Text_Screen     EQU $400
Base_Character      EQU %11000000   ; Only change the first four bits!

            ORG $E00    ; First free ram after disk area
Start
            LBSR    SetIntHandler           ; Set up Interrupts
            LDX #$0             ; Seed refresh counter
            STX UpdateCounter

MainLoop

            ORCC    #$50            * Set I and F bits of CC

            ;LDA    #$1
            ;STA    CantUpdate

            ; Process chip8 ram to coco video buffer
            INCLUDE "./chip-vidram.asm"

            ANDCC   #$EF            * Clear I bit (allow ints)

            ;LDA    #$0
            ;STA    CantUpdate

            LDX #Video_RAM+192
            LDY #64
!           LDA ,X
            COMA
            STA ,X+
            LEAY    -1,Y
            BNE <


            LDX UpdateCounter
            LEAX    1,X
            STX UpdateCounter

            CWAI    #$EF
Loop            JMP MainLoop

*************************************************
* SetIntHandler - Sets up the Interrupt Handler
*************************************************
SetIntHandler
        ORCC    #$50            * Set I and F bits of CC
        LDA #$7E            * JMP Opcode
        STA $010C           * JMP Opcode in Vector Table
        LDX #IntHandler
        STX $010D

        LDA $FF03           * Read CRB
        ORA #$05            * Set bits 0 and 2
        ;ANDA   #%11111101      * Ensure bit 1 is clear
        ORA #%00000010
        STA $FF03           * Put in CRB

        LDA $FF02           * Read DRB(Clear Flag)
        ANDCC   #$EF            * Clear I bit (allow ints)
        RTS
*************************************************

*************************************************
* IntHandler - Interrupt Handler
*************************************************
IntHandler

            ;TST    CantUpdate
            ;BEQ    @Go
            ;LDA    $FF02
            ;RTI
@Go         LDX #Text_Screen
            LDY #TextScreenBuffer
!           LDD ,Y++
            STD ,X++
            CMPX    #$600
            BNE <

IntExit         LDA $FF02
            RTI

TextScreenBuffer    RMB 512


            ;ORG    $7D00           ; Video RAM

Video_RAM       INCLUDEBIN  "./chip09.dat"

CantUpdate      RMB 1
UpdateDone      RMB 1
UpdateCounter       RMB 2


            END Start