#signetics

[commodorez]

Sometimes you don't have the part you need. Sometimes it's because the pinout is different from the closest equivalent you have on hand.

Turns out that a common 7402 quad NOR gate doesn't match the pinout of an old Signetics N8885A quad NOR gate: they switched around one of the input pins and the output pins of each gate.

Solution? Build a little chip tower adapter until you can get a replacement N8885A in. It's not ideal, but it's good enough to progress.

[takeshitakenji]

Out of frustration with the long and seemingly useless chain of approvals required of component specifications during which no actual checking seemed to occur, an engineer at Signetics once created a specification for a write-only memory and included it with a bunch of other specifications to be approved. This inclusion came to the attention of Signetics management only when regular customers started calling and asking for pricing information. Signetics published a corrected edition of the data book and requested the return of the 'erroneous' literature.

Later, in 1972, Signetics bought a double-page spread in the April issue of Electronics and used the specification as an April Fool's Day joke. Instead of the more conventional characteristic curves, the 25120 "fully encoded, 9046×N, Random Access, write-only-memory" data sheet included meaningless diagrams of "bit capacity vs. Temp.", "Iff vs. Vff", "Number of pins remaining vs. number of socket insertions", and "AQL vs. selling price". The 25120 required a 6.3 VAC Vff (vacuum tube filament) supply, a +10 Vcc (double the Vcc of standard TTL logic of the day), and Vdd of zero volts (i.e. ground), ±2%. It was specified to run between 0 to -70°C.