Germanium transistors: logic circuits in the IBM 1401 computer

Re:Germanium transistors: logic circuits in the IBM 1401 com... by addaon on Wednesday March 03, 2021 @02:35PM (#26333235)

How similar or different are the performance characteristics of the NPN-based and PNP-based gates? Assuming there's a meaningful difference, are there signs in the design anywhere where this was considered? Thinking of cases where complex logic is pushed to the NPN stages and the PNP stage is used for just an inverter, or similar patterns.

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Re:Germanium transistors: logic circuits in the IBM 1401 com... by kens on Wednesday March 03, 2021 @03:01PM (#26333610)

That's an interesting question. Looking at the documentation the NPN card (CHWW) and the PNP card (CGWW) have different switching characteristics (NPN is faster on and slower off). But I haven't noticed any difference in usage patterns.

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Re:Germanium transistors: logic circuits in the IBM 1401 com... by Ccecil on Wednesday March 03, 2021 @02:48PM (#26333422)

My memory...which is very hazy and limited on this topic...is that the Germanium based transistors have a VBE of .3v instead of silicon's VBE of .7v

So in things like amplifiers it gives you less zero point crossover distortion. In digital I believe it lends to a faster switch time but I could be very wrong on this part.

Germanium is much more rare so the cost is naturally higher...from what I know.

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