474: Advanced Assembly Programming
====================================

In-depth study of x86 assembly language, covering hardware interfacing and low-level I/O.

Topics
------

- x86 register architecture and addressing modes
- Procedure calls, stack frames, and calling conventions
- String and array operations using REP prefixes
- Interrupt-driven I/O
- Interfacing assembly routines with C

Projects
--------

Homework Series (``474/hw4_*.asm``, ``474/hw5_*.asm``, ``474/hw6_*.asm``)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A progressive series of assembly assignments covering arithmetic, logical operations,
string manipulation, and hardware I/O using DOS/BIOS interrupts. Includes a custom
``stdio.asm`` utility module implementing formatted output routines.

.. code-block:: nasm

   ; stdio.asm — reusable I/O routines for the homework series
   STDIO   PUBLIC  OUTCH, GETCH, CRLF, CLEAR, OUTSTR

   OUTCH   MOVEM.L A0-A6/D1-D7,-(A7)   ; save registers
           MOVE.B  #248,D7              ; output character in D0
           TRAP    #14
           MOVEM.L (A7)+,A0-A6/D1-D7   ; restore registers
           RTS

   GETCH   MOVEM.L A0-A6/D1-D7,-(A7)
           MOVE.B  #247,D7              ; read character into D0
           TRAP    #14
           BSR     OUTCH                ; echo to screen
           MOVEM.L (A7)+,A0-A6/D1-D7
           RTS

   CRLF    MOVEM.L A0-A6/D1-D7,-(A7)
           MOVE.B  #227,D7              ; output CR+LF
           TRAP    #14
           MOVEM.L (A7)+,A0-A6/D1-D7
           RTS