On Apr 17, 22:09, Peter Pachla wrote: do? system assembly Ah, well I might have an assembler somewhere -- there were two flavours: one produced executable object code directly (I think) and the other produced object modules which could be linked with modules produced by high-level languages such as C, Fortran, and Pascal. I'm sure some of the remaining Acorn web and/or FTP sites, like Stuttgart or HENSA, still have instruction set lists. But you don't even need that to get going -- BBC BASIC V contains a reasonable 2-pass ARM assembler. It works just like the 6502 assembler in BBC BASIC II (et al). Here's a sample so you seen what I mean (don't ask me exactly how it works, it's intimatley bound up with the interactions between the desktop palette, the OS palette, and the hardware palette, and anyway I wrote this 12 years ago :-)): REM part of palette control program for RISC OS 2.0 DIM code% 408 PROCassemble REM main program loop here REM followed by several other procedures/functions DEF PROCsupremacy CALL getpal : REM read actual colour mapping D%=colour% : REM R3=colour% H%=windowhandle% : REM R7=windowhandle% CALL do_sup ENDPROC DEF PROCassemble LOCAL cnt,sup,bm,sptr,vptr,val,ptr,ccol,sp,link,pass% ptr=1 : ccol=3 : cnt=6 : sp=13 : link=14 : REM windowhandle passed in R7 sup=10 : bm=4 : sptr=5 : vptr=8 : val=9 : REM arbitrary register choice log=0 : phys=1 : bpp=4 : wptr=5 : tmp=9 FOR pass%=0 TO 2 STEP 2 P%=code% [ OPT pass% .do_sup STMFD (sp)!, {link} ADR sptr, supremacy% ; set up pointers ADR vptr, vpalette% LDR sup, [sptr] ; get supremacy word MOV bm, #&80 ; supremacy bit mask MOV R0, #12 ; for OSWORD 12 ; In case of moving from 16-colour mode to 256-colour mode, ; we need all the clrs separate from all the sets - because ; several colours may share one physical palette register ADD ptr, vptr, #95 ; ptr to last vpalette entry MOV cnt, #19 ; counter .clr TST sup, bm, LSL cnt ; s-bit for this palette entry LDRB val, [ptr, #1] AND val, val, #&7F STRB val, [ptr, #1] SWI "OS_Word" SUB ptr, ptr, #5 SUBS cnt, cnt, #1 BPL clr ; Do sets after clrs to ensure that if any colour in a group ; is set, all will be. If we did set/clr together, might ; finish a group with a clear. ADD ptr, vptr, #95 ; ptr to last vpalette entry MOV cnt, #19 ; counter .set TST bm, sup, LSR cnt ; s-bit for this palette entry LDRNEB val, [ptr, #1] ORRNE val, val, #&80 STRNEB val, [ptr, #1] SWINE "OS_Word" .next SUB ptr, ptr, #5 SUBS cnt, cnt, #1 BPL set ; If there is a current colour, and it should be clear, then ; we need to clear it explicitly in case it's been set as part ; of a group which is set TST ccol, ccol ; see if there IS a current colour BMI newsup ADD ptr, ccol, ccol, ASL#2 ; if so, point to vpalette%+ccol*5 ADD ptr, ptr, vptr LDRB val, [ptr, #1] ; get logical colour ORR val, val, #&80 TST sup, bm, LSL ccol ; should it be set ? ANDEQ val, val, #&7F ; clear supremacy if not STRB val, [ptr, #1] SWI "OS_Word" ; now we re-get supremacy in case of interactions above .newsup ADD vptr, vptr, #95 ; ptr to final vpalette entry MOV cnt, #19 ; counter MOV val, #0 .nsloop LDRB R0, [vptr] ; logical colour LDRB R1, [vptr, #1] ; supremacy+programming info AND R1, R1, #&7F ; just programming info SWI "OS_ReadPalette" AND R2, R2, #&80 ; return just supremacy ADD val, R2, val, LSL#1 ; shift into new supremacy word AND R0, bm, sup, LSR cnt ; corresponding bit in old word TEQ R0, R2 ; see if same BLNE toggle SUB vptr, vptr, #5 SUBS cnt, cnt, #1 BPL nsloop STR val, [sptr] LDMFD (sp)!, {PC} ; pop PC to return .toggle ADR R1, wimp%+1024 SUB R1, R1, #1024 STR R7, [R1] ; wimp%!0=windowhandle% STR cnt, [R1, #4] ; wimp%!4=icon% or cnt (ie R6) CMP cnt, #16 MOVLT R11, #&00000005 ; depending on which icon, MOVGE R11, #&77000000 ; change different things STR R11, [R1, #8] ; wimp%!8=icon flags EOR word MOV R11, #0 STR R11, [R1, #12] ; wimp%!12=icon flags clear word SWI "Wimp_SetIconState" MOVS pc, link .getpal MVN R0, #0 ; get bits-per-pixel for mode#-1 MOV R1, #9 SWI "OS_ReadModeVariable" MOV bpp, R2 ; save Log2BPP ADR wptr, wpalette% MOV R1, wptr SWI "Wimp_ReadPalette" ; get wimp palette mappings ADR vptr, vpalette% ADD vptr, vptr, #95 MOV cnt, #19 .pal CMP cnt, #16 LDRMIB log, [wptr, cnt, LSL#2] ; get colour programming info ANDPL log, cnt, #7 ; for 16-19, log=cnt MOD 16 MOVMI phys, #16 MOVEQ phys, #24 MOVHI phys, #25 BPL lc_ok CMP bpp, #3 ; if 256 colours, GCOL => LogColNo ANDEQ tmp, log, #&40 ANDEQ log, log, #7 ADDEQ log, log, tmp, LSR#3 .lc_ok STRB log, [vptr] SWI "OS_ReadPalette" BIC R2, R2, #&1F ; correct physical colour ADD R2, R2, phys MOV tmp, #3 .byte STRB R2, [vptr, #1]! ; save RGB, prog info, supremacy MOV R2, R2, LSR#8 SUBS tmp, tmp, #1 BPL byte SUB vptr, vptr, #9 SUBS cnt, cnt, #1 BPL pal MOV pc, link ; claims upcall to permit OS_ChangeDynamicArea ; as it does no checking, it must only be enabled immediately prior ; to calling OS_ChangeDynamicArea, and disabled immediately thereafter .upcall MOV R0, #0 LDMFD R13!, {PC} ] NEXT pass% ENDPROC -- Pete Peter Turnbull Dept. of Computer Science University of York