Mercurial > hg > Members > kono > nitros9-code
diff level2/modules/boot_rom.asm @ 0:6641a883d6b0
Initial revision
| author | boisy |
|---|---|
| date | Thu, 04 Apr 2002 16:34:12 +0000 |
| parents | |
| children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/level2/modules/boot_rom.asm Thu Apr 04 16:34:12 2002 +0000 @@ -0,0 +1,159 @@ +******************************************************************** +* Boot - OS-9 Level Two ROM Boot module +* +* $Id$ +* +* Ed. Comments Who YY/MM/DD +* ------------------------------------------------------------------ +* 1 Created BGP 98/??/?? + + nam Boot + ttl OS-9 Level Two ROM Boot module + + ifp1 + use defsfile + endc + +tylg set Systm+Objct +atrv set ReEnt+rev +rev set $01 +edition set 1 + + mod eom,name,tylg,atrv,start,size + +size equ . + +name fcs /Boot/ + fcb edition + +start equ * +* obtain bootfile size at known offset + pshs u,y,x,a,b,cc + orcc #IntMasks mask interrupts + +* allocate memory from system +* memory will start at $8000, blocks 1, 2, 3 and 3F +* we allocate $100 bytes more so that the memory will start +* exactly at $8000 + ldd #$8000-$1300 + os9 F$BtMem + bcs Uhoh + + stu 3,s save pointer in X on stack + std 1,s save size in D on stack + +* TRICK! Map block 4 into $4000, copy our special ROM copy code +* there, then jmp to it! + lda $FFA2 + pshs a + lda #$04 + sta $FFA2 + ldd #RelCodeL code less than 256 bytes + leax RelCode,pcr + ldy #$4800 +Copy lda ,x+ + sta ,y+ + decb + bne Copy + +Jump jsr $4800 * jump to rel code + puls a restore original block at $4000 + sta $FFA2 + +* Upon exit, we return to the kernel with: +* X = address of bootfile +* D = size of bootfile +* CC = carry cleared +ExitOK andcc #^Carry clear carry +Uhoh puls u,y,x,a,b,cc,pc + + +* this code executes at $4800 +RelCode equ * + lda #$4E CC3 mode, MMU, 32K ROM + sta $FF90 + sta $FFDE ROM/RAM mode + +* Map ROM Blocks in + ldd #$3C3D + std $FFA4 + lda #$3E + sta $FFA6 + +* Map block 1 at $6000 + lda $FFA3 + pshs a + lda #$01 + sta $FFA3 +* Copy first 8K of ROM + ldx #$8000 + ldy #$6000 +Loop1 ldd ,x++ + std ,y++ + cmpx #$A000 + blt Loop1 + +* Map block 2 at $6000 + lda #$02 + sta $FFA3 +* Copy second 8K of ROM + ldx #$A000 + ldy #$6000 +Loop2 ldd ,x++ + std ,y++ + cmpx #$C000 + blt Loop2 + +* Map block 3 at $6000 + lda #$03 + sta $FFA3 +* Copy third 8K of ROM + ldx #$C000 + ldy #$6000 +Loop3 ldd ,x++ + std ,y++ + cmpx #$E000 + blt Loop3 + +* Copy remaining ROM area ($8000-$1400) + lda #$3F + sta $FFA3 + ldx #$E000 + ldy #$6000 +Loop4 clr $FFDE put in ROM/RAM mode to get byte + ldd ,x++ + clr $FFDF put back in RAM mode to store byte + std ,y++ + cmpx #$EC00 + blt Loop4 +* ldx #$6000 +* ldy #$E000 +*Loop5 ldd ,x++ +* std ,y++ +* cmpx #$6C00 +* blt Loop5 + + lda D.HINIT restore GIME HINIT value + sta $FF90 + puls a restore org block at $6000 + sta $FFA3 + lda #$03 + sta $FFA6 + ldd #$0102 + std $FFA4 + rts + +RelCodeL equ *-RelCode + +* Fillers to get to $1D0 + fcc /99999999999999999999999999999999999999999999999999/ +* fcc /99999999999999999999999999999999999999999999999999/ +* fcc /99999999999999999999999999999999999999999999999999/ + fcc /99999999999999999999999999999999999999999999999999/ + fcc /99999999999999999999999999999999999999999999999999/ + fcc /99999999999999999999999999999999999999999999999999/ + fcc /999999999999999999999999999999999999999999999999999/ + + emod +eom equ * + end