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Date:	Wed, 16 Jan 2002 13:24:28 PST7
From:	Peter Skye <pskye@peterskye.com >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: Re: MAX HeadRAM

Content Type: text/plain

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> Peter Skye said:
>
> >This is true for some older chipsets (and maybe
> >some stupid new ones, too). With those, memory
> >above 256 MB used a slower hardware access
> >cycle *and* sometimes it wasn't cached, either.

Steven Levine wrote:
>
> This pretty much stopped in the middle of the 486 era, possibly before.

More than 256 MB on a 386? Neat! You'll have to show me one of those.

More than 256 MB on a 486? Neat! You'll have to show me one of those.

(Lemme see, at that time $500 for 16 MB times 16 banks would be $8,000
for the memory.)

My cranially-incarcerated gray matter thinks (with difficulty) that them
thar Pentium chipsets had this problem.

> >on a /360 model 50 with a memory configuration that
> >was large for the time your programs could run three
> >to four times *slower* when the extra memory was
> >plugged in. The reason was pretty darn simple but
> >the bottom line was "yes, more memory meant you
> >ran slower.
>
> I've run stuff on a 360/50 with 256KB, which was quite
> a step up from the 360/30 with 64MB, at the time.

Only 256 KB on yours? Ahahahahahahaha!!! The 360 mod 50 at Washington
University in St. Louis had a little over 2 MB.

The add-on memory boxes were third-party core. [Young lurkers: "core"
memory was magnetic, not electronic, memory.] The big (1 MB) add-on
memory frame had a much slower cycle time (the x-y-sense wire length was
longer), thus your programs ran slower.

> I do recall being able to run dozens of programs
> under MFT rather than the 3 allowed by DOS
> certainly offered to opportunity for more contention.

We ran MFT on it. There was also MFT II and MVT.

Running dozens of programs was easy, but running them *simultaneously*
was a bit difficult since MFT had a maximum of 16. ("MFT =
Multiprogramming with a Fixed number of Tasks".)

You probably ran them as a batch process (JCL - Job Control Language).
The system scheduled the programs. JCL was cryptic but quite powerful -
you could specify your memory requirement, tapes and disks to be loaded,
sequences of the programs to be run, "return code values" which could
skip or run other programs, lots of other stuff.

- Peter

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