🚀 go-pugleaf

------------------------ The "original" article ------------------------

>From drutx!ihnp4!mhuxn!mhuxr!ulysses!burl!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!panda!talcott!harvard!seismo!lll-crg!gymble!umcp-cs!eneevax!ravi Mon Sep  9 18:14:26 1985
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From: ravi@eneevax.UUCP (Ravi Kulkarni)
Newsgroups: net.micro.atari
Subject: 1 Meg ST upgrade (long)
Message-ID: <360@eneevax.UUCP>
Date: Mon, 9-Sep-85 18:14:26 MDT
Article-I.D.: eneevax.360
Posted: Mon Sep  9 18:14:26 1985
Date-Received: Wed, 11-Sep-85 23:00:50 EDT
Distribution: net
Organization: U of Maryland, EE Dept., College Park, MD
Lines: 213

I am forwarding these instructions to the net as the original
author does not have access to usenet. So far he and I as far as
I know are the only ones who have upgraded to 1 meg. If you are
brave enough to try this upgrade you might want to let us know
if you succeeded or perish the thought failed.

-ravi

================================================================

Date: Wed, 28 Aug 85 20:53:05 pdt
From: Gert Slavenburg <gert@Pescadero>
Subject: manual to 520ST 1 Meg upgrade
To: info-st@eneevax
Status: RO

I had enough requests to justify sending this out to all of you at info-st.
Good luck with the modification. Cheers will be appreciated, as well as
examples of use of the full 1 Meg - it's lonely at the top.

Directions for expanding the Atari 520ST memory to 1 MByte
==========================================================

WARNING : This is a hardware modification that will void the warranty of
your 520ST. If you do not have the appropriate tools or experience you
have a substantial chance of ruining your 520ST. Proceed at your own risk !
This modification has been in my 520ST without any problems for 6 days now.
However, I have (of course) not checked with knowledgable sources at Atari
to verify if this modification endangers the long term machine reliability
and/or software compatibility (I suspect it may endanger their software
compatibility if enough of us do  it !).

tools/components needed :
=========================

16 256k * 1 RAM chips, 150 nSec. access time type, e.g. NEC 41256C-15.
(available at e.g. Fry's Electronics, Sunnyvale, CA for $ 2.77 each)

A good quality, preferrably temperature controlled soldering iron, with
a miniature tip (tip should be narrow enough to avoid touching 2 I.C. pins
at the same time). E.g. Weller type soldering station.

Good quality resin core solder (thin).

Approximately 4 foot of wire-wrap wire and a good stripper for it.
(you will have to route 3 wire's over a sequence of I.C. pins. The
easiest way to do this is to have a stripper allowing you to shift the
isolation forward over the wire, solder the next point, measure new length,
shift over insulation etc. until the endpoint). The "No Nik" .014" (dark
green handle) wire wrap stripper is the best tool for this. Available
e.g. at Jensen tools, Phoenix, AZ (602) 968-6231 catalog no H4B305.

De-soldering wick and solder suction tool.

Philips type screwdriver (for opening your ST), tweezers, pliers etc.

A steady hand and self-confidence.


explanation of the modification :
=================================

(Please read the rest of this document before starting. It may save you
time and a 520ST)

The current memory inside the 520ST consists of 16 256k*1 RAM chips.
Address (A0..A8) lines are common to all those chips. 
The WriteEnable line is also common to all chips.
Data (in and out) lines are (of course) individual. The RAS (Row-Address 
Strobe) line is common to all chips. The 8 chips forming the high order byte 
group have one common CAS line, and the 8 forming the low order byte group
have one common CAS line (CAS is used as enable for write operations,
suchthat WriteEnable can be common to both groups). 
The high order group from MSB to LSB consists of U45,44,43,42,38,34,33,32.
The low order group of U30,29,28,25,24,18,17,16. Note that all chips are
adjacent, though the numbering has gaps. RAS0, CAS0H and CAS0L are supplied
from U15 pin 8,6 and 7 respectively. (The 0 indicates bank 0)

Bank 1 that you are going to build in will be "piggy-backed" on
top of the current chips, where all pins of the new chips EXCEPT RAS (pin 4)
and CAS (pin 15) are soldered to the old chips equivalent pin. Thus they will
end up sharing addresses, data, WriteEnable and power and ground with the
existing chips.

