Lesson 5: CPU and Memory
From "AMERICAN LABORATORY"
by David G. Larsen, Peter R. Rony, and Jonathan A. Titus
The structure of a microcomputer
IN THIS month's column we
shall discuss the structure of a
typical microcomputer system,
which is shown in Figure 1. This
system is based upon the 40-pin
8080 microprocessor chip and possesses
all the minimum requirements
for a computer, i.e.:
1. It can input and output data.
2. It contains an arithmetic/logic
unit (ALU), located within the
8080 chip that performs arithmetic
and logical operations.
3. It contains "fast" memory
(we believe that speed is an important
requirement for a functional
computer these days).
4. It is programmable, with the
data and program instructions capable
of being arranged in any sequence
desired.
5. It is digital.
Figure I shows the important data
paths within the microcomputer. In
the following subsections, we shall
dissect this diagram and discuss
each of the individual data paths.
Read More: The Structure Of A Microcomputer.pdf [41.3KB]
FIFO Memories
I N THIS MONTH'S COLUMN,
we would like to discuss
the transfer of data between
digital devices whose datahandling
speeds are mismatched.
This is a common problem in computer
interfacing, especially when
the rate of data generation bya digital
instrument is either considerably
faster or else considerably slower
than the rate of data acquisition by a
computer.
The most common solution to
mismatched data rates is to employ a
buffer memory, between the digital
device and the computer, which
"blocks" the data into groups of 64
or 128 words for subsequent transmission
to the computer. The computer
software required to handle
such data blocks is usually simpler
than that required to handle the
individual data bits.
Read More: FIFO.pdf [37.8KB]