Path: utzoo!attcan!uunet!husc6!rutgers!cs.utexas.edu!ut-sally!nather
From: nather@ut-sally.UUCP (Ed Nather)
Newsgroups: comp.arch
Subject: Re: why people create write-only registers
Message-ID: <12135@ut-sally.UUCP>
Date: 19 Jun 88 18:07:21 GMT
References: <12441@apple.Apple.COM>
Distribution: na
Organization: U. Texas CS Dept., Austin, Texas
Lines: 20

In article <12441@apple.Apple.COM>, aek@Apple.COM (Al Kossow) writes:
> 
> Sometimes when you're running tight on pcb (or chip) real-estate
> you have to weigh how important it is to have lots of area tied up in
> space-hogging buses just for reading a register back.
> 

As a matter of interest, is this also true when the original specification
demands that registers be readable, or is it primarily because the rest of
the design is already done, and the read process becomes an "add-on" that
is costly?  I realize this question is application-dependent, but are there
some applications where an early awareness of the requirement might lead to
a somewhat different architecture that could accomodate read-back in a more
economical manner?

-- 
Ed Nather
Astronomy Dept, U of Texas @ Austin
{allegra,ihnp4}!{noao,ut-sally}!utastro!nather
nather@astro.AS.UTEXAS.EDU