All RAS pins of the new chips are wired together and will be supplied with
the "RAS1" signal generated on pin 18 of U15 (the Memory Controller, marked
3H-2119CC or so).
The CAS pins of the 8 new high order byte chips (on top of U45..U32)
are wired together and supplied from the "CAS1H" signal generated on 
pin 22 of U15.
Analogously, the CAS pins of the new U30 to U16 are wired together and
supplied with "CAS1L" from pin 21 of U15.

how to go about it :
====================

step 1 : Open up your 520ST, pull of the keyboard connector, and remove 
         the main circuit card from its top and bottom shielding. 
         Make sure to remember which screws go where and note the 
         keyboard connector orientation.

step 2 : Desolder all the capacitors adjacent to the existing RAM chips.
         (DO NOT SKIP THIS STEP. You'll loose time if you do, and worse,
         the modification will not be reliable since you can't solder
         the pins obstructed by the capacitors reliably (if at all)).
         To desolder them, I found it easiest to heat the island on the
         non component side, and bend the wires straight. After doing that
         for each capacitor, turn over to the component side and heat the
         islands while pulling the capacitor out with tweezers.

step 3 : Open up the holes of all the desoldered capacitors, using a
         combination of de-soldering wick and suction tool. Do this from
         the non-component side. If certain holes are difficult to open
         up, you may want to use a wood splinter. (push it through while
         heating). Be carefull to remove all solder debris !
         THE REASON for opening the holes NOW is that they will be less
         accessible once you've done the other steps ! Patience is a virtue.

(NOTE : Step 2 and 3 are the only ones that may damage your ST PCboard.
Be sure not to use excessive force while pulling out the capacitors. If
you damage your PCboard anyway, cure the problem now and not later).

step 4 : In this step we will piggyback the new RAM's on top of the old ones.
         Be sure to connect all pins except pin 4 (RAS) and 15 (CAS).
         The best way to go about this is to do chip by chip. First bend
         the pins of the new RAM's suchthat they are perpendicular to the
         package (instead of having slightly spread "cowboy legs"). Use
         pliers to bend pin 4 and 15 suchthat it comes out of the I.C. package
         horizontal, and cut of the excess length of pins 4 and 15 (I mean
         part of the pin, you still need to be able to solder to it!). Make
         sure that the new RAM fits snugly on top of the old one (in the
         same orientation !!!!), without intervening space and with the new
         pins touching the old ones. Now solder
         each pin (except the non-touching 4 and 15) to the other RAM's.
         The best way to do this with least chance of damage is to touch 
         both the new RAM's pin and the old RAM's pin. Heat them both for
         a second and add A LITTLE solder then. Wait till the solder flows.
         After each IC, check all pins carefully to assure a good connection.
         (use a magnifying glass)
         NOTE : This step is crucial for the long term reliability of the
         memory extension. A badly soldered joint may show up later as
         sporadic memory errors. TAKE YOUR TIME.

(NOTE : until step 6 is finished, do not in any way apply power to your ST.
This intermediate state of affairs will damage your memory chips !)

step 5 : Re- mount all the desoldered capacitors. Bend the pins like they
         were before re-soldering, suchthat they will not touch the lower
         shielding. Solder from the non-component side.

step 6 : In this step you will route the 3 wires mentioned earlier. The
         first wire connects pin 4 (RAS) of all new RAM's to pin 18 of U15.
         The second wire connects pin 15(CAS) of the new U45 to U32 to pin
         22 (CAS1H) of U15. The third wire connects pin 15 (CAS) of the
         new U30 to U16 to pin 21 of U15. 
         The best way to do this is to use the stripper to remove 5 inches
         of isolation. Solder the first IC pin to the end of the blank wire,
         measure the distance to the next pin in sequence and shift over
         that amount of isolation. Continue in this fashion untill all pins 
         in the sequence are done.
         Work from U45 to the left, soldering directly to the leftover pins
         on the new chips. Make sure that no wire or solder sticks out 
         above the top plane of the new chips, since they will almost
         touch the top shielding !
         Route the wires through the PC board hole below and to the left
         of U15 to connect to U15 on the non-component side.

