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84 lines
1.3 KiB
84 lines
1.3 KiB
;
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; USRROM TEMPLATE FOR A CUSTOM USER ROM
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;
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#INCLUDE "std.asm"
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;
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CR .EQU 0DH
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LF .EQU 0AH
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;
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.ORG USR_LOC
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;
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LD SP,USR_END
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;
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LD HL,BOOTMSG ; INTRODUCTION
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CALL PRTSTR
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;
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CALL CIN ; DO STUFF
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;
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LD B,BF_SYSRESET ; SYSTEM RESTART
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LD C,BF_SYSRES_WARM ; WARM START
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CALL $FFF0 ; CALL HBIOS
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; RET
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;
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;
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;
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; PRINT A STRING AT ADDRESS SPECIFIED IN HL
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; STRING MUST BE TERMINATED BY '$'
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; USAGE:
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; LD HL,MYSTR
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; CALL PRTSTR
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; ...
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; MYSTR: .DB "HELLO$"
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;
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PRTSTR: LD A,(HL)
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INC HL
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CP '$'
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RET Z
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CALL COUT
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JR PRTSTR
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;
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; OUTPUT CHARACTER IN A TO CONSOLE DEVICE
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;
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COUT: PUSH AF
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PUSH BC
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PUSH DE
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PUSH HL
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LD B,01H
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LD C,80H
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LD E,A
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RST 08
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POP HL
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POP DE
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POP BC
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POP AF
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RET
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;
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; WAIT FOR A CHARACTER FROM THE CONSOLE DEVICE AND RETURN IT IN A
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;
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CIN: PUSH BC
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PUSH DE
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PUSH HL
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LD B,00H
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LD C,80H
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RST 08
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LD A,E
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POP HL
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POP DE
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POP BC
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RET
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;
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BOOTMSG:.DB CR,LF,CR,LF
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.DB "No User ROM Installed."
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.DB CR,LF,CR,LF
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.DB "Press a key to return to Boot Loader.$"
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;
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; IT IS CRITICAL THAT THE FINAL BINARY BE EXACTLY USR_SIZ BYTES.
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; THIS GENERATES FILLER AS NEEDED.
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;
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SLACK .EQU (USR_END - $)
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.FILL SLACK,00
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.ECHO "User ROM space remaining: "
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.ECHO SLACK
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.ECHO " bytes.\n"
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.END
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