On 22 Feb 99, at 11:10, Michael Eisenstadt wrote:

> I am thinking of building a new Pentium box with 128Mb RAM for a new
> project which requires manipulating 25Mb photo images in Photoshop,
> an obvious impossibility with my present 486/66 + 20Mb RAM box.

  Not impossible -- but with lots of swapping to disk, it's gonna be
SLOW.

> OTOH, my present m/b supports 128Mb RAM and I was thinking of adding
> one 16Mb RAM module to the present box as a cheap experiment to see
> what kind of increased functionality I get.  If the functionality
> scales up and if I can locate used modules, this might be an
> economical alternative to a new box for my project. However, I need
> a little help in deciphering the m/b's user's manual.

  Agreed.  Read on.

> The m/b has 4 sockets denominated Bank 0 which take 30-pin fast-page
> mode SIMM modules and 2 sockets which take 72-pin fast-page SIMM
> modules.  One of the 72-pin slots is denominated Bank 0 & Bank 1, the
> second Bank 2 & Bank 3.  The manual says each 72-pin socket supports
> double bank memory and that the 4 30-pin sockets share Bank 0 memory
> location with (half of?) the adjoining 72-pin socket and that only
> one pin type will be recognized so "please don't plug in two types of
> SIMMs on Bank 0 simultaneously."
>
> What is "double bank memory"?

  256KB, 1MB, 4MB and 16MB 30-pin SIMMs, and 4MB, 16MB and 64MB 72-pin
SIMMs are sometimes called "single-sided" or "single-density" or,
apparently, "single-banked".  9MB and 32MB 72-pin SIMMs are "double-sided"
or "double-density" and don't work with some motherboards.  Apparently,
they *will* work with your board, but you cannot use the first 72-pin slot
if you also have 30-pin SIMMs installed.
  This leaves two ways that you can get to 128MB:

(a) 4x 16MB 30-pin SIMMs, and one 64MB 72-pin SIMM in slot 2/3.

(b) 2x 64MB 72-pin SIMMs, one in slot 0/1 and one in slot 2/3.

> The 16M module in the Bank 2 & Bank 3 socket fills the socket
> entirely (there are 4 1M modules in the 30-pin sockets and the Bank 0
> & Bank 2 72-pin socket is empty).

  You could also have had 4x 4MB 30-pin SIMMs and one 4MB 72-pin SIMM.

> Finally, there is the memory configuration table in the manual for
> 128M total RAM but I can't figure out how it is supposed to add up to
> 128M RAM:
>
>   Bank 0     Bank 1      Bank 2       Bank 3     Total
>
>  16M x 9      None      16M x 36       None      128MB
>
> How can this add up to 128: the 4 16Mb modules in the 30-pin sockets
> I see, but how do the other 4 modules go into 2 72-pin sockets?

  See (a) above.  x36 is a 72-pin module (with parity).


  I expect that you will find that not only will your CPU be smaller
than you'd like, but your L2 cache won't help beyond 64MB (if that).
So if you want to experiment, I'd go for option (b), with the firm
intention that you're buying RAM you intend to move to the Pentium --
get 60ns RAM (probably FPM -- not all 486s like EDO) and plan to get a
Pentium board that likes 72-pin FPM and can cache above 64MB -- I like
the EFA Viking II or the FIC VA-503+ for those specs.  Careful -- EFA
makes a very similar board (and so do others) with the Intel 430TX
chipset, and it only caches to 64MB; EFA's Viking III has no SIMM
slots, so it won't re-use this memory....


David G

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