Pre-PDF, pre-Internet, these tomes were how we sourced parts. Once a year the distributors would have an open-databook day we’d fill the trunks of our cars with books about all sorts of components.
Every year it got thicker till they started producing multi-volume sets. For many years it was beautifully hard-bound, though later editions were paperbacks. Though lots of vendors sold, and still sell, 7400 logic, old timers remember the industry bible: TI’s TTL Data Book. Only 13 DIP devices appear from the thousands of TTL part numbers they sell. DigiKey doesn’t list any 7400-series parts, though they still supply 74LS and some others that are well into their dotage. Most of the early parts are unavailable today. I’ve been using 74AUC08 gates recently, which are blazing fast. Today there are a dizzying number of families, and it can be a chore to pick a component from the cornucopia. 74LS parts were lower power and faster than the original components. These boards were enormous.Ĭomponents were so expensive that the earliest Novas used one 74181 four-bit ALU it pushed a word through one nibble at a time.Īs time went on many versions of the 7400/5400 devices appeared. All of these DIP packages are 7400-series TTL devices.Ī Nova logic board. There were no MOS memories at the time another board held core memory.
The following picture is the CPU board from a Nova 1200 16-bit minicomputer. The DIP package had 24 pins, which was enormous in those days.īy the late 60s most computers had oceans of TTL components.
The 74181 was an example: it contained an ALU that could add, subtract, and do logic operations on two four-bit inputs. TTL devices were either SSI (small scale integration), which meant one package contained a couple of flip flops or a few gates, or MSI (medium scale integration), which were more complex parts like multiplexors. Though the 5400 family was often called the “military” version, a lot of commercial applications demanded their extended temperature range. The main difference between the two was the temperature range 5400-series devices generally operated from -55 to 125C, while the 7400 parts, housed in inexpensive plastic packages, were rated from 0 to 70C. Note the “totem pole” output transistors.Īs mentioned, the anonymous experts at Wikipedia believe the 5400 series predated the much more common 7400 family by a couple of years.
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