[PLUG-TALK] It really is an analog world -- was: Field-Programmable Analog Arrays

[M. Edward (Ed) Borasky]

Richard C. Steffens wrote:
> In another thread (Cold Boot attacks on RAM), Kieth gave us an
> interesting description of the innards of SDRAM chips. While the way
> they talk to the world is digital, it sounds like some of the stuff that
> goes on inside is analog. Digital makes lots of stuff easier, but just
> because we can do something doesn't mean we should. I realize it's
> probably cheaper to do it digitally, but I don't like digital volume
> controls on audio gear. Many of the digital gadgets I have don't have
> enough steps for my taste.
> 
> Anyway, as the analog guys get cheaper stuff to work with, maybe we'll
> see a swing back in that direction.

Well ...

1. For more than you *ever* want to know about memory, see 
http://www.google.com/url?sa=t&ct=res&cd=3&url=http%3A%2F%2Fpeople.redhat.com%2Fdrepper%2Fcpumemory.pdf

2. Back in the good old days (IBM 7030 and Univac LARC were 
supercomputers), analog gear was cheaper than digital by a wide margin. 
If you could live with 3 significant figure accuracy, electronic analog 
would do the job. If you needed 5 digits, you had to go to a mechanical 
analog computer. And if you needed more than that, you had to go digital.

3. There were also (very popular) hybrid analog-digital computers. I 
actually think somebody still makes them, but I haven't done the Google 
thing on the subject.

4. The first integrated circuits appear in digital and analog parts in 
almost equal measure. The most popular analog IC was probably the uA741 
operational amplifier. They can probably put a few thousand of them on a 
chip now -- there were only a couple of transistors in one IIRC.