/standard-delivery">Standard Delivery</a> loader, and <a href="http://pferrie.host22.com/misc/aplibunp.zip">aPLib</a> compression.