conceptual diagram of the internals of a typical
early (e.g. 6502 or the like) microprocessor:
<br>
<img src=microprocessor_operation.gif>
<br>
<p>
<h1>typical instructions</h1>
<pre>
$00    zero page
$FF    zero page
$100   stack
$1FF   stack
typical program begins at $200
$200 AD 00 03   =   LDA $0300
$203 8D 01 03   =   STA $0301
</pre>
(note the "little endian"
byte ordering)
<br>
<img src=6502machine_cycles.gif>
<br>
<a href=instructionexecuter.htm>instruction executer (microprogram sequencer)</a>