Mercurial > hg > Members > kono > nitros9-code
view level1/modules/oscode.asm @ 253:762792d92c57
Slight changes to source
author | boisy |
---|---|
date | Sat, 20 Jul 2002 04:43:05 +0000 |
parents | 3fa31ecd389a |
children | 51e03621e721 |
line wrap: on
line source
******************************************************************** * oscode - OS-9 Level One V2 bootstrap code * * $Id$ * * Ed. Comments Who YY/MM/DD * ------------------------------------------------------------------ * From Tandy OS-9 Level One VR 02.00.00 * Also put in conditionals for the Dragon 64 ifp1 use defsfile endc ScrnLoc equ $8000 OS9Start equ $EF00 OS9Size equ $0F80 * Initial code executed upon booting up to OS-9 Start fcc /OS/ bra L2620 fdb $1204 BootMsg fcc /OSy/ fcb $60 fcc /BOOT/ BootMLen equ *-BootMsg L2620 clr PIA.U4+3 ifne Dragon64 clr PIA.U4+1 added for Dragon, works on CoCo endc sta $FFDF turn off ROM * locate Boot Text Screen at $8000 ldb #$06 ldx #$FFC6 L262B sta ,x++ decb bne L262B sta 1,x * Clear VDG screen ldx #ScrnLoc ldy #512 lda #$60 L263B sta ,x+ leay -1,y bne L263B * Copy "OS9 BOOT" to screen area ldx #ScrnLoc+$10C leay <BootMsg,pcr ldb #BootMLen L2649 lda ,y+ sta ,x+ decb bne L2649 ifne Dragon64 tst <$72 else ldd #$1212 cmpd <$0078 endc beq L266E leau >Start,pcr ldx #OS9Size ldy #OS9Start L2663 lda ,u+ sta ,y+ leax -1,x bne L2663 jmp >OS9Start+L266E L266E leax <eoc,pcr ldd $09,x jmp d,x eoc equ * end