step 7 : Sit back. Use brain. Do you feel confident about the quality of
         your work ? No mistakes ? Check everything once again if you are
         but a little uncertain. Applying power with errors might make your
         ST into a decorative, non-functional piece of art.
         OK. Either rebuild your ST into its shielding and cabinet, or put
         it onto a surface clear of wires and solder-remains and connect it
         to monitor, disk and supply. Boot it. 

         If it boots, you're probably there. Test if the new memory works
         by looking at the phystop variable ($42E) with SID if you have the 
         developper stuff. It should read $100000 (1M hex). Also note that
         memcntlr ($424) now holds 5 instead of 4, and that v_bas_ad ($44E)
         now holds $F80000 (screen bitmap origin).
         If you don't have the developper stuff, try a single drive copy and 
         check that you get the whole disk in one buffer instead of two.

         If the new memory does not seem to exist, use SID to deposit and
         retrieve words on locations $80000 and up (1/2 M hex). If bit errors
         occur, the ST bootROM did not detect the extension (it checks all
         bits of 512 locations by testing a pseudo random sequence, before 
         accepting a memory bank). Try to pinpoint the faulty chip(s) and
         remove the error.

         If it doesn't boot, you're in trouble. I'm sorry. It is difficult
         to give hints on what to do here. So many possibilities. 
         Desoldering the new chips probably won't work (if the old ones
         were functional, the ST would still boot). Check for hidden
         short-circuit on RAM pins. May also be that you have a flaky
         new pin connection.
         Good luck. I feel bad. Well, I might be able to help you a little,
         call me when you're really stuck ! Evenings at (415) 965-7696.
         Not after september - I'll be out of USA by then.

PLEASE :
========

Let me know if you did the modification and failed or succeeded. I'd like
to know how many people benefit from this and if it's safe enough for large
scale application. Mail to arpanet address gert@su-pescadero.

====================================================================


-- 
ARPA:	eneevax!ravi@maryland
UUCP:   [seismo,allegra]!umcp-cs!eneevax!ravi


--------------------------- The "second" article --------------------

> ~~~~~~~~~~~~~~~~~~~pop goes the ST~~~~~~~~~~~~~~~~~~~
> 
> i just fried my ST and after talking to atari and my local dealer i
> have tracked down the problem. It is related to the 1 Meg upgrade
> and the new proms, it seems that the early postings of "how to
> upgrade ...." left out 4 critical resisters (60 ohm 10% tol); 2 must
> be placed on the CAS lines and 2 on the RAS lines, all 4 go on the
> MMU (i know it isnt really an MMU) side. the upgrade will work fine
> w/o the resistors until you put in the new proms, the difference in
> the current drain will cost you all your memory chips and possibly
> the MMU.
> -- 
> 			god bless Lily St. Cyr
> 			 -Rocky Horror Picture Show
> 
> Name:	James Turner
> Mail:	Imagen Corp. 2650 San Tomas Expressway, P.O. Box 58101
>         Santa Clara, CA 95052-9400
> AT&T:	(408) 986-9400
> UUCP:	...{decvax,ucbvax}!decwrl!imagen!turner

After reading the above article, I downloaded the revised procedure
from Compu Serve. I have had the upgrade for about 3 months, and has
worked without a flaw. I would have probably added the proms without
the resistors. Thanks to Mr. Turner for the warning.
Here is a copy of the revised procedure:

NOTE: This is an REVISED,TESTED version of the original text
downloaded from CompuServe. December 6, 1985

(This  was  REVISED  AND TESTED by an annonymous engineer on
Atari's  developement  staff.  The addition of the resistors
should  provide a long life to your machine, but the warning
below  is  STILL IN EFFECT. This is not an official sanction
of the modification. USE WITH CARE!!!)

