ZX Interface Z - The Hardware, part 2
How many volts, you say? Welcome to the second part of the ZX Interface Z hardware overview. On the first part we looked with some detail at the expansion connector and the power supplies. In this blog post we will dwelve into other areas of the hardware. Voltage level converters Digital designs come in several flavours. One thing that can (and usually differ) from one digital design and other digital design are the logic standards used. Some of you might already have heard of TTL and CMOS , and maybe ECL technologies. Each of these technologies usually implements a different logic standard, where voltages which are used to represent 0 (zero) and 1 (one) vary according to a certain "range". Many other technologies exist now, and also many other logic standards, such as RSDS, LVPECL, LVDS, SSTL, too many to enumerate here. Going back to the logic standard voltages, the ZX Spectrum use mainly 5V for the logic, since it is almost entirely made out of TTL. Some chips inside t...