Routine:        Err     
Function:       Display error message
Called by:      Error, Print
Calls:          None
Entry:          A holds error code
Exit:           None
Preserved:      B,C,D,E,H,L,IX,IY


ERR     PUSH    AF
        AND     15
        OUT     (8),A
        LD      A,14
        OUT     (13),A
        LD      A,33
        OUT     (144),A
        POP     AF
        SRL     A
        SRL     A
        SRL     A
        SRL     A
        OR      A
        RET     Z
; The error code is a single byte. The lower 4 bits are displayed at the right of the display; if the higher 4 bits are zero the digit is not displayed.
        OUT     (9),A
        LD      A,49
        OUT     (144),A
        RET