From: lhawkins@olaf.wellesley.edu (Lee Hawkins)
Subject: How to upgrade BOTH types of Unix-Pc/3b1 1Mb motherboards to 2Mb.
Keywords: upgrade 3b1 unix-pc 7300 memory
Organization: Wellesley College
Date: Sat, 25 Jul 1992 20:59:14 GMT


Below is an article that I have put together with the help of Robert
Dalla Costa and Franco Barber on how to upgrade the two different
types of Unix-Pc/3b1 1Mb motherboards to 2Mb.  It is rather long, 
as I decided to include not only instructions on the upgrade itself,
but also a set of useful references and detailed instructions on
getting the motherboard out of and back into the machine.  I am also
sending a copy of this to Dave, in hopes that he can include it in 
the RAMupgrade file at the OSU archives.  Hopefully, this file will
make it a bit easier for those who have 1Mb motherboards to upgrade
them.  Enjoy!


------CUT HERE--------CUT HERE--------CUT HERE-------CUT HERE--------CUT HERE

	What follows is a list of the necessary parts and instructions
for converting a 1.0Mb. Unix-Pc to a 2.0Mb Unix-Pc.  Please note:

=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*

	DO THIS AT YOUR OWN RISK.  IF YOU HAVE NEVER SOLDERED BEFORE,
	OR HAVE LIMITED EXPERIENCE, OR NO EXPERIENCE WITH SOLDERING/
	DESOLDERING ON IC CIRCUIT BOARDS, STOP _NOW_ AND FIND SOMEONE
	WHO HAS TO ADVISE YOU!  I CANNOT BE HELD RESPONSIBLE IF YOU
	FOLLOW THESE DIRECTIONS AND STILL DESTROY YOUR MOTHERBOARD.

=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*

Also, please print out a copy of this and read it over twice before
trying it.  It's bloody hard to read it if the only computer
you have is your Unix-Pc, and you've already started wrenching
on it!

Now, with that said, this is one of the easier Unix-Pc memory
upgrades, as you don't have to desolder any chips to do it!  You just
need to desolder the holes for the extra memory, capacitors, and
resistors that are necessary, add the additional components, change a few
jumpers, and voila, you have a 2.0Mb Unix-Pc, just like Ma Bell used to make.

I have listed several suppliers.  I have no connection with them, except as a
satisfied customer.  Prices are only to give folks a ball-park estimate
of what all this will cost.

This upgrade should take around 6 hours depending on your experience
level.  I recommend splitting that into three sessions:
	1) Motherboard removal and hole desoldering.
	2) Capacitor, resistor pack, and decoder installation.
	3) Memory installation, patches, reassembly, and testing.
I also recommend that, if you haven't already done so, that you apply
the DRUN patch and install a new battery in a battery holder, so that
changing batteries later will be easier.  Refer to the Unix-Pc/3b1
FAQ on how to do these things.

Note that there are two different types of 1Mb motherboards.  The only
things that are different between the two are the jumpering changes.

My gratitude goes to Robert B. Dalla Costa (rbdc@ihlpe.att.com) and
Franco Barber (feb@febpc.cmhnet.org).  Robert supplied the jumpering
changes for the old style 1Mb board, while Franco supplied the jumpering
changes for both the old and new style boards.  These changes are obscure, 
and almost impossible to divine from the schematics.  If you use these 
instructions and they are helpful, be sure to send them a note of thanks!
Article 2839 of comp.sys.3b1, posted by Nick Miljkovic
(nmil@phoenix.princeton.edu), included only the patches for the new
style motherboards, but it is unclear who originally wrote the article.
In any event, thanks to Nick for posting it!

The parts:

	1 1.0Mb Unix-Pc motherboard.  I assume that you had realized
	this already, but, well, one never knows....

