I was looking at some classic logic IC:s like the 74-series and could not help to wonder when they where designed, since it feels like they have been around a very long time.

If we take a example, how old is the 74HC595 design?

  • \$\begingroup\$ We've had a few questions like this before, about the history of parts/standards. They were all closed, so this may also happen to your question. \$\endgroup\$ – stevenvh May 25 '12 at 8:02
  • \$\begingroup\$ To answer your question: it's old. I found traces of the 74595, that's even from before LS-TTL. Might be mid-70s. \$\endgroup\$ – stevenvh May 25 '12 at 8:04
  • \$\begingroup\$ Very interesting. \$\endgroup\$ – Johan May 25 '12 at 8:06
  • \$\begingroup\$ I don't think it's before LS TTL became common. My second edition of the TI TTL databook from 1976 lists many LS parts, but no mention of the '595 in any form. \$\endgroup\$ – Olin Lathrop May 25 '12 at 11:53
  • \$\begingroup\$ @Olin - still, odd that they also released it in TTL, which didn't have any advantages over LS-TTL. Would there have been other new TTL devices released after LS-TTL became available? \$\endgroup\$ – stevenvh May 25 '12 at 16:30

The Fourth Edition, 1980, of TI's "The TTL Data Book for Design Engineers" (the TTL reference at the time!) doesn't list the 595.
I found references to the original TTL 74595 (pre-LS) on the 'Net, though. Probably will be from well before 1980, the Data Book already contains many LS-TTL ICs. It's old.

I've advised here before against using the 74HC595 to drive LEDS: 8 LEDs @ 20mA/LED exceeds the maximum device current of 70mA. The original 74595 may not have been used to drive LEDs, they weren't that common mid-70s. I remember seeing 7-segment displays in a Radio Shack (Tandy in Belgium) catalog at the time, which used electric filaments instead of LEDs. That was already in the same housing the LED displays use, not a tube.

  • \$\begingroup\$ @Johan - Thanks for the accept. Your next question may be: how long back dates LS-TTL? ;-) I don't know, I know the first TTL ICs appeared 50 years ago. \$\endgroup\$ – stevenvh May 25 '12 at 8:58
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    \$\begingroup\$ I figured since you did answer the question and since the question is about to be closed I better hurry and accept ;) \$\endgroup\$ – Johan May 25 '12 at 10:22
  • \$\begingroup\$ One thing that is cool is that some of those 74 IC:s still is in use in some places, I mean how many of the modern MCU:s will be around 30-40 years from now. \$\endgroup\$ – Johan May 25 '12 at 10:25
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    \$\begingroup\$ @Johan - I don't think a closed question will stop you from accepting an answer. I guess I upvoted closed questions too. It just means no new answers are accepted. \$\endgroup\$ – stevenvh May 25 '12 at 10:25

According to Wikipedia, the HC logic family was only introduced in 1982. Whether the '595 was part of the original roll-out, I couldn't say, but the specific part you called out couldn't have been developed before that time.

  • \$\begingroup\$ I interpreted it differently. To me the design of the HC595 and the 74595 are the same. Functional diagram is the same. It's just the technological implementation that's different. \$\endgroup\$ – stevenvh May 25 '12 at 16:27
  • \$\begingroup\$ @stevenvh, your interpretation is reasonable; But OP asked specifically about the "74HC495" and I thought especially the link to the WP article naming the introduction dates of the various families was relevant. \$\endgroup\$ – The Photon May 25 '12 at 17:32
  • \$\begingroup\$ ...and anyway the 74595 was probably just a new technological implementation of an RTL part. And the RTL part was just a new technological implementation of a tube circuit ... \$\endgroup\$ – The Photon May 25 '12 at 17:34
  • \$\begingroup\$ Would it? I guess the real growth of the number of different devices only started with TTL. I think many/most TTL parts, especially not the more complex, were ever released in RTL/DTL. Just guessing. \$\endgroup\$ – stevenvh May 25 '12 at 17:38
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    \$\begingroup\$ I would be surprised if there wasn't an RTL serial-in parallel-out shift register of some sort, but would not be surprised if the only way to get a shift register whose outputs wouldn't change until shifting was complete would have been to combine a '164-style shifter with a '373- or '374-style latch. \$\endgroup\$ – supercat May 25 '12 at 18:05

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