In this series of lectures we will discuss devices that are commonly used for data acquisition. The following represents a broad survey of such devices.

1. Logic Circuits (AND, OR, XOR, NAND, NOR, INVERT)

These devices are based on Boolean Logic. It means that the single output depends logically on the inputs. There may be 2 or more inputs. The output of an OR is high if any of the inputs are high. The output of an AND is high only if all of the inputs are high.

2. Monostable Multivibrator with Schmitt-Trigger Input

This is also called a 'timer' because that is a main use. One uses an external resistor/capacitor circuit to determine the width of an output pulse. The output pulse is usually triggered by a change in the input level (low to high or high to low).

3. Bus Buffer (3-state)

This device buffers the input, in other words, the output is the same as the input except that more current available to drive devices that are further along in the circuit. '3-state' means that the output, besides high or low, can take on a third state, which is 'high impedance'. The high impedance state makes the device look as though it is not connected to the rest of the circuit at its output.

4. Data Selector/Multiplexer

This device selects one of many inputs and sends it to the single output line. The process is called 'multiplexing'.

5. 2-line to 1-line Data Selector/Multiplexer

These devices are special in the sense that they take two input words and select one to be at the output. Typically, they work with nibbles so that one of the two nibbles is selected to be at the output.

6. Shift Register

This devices takes a single digital input signal and sends it to a number of outputs i=1 to n. The input signal first appears at output 1, then output 2, ..., output n. The delay between the time it appears from one output to the next is one clock tick.

7. Buffer/Line Driver (3-state)

This device buffers the signal and is specifically used to 'drive' (determine the level of, low or high) long data lines that are used to connect a number of devices (called a bus). It is 3-state, therefore, when the output is set to 'high impedance' it looks as though the device is not connected to the bus lines, which allows another device to drive them.

8. Odd/Even Parity Generator/Checker

This chip determines whether the sum of the bits of a data word (i.e., the parity) is odd or even.

9. Binary Full Adder (with Fast Carry)

This device adds two binary words, usually nibble-length. The 'fast carry' means that multiple adders can be used in synchrony to add longer words.

10. Parallel Binary Multiplier

This device multiplies two binary words, usually nibble-length.

11. Transparent Latches/Edge Triggered Flip-Flop

This device can store a data word indefinitely by setting the 'latch' bit high or low. It is 'transparent' meaning when the latch is not set, the output lines follow the input lines.

12. BCD-to-Decimal Decoder/Driver

This device takes a binary word and selects a single output representing a digital number. It is used, for example, to drive certain LED lamps.

13. Binary Counter (with Output Register)

This devices counts up or down in binary at each tick of a clock.

14. Voltage-Controlled Oscillator

This device acts as a clock, with the clock frequency depending on the voltage at an input.

15. Error Detection and Correction Circuit

To ensure that no data is lost, error correction bits can be stored with the data. The device uses the data and error correction bits to determine if there is an error and correct it if so.

16. Identity Comparator

This is also called an 'Address Decoder'. It works by comparing a stored data word with an input data word. When the two words are the same, the level of an output pin becomes 'valid'. These are used to identify and distinguish between differing electronics boards and/or circuit components.