	36 41256-15 DRAMs.  About the cheapest you can find these days,
	and they can often be had used for as little as $15/meg.  Chips
	faster than 150ns should work fine also, as should 4256's.  I
	suggest you buy used ones off the net or at ham fests.  They are
	much cheaper, and I've bought several megs with no bad chips.
	Total Price: $15.00

	40 Slim-line 16-pin machine-pin sockets.  Get good ones, as they
	are more reliable.  They can, however, cost more than used
	41256-15 memory chips.  Make sure they are narrow enough to fit
	side by side on the motherboard.  Some Augats are too wide.
	DigiKey part number: ED3316
	Total Price: $28.92

	4 74F258's Note the F.  No substitutions allowed.  These are
	decoders for the second bank of memory that you add.
	DigiKey part number: 74F258APC
	Total Price: $3.36

	4 33-Ohm resistor packs.  You want the type that have four
	separate, unconnected resistors in one in-line package.  The 
	markings on the package of these are misleading.  They are
	usually marked 330, which I assume means 33.0, but to a novice
	is easily mistaken for 330 ohms.  These are used as pull-ups for
	the 4 74F258's that you add.
	DigiKey part number: 770-83-R-33
	Total Price: $1.28

	20 .1uF monolithic capacitors.  These are small and are usually
	marked 104, for 10^4 pico farads.
	DigiKey part number: P4887
	Total Price: $5.24

	16 .01uF monolithic capacitors.  As above, but marked as, you
	guessed it, 103, for 10^3 pico farads.
	DigiKey part number: P4881
	Total Price: $2.56

The equipment (required):

	1 Weller EC3001 or equivalent soldering station.  These cost
	around $150 and are well worth it.  If you absolutely can't
	afford/get access to one of these, one of the modular soldering
	irons that Radio Shack sells with the 23 watt heating element
	and the small tip from the special-order surface-mount tip set
	will do IF YOU ARE VERY CAREFUL.  These irons are apparently
	made by Ungar, and can be had from other vendors (Techni-Tool,
	Jensen) with a wider range of tips.  If you are really worried
	about static damage, special order the grounded handle.
	Radio Shack part numbers:
		Handle: 64-2080
		Grounded handle: 64-2077 
		23W heating unit: 64-2081
		Surface-mount tips: 64-2074
	Total Price: $17.47
	Total Price: $21.90 (grounded handle)

	1 Radio Shack Vacuum Desolder Pump.  Cheap, but works
	about as well as any I've used.  Paladin also make a good line
	of these.
	Radio Shack part number: 64-2098
	Price: $5.99

	1 pair small flush-cutting pliers.  If you really don't want to
	pay the price for the Diamond Brand cutters, the Radio Shack
	Nippy Cutters look like they will work.
	DigiKey part number: GA54 (Diamond Brand)
	Price: $22.70
	Radio Shack part number: 64-1833 (Nippy Cutters)
	Price: $3.79
	
	2.5oz. .032 diameter Rosin Core solder.  If you need more than 1/2
	this, you're using WAY too much solder!
	Radio Shack part number: 64-005
	Price: $3.19

	1 Can Radio Shack Solder Flux Remover Spray.  Used
	to get rid of any excess rosin after you solder the new
	components in.
	Radio Shack part number: 64-3324
	Price: $2.99

	1 Oral B #60 or equivalent toothbrush.  Used for brushing excess
	resin off the board.
	Price: $2.89

	1 Large anti-static bag.  Used for storing the board when you
	are not working on it, and giving your work surface an 
	anti-static top.  Buy this at a ham fest, shouldn't be over
	$2.00

	1 Firm-but-soft work area.  I use a stack of PCWeek's and 
	Open Systems Today's.
	Price: Free!
	
	4 paper towels.
	Price: Not enough to mention.

	1 5x magnifying lens.  The ideal thing is one of those circular
	fluorescent lights with a big lens in the middle.  Barring that,
	a good loupe will do.
	Price: About $10.00 (for a good loupe).

	Lots of light.
	Price: About $0.04/kWhr., depending on your location.

	1 3/16" Nutdriver.  For removing the RS-232 port standoffs.

	1 1/4" Nutdriver.  For removing the printer port standoffs and the
	four motherboard standoffs.

	1 #1 Phillips screwdriver.  For removing the motherboard hold
	down screws and any expansion board retaining screws.

	1 #2 Phillips screwdriver.  For removing the cover and chassis screws.
	
	1 small straight screwdriver (some people call it a flathead).

