Language-specific CPUs

[Chuck Guzis]

On 31 Dec 2008 at 17:03, Jim Battle wrote:

> I remember reading a computer architecture book back in the early/mid 80s, I think it was 
> by Stone.  The subject was "advanced" architectures.  One section described on attempt to 
> build a timesharing system for running a BASIC-like subset, and everything was hardwired 
> -- parsing was via gate-level state machines, not microcode.  The intended audience was 
> college-level computer classes.  As I recall, they gave up after getting a simplified 
> version going.

Such efforts seemed to me almost always to come from the university 
environment.  In the commercial setting, languages didn't seem to 
matter as much (unless they were mandated by goverument contract).  I 
haven't the faintest idea how many different anguages that I've had 
to learn during my life, but it's been a lot.

The nice part is that now I forget them as easily as I learned them.
 
> The exposed pipe hazards weren't the real issue.  The problem was exceptions.  In certain 
> states, there was no simple way to restore the pipe, so the interrupt handler had to 
> detect when one of those bad cases existed, then nudge the state along one instruction at 
> a time until it go to a point where it could restore the state fully and really return 
> from the interrupt.
> 
> I never saw it, but I heard the return from interrupt code was a couple thousand lines of 
> tricky assembly.

I'd heard that the latency of interrupt servicing could vary wildly, 
which meant that the most successful i860 applications were those 
where no interrupts or context switches were required.  The MS 
implmentation of NT must have been a riot to use.  Did any copies 
ever make it out of Redmond?

I have the Margulus (sp?) book on the i860.  I remember initially 
being very interested but noticing that I seemed to develop a 
headache every time I picked the book up to read it.  Just found the 
book on my bookshelf, opened it and now my head hurts.  I guess the 
book still works.

Cheers,
Chuck