Here's the 1 Meg upgrade directions:

I have brought this over un-editted from the arpanet info-st
mailing  list.  I  TAKE NO RESPONSIBILITY FOR ITS CONTENT OR
ACCURACY. I HAVE NOT TRIED THIS MODIFICATION ON MY OWN ST AS
YET. I AM PASSING THIS ALONG TO THOSE WHO DO WISH TO TRY IT.
FOLLOW THE DIRECTIONS AT YOUR OWN RISK.
--Dwight McKay (75776,1521)

From: gert@pescadero

WARNING:  This is a hardware modification that will void the
warranty  of  your 520ST. If you do not have the appropriate
tools or experience you have a substantial chance of ruining
your  520ST. Proceed at your own risk! This modification has
been  in  my  520ST  without  any  problems  for 6 days now.
However,  I  have  (of course) not checked with knowledgable
sources  at  Atari  to verify if this modification endangers
the   long   term   machine   reliability   and/or  software
compatibility  (I  suspect  it  may  endanger their software
compatibility if enough of us do it!)

Tools & components needed :

16  256k  *  1 RAM chips, 150 ns access time type, e. g. NEC
41256C-15  (avilable  at e. g. Fry's Electronics, Sunnyvale,
CA for $2.77 each)

A good quality, preferrably temperature controlled soldering
iron,  with  a  minature tip (tip should be narrow enough to
avoid  touching 2 I. C. pins at the same time). E. g. Weller
type soldering station.

Good quality resin core solder (thin).

Approximately  4  foot  of #24 AWG insulated wire and a good
stripper  for  it  and 2 feet of #22 AWG solid tinned copper
bus  wire. You will have to route 3 wires over a sequence if
I.C. pins.

Desoldering wick and solder suction tool.

Philips  type  screwdriver  (for opening your ST), tweezers,
pliers, etc.

A steady hand and self-confidence.

Explaination of the modification :

(Please  read  the rest of this document before starting. It
may save you time and an 520ST)

The  current  memory  inside the 530ST consists of 16 256K*1
RAM  chips.  Address  (A0..A8) lines are common to all those
chips.  The  WriteEnable  line  is also common to all chips.
Data  (in  and  out) lines are of course individual. The RAS
(row-address strobe) line is common to all chips. The 8 chis
foring  the  high order byte group have one common CAS line,
and  the  8 forming the low order byte group have one common
CAS  line  (CAS is used as enable for write operations, such
that  WriteEnable  can  be  common to both groups). The high
order group from MSB to LSB consists of U45, 44, 43, 42, 38,
34,  33, 32. The low order group of U30, 29, 28, 25, 24, 28,
27,  26.  Note  that  all  chips  are  adjacent,  though the
numbering has gaps. RAS0, CAS0H, and CAS0L are supplied from
U1 pin 8,6 and 7 respectively (The 0 indicates bank 0)

Bank 1 that you are going to build in will be "piggy-backed"
on top of the current chips, where all pins of the new chips
EXCEPT  RAS (pin 4) and CAS (pin 15) are soldered to the old
chips  equivalent  pins.  Thus  they  will  end  up  sharing
addresses,  data,  WriteEnable and power and ground with the
existing chips.

All  RAS pis of the new chips are wired together and will be
supplied  with  the "RAS1" signal generated on pin 18 of U15
(the memory controller, marked 3H-2119C or so). The CAS pins
of  the 8 new high order byte chips (on top of U45..U32) are
wired   together   and  supplied  from  the  "CAS1H"  signal
generated on pin 22 of U15. Analogously, the CAS pins of the
new  U30 to U16 are wired together and supplied with "CAS1L"
from pin 21 of U15.

How to go about it:

Step  1: Open up your 520ST, pull off the keyboard connector
and  remove  the  main  circuit card from its top and bottom
shielding.  Make  sure to remember which screws go where and
note the keyboard connector orientation.

