Creative Computers/Creative Computers CD-ROM, Volume 1 (Legendary Design Technologies, Inc.)(1994).iso/text/hacks/ks20rom.txt.pp/ks20rom.txt

Internet Message Format | 1994-11-17 | 19KB

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From: [e-mail] (AMOEBOID)
Newsgroups: comp.sys.amiga.hardware
Subject: Amiga 2.04 ROM in modified A1000
Keywords: AmigaDOS 2.04, Amiga 1000
Message-ID: <[e-mail]>
Date: 20 Nov 91 04:27:27 GMT
Distribution: usa
Organization: U.C. Dept. of Biology

Here is an article (I posted it last year some time) that we
had published in Amazing.  With the advent of 2.04, we thought
there might be some more interest in using Kickstart ROMs in
your A1000.


Here is a slightly modified version of the article that was published in the
May, 1990 edition of Amazing Computing. With the advent of AmigaDOS 2.04
ROMs, we thought it might be of interest to folks as this is an inexpensive
way to have the ability to use 2.04 ROM in your Amiga 1000.

Duplication of this article without express written permission of
the authors will probably result in your not winning the
Publishers Clearing House sweepstakes (and you thought you were
going to meet Ed himself :-)).

---------------------------------clip here--------------------------

        How to turn your A1000 into a ROM based machine
                        by
            Dwight Blubaugh and George Gibeau, Jr.
            Ohio Valley Amiga Users Group (OVAUG)

        WARNING - This hardware modification will VOID your warranty
(GRIN).  It requires some electrical component assembly experience,
such as soldering and desoldering printed circuit boards.  Do not try
it if you do not feel comfortable disassembling your computer and
working inside your machine.  Please read this entire article before
actually starting any of the described work.

        Are you tired of spending extra time looking for that misplaced
Kickstart disk in order to get your A1000 up and running?  Do you want
to run a BBS but don't want to deal with the infamous Kickstart "hand"
screen after a power outage?  Would you like to get rid of the
daughterboard and eliminate a potential source of GURU visits?  If you
answered yes to any of the above questions, then this hardware
modification will be of interest to you.  With a little bit of work and
the following information, you can make your A1000 a ROM based machine.

        The first choice you have to make is to decide which version of
the Amiga ROM you want to use.  When deciding which ROM version to run,
carefully consider whether you will be running an autoboot hard drive
or not.  If you are not going to run an autoboot harddrive, then you
can probably go down to your friendly local dealer and talk them out of
a 1.2 ROM that they acquired during an upgrade to 1.3 for a 500/2000
owner.  If you will be running an autoboot hard drive, then you can buy
the 1.3 ROM for about $35. [ed. 2.04 kits are about $99]

        You will need to gather the following tools before you begin:
25 watt soldering iron, desolderer (vacuum type - piston, not bulb -
works best), thin electronic solder, small pair of wire snips, small
needle nose pliers, Phillips screwdriver, flathead screwdriver,and a
good volt/ohm meter.

            parts list

        QTY     PART TYPE
        2       74F257
        2       74LS244
        2       20 pin IC machine socket
        1       40 pin IC machine socket
        1       piece 30-22 gauge wire
        1       1.2 or 1.3 ROM (or 1.4 - grin) [ed. or 2.04]
        36      gold posts (use the ones removed from the motherboard).
        1       16L8 PAL (CAS)
        1       16L8 PAL (EN) (for engineers, we can supply JED file
                for these, or the PAL equations
                - *** The CA A1000 docs have wrong equations!!

        The TTL's can be obtained from any electronics supply house
such as Digi-Key Corp..  PALs can be obtained from several different
sources; Commodore, Spirit, or if needed, we can supply them.  If
possible, order 15ns PALs instead of the 25ns, as these will perform
better.

    Disassembly of the machine.

        Find a large, clean work area with plenty of light and
electrical outlets.  Cover the work area with some sort of static-proof
material to keep from damaging the parts.  Unplug the power cord to
your machine and disconnect all external devices from the computer
(drives, monitor, mouse, etc..).  Turn the computer upside down and
remove the 5 Phillips screws holding the top and bottom parts of the
case together (it will greatly facilitate reassembly if you organize
the screws into groups based on their origin within the machine as you
remove them).  Carefully turn the computer back to its normal position
and remove the front 256K memory cartridge (if installed) and then the
entire front faceplate.  Next, GENTLY separate the case halves (if you
start on one side at a time, and pry the top away from the bottom, you
will get better results).  The case is connected by 2 small hooks on
each side, be careful not to pry too hard or you will break them.  Set
the top of the case off to the side where it will not get in the way.
Next, remove the metal RF shield which is held in place by 14 screws
and 2 metal tabs (tabs can be straightened with a small pair of needle
nose pliers).  Remove the screws and posts securing the disk
drive and remove the drive, including power and data cables.  The
floppy LED must be removed from the front panel or disconnected at
in-line coupling, depending on the model.  Disconnect the power supply
cable (a screwdriver may be needed to get the plastic tab to unhinge
enough) as well as the power LED.

        You should now have just the mother and daughter boards
remaining.  To remove the daughterboard, unscrew the 3 small screws
holding the board down.  The daughterboard is now held in
place by numerous gold posts.  In order to separate the daughterboard,
begin on one side and gently pry up while moving around the board (do
not apply too much pressure as you do not want to break the board).
After removing the daughterboard, grasp the motherboard near the side
where the mouse and joystick plug in, slightly pulling the side of the
case away from the board, and remove it from the case.  It will come
away with the bottom RF shield attached.  To remove this, straighten
out the remaining metal tabs securing the shield to the board.  Finally,
remove the 3 plastic stand-offs that support the daughterboard, they
are secured from the bottom of the motherboard by 3 small screws.

        You should now have nothing in front of you but the
motherboard.  Now comes the fun part :-), this will go faster if you
have a friend handy, but it can be done by one person.  You will need
to desolder and remove ALL of the gold posts.  This is best
accomplished by sucking the solder from the holes first, then gently
pulling on the post with the needlenose pliers from the component side
while heating it up from the solder side.  Try not to bend the gold
posts during removal as they will be used later.  Also, do not apply
too much pressure so as to damage the plate though holes.  There are a
total of 124 gold posts to remove, so take your time, and be careful
not to gouge into the board with the soldering iron or you may
inadvertently cut traces.  After all posts have been removed, you will
need to clean the old solder from the holes.  This can best be done
with a vacuum type desolderer.  To facilitate solder removal, fill the
holes with new solder, then heat up the solder and suck it out.  This
works better than trying to remove the old solder by itself.  A final
cleaning of the area around the holes can be done with the aid of
solder wick, this will help remove any splashes or flakes of solder
that may cause problems.

        Next, carefully desolder the capacitor located at C137 and save
this, it will be used later.  Solder the 4 TTL chips into the following
locations (machine pin sockets are optional): the 74F257's into U2I and
U2J (**NOTE** the board is silk screened at these spots with the label
S257, however F series chips are used on the daughterboard.  The F
series is a better chip than the S series), the 74LS244's into U3G and
U3I