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From: peirce@outpost.UUCP (Michael Peirce)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Comparing the Mac+ and SE
Message-ID: <0B010004.a56ymb@outpost.UUCP>
Date: 27 Apr 91 07:16:59 GMT
Reply-To: peirce@outpost.UUCP
Organization: Peirce Software
Lines: 27
X-Mailer: uAccess - Mac Release: 1.0.3


In article <1991Apr26.191830.18589@visix.com>, amanda@visix.com (Amanda Walker) writes:
> 
> In article <1991Apr26.153645.5151@rodan.acs.syr.edu>
> amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes:
> 
>    Wrong.  Code in ROM executes SLOWER because of the slow access
>    times of the roms themselves.  If this weren't the case, you
>    wouldn't see a drastic system improvement when you copy rom to ram
>    (and you do, period).
> 
> Bzzzzzt.  Thank you for playing.
> 
> On the Macintosh Plus and SE (which the original poster was discussing),
> ROM accesses are indeed faster than RAM accesses.  RAM is time-division
> multiplexed between the CPU and the video circuitry, while the ROM is
> not.  Since accessing RAM incurs up to four additional wait states, aggregate
> ROM execution speed is (on average) from one one and a half to two
> times faster than RAM, depending on stack and other RAM usage.

This is a PC-ism.  Some PC clone machines do have ROM that is slower
than their RAM.  But you are right, Macs don't.

--  Michael Peirce         --   outpost!peirce@claris.com
--  Peirce Software        --   Suite 301, 719 Hibiscus Place
--  Macintosh Programming  --   San Jose, California 95117
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