Step  2:  Desolder  all  of  the  capacitors adjacent to the
existing RAM chips. (DO NOT SKIP THIS STEP. You'll lose time
if  you  do, and worse, the modification will no be reliable
since  you  can't  solder  pins obstructed by the capacitors
reliably  (if at all)). To desolder them, I found it easiest
to  heat  the island on the non component side, and bend the
wires  straight.  After  doing  that or each capacitor, turn
over to the component side and heat the islands wile pulling
the capacitor out with the tweezers.

Step  3: Open up the holes of all the desoldered capacitors,
using a combiation of de-soldering wick and suction tool. Do
this  from  the  non  component  side.  If certain holes are
difficult  to  open up, you may want to use a wood splinter.
(push  it  through while heating). Be carefull to remove all
solder debris!! THE REASON for opening the holes NOW is that
they  will  be  less  accessible  once you've done the other
steps! Patience is a virtue.

(NOTE:  Step 2 & 3 are the only ones that may damage your ST
PC  board. Be sure not to use excessive force while pullling
out the capacitors. If you damage your PC board anyway, cure
the problem now and not later).

Step  4: In this step we will piggyback the new RAM's on top
of  the  old  oes.  Be sure to connect all pins except pin 4
(RAS)  and  15 (CAS). The best way to go about this is to do
chip by chip. First, bend the pins of the new RAM's suchthat
hey  are  perpendicular  to  the  package (instead of having
slightly spread "cowboy legs"). Use pliers to bend pin 4 and
15  such  that  the  legs  are 180 degrees from their normal
position, so they stick up in the air above the plane of the
top  surface  of the chips. Don't make an absolute sharp 180
degree  bend  since  some  manufacturers' pins may snap off.
Leave  a  little  curve in the leg, but insure that is above
the plane of the top surface of the chip.

Using  #22  AWG to #16 AWG tinned solid copper wire you will
form  three  buses  along the top surface of the new d-rams.
Cut  a #22 AWG solid copper wire the length of the 16 d-rams
on  the  PCB. The RAS bus is formed by soldering all the pin
4's of the new d-rams to the solid copper wire. The bus wire
must  be  seated  against  the top surface of the new d-rams
without a gap. This insures clearance between the top shield
and the pins of the d-rams.

After  soldering  all  16  d-rams  to  the  bus clip off any
portion  of  the  pins  that extend above the top of the bus
wire.  Now cut a #22 AWG solid copper wire the length of the
16  d-rams.  Place the bus wire along the top surface of the
new  d-rams  in  contact  with  all  the pin 15's of the new
d-rams.  Solder every pin 15 to this bus and as above insure
that  the  wire is seated solidly against the top surface of
the  new  d-rams.  Cut off all excess pin length sticking up
above the top of the bus wire. Using diagonal cutters remove
the  section of the bus connecting the new U30 pin 15 to the
new  U32  pin  15. This divides the bus in half with the new
U16, 17, 18, 24, 28, 29 having a common pin 15. The new U32,
33,  34,  38,  42,  43,  44,  45  now  have a common pin 15,
seperated from the other common bus.

(NOTE:  until  step  6  is  finished, do no in any way apply
power  to  your  ST. This intermediate state of affairs will
damage your memory chips!!)

Step 5: Remount all the desoldered capacitors. Bend the pins
like  they  were  before resoldering, suchthat they will not
touch  the  lower  shielding.  Solder from the non component
side.

Step  6: Orient the 520ST PCB so that you are looking at the
solder side of the PCB (non-component side), with the row of
d-rams  nearest  you. Find the double square pattern of pads
at the 68-pin socket of the memory controller, U15 (3H2119).
The  following  is  a  guide  to  locating  the  six  memory
controller pins necessary to complete the wiring. The socket
is numbered conterclockwise, starting with pin 1, the square
pad  (look closely) in the middle of the bottom outside row.
The  sequence,  moving counterclockwise from pin 1, first on
the  outside  square ONLY: (NOTE: the sequence ")(" means to
make  a  90-degree  turn  counterclockwise,  i.e. around the
corner)

1,3,5,7,9)(10,12,14,16,18,20,22,24,26)(27,29,31,33,35,37,39,
41,43)(44,46,48,50,52,54,56,58,60)(61,63,65,67

