| 1 | ; FLASH GORDON driver
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| 2 | ; Copyright 2012, Adrien Destugues <pulkomandy@gmail.com>
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| 3 | ; This program is distributed under the terms of the MIT licence
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| 4 |
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| 5 | ; Start here.
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| 6 | DI
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| 7 |
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| 8 | ; Move the screen to $8000 or $0000 so we can display things to the user, while
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| 9 | ; C000 will write to the ROM and 4000 will hold the data to write... That could
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| 10 | ; get a bit messy so maybe we will need to use the screen at 4000 as a buffer
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| 11 | ; for the ROM data as well. Or just use a bank for that ?
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| 12 |
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| 13 | ; Map the ROM in
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| 14 | ; TODO
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| 15 |
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| 16 | ; ask the user to enable writing
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| 17 | ; TODO
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| 18 |
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| 19 | ; Check if we can read the ROM type
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| 20 | LD A, 0x90
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| 21 | CALL send_command
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| 22 |
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| 23 | LD HL, 0xC000
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| 24 |
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| 25 | LD A,(HL)
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| 26 | CALL printhex
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| 27 | INC L
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| 28 | LD A,(HL)
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| 29 | CALL printhex
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| 30 |
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| 31 | ; We should get 0x8F 87
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| 32 | ; TODO check that before continuing with writing the data
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| 33 | JR $
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| 34 |
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| 35 | ; Now reuse and adapt the code from OUL guys !
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| 36 |
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| 37 | ; That's all folks !
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| 38 | RET
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| 39 |
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| 40 | ; Helper routines -----------------------------------------------------
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| 41 |
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| 42 | ; Send a command to the ROM. The available commands are :
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| 43 | ERASE equ 0x80
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| 44 | IDENTIFY equ 0x90
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| 45 | BYTEPROG equ 0xA0
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| 46 | RESET equ 0xF0
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| 47 |
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| 48 | ; Input: Commend to send in A register
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| 49 | send_command:
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| 50 | ; Select ROM 1
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| 51 | LD BC,0xDF01
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| 52 | LD HL,0xD555
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| 53 | LD DE,0xEAAA
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| 54 |
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| 55 | ; Select ROM 1 and write 0xAA to address 0xD555
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| 56 | OUT (C),C
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| 57 | LD (HL),E
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| 58 |
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| 59 | ; Select ROM 2 and write 0x55 to address 0xEAAA
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| 60 | INC C
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| 61 | OUT (C),C
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| 62 | EX DE,HL
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| 63 | LD (HL), E
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| 64 |
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| 65 | ; Select ROM 1 again and write the command to address 0xEAAA
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| 66 | DEC C
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| 67 | OUT (C),C
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| 68 | EX DE,HL
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| 69 | LD (HL), A
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| 70 |
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| 71 | RET
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| 72 |
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| 73 |
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| 74 | ; Print value of A, as 2 hex digits
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| 75 | printhex
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| 76 | PUSH AF
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| 77 | RRA
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| 78 | RRA
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| 79 | RRA
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| 80 | RRA ;divise A par 8
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| 81 | CALL PRNHEX1 ;affiche le premier morceau
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| 82 | POP AF ;r{cup la valeur originale pour la suit
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| 83 | PRNHEX1 ;affiche la valeur de A sur 1 chiffre
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| 84 | ;affiche A sur 1 chiffre en Hexa
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| 85 | AND 0xF ;ne prend que les unit{s
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| 86 | OR A
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| 87 | DAA ;convertit en d{cimal
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| 88 | ADD A,0xF0 ;ajoute 240
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| 89 | ADC A,0x40 ;ajoute 64+le carry (si >15)
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| 90 | ;on a le code ascii du chiffre @ afficher
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| 91 | JP 0xBB5A ;call-ret
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| 92 | ;
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