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Routines |
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| 54097 | PUSH HL | Store HL | ||||||
| 54098 | LD DE,64500 | Point to (effective) start of character set graphics | ||||||
| 54101 | ADD A,A | Load index of character into HL and multiply by 8... | ||||||
| 54102 | LD H,0 | ... | ||||||
| 54104 | LD L,A | ... | ||||||
| 54105 | ADD HL,HL | ... | ||||||
| 54106 | ADD HL,HL | ... | ||||||
| 54107 | ADD HL,DE | ...and add to DE to obtain memory location of required character in the character set | ||||||
| 54108 | EX DE,HL | Swap values (DE now holds memory location of character to print and HL holds 64500) | ||||||
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The operand of the instruction at 54109 represents the address of the bitmap virtual text cursor. This is modified by the instructions at 27725, 27737, 27753, 27966, 28180, 28230, 35119, 35206, 35630, 36742, 54188, 54297, 54532 and 54549.
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| 54109 | LD HL,0 | Load (video) memory location to start printing character into HL | ||||||
| 54112 | LD B,8 | For eight bytes (i.e. full height of character)... | ||||||
| 54114 | LD A,(DE) | ...get graphic data from character set... | ||||||
| 54115 | LD (HL),A | ...and load into video memory... | ||||||
| 54116 | INC DE | ...move to next pixel row in character set... | ||||||
| 54117 | INC H | ...and move to next pixel row in video memory | ||||||
| 54118 | DJNZ 54114 | Loop back to 54114 | ||||||
| 54120 | CALL 54215 | Update attribute virtual text cursor based upon current bitmap virtual text cursor | ||||||
| 54123 | LD A,(23695) | Load A with attribute stored at 23695 (71 = BRIGHT white) | ||||||
| 54126 | LD (HL),A | Apply attribute to character just printed | ||||||
| 54127 | CALL 54176 | Advance bitmap virtual text cursor right by one character | ||||||
| 54130 | POP HL | Restore HL | ||||||
| 54131 | RET | Return | ||||||
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