An assembly language listing for a Motorola 6800 8-bit microprocessor. This is a page from a "Monitor" program that communicates to a serial terminal connected to a MC6850 Asynchronous Communications Interface Adapter (ACIA). The routines here initialize the ACIA (INITA), read an ASCII character (INCH) and read a hexadecimal digit (INHEX).

The first line of the INCH routine is located at hexadecimal memory address C010 and has the label INCH in the first text column. The instruction "LDA A ACIA" is a load accumulator A (opcode B6) from location 8004. (The symbol ACIA is defined as 8004 on a previous page.)