Re: Number of NAND gates in the HACK computer

Posted by pm100 on Jan 10, 2025; 1:30am
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Number-of-NAND-gates-in-the-HACK-computer-tp4038281p4038284.html

A few things. First here is a video by a guy building a tube based cpu. Right at the start you see his circuit diagram for a NOR gate https://www.youtube.com/watch?v=o0ZmcvvznTY&t=959s

Second, in the tube and early transistor days memory was ferrite core. https://en.wikipedia.org/wiki/Magnetic-core_memory . not implemented as logic gates at all

Then came static ram chips(this is where intel got their start) https://en.wikipedia.org/wiki/Random-access_memory#SRAM I started in 74 and 1k (bit) chips were just being replaced by 4k chips on the machine I worked on (cpu was implemented using TTL)

Then came dram. DRAM is much, much denser but slower. This is what enabled large RAMS (gigs)

We then come full circle. To overcome the slowness of DRAM on chip SRAM caches were implemented. These basically work the same way the original SRAM chips worked, JK flip flops. Lots of them, maybe > 50% of transistors in a modern CPU