The equipment II (optional, but nice):

	1 3-inch or equivalent muffin fan.  Used to carry away all those
	nasty solder fumes.  Buy at a ham fest.
	Price: $7.00 or less
	
	1 IC insertion tool, 14-16 pin.  For putting all those chips in.
	If you use this, though, be careful to check carefully for bent
	pins!
	DigiKey part number: K153-ND
	Total Price: $7.87

	1 IC Pin Straightener.  Used to straighten any bent pins on
	your chips.
	Radio Shack part number: 276-1594
	Price: $3.49

	1 Anti-static wrist grounding strap.  Some of you will,
	no doubt, recoil in horror that I don't mention this as
	a required item.  Fact is, I've worked on lots of boxes,
	from Commodores to PC's to Mac's to DECstations, and I've
	seldom used one and have never statically destroyed a chip.
	You might not be as lucky, though :)
	Radio Shack part number: 276-2397
	Price: $3.29

The suppliers:

	DigiKey
	701 Brooks Avenue South
	PO Box 677
	Thief River Falls, MN  56701-0677
	Ph. 800-344-4539

	Radio Shack
	Nearly one per every damn street corner.

Useful references:
	
	AT&T Unix-Pc Reference Manual.  Hard to find, but worth
	it.  This one has the schematics and discussions on 
	component-level troubleshooting, along with general
	discussions on how this box works at the hardware level.
	
	AT&T Unix-Pc Service Manual.  Also hard to find.  Pretty
	pictures and descriptions on how to get the case apart.
	Most of the troubleshooting stuff in this manual is useless,
	as most of the solutions end with 'Replace the logic board.'  It
	even suggests this approach for a dead battery!

	HWNotes01-15.  A file on the OSU archives by John Milton on
	various Unix-Pc/3b1 hardware hacks.  Well worth getting and
	reading many times.

	RAMupgrade.  Also a file at OSU.  How to upgrade a 512k
	expansion board to 2Mb, and how to upgrade a 512k 
	motherboard to 2Mb.  Lots of good advice--these are what
	got me into all this.

	s4test.info.  Once again, at OSU.  Info on the "expert"
	mode of the diagnostics.

The upgrade thus costs about $70.00 if all you need to buy are
the components, solder, and flux remover.  You can cut this 
down quite a bit if you can find sockets and other components for 
a low price at a ham fest.  My upgrade only cost about
$33.00.


Removing the motherboard:

	0) Reboot with the Diagnostic Disk, and park your hard drive,
	then power off and remove the power cord from the computer.

	1) Place the computer on a table such that the rear edge is
	hanging off the edge of the table, and remove the two #2
	Phillips screws at the rear that hold the monitor on.  Repeat 
	this process for the one/two #2 Phillips screws (depending on model) 
	on the left and right edges of the computer.	

	2) Remove the two #2 Phillips screws in the rear that hold the 
	cover on.  Then tilt the monitor assembly forward and off.  
	Lay it down on its back behind the computer.  I prefer to take 
	the monitor off, since it is easier to get the cover back on in 
	pieces as opposed to all at once, and you are less likely to 
	pinch the ac wires.

	3) Use the small straight screwdriver to pry off the cover
	screw covers located on the top of the keyboard posts on the 
	front of the computer.  Remove the #2 Phillips screw under each
	of them.

	4) Pull the cover off and tilt it back so that it is sitting
	vertically between the monitor and the rest of the cover.  On
	some models this requires that you do a little prising on the
	front edge to get the cover to come up.

	5) Remove the three #2 Phillips screws from the front edge of the 
	metal chassis.

	6) Remove the #2 Phillips screw at the left rear of the chassis
	that is holding the monitor cable down.
	
	7) Remove the power supply connector from the power supply at
	the right side of the chassis.

	8) Remove the power cables from both the floppy and hard drives.

	9) Tilt the pan up a couple of inches and reach into the left side of
	the chassis and unplug the monitor cable.

	10) Tilt the pan up a bit more and reach in and unplug the
	floppy and hard drive cables from the motherboard, noting the
	orientation of the connector.  Pin 1 is on the left of each
	connector on the motherboard, and pin 1 is usually marked with
	a red or blue stripe on each of the cables.

	11) Now remove the pan completely and set it aside.

	12) Balance the case on its front and remove any expansion
	cards, being sure to put them in an antistatic bag.

	13) Remove the four 1/4" standoffs in the central quadrant of 
	the motherboard.

	14) Remove all the #1 Phillips screws around the outside edge of
	the motherboard.

	15) Remove the two 1/4" standoffs on either side of the printer
	connector.

	16) Remove the two 3/16" standoffs on either side of the RS-232
	connector.

	17) Remove the four #1 Phillips that hold the chassis back on.
	There are two on the bottom and one on either side at the back 
	edge of the chassis.

	18) Remove the chassis back.  The only thing holding the
	motherboard in now is the expansion bus connector.  Disconnect
	the volume slider from the volume pot at the right front edge of
	the motherboard, grasp the motherboard, and gently pull it free of
	the bus connector and out of the chassis bottom.

