At a local electronics shop I recently found quite a few ICs that were manufactured more than 43 years ago. These are "new old stock": never used before and the pins still unbent. Some are indeed original TTL series as existed in the 1960s, not 74LS (Low-power Shottky) as introduced in 1971. They're plug-in compatible with the Gigatron design and the system works fine at full speed:
Although it is cool, it also gets HOT! Original TTL consumes an order of magnitude more power. Due to this so far I only "upgraded" to original TTL the upper half the logic unit, the X register, the memory address unit and the program counter. Those 14 chips, together with a few 74LS replacements as well, already increase the current to 740 mA, or about a ten-fold from the kit version. Above that the multi-fuse and MCP start to do their thing. Remember that USB safety is the reason the kit comes with much more power-efficient 74HCT components in the first place.
What happened in 1975?
- The Altair 8800 computer was released
- "Micro-soft" became a registered trademark
- Stevie Nicks and Lindsey Buckingham joined Fleetwood Mac
- The "Wheel of Fortune" gameshow premiered
- Betamax and VHS launched
- The original Jaws movie was released