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OS-9:REL - Revision history
2026-04-28T00:09:21Z
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ExileInParadise: initial RELocate boot track for OS-9 Level 1 v1.0 disassembled and commented
2024-05-19T13:09:45Z
<p>initial RELocate boot track for OS-9 Level 1 v1.0 disassembled and commented</p>
<p><b>New page</b></p><div><br />
<pre><br />
;****************************************************<br />
;* Used Labels *<br />
;****************************************************<br />
<br />
M0000 EQU $0000<br />
M0001 EQU $0001<br />
M0008 EQU $0008<br />
M000C EQU $000C<br />
M0012 EQU $0012<br />
D.FMBM EQU $0020<br />
M0022 EQU $0022<br />
D.MLIM EQU $0024<br />
D.ModDir EQU $0026<br />
M0028 EQU $0028<br />
M002A EQU $002A<br />
D.NMI EQU $002C<br />
M002E EQU $002E<br />
M0036 EQU $0036<br />
D.SvcIRQ EQU $0038<br />
Z003A EQU $003A<br />
M003C EQU $003C<br />
M003E EQU $003E<br />
M003F EQU $003F<br />
M0040 EQU $0040<br />
M0041 EQU $0041<br />
M0042 EQU $0042<br />
M0043 EQU $0043<br />
D.UsrDis EQU $0044<br />
D.SysDis EQU $0046<br />
M0048 EQU $0048<br />
M0049 EQU $0049<br />
D.PROC EQU $004B<br />
M004D EQU $004D<br />
M004F EQU $004F<br />
M0051 EQU $0051<br />
M0053 EQU $0053<br />
M0055 EQU $0055<br />
M0057 EQU $0057<br />
M005B EQU $005B<br />
M0066 EQU $0066<br />
M0068 EQU $0068<br />
M0072 EQU $0072<br />
M0081 EQU $0081<br />
M00FF EQU $00FF<br />
M0100 EQU $0100<br />
M0109 EQU $0109<br />
M010A EQU $010A<br />
M016F_via_cvec_2e46 EQU $016F<br />
M0175_via_cvec_2e48 EQU $0175<br />
M017B_via_cvec_2e4a EQU $017B<br />
M017C_via_cvec_2e4c EQU $017C<br />
M0180_via_cvec_2e4e EQU $0180<br />
M01CA_via_cvec_2e44 EQU $01CA<br />
M01FF EQU $01FF<br />
M0200 EQU $0200<br />
M03E0 EQU $03E0<br />
M0F00 EQU $0F00<br />
M0FE3 EQU $0FE3<br />
M222E EQU $222E<br />
M8000 EQU $8000<br />
M8021 EQU $8021<br />
M810C EQU $810C<br />
M87CD EQU $87CD<br />
MC350 EQU $C350<br />
MF000 EQU $F000<br />
ZF056 EQU $F056 ; LOCATE OS9 MODULE START<br />
PIA0AD EQU $FF00<br />
PIA0BC EQU $FF03<br />
DSKREG EQU $FF40<br />
FDCREG EQU $FF48<br />
FDCTRKREG EQU $FF49<br />
FDCSECREG EQU $FF4A<br />
FDCDATREG EQU $FF4B<br />
SAMF0CLR EQU $FFC6<br />
SAMTYSET EQU $FFDF<br />
RESETV EQU $FFFE<br />
RESETV EQU $FFFF<br />
<br />
;****************************************************<br />
;* Program Code / Data Areas *<br />
;****************************************************<br />
<br />
ORG $2600<br />
<br />
BOOTSIG FCC "OS" ;2600: 4F 53 'OS' DOS BOOTTRACK OS SIGNATURE<br />
EXECADDR FDB REL ;2602: 26 0C '&.' EXECUTION START ADDRESS<br />
OS9_BOOT FCC "OSy`BOOT" ;2604: 4F 53 79 60 42 4F 4F 54 'OSy`BOOT' OS-9 BOOT SCREEN STRING<br />
; START OF REL "MODULE"<br />
REL CLR PIA0BC ;260C: 7F FF 03 '...' DISABLE VSYNC<br />
STA SAMTYSET ;260F: B7 FF DF '...' SAM MAP TYPE=1 "ALL RAM"<br />
LDB #$06 ;2612: C6 06 '..' SET COUNTDOWN TO CLEAR 7 BITS (B=6)<br />
LDX #SAMF0CLR ;2614: 8E FF C6 '...' START WITH SAM DISPLAY OFFSET F0 BIT<br />
REL10 STA ,X++ ;2617: A7 81 '..' CLEAR THE DISPLAY OFFSET BIT THEN X=X+2<br />
DECB ;2619: 5A 'Z' COUNT DOWN 1<br />
BNE REL10 ;261A: 26 FB '&.' DID WE CLEAR OUR 7TH BIT (B=0)<br />
STA $01,X ;261C: A7 01 '..' YES, SET DISPLAY OFFSET SCREEN AT $8000<br />
; CLEAR SCREEN WITH SPACES<br />
LDX #M8000 ;261E: 8E 80 00 '...'<br />
LDY #M0200 ;2621: 10 8E 02 00 '....'<br />
LDA #$60 ;2625: 86 60 '.`'<br />
REL20 STA ,X+ ;2627: A7 80 '..'<br />
DEY ;2629: 31 3F '1?'<br />
BNE REL20 ;262B: 26 FA '&.'<br />
; PUT BANNER ONTO SCREEN<br />
LDX #M810C ;262D: 8E 81 0C '...'<br />
LEAY OS9_BOOT,PCR ;2630: 31 8C D1 '1..'<br />
LDB #$08 ;2633: C6 08 '..'<br />
REL30 LDA ,Y+ ;2635: A6 A0 '..'<br />
STA ,X+ ;2637: A7 80 '..'<br />
DECB ;2639: 5A 'Z'<br />
BNE REL30 ;263A: 26 F9 '&.'<br />
; FIXME WHAT IS THIS<br />
TST M0072 ;263C: 0D 72 '.r' FIXME TEST ALREADY RELOCATED FLAG?<br />
BEQ REL50 ;263E: 27 13 ''.'<br />
; START RELOCATING<br />
LEAU >BOOTSIG,PCR ;2640: 33 8D FF BC '3...'<br />
LDX #M0F00 ;2644: 8E 0F 00 '...'<br />
LDY #MF000 ;2647: 10 8E F0 00 '....'<br />
REL40 LDA ,U+ ;264B: A6 C0 '..'<br />
STA ,Y+ ;264D: A7 A0 '..'<br />
DEX ;264F: 30 1F '0.'<br />
BNE REL40 ;2651: 26 F8 '&.'<br />
; RELOCATION COMPLETE, PREPARE FOR OS9 MODULE COLD START<br />
REL50 JMP ZF056 ;2653: 7E F0 56 '~.V' JUMP TO RELOCATED MODULES<br />
LEAX <M01SYNC,PCR ;2656: 30 8C 04 '0..' LOCATE OS9 MODULE START<br />
LDD $09,X ;2659: EC 09 '..' LOCATE OS9 EXEC ADDRESS<br />
JMP D,X ;265B: 6E 8B 'n.' JUMP INTO OS9 MODULE<br />
<br />
</pre></div>
ExileInParadise