Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!lll-winken!lll-lcc!ames!killer!elg
From: elg@killer.DALLAS.TX.US (Eric Green)
Newsgroups: comp.arch
Subject: Re: Self-modifying code
Message-ID: <5035@killer.DALLAS.TX.US>
Date: 31 Jul 88 05:21:11 GMT
Article-I.D.: killer.5035
References: <1988Jul22.164129.5495@utzoo.uucp> <4912@killer.DALLAS.TX.US> <1988Jul26.024039.28579@utzoo.uucp> <4929@killer.DALLAS.TX.US> <1988Jul28.173620.7325@utzoo.uucp>
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In message <1988Jul28.173620.7325@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) says:
>In article <4929@killer.DALLAS.TX.US> elg@killer.DALLAS.TX.US (Eric Green) writes:
>>... To go faster, they would have
>>needed a faster 68000. Which in 1985 would have probably added $200 to
>>the cost of the machine (after going through two levels of markups).
>
>Which, I would guess, is the same order of magnitude as the cost added
>by the custom chips, after the same markups.

An Amiga 500 costs $650 retail. That's with power supply, disk drive,
512K of RAM (which probably accounts for 1/3rd of the cost, by
itself), etc. Somehow, I don't see $200 of that as being blitter,
especially since there's four custom chips in there and the blitter is
only part of one of them.

Commodore has a long record of building inexpensive custom chips,
dating back to the lowly Commodore 64 (which had a custom video chip
and a custom sound chip, along with a gate-array for general "glue"
purposes). Perhaps Sun cannot build a blitter for less than $500, but
that's Sun's problem.

You cannot build an argument against blitters on the basis of cost
(also see the $30 NSC chip). You will have to fall back to the bus
bandwidth argument. On a 68000, which cannot saturate modern memories,
period, having a blitter use the extra bandwidth is smart. On a 68030
with an icache, the CPU can already saturate the bus, so having a
blitter is more of a tradeoff. Unless you have a seperate bus for the
blitter and video memory, a blitter buys you nothing with a 68030 (or
a cached 68020, for that matter).

--
Eric Lee Green    ..!{ames,decwrl,mit-eddie,osu-cis}!killer!elg
          Snail Mail P.O. Box 92191 Lafayette, LA 70509              
       MISFORTUNE, n. The kind of fortune that never misses.