Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!grebyn!ckp
From: ckp@grebyn.com (Checkpoint Technologies)
Newsgroups: comp.sys.amiga
Subject: Re: Memory question
Message-ID: <12262@grebyn.com>
Date: 11 Aug 89 17:17:17 GMT
References: <21467@louie.udel.EDU>
Reply-To: ckp@grebyn.UUCP (Checkpoint Technologies)
Organization: Grebyn Corp., Vienna, VA, USA
Lines: 25

In article <21467@louie.udel.EDU> OHA101%URIACC.BITNET@mitvma.mit.edu (F. Michael Theilig) writes:
>
>     It is my understanding that each memory location is 8 bits wide
> even on a 16 bit machine.  And that this holds true for 32 bit machines.
> What (without getting TOO technical) is the difference between 16 and 32
> bit RAM?  Someone refered to 32 bit RAM as being wider.  I'm confused.
>
	Good question. All memory *addresses*, to the programmer, are
the address of a particular byte. However, the memory organization can
be different.

	The memory 'width' indicates the number of bits that can be
moved between the CPU and memory in one 'memory cycle', whose duration
depends on the machine; on the Amiga, one 'memory cycle' is usually 4
clock cycles, each being 1/7,160,000th of a second). On an 8 bit CPU,
you can get 8 bits at a time, exactly one 'byte'. On the 68000 in the
Amiga, it can get 16 bits at one time, meaning it can move twice as
many bits in the same amount of time. (It doesn't *always* use 16 bits
at a time; it depends on the program.) The 68020 can get 32 bits at a
time, twice as many as the 68000.
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