Stupid question alert: I have a 386SX clone with 4 megs of memory and
would like to go to 8.  The motherboard will take up to 16.  Is this
a fairly simple thing with the appropriate sockets easily visible or
something only computer technicians should mess with?  Where is a good
source for memory chips?  How much should such an upgrade cost?

59 responses total.

Well, most of the newer systems have SIMM sockets.  If your PC has these,
then anyone who is comfortable with a screwdriver should be able to 
install them.  Good source and good price are beyond me...I work for
a company which sells and installs them in our systems, but I don't
think we would be the best price.

Kinda a ball park - $40/Meg. A buck or two here or there, but that's
aboutwhat I've been reading - 
  
Oh, put some thing in the classified .cf - I'm *certain* there would
be a response .........

  If the motherboard was designed to use SIMMs, all you have to do
is pop them in (well, it's not always that simple, but it's pretty
close..)

  Though memory proices have gone up recently, I think $40/MB is still
a little on the high side..

I don't know about too many boards, but some require that you fill a whole
bank, not just part of it.  So, the type of memory you are going to buy
really depends on that.  Prices vary on memory, however, $40/meg is pretty
close if you are going for 1MB x 9 SIMM modules.  Some boards are said not
to like 3 chip SIMMs, and also memory speed would matter on the price.

I recently quoted someone $40/MB for 1 MB 80 nsec SIMMs, but this changes
daily, even thruout the day.  If you can work with 4MB SIMMs, they seem to
cost slightly less per MB.

It depends a great deal on what the memory architecture is.  Best bet
is to open up the machine and count how many SIMMs it has; four
SIMMs probably means you have 1MBx9 SIMMs, while one SIMM probably
means you have a 4MBx36 SIMM.  If the former, you'll have to get
four 1MBx9 SIMMs and put them in the remaining SIMM slots on the
motherboard (assuming there are some; if not it becomes a bit
more difficult).  Shouldn't be difficult at all.

As this is a 386SX system, you have a 16 bit memory path, so I assume you
must put the memory in in pairs.  Given this assumption, the computer probably
has 4 1MB SIMMS currently and should support at least 4 more 1MB SIMMS.

Okay, so I'll start looking around for 4 SIMMS.  I've always had
pretty good luck with PC Connection and will check with them 
pronto regarding price and availability.  I take it no special
chip removal/placement tools are needed.  And what prayer do I say
to ward off static electricity so I don't fry the motherboard?

Once you get the top off of the computer, touch the top of the power 
supply (while it's turned off but still plugged in to a grounded outlet)
to discharge any static electricity.

As service manager, I use the technique in #8 extensively...

Prior to the last year, and excluding the first, I was quite cavalier
about static.  As far as I know, I never lost any memory chips to
static electricity.

   <<you don't remember, huh?>>   sfsf
  
The technique in #8 is the right way to start. And you can always
equalize the potential (discharge accumulated static) at any time
during the process. 
  
Without being s scare-monger, shuffling you feet on the carpet
while wearing synthetic cloths is a bozo-no-no. Discharge immediately.
  
Another extra-safety-precaution, if you are really worried - (but
don't be too worried, please) is: 
  
    Wear a metalic bracelet and obtain a fairly long alligator clip (a
wire with a spring-loaded clip on each end). 
  
    After the initial discharge, (ac plug still grounded in wall socket),
    stay in physical contact with the metal plates of the power supply 
    and unplug the computer from the wall. Then attact the alligotor
    clip both to your metal bracelet and also one of the screw-heads, or
    edge of a vent hole, in the PS cover. That provides continuous
    discharge throughout the process.
  
    Just before you remove the memory chips from their conductive
    plastic foam carrier, place and hold the plastic foam on the PS
    cover - the remove the chip adn insert into appropriate socket.
  
    Not a good idea to finger the exposed chip-leads either. 
  
    And again, don't shuffle feet.
  
That's about as paranoid as I can get without talking about humidity
and discharge mats and all that other stuff. Static electricity
is fun stuff to play with - and the events that create it must be
reversed to eliminate it. 
  
In one of the electronics classes I ahve taught, we were ablee to
generate, repeatedly, a 1/4"-3/8" spark. (0.250"-0.375") AS reference,
consider that your sparkplugs' gap is only about 0.042" and car ignition
systems operate around 30,000 volts (not static, but voltage none-the-less.)
  
   Happy chipping!

For safety, I would advise against simply using a wire with an
alligator clip at each end.  The wrist straps used in electronics
manufacturing have built-in resistors to limit current should the clip
or the person wearing the strap come into contact with a live wire.
Static is a real danger, but I don't think it's worth getting paranoid
about.

btw, I have such a wrist strap if anyone wants to borrow it.

