Jonathan A. Titus

Microcomputer Pioneer

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Lesson 7: Addressing Modes

From the original article in Radio-Electronics
by Jonathan A. Titus
The Memory Address/Manual Control module is used to hold data which is to be used as the memory address. Two 8-bit latches are provided since the computer will use one set of eight bits for a memory address and the other set of eight bits for control functions. Since the microprocessor can directly address up to 16,424 words of memory, commonly noted as 16K, we will need 14 binary bits for the complete address. The complete memory address of any location is given by a 16-bit binary number; X X B3 B3 B3 B3 B3 B3 / B2 B2 B2 B2 B2 B2 B2 B2. where the X's represent bits that are not used. The computer specifies any address by first sending out the B2 bits to one of the eight-bit latches, followed by the six B3 bits and two X bits. Control of the correct latch is supplied from the CPU module.
Read More: Adobe Acrobat PDF FileMark-8 Construction.pdf, p.2 [2.54 MB]