
124 LOGIC CIRCUITS
'original' (now obsolete) unbuffered series, and Β to denote the improved
(buffered) series. A UB suffix denotes an unbuffered B-series device.
Logic gate symbols and truth tables
The British Standard (BS) and American Standard (MIL/ANSI) symbols
for some basic logic gates are shown in Figure
6.1.
The MIL/ANSI standard
has overwhelming support (even in the UK) and is often preferred by
equipment manufacturers. It is important to be aware of both standards
and be prepared to present logic diagrams using both sets of symbols.
They should not, however, be mixed within the same logic diagram.
We shall now briefly consider th