This is the second of a series of articles covering electronics material which is common to A-level physics syllabuses offered by the various examination boards. The articles are aimed at teachers who are not familiar with this area of study. The first article dealt with elementary Boolean algebra and the AND, OR, NOT gates. Copies of this may be obtained from the Editor of Electronic Systems News. This second article is concerned with NAND and NOR gates and includes a simple design problem. Further articles will study the operational amplifier.