When looking at the the 7400, we can consider truth table per gate, schematic per gate, package layout and logical layout. When looking at the full schematic, we’ll just look at the ‘standard’ 74 series rather than the LS, F, HCT etc. As far as standard TTL is concerned, the transistor equivalent circuits are easier to understand than the 4000 series.There are vastly more TTL 74 series devices than CMOS 4000 series.In this article we focus mainly on classic TTL 74 series devices for two reasons: Often it is not practical to show full truth tables for such devices, and the data sheet may focus in on some particular aspect of a truth table, or focus on state transition as opposed to static state. As devices become more complex, it is not practical, and of little value to show full transistor equivalent circuits and truth tables, and the devices are instead described as being system built of gates, or built out of sub-systems of gates. For low number devices such as simple logic gate arrays, the data sheets opt to show the full transistor circuit equivalent, together with full truth tables. If you look at datasheets or a handbook for a logic family such as the TTL 74 series or the CMOS 4000 series, typically devices become more complex and specialised as the device numbers increase.
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