Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!ucsd!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.hardware
Subject: Re: What Would I Do With 20 Megs of RAM in a SE/30?
Keywords: 4 Meg SIMMS, SE/30
Message-ID: <9365@hoptoad.uucp>
Date: 20 Dec 89 09:43:46 GMT
References: <634@ajpo.sei.cmu.edu>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 61

In article <634@ajpo.sei.cmu.edu> eberard@ajpo.sei.cmu.edu (Edward Berard)
writes:
>My question is this: What can I do with 20 megabytes of RAM that I
>could not do with 8 megabytes of RAM, which would justify the extra
>$3000?

I don't think you can justofy the price unless you have some specific
RAM-intensive application in mind.  However, that doesn't mean that
you couldn't get a lot of value out of it.

>	- I love Multifinder, and it is not unusual for me to have 3
>	  or 4 applications open at once, and to transfer information
>	  (e.g., graphics and text) among them.

You could run each of them in a very large partition, allowing a huge
number of open files and very large sizes for the open files.

>	- I currently have a "plain" SE with 4 megabytes of RAM.

This should give you a handle on whether you're pushing your actual
RAM needs and whether 20 megs would be total overkill.

>	- I am aware that System 7.0 is "just around the corner,"
>	  i.e., April (maybe). Will this have (or should it have) an
>	  impact on my decision?

Yes.  With an SE/30 and the virtual memory features of 7.0, your
effective RAM size becomes equal to your actual RAM plus most of
the free space on your hard disk.  So, with 4 meg RAM and twenty
megabytes of free space, you could do anything you could do with
twenty megabytes of main RAM.  However, virtual memory is slower
than main memory.

If I had twenty main megs to play with, I'd set all my applications to
run in 3 megs and allocate a five-megabyte cache.  The large cache
would mean that probably every file you touched during a boot session
would remain in memory until the machine was restarted.  (Not quite,
but close to it.) This should have a rather noticeable effect on speed,
particularly if you are doing development work on medium or large sized
software projects; all your source and all your tools should stay in
cache constantly.  And the large heaps for the applications should also
minimize the time spent shuffling the heap around, and keep resources
from being purged.

On the other hand, for $3000, you can get a pretty speedy accelerator
card, somewhere in the 33MHz to 50MHz range, and compilation tends to
be compute-bound rather than disk-bound.  The same goes for many more
common tasks, such as page reformatting and spreadsheet recomputation.
Your twenty megs would still leave, say, FullWrite, creeping along;
a 40 MHz accelerator, however, would make it blazing fast.

Overall, you'd probably make out better with the accelerator card,
unless you are currently spending a lot of time waiting on the disk.
That's why I say you probably can't justify the cost.
-- 
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com

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