The Nibbler is pretty cool. Lacking indirect addressing and a stack isn&#x27;t that strange. The IBM 1401 mainframe (1959) for instance doesn&#x27;t have indirect addressing or a stack. [<i>] Self-modifying code was used to get around this. E.g. you store the return address into a jump instruction at the end of the subroutine. However, the big difference with Nibbler is it&#x27;s not a von Neumann architecture, so you can&#x27;t modify the code.<p>[</i>] Indirect addressing was an optional feature on the IBM 1401 for an additional monthly fee.<p>On the topic of processors made from 74xx TTL, I&#x27;ll point out the Datapoint 2200 desktop computer. This had a board of TTL chips equivalent to the 8008 microprocessor. The 8008 was actually designed to replace this TTL-based processor. Trivia: the x86 is little-endian because when building a serial computer from TTL it&#x27;s easier to use little-endian. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Datapoint_2200" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Datapoint_2200</a><p>The Nibbler is different from the PDP, Datapoint, etc in that the Nibbler has very, very few chips; almost all the logic is done in microcode. This is the same trick used to build a &quot;single-chip&quot; processor from the Four Phase AL1. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Four-Phase_Systems" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Four-Phase_Systems</a>