My Thoughts on Computer Programming:

Part 2 – Basic CPU Comparisons

ddf – 06/06/2013

For anyone interested in methods used by any Processor (CPU), you should take a look at "Accessing Memory", as this explains the various processes or methods to address or locate a specific location, or series of locations in memory (RAM). An important consideration in that just about all CPU Instruction sets, the only difference between "Load Data" and "Store Data" is a single data bit in the instruction command, with the data bit being high (1) for one and low (0) for the other. Other bit locations in the instruction command, are often used to determine which Register is to be employed as a Memory Address Pointer, and other data bits in that instruction command are often used as "Modifiers" as for additional information for either the Register or Memory during the Memory Access. Some of these Modifiers may indicate a +/- Offset of the indicated memory location, Increment or Decrement the value in the Register or in the contents of the memory pointed to.

Other general instructions (which may be a series of complex steps) might accomplish mathematical operations, conditional operations, Indexing (Setup &/or Incrementing/Decrementing Registers), Device I/O controls, Data I/O, Logicical Decisions.

In reality, many of the instructions that might seem to be somewhat complex are actually clusters of similar instructions, that are conditional on "Status Flags". These flags (composed of specific flag bits) come about from previous operations, be they from devices or mathematical operations. These same "Status" situations bubble up into the so-called High-Level Languages, and are delt with in the same manner.


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