Relay computer 2 read through

Day 1 study notes

These may not be well laid out grammatically or even punctuated  at all but they are my notes on what I'm reading and seeing so far. This is just a quickish read through of the text on the Relay Computer 2 page I will be noting the things I intend to study next and my game plan for understanding this particular computer when all of that is finished we will move onto another relay computer and likely another after that then once we've chased all the rabbits we'll begin laying out and prototyping the physical computer. 



The three registers and the ALU

Reading through this the floating zero is pretty straightforward but the first diagram makes little sense to me so far. ISA(instruction set architecture) is mentioned I need to look into that in depth elsewhere and I need a refresher on registers. ISA link Looking at the second diagram the construction of the 8 bit registers seems pretty straightforward if the hold line has power then any bit that gets set will remain set until the hold line is cleared (power removed) the 10 uF cap on the select line gives the momentary hold in power while the load relay switches from select to hold to latch the bits into memory.
And now I'm lost already what the heck is an ALU keep reading hoping to find out but just get more lost I see the various functions this carries out but am not seeing the point yet hopefully it explains otherwise it's yet another research project. OK working out the ALU on Wikkipedia looks like this is where I'm gonna spend a few days of my time the operation seems pretty straightforward but I'm going to link chase this into the ground just to cover my bases. FYI ALU is Arithmetic logic unit so the logical assumption about what that paragraph was talking about is correct I just need to follow this and my other research points before I move on. so this ALU which has all of these full bit adders is waht feeds into the memory registers and thus gives us the flow of data so far I think I'm getting the flow of this shindig but it's still way complicated but really intriguing. I may need to mock a small version of this up on a breadboard just to see it in action.The rest of the ALU seems pretty simple just different versions of the analog Boolean operators I built in high school (Thank you Mr Elwell) though they are pretty neat it reminds me I need to show my son these things in action.

The program counter and memory address registers

This jumps right into some level of confusion about memory but we'll puzzle that out as time goes by it feels like the kind of thing that I'll just pick up through the rest of my studies...time will tell. the half adder for the program counter looks pretty basic but my brain is hitting the end of the line for the day I think I need to take a walk after this and let it all soak in.  The pc register issue described in paragraphs 3 and 4 is interesting I need to chase more of it down. Looking at all of this has led me to well over my hour desire and my brain hurts lots of new stuff to ponder even without to much link chasing I will reconvene this tomorrow and likely restart this program counter section with fresh eyes and hopefully a slightly better understanding of things if not I'll break from the read through and start chasing down the first sections answers.