On 11-5-2010 15:29, Mike Raiford wrote:
> On 5/11/2010 7:41 AM, Invisible wrote:
> 
>>
>> You know that there are people who do scientific experiments *about*
>> computer programs, right? ;-)
>>
> 
> Yeah :)
> 
> Actually, in the vein of computer science: For the fun of it I'm 
> designing CPU from scratch. I plan to build it with TTL gates after I 
> have the design complete and have vetted it through simulation. I have 
> the ALU designed. (Fairly simple, it can add, perform bitwise logic and 
> shift, as well as calculate the twos complement. Other operations will 
> take multiple cycles) I also have most of the control logic put 
> together, but I need to make some changes to ensure an ALU instruction 
> can occur within 2 cycles (One to latch the ALU result, one to store the 
> result in the accumulator)

Still more complicated than my own 1984 design. ;)

> Eventually, I want to take a simplified version of that design and 
> create a CPU entirely out of relays. Obviously, I'd need keep the design 
> as simple as possible, but still functional to keep the relay count 
> down. Something about a bit stack of clacking relays with blinking 
> lights really appeals to me. That machine will likely still have IC 
> memory, though, but the registers will be relay latches.
> 
> One consideration for the relay version is that the machine should be 
> able to halt and only resume processing on an interrupt. So, ideally, 
> you'd give it inputs, issue a command, and send it clacking away to get 
> a result.
> 
> It's fun stuff, and occupies a good deal of time. Also a great way to 
> learn HOW a computer like the one you're sitting at actually works. e.g. 
> how each instruction of machine code does what it does, etc...
> 
> The TTL version should be fun, too. I plan to have lots of LEDs to show 
> what's happening inside the machine.

If you do it to give you new insights into how to make a CPU than that 
might qualify you as a scientist. The border is vague, possibly 
something along the line of how deep the insight is, how many people 
already know it (if nobody than you are definitely in) and if you are 
able to pass on that knowledge. If you are paid to do so that also 
helps, but you aren't.

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