.define Printhex ! This subroutine print the contents of register A to the screen ! in hexadecimal form. ! The subroutine WRCH is a special one provided by the BBC ! microcomputer. Printhex: pha ! save A lsr a lsr a lsr a lsr a ! get four high bits jsr 1f pla ! restore A and #0Fh ! get four low bits jsr 1f rts 1: sed ! print in hex clc adc #90h adc #40h cld jmp WRCH