Routines
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60580: Initialise Display and Set Border
Used by the routines at Display_High_Score_Entry_Screen and Save_Or_Load_High_Scores.
Clears the display pixel area (16384-22527) to black and fills the 768 attribute cells with the byte in A, then derives the border colour from A's paper bits and updates both BORDCR (23624) and the ULA border port (254).
Input
A Attribute byte for the display fill
Initialise_Display_And_Border 60580 LD HL,16384 Set up to clear the pixel area (16384-22527 6144 bytes).
60583 LD DE,16385
60586 LD BC,6144
60589 LD (HL),0 Clear the first pixel byte and fill the remaining display pixels to black via LDIR.
60591 LDIR
60593 LD BC,768 Set the attribute fill count to 768 cells.
60596 LD (HL),A Seed the first attribute cell with A and fill all 768 attribute cells via LDIR.
60597 LDIR
60599 AND %00111000 Isolate the paper colour bits from the attribute.
60601 BIT 5,A Skip to Set_Border_Colour if the paper colour is in the upper range (4-7).
60603 JR NZ,Set_Border_Colour
60605 XOR %00000111 Complement the ink colour bits to contrast with dark paper.
Set_Border_Colour 60607 LD (23624),A Write the background colour to *BORDCR.
60610 AND %00111000 Re-isolate the paper colour bits.
60612 RRCA Shift the paper colour into the low 3 bits.
60613 RRCA
60614 RRCA
60615 OUT (254),A Write the paper colour to the ULA border port 254.
60617 RET Return.
This entry point is used by the routine at Display_High_Score_Entry_Screen.
Alternate entry: compute a score character position as A × 8 + B and highlight its attribute row via Calculate_Attr_Cell_Address and Highlight_Score_Entry_Row.
Render_Score_Character 60618 ADD A,A Compute the character position index as A × 8 + B.
60619 ADD A,A
60620 ADD A,A
60621 ADD A,B
60622 CALL Calculate_Attr_Cell_Address Calculate the attribute cell address for this position via Calculate_Attr_Cell_Address.
60625 CALL Highlight_Score_Entry_Row Highlight the score entry row with bright white via Highlight_Score_Entry_Row.
60628 RET Return.
This entry point is used by the routine at Display_High_Score_Entry_Screen.
Alternate entry: highlight a single score entry attribute cell on row 89 directly, using A × 2 + 1 as the cell offset.
Highlight_Score_Entry_Cell 60629 ADD A,A Compute the attribute cell offset as A × 2 + 1.
60630 ADD A,1
60632 LD L,A
60633 LD H,89 Write INK: WHITE, PAPER: BLACK (BRIGHT) to attribute row 89 at the computed offset.
60635 LD (HL),71
60637 RET Return.
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