3 ms·
The Z80 had that many transistors, not gates The CMOS rule of thumb is one gate is 4 transistors (eg a 2-input NAND). But the first Z80 was nmos, and so the eq
by tasty_freeze 7y ago
The Z80 had that many transistors, not gates
The CMOS rule of thumb is one gate is 4 transistors (eg a 2-input NAND). But the first Z80 was nmos, and so the equivalent count is harder to state. 3 transistors per 2 input nmos gate is a rough first order guess, but in nmos wide gates still need only a single load resistor, and designers sometimes used dynamic logic to save even more transistors.
- vardump 7y agoOhh... This is embarrassing! I work in embedded/low level and I have always thought that gate == transistor. It's really obvious in retrospect... I stand corrected.
- marshray 7y agoIt's not a crazy idea, there are indeed logic types that implement some gate types with a single transistor. For example, https://en.wikipedia.org/wiki/Resistor–transistor_logic https://en.wikipedia.org/wiki/Resistor–transistor_logic These were more commonly used back when transistors were expensive.