Yes there should be a resistor in series with the wire going from your
body to ground.  The value should be about 1 Meg-Ohm.  I don't use ground
straps myself.  They tend to get tangled in whatever I'm working on.  I
just touch metal, as mentioned above, be it grouded or not.  I'm only
concerned about _relative_ potential between me and whatever I'm working
on.  If we are both at, say, 100,000,000 volts, there will be no spark
between us.  (Though there might be a blinding flash between either of as
and ground!)
When passing boards or chips from one person to another, it is a very good
idea to first touch the other persons hand *before* touching the item being
passed.  Doing so will reduce any potential differance between both of you.

Ditto #13--This is what I do.

All this laying on of hands stuff sounds awfully religious and
ceremonial to me.

They get a charge out of it. Say, Re; #10 and sparkplugs: one needs a much
higher voltage at high pressure, though the most important reason is
probably that they want more joules in the spark, which is required to
bring enough of the mixture locally to ignition temperature to get the
flame going. 

I'll give you some more advice... Don't pet your cats just before
installing the memory.  :)

For a while, I used the touch first technique with one girlfriend, she would
zap me otherwise.

On the lips?  (I've had that happen ;-)

It sure helps keep that "spark" in your relationship...

Mary, I checked out my prices...If you want to install it yourself,
I can sell you the memory for $40/MB.

I've spoken with Dave Simmons (what a guy!) and have a 
quasi-arrangement to have my machine's memory upgraded
by professionals who are static-free.  I'll probably see
to this right after the holidays.  With installation costing
only $5 a chip it's sounds like a good idea.

Thanks for all the information.

The moral is that it pays to use people who are well-grounded in
their profession.

That's true. Neophytes are often all charged up and sparking with 
enthusiasm.

re 21:  Well, Mary, what do you mean by "what a guy!" anyway?  <*BLUSH*>

Generally, in 50% humidity, it takes 30KV to bridge 1 cm nitrogen/oxygen/argon
atmosphere in a static discharge.  At least, it takes that much to make the
arc, after that the voltage requirement drops radically.

I got zapped by a VandeGraff generator once, at a distance of about 22 cm ,
right in the forehead.  I don't remember much of that day.

I've got a 5KV neon light transformer...assuming some average level of
humidity, how far will a discharge jump in our regular Ann Arbor atmosphere?

That's only 5KV in operating mode - it's the *discnnnect* that really
jerks your head around. There's probably a lot of inductance in both
the primary and secondary, so I wouldn't be very surprized at 200KV
available (maybe more) to jump up to a foot under relatively
ideal conditions adn with a healthy current kick as well. The limiting
factor would be the dc-wire resistance in the secndary - a collapsing
magnetic field is a terrible thing to try to "waste."

Neon light transformers have very high secondary resistance. They are
made for only a few milliamps secondary current. I have, though, made
an x-ray generator with a 5 kv neon xformer.

I built a Jacob's ladder with one just for the heck of it.  Mine is 7.5Kv
and will streach to an inch or two.  (7.5Kv, 30ma)

Glad there is a lot of wire resistance in the secondary and other 
current limiting stuff. Couple inches on 7.5Kv - not bad! Was that
30ma the input current or output current, I wonder?

Don't short it. It has very fine wire on the secondary, which could melt.
You must have pulled the arc, to get to a couple of inches. 30 ma at 
7.5Kv is 225 VA! It won't last long, at that load.

   Uh, 225VA or 22.5?  I can't do that in my head... ;-)

(You can't?  7.5*30 ~= 7*30 ~= 210.)

 ... and K*m=1 ...  sfsf ...

Yea, 225 VA.  That's what it's rated for, so I shouldn't burn up any
secondary wires.  Neon sign X-formers are more or less self limiting
so burning one up may not be that easy.  (My Jacobs ladder has several
hours of operation on it to date.  Also, It'll go to about 2 inches
because the air is ionized as it climbs the V.  The initial gap is about
3/16 inch.)

I agree. That 30 ma was its *rated* current. What is the secondary DC
resistance? I still wouldn't short out the secondary.

Getting back to memory upgrades.....
I have WORD5.5 in a Zenith151 with only 640K RAM, and find it a bit slow
on refreshes, and generally moving things around. Would adding a LIM EMS
4.0 / Board for 1M of expanded memory, speed things up a lot? The WORD5.5
manual suggests it would speed up some operations, if used as a RAMdisk
with WORD.EXE and accessory files (and HELP) loaded there, but gives no
estimates of by how much. (I realize it depends upon how one uses the
program, but perhaps there are a variety of opinions, to average? :)
Also, I know where I can get a BOCARAM 8-bit EMS board with 1 Mb loaded
for $147. Does anyone know of one on the 2nd hand market, or cheaper (after
all, this *is* an obsolete computer).

A 386/40 motherboard would probably be a better value, if you're going
to spend $150 on the machine.

Sigh. The Zenith 151 doesn't have a motherboard - a mothercard, yes.

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