Yes, there are 4 banks for 30-pin SIMMs and 2 for 72-pin
SIMMs.  So 2 64M SIMMs or 1 64M SIMM and 4 16M SIMMs would
do it.  However, the manual's list of supported SIMMs stops
at 16Mb and its chart of possible combinations likewise
shows 16Mb SIMMs as the largest size supported as follows:

            Bank 0     Bank 1      Bank 2       Bank 3     Total

Option 16  16M x 36     None      16M x 36       None      128MB

Option 21  16M x 9      None      16M x 36       None      128MB

Another possibility is that the term 16M x 39 can designate a
64Mb SIMM and the manual's list of supported SIMMs is incomplete.

I might add that the manual and its m/b are not identical in every
respect: the manual shows a jumper to switch between 5 and 3.3 V
but the m/b is hardwired at that location and a voltage test of
the appropriate CPU socket pin with the CPU removed showed that
3.3V is not supplied.

At this point, however, another consideration intrudes: fast-page
mode SIMMs when purchased new are now almost double the cost of
less obsolete RAM and my attempts to locate used FPM SIMMs on
various newsgroups have drawn a blank.  So unless I can soon find
a used 64Mb x 36 72-pin parity SIMM to test the m/b, I had best
work on assembling a new box so my new, possibly money-making,
project can move ahead.

Thanks for your help.

Michael Eisenstadt

Larry Atlow wrote:
>
> ...
> > with my present 486/66 + 20Mb RAM box.
> >
> > 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.
> >
> > 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"?  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).
> >
> > 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?
> ...
>
> >From what you've written, it is my understanding that you have a total
> of six SIMM slots, four 30 pin for bank 0 and two 72 pin for bank 0/1
> and bank 2/3, for a total of four banks.  You can use either 30 pin
> SIMMs -OR- 72 pin SIMMs for bank 0, but not both at the same time.  It
> appears that parity memory is required.  My guess is that in order to
> get the maximum of 128MB, you need to plug in two 64MB 72 pin SIMMs, or
> alternatively four 16MB 30 pin SIMMs, and one 64 MB SIMM in bank 2.
> I've never heard the term before, but it appears that 'double banked'
> means that each 72 pin SIMM slot comprises two banks instead of one,
> thus 0/1, 2/3.  Anybody have a clearer explanation?       HTH

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