Performing the upgrade:

	0) Set up the board on a firm-but-soft work surface topped by 
	the antistatic bag, in a well lighted area.  Situate the fan 
	so that it gently blows over the board so as to carry any solder 
	fumes away.

	1) Set your soldering station on about 680 degrees F, and desolder, 
	from the back (solder) side of the board, the following:
		a) Locations 2A-10D
		b) The locations marked CW and CX associated with 2A-10D
		c) Locations 11B, 11C, 11D, and 12A.
		d) Holes for RP1, RP3, RP7, and RP8.
	Heat each hole until you see the solder flow, then suck it away
	with the desolder vacuum.  This should take no more than 10 
	seconds/hole.  Be sure to stop occasionally and clean out
	your solder vacuum.  Also be sure not to cock the vacuum
	while it is over the motherboard.  This can result in little
	pieces of solder all over your motherboard!

	2) Examine the holes that you have just desoldered, along with
	the area around them, for solder bridges and splashes.  Use the
	magnifying lens, and clear off any stray solder.  Make sure to 
	check both the top and bottom of the holes!

	3) Insert a .1uF (104) capacitor in each of the positions marked
	CX, and a .01uF (103) capacitor in each of the positions marked
	CW, and solder them in.  Clip the excess leads close to the
	solder, using a pair of flush-cutting pliers.  The fourth row
	of these (nearest the original memory chips) will probably
	already be in place, leaving you with 4 .01uF and 5 .1uF 
	capacitors left over.
	
	4) Insert and solder in each of the resistor packs, and trim
	any excess leads.  Make sure that pin 1 of the packs faces the
	front edge of the motherboard.  In this case, it doesn't 
	strictly matter, but it IS a good habit to get into.  Not all
	resistor packs are symmetrical.

	5) Solder in the sockets for the 4 additional decoder chips, at
	positions 11B, 11C, 11D, and 12A.  As you solder these in, be 
	careful of solder splashes and bridges.  Make SURE that there
	are no solder bridges on the top (component) side of the board,
	because once you have soldered the sockets down, they will be
	difficult to find.

	6) Solder in the sockets for the new memory chips at positions
	2A-10D.  See cautions for 5) above.
	
	7) Place the front edge of the motherboard on the paper towels,
	solder side up, angle the motherboard about 60 degrees from the
	horizontal, and spray flux remover over the pins that you have
	just soldered in, going from top to bottom.  Then gently brush
	the pins with the toothbrush to remove any stubborn resin.
	Spray again, then use your muffin fan to dry off any remaining
	residue.  DON'T use the paper towels to dry the board--they will
	rip up on the sharp pins and cause a mess.	

	8) Insert the four 74F258 decoders into the sockets at 11B, 11C,
	11D, and 12A.  Make sure not to bend any pins, and check to make
	sure that pin 1 faces the front edge of the motherboard.

	9) Insert the 36 new memory chips in their sockets at positions
	2A-10D, observing the cautions for 8) above.

	10) Perform the following patches (thanks, Robert & Franco!):
		First, determine whether you have an old or new style
		1Mb board.  The old style is characterized by a 
		jumper from pin 11 of 13B to pin 15 of 25F.  The 
		new style lacks this jumper.  Once you have determined
		this, perform EITHER the old: or new: instructions
		below, BUT NOT BOTH!
	
		a) old: Remove the jumper between pin 3 of 6J and pin 1 of 6K.
		   new: Remove JR10

		b) old: Disconnect the jumper from pin 15 of 25F.
		   new: Insert JR9

		c) old: Reconnect pin 15 of 25F with its hole in the 
			motherboard, using the piece of jumper wire that
			you removed in a).
		   new: Remove R145

		d) old: Connect the jumper that you removed from pin 15 of
			25F to pin 8 of 25F.  The other end of this jumper
			should still be connected to pin 11 of 13B.
		   new: Insert JR5
	
	11) Perform any other patches (battery holder, DRUN) that you
	need to.

	12) Recheck both sides of the motherboard for solder splashes
	and bridges, then check to make sure all the chips are
	inserted in the correct direction, then check to make sure
	you applied all the motherboard patches correctly.

Reassembly:

	1) Align the plastic insulator and metal shield holes with those
	in the chassis bottom.

