Learn Electronics/Microprocessors

Microprocessors do a lot of things, but before buying one it is very important to ensure it will be the right one for the specific application(s) in which it will be used. Compare with Central Processing Unit (CPU). There is an urgent need to ensure that sufficient information about usage and instructions are available.

An example

Reference: "Commodore 64 Personal Computer Programmer's Reference Guide" published in 1982 by Commodore Business Machines, Inc. There is a detailed description of that computer's "brain", the 6510 microprocessor chip's specifications, starting at page 402. This microprocessor looks like an insect with a rectangular body, and 20 legs on each of two sides of that body.

The power supply should normally be close to 5 volts DC, although the absolute maximum voltage range is minus 0.3 to plus 7.0 Volts, with about 125 milliamps (mA) normally used.
A 2-phase non-overlapping clock signal is required as well, also at about 5 Volt.
There are 16 connections to the address bus, and an address can therefore be any number between 0 and 65535 (=2¹⁶minus 1)
The data bus has 8 connections, so that any address can have any number between 0 and 255 (=2⁸minus 1) in it.
A part of the external memory can be used as a set of instructions, the rest being available for data; there is a lot that this microprocessor can do.
For example, feeding in the instruction 169 followed by 123 will put the number 123 into a small memory (address 780) called the Accumulator; this is called "Accumulator addressing". There are also "Immediate addressing", "Absolute addressing", "Zero page addressing", "Indexed zero page addressing", "Indexed absolute addressing", "Implied addressing","Relative addressing", "Indexed indirect addressing", "Indirect indexed addressing", and "Absolute indirect".
Various kinds of calculations are possible, some of them quite involved, using proper software. This microprocessor can be used also in very many other applications.

An example

See also