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  • Author Author: baldengineer
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Are you still using 7400-Series Logic, if so, where?

baldengineer

Over the past several months, I have been learning about and repairing 8-bit computer and video game systems. So far, I have worked on the VIC-20, C64, ZX-81, Apple II, and have been learning about the TI 99/A.

 

It always amazes how much of these early computer systems were built almost entirely with standard 7400-series (LS and HC) chips.

 

Occasionally, I need to replace a 7400-series chip. (I always hope it is one of those and not one of the ASICs!) While looking for modern replacements, I have noticed the trend that they are becoming more scarce. The LS-series is almost entirely gone--and with good reason. While HC and HCT continue to be somewhat available, they are usually only available in surface-mount packages.

 

That leads me to the question: Who is still using the venerable 7400-series logic chips today?

 

To me, there are three groups that might be using them:

  1. Learning. Students and hobbyist learning about digital logic
  2. New Design. Hardware that needs glue-logic. Are these using multi-gate chips or the single-gate variants?
  3. Repair. Older electronics in need of replacements. Here is where I mostly sit.

 

Do you fit into one of those categories? If not, where do you land?

 

And THEN, which chips are the must-have on-hand?

Obviously, the answer depends on how you might be using them. But, I'm curious to know how you use 7400-series chips and which ones would you keep in stock?

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  • I just used a couple of 4000 series logic chips in the Pong game that I rebuilt.  And I have an assortment of 74 and 74LS (even some 54 mil grade parts) from the late 70s and early 80s when I did a lot of prototyping.  I even have early 555s from 1972.  And I have a bunch of early op-amps (709, 741, 747) from the 70s.  A lot of them in ceramic packages and hand marked because we used to hand screen them for better than spec performance.

     

    The most interesting thing I found that I had forgotten that I had is a National Semi MM5738 8-digit algebraic 5 function calculator chip.  Might be a fun retro build for later.

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  • I just used a couple of 4000 series logic chips in the Pong game that I rebuilt.  And I have an assortment of 74 and 74LS (even some 54 mil grade parts) from the late 70s and early 80s when I did a lot of prototyping.  I even have early 555s from 1972.  And I have a bunch of early op-amps (709, 741, 747) from the 70s.  A lot of them in ceramic packages and hand marked because we used to hand screen them for better than spec performance.

     

    The most interesting thing I found that I had forgotten that I had is a National Semi MM5738 8-digit algebraic 5 function calculator chip.  Might be a fun retro build for later.

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