	2) Replace the motherboard in the chassis bottom, being sure to 
	completely insert the forward edge connector into the expansion
	bus slot, making sure to also put the volume slider back on the
	volume pot.

	3) Screw the four 1/4" standoffs back into the center quadrant
	of the motherboard.
	
	4) Replace all the #1 Phillips screws around the periphery of
	the motherboard.

	5) Replace the chassis back, chassis back screws (four #1 Phillips), 
	and the serial and parallel port standoffs.

	6) Replace any expansion cards that you removed.

	7) Replace the pan and reconnect the disk drive cables (3). 
	Be CAREFUL not to bend any pins or offset the connectors to
	one side.

	8) Tilt the pan partially down and reconnect the monitor cable.

	9) Tilt the pan the rest of the way down and reconnect the power
	supply cable, along with the power cables for both disk drives.

	10) Replace the three #2 Phillips screws along the front edge of
	the chassis that secure the pan, along with the #2 Phillips screw
	that secures the monitor cable to the chassis.

	11) Replace the bottom part of the cover, being careful not to
	break off any of the fingers that press against the hard drive
	shield, or to pinch any wires.

	12) Replace the two #2 Phillips screws on the keyboard posts
	at the front of the cover, along with the covers that conceal 
	them.

	13) Replace the monitor onto the cover.

	14) Replace the two #2 Phillips screws that hold the cover down
	at the rear of the machine.

	15) Move the computer so that one side is hanging off the edge
	of a table, and replace the corresponding monitor hold-down
	screw(s).

	16) Repeat 15 for the other side of the computer.

	17) Move the computer so that the rear is hanging off the edge
	of the table, and replace the remaining two monitor hold-down screws.

	18) Replace the keyboard and power cord and boot the diags.  
	They should report that you have 2Mb. of memory.  
	IF NOT, GO DIRECTLY TO "In case of trouble", below.

Testing:

	1) Type s4test at the diags menu prompt.  This takes you into
	expert diags mode.

	2) Type 100:0,0   This will run the memory tests approximately
	all night.  Turn the brightness on your monitor down, and if
	it still hasn't caught an error when you wake up the next day,
	you should be ok.  Pat yourself on the back for a job well done!
	
	3) If you got errors, go to "In case of trouble", below.

In case of touble:

	1) OOPs, something is amiss, several things are possible:

	2) If the computer doesn't come on, you have probably
	managed to short +5 to ground.  CUT OFF THE POWER IMMEDIATELY,
	or you will fry your power supply.  Remove the motherboard and
	check for solder splashes and bare places on your jumper
	wires.

	3) If the computer still only recognizes 1Mb, your patches might
	not have worked, you might have a bad decoder chip, or you might
	have solder splashes and/or bridges that are causing the
	problem.  Remove the motherboard and check for all these
	things.

	4) If you get errors during the memory tests, you might have
	solder bridges in the memory area or a bad chip.  Try replacing
	one row of memory at a time.  When the problem goes away, 
	take the row that you just removed and replace a chip at a time
	until the problem returns.  Then remove the chip that you just
	put in and cut it in half so that you never make the mistake
	of using it again.  (I once had a professor who threw known
	bad chips back into the parts box.  What a pain.)
	If the error doesn't go away, remove the motherboard and look
	for solder splashes.

	5) If none of these solutions work, feel free to give me a
	call/email.  I doubt I'll be able to help much, but I'll
	try.  However, I said it before, and I'll say it again:

=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*

	DO THIS AT YOUR OWN RISK.  IF YOU HAVE NEVER SOLDERED BEFORE,
	OR HAVE LIMITED EXPERIENCE, OR NO EXPERIENCE WITH SOLDERING/
	DESOLDERING ON IC CIRCUIT BOARDS, STOP _NOW_ AND FIND SOMEONE
	WHO HAS TO ADVISE YOU!  I CANNOT BE HELD RESPONSIBLE IF YOU
	FOLLOW THESE DIRECTIONS AND STILL DESTROY YOUR MOTHERBOARD.

=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*!=*

And once again, thanks to go to Robert and Franco for the patches needed to make
this all work!

Good luck!
--Lee
________________________________________________________________________________
R. Lee Hawkins	 	    			lhawkins@annie.wellesley.edu
Department of Astronomy     		        lhawkins@lucy.wellesley.edu
Whitin Observatory         		      	    
Wellesley College				Ph. 617-283-2708
Wellesley, MA 02181				FAX 617-283-3642
________________________________________________________________________________


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