Disk Drive Test

!zone Main
    !to "disk_32e5370fc2358b90.img"
    *=0x500
    JMP Main

!zone Init {
Init    SEC
    XCE
    REP #$30        ; 16-bit mode
    !al

    LDA #$1
    MMU #$0         ; map device 1 to redbus window
    LDA #$300
    MMU #$1         ; redbus window situated at 0x300
    MMU #$2         ; enable redbus

    LDA #$400
    MMU #$3         ; external memory situated at 0x400
    MMU #$4         ; enable external memory

    LDA #$500
    MMU #$6         ; POR = 0x500, whatever that might be

    LDA #0
    JSR Output      ; Clear IO Expander

    RTS
}

!zone Output {
Output  PHA         ; Only works in 16-bit mode!
    LDA #$3
    MMU #$0

    PLA
    STA $302

    PHA
    LDA #$1
    MMU #$0
    PLA
    RTS
}

!zone {
Main    JSR Init        ; Initial stuff
    LDA #0
    STA $303        ; Hide cursor

    SEP #$30        ; 8-bit
    !as

    LDA Text
    STA $310        ; Display saved character

    REP #$30        ; 16-bit
    !al

-   WAI
    LDA #1
    MMU #0          ; Monitor
    LDA $305        ; Amount of keys
    AND #$FF        ; We are in 16 bit mode and we only need one byte. Let's Mask it.
    CMP #0
    BEQ -           ; If there are no key presses, jump back

    DEC

    STA $304        ; Read last key

    LDA $306        ; A = Pressed key
    JSR Output      ; Output the pressed key

    SEP #$30
    !as
    STA $310        ; Display pressed key
    REP #$30
    !al

    TAY         ; Save the pressed key in Y

    LDA #0
    STA $305        ; Reset amount of keys

    LDA #2
    MMU #0          ; Disk drive

    LDA #128
    STA $D
    LDA #Text
    SBC #$500

    DIV $D          ; (Text-0x500)/128 =
    STA $380        ; Disk Sector

    SEP #$30        ; 8-bit
    !as

    LDA #4
    STA $382        ; Read sector content

--  WAI         ; Wait for ready
    LDA $382
    CMP #$FF
    BEQ .Fault      ; Something bad happened. Let's signal the user and panic
    CMP #0
    BNE --          ; Not ready yet, try again

    TDA         ; A = remainder of last division
    TAX         ; X = remainder of last division
    TYA         ; A = The key

    STA $300, X     ; Save the key into the disk buffer

    LDA #5
    STA $382        ; Issue write command to disk drive

--  WAI         ; Wait for ready
    LDA $382
    CMP #$FF
    BEQ .Fault      ; Something bad happened
    CMP #0
    BNE --          ; Not read yet

    STP         ; Repeating doesn't work for some reason, so let's stop here

    ;REP #$30       ; 16-bit
    ;!al

    ;JMP -

.Fault  REP #$30
    !al
    LDA #$FFFF
    JSR Output
    STP
}

!zone Data {
Text    !8 0x20

!align 128, 0, 0
}