The  sequence,  moving  counterclockwise  along  the  inside
square  only,  and starting with the left side of the bottom
row:

(62,64,66,68,2,4,6,8)(11,13,15,17,19,21,23,25)(28,30,32,34,3
6,38,40,42)(45,47,49,51,53,55,57,59)

Six 68-ohm 1/4W plus/minus 10% carbon film resistors must be
added when adding memory. These series terminating resistors
minimize undershoot which may damage BOTH BANKS of d-rams if
omitted.  Solder  a  68-ohm resistor to pin 18 of U15, RAS1.
Solder a #24 AWG stranded wire from the remaining end of the
68-ohm  resistor  to  the  pin  4  bus  (RAS) of all the new
d-rams. that is the new U16, 17, 18, 24, 25, 28, 29, 30, 32,
33, 34, 38, 42, 43, 44, and 45.

Solder  a  68-ohm resistor to pin 22 of U15, CASH1. Solder a
#24  AWG  stranded wire from the remaining end of the 68-ohm
resistor    to    pin    15    bus    (CAS)   of   the   new
U45,44,43,42,38,34,33,32.

Solder  a  68-ohm resistor to pin 21 of U15, CASIL. Solder a
#24  AWG  stranded wire from the remaining end of the 68-ohm
resistor   to   pin   15   bus   (CAS)   of   the  new  U30,
29,28,25,24,18,17,16.

For  best  results in all three cases above solder the wires
coming  from  the  resistors  to the middle of the three bus
wires in a "T" fashion rather than at one end of the buses.

Use  a  continuity tester to find the following three traces
--  do  not  depend  on visual inspection. Now install three
68-ohm  series  terminating  resistors  in the original 512K
bank of ram. Be very careful while soldering to these narrow
traces,  since  excessive  heat can easily lift a trace from
the  board. Use an Exacto knife to gently remove solder mask
from traces.

Cut  the  trace  leading  from pin 8, RAS0, of U15 near U15.
Solder a 68-ohm resistor in series with the trace.

Cut  the  trace  leading from pin 6, CAS0H, of U15 near U15.
Solder a 68-ohm resistor in series with the trace.

Cut  the  trace  leading from pin 7, CAS0L, of U15 near U15.
Solder a 68-ohm resistor in series with the trace.

Step 7: Sit back. Use Brain. Do you feel confident about the
quality  of  your  work?  No  mistakes? Check evrything once
again if you are but a little uncertain. Applying power with
errors  might  make your ST into a decorative, nonfunctional
piece  of art. OK. Either rebuild your ST into its shielding
and  cabinet,  or  put  it onto a surface clear of wires and
solder  remians  and connect it to monitor, disk and supply.
Boot it.

It  it  boots, you're probably there. Test if the new memory
works  by looking at the phystop variable ($42E) with SID if
you  have  the  developer  stuff. It should read $100000 (1M
hex).  Also note that memcntlr ($424) now holds 5 instead of
4, and that v_bas_ad ($44E) now holds $F80000 (screen bitmap
origin). If you don't have the developer stuff, try a single
drive  copy  and  check  that  you get the whole disk in one
buffer instead of two.

If the new memory does not seem to exist, use SID to deposit
and retrieve words on locations $80000 and up (1/2 Meg hex).
If  bit  errors  occur,  the  ST  bootROM did not detect the
extension  (it checks all bits of 512 locations by testing a
psedo  random sequence, before accepting a memory bank). Try
to pin point the faulty chip(s) and remove the error.

If  it  doesn't  boot,  you're  in trouble. I'm sorry. It is
difficult  to  give  hints  on  what  to  do  here.  So many
possibilities. Desoldering the new chips probably won't work
(if  the old ones were functional, the ST would still boot).
Check  for hidden short:circuit on the RAM pins. May also be
that you have a flaky new pin connection.

That's all there is...

-- 
					Jwahar R. Bammi
			       Usenet:  .....!decvax!cwruecmp!bammi
			        CSnet:  bammi@case
				 Arpa:  bammi%case@csnet-relay
			   CompuServe:  71515,155


------------------------- That's all folks! ------------------------