; Disassembly of the file "Z:\home\knoppix\CoBra Project\Software\CPM\CPM CHRIS_INST analysis\Boot_Sector.bin" ; ; CPU Type: Z80 ; ; Using the opcode map file "Z:\home\knoppix\CoBra Project\Software\CPM\CPM CHRIS_INST analysis\Boot_Sector.bin.opmap" ; ; Created with dZ80 2.0 ; ; on Thursday, 26 of January 2017 at 01:27 PM ; ORG $0000 JR START DEFB $00 DEFB $80 ; This will be left behind as I/O Byte DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 DEFB $00 START: DI LD HL,$0100 LD SP,HL ; set stack at $0100 LD A,$92 ; control word for 8255: Mode Set flag=active, ; Group A: Select Mode 0, ; Port A set to Input mode, ; Port C (upper half) set to Output Mode, ; Group B: Select Mode 0, ; Port B set to Input Mode, ; Port C (lower half) set to Output Mode OUT ($DF),A ; write control word to 8255 OUT ($DF),A ; write control word to 8255 (again !?) LD A,$41 OUT ($FE),A ; set 06 to "1" for VRAM access, border to blue LD DE,$6200 LD BC,$1E00 LDIR ; copy $0100-$1EFF to $6200-7FFF BLOCK#1 ($6200-77FF) + CCP ($7800-$7FFF) ; when done, HL=$1F00 ##### CCP WILL BE COPIED TO $E000-$E7FF BY BIOS CTC INT. ROUTINE #2 ##### LD DE,$E800 LD BC,$1800 LDIR ; copy $1F00-$36FF to $E800-$FFFF (BDOS+BIOS) ; when done, HL=$3700 ; ################### BIOS MODIFICATIONS ###################### LD A,$D9 ; ----------- BIOS DPH area ------------ LD ($FB00),A ; change XLT in DPH#0 in BIOS LD ($FB10),A ; change XLT in DPH#1 in BIOS ; LD ($FB40),A ; change XLT in DPH#4 in BIOS LD A,$CA LD ($FB0A),A ; change DPB in DPH#0 in BIOS LD ($FB1A),A ; change DPB in DPH#1 in BIOS ; LD ($FB4A),A ; change DPB in DPH#4 in BIOS ; LD ($F659),A ; change DPB addr stored parameter in BIOS LD HL,$FDA0 LD ($FB1C),HL ; change CSV in DPH#1 to $FDA0 (for DD it is double the size of SD, so we have to move CSV area somewhere else) LD HL,$FE60 LD ($FB1E),HL ; change ALV in DPH#1 to $FDC0 (for DD it is double the size of SD, so we have to move CSV area somewhere else) ; ----------- BIOS SECTRAN fix for A:,B: to be 860K DSDD drives ----------- LD HL,$0000 LD ($F80C),HL ; changes 2804="JR Z,$F812" to NOP NOP ; ----------- BIOS BLOCK#1 fix for A:,B: to be the same as C:,D: ---------- LD ($7035),HL ; changes 2808="JR Z,$703F" to NOP NOP LD ($6EA9),HL ; changes 2802="JR Z,$6EAD" to NOP NOP LD ($70AC),HL ; changes 2805="JR Z,$70B3" to NOP NOP LD A,$18 LD ($6EC3),A ; changes $20="JR NZ, ..." to "JR ..." ; ############################################################# ; RES 6,A ; A=$01 LD A,$01 ; A=$01 OUT ($FE),A ; set 06 to "0" for DRAM access LD HL,$3700 LD DE,$0100 LD BC,$0900 LDIR ; copy $3700-$3FFF to $0100-$09FF (CHRIS DEMO) LD HL,$0AFF LD DE,$0B00 LD BC,$DD06 LDIR ; fill $0B00-$E805 with ($0AFF)=$1A JP $F600 ; jump to start of BIOS (BIOS function #0, BOOT)