176 lines
8.1 KiB
Plaintext
176 lines
8.1 KiB
Plaintext
This is the CORRECT way to make your A501 chip ram!!
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There have been other docs floating around saying to toggle the JP7A jumper,
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but this is not true! Clear it instead! For all of you who have tried the
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A501 chip ram fix and got nothing but a system crash on bootup, this is the
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doc 4 u :-)
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Thanks to Greg Change (gchance@ecst.csuchico.edu) for information on how to
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correctly do this :-)
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<<<DIRECTIONS ON HOW TO CONVERT YOUR A501 CARTRIDGE TO CHIP RAM>>>
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DISCLAIMER: Attempting to conduct this procedure will by all means VOID YOUR
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WARRANTY! I shall not be held responsible for any problems due
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to this modification. I shall not be held responsible for any
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problems whatsoever.
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Now I've got myself covered, lets' go on.
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First off, it is required you have a revision 6A motherboard for this pro-
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ject. It will work with others, but requires a 1mb Agnus chip and also re-
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quires cutting a trace, which I am not familiar with at the moment.
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If you are unfamiliar with electronic repair and modifications, ask an ex-
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perienced technician to proceed with the modification.
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READ THESE INSTRUCTIONS CAREFULLY AND THOROUGHLY BEFORE INITATING PROCEDURE!!
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Tools needed:
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#10 Torx Screwdriver
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Flat Head Screwdriver
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Low Power Soldering Iron
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Razor Blade or Exacto-Knife
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Anti-Static Guard (optional)
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1. Turn off computer and unplug ALL cords and peripherals from the computer.
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This includes the A501.
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2. Now carefully flip the computer over. WARNING! Do NOT grab the A500 on
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the left side if the expansion dust cover is off! If you tug hard enough,
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you will snap off the connector, and the only way to replace that is by
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buying a new motherboard! It's just an edge-connector and can snap easily.
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3. Plug in the soldering iron, just to get it all nice and warm. (make sure
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the iron has been on for at LEAST 15 minutes to avoid cold solder joints.
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4. Now take the #10 Torx screwdriver and remove the 6 Torx screws around the
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edge of the case (at this point the bottom is facing up, of course. Do
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NOT remove any other screws on the bottom of your computer. Save the po-
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sition of each screw, because some may be intentionally different lengths
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5. Flip the computer over again and carefully remove the top. If it doesn't
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remove with ease, use the flat head screwdriver to pry open the sides.
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Using a large screwdriver will make less pry marks in the case, or put a
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cloth around it or something. :-) Hopefully this won't permanently de-
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stroy the latches in the sides. They should just snap right back togethor
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6. Now remove the cable going from the keyboard to the socket on the mother-
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board. It should just pull right out.
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7. Now take the keyboard out and set it off to the side for now.
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8. Now remove the two Torx screws on the left side of the computer facing
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the front. Remove the other two Torx screws holding down the grounding
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plate of the external expansion port. Now carefully remove these screws
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and the grounding plate. Remember the positions of each screw! Try not
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to mix them up! Also- Make note of the text under the disk drive. It
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should tell you the model, "B52/ROCK LOBSTER" (if you're lucky) and some
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other junk. Now look for the text "Rev. 6A". If your motherboard is not
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6A, like I mentioned before, you can still do the mod, but you need to
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cut a special trace and unfortunately, I cannot help you with this.
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9. Now is the time to don your anti-static wrist strap, or whatever have
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you.
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10. Look around the edge of the RF shield for small metal tabs holding the
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cover down. Now carefully bend these tabs up with the flat head screw-
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driver. Becareful not to bend them too much, or they will snap off.
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This is what happened to mine. :-)
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11. Now remove the RF shield cover.
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12. Get ready, here is the time to do the modification. Be careful not to
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hit the Amiga's plastic case with the soldering iron. I did this on some
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practice soldering equipment (broken VCR's etc) a while ago and once you
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destroy the case you're Amiga will no longer look pretty. (thank god I
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didn't do THIS :-)
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Left|
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Side| *BE CAREFUL WHEN CUTTING - Be careful NOT to cut any other traces*
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of |
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Ami | Fig 1
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++ ____
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E :: -| |-
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X :: -| |-
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P :: -| M |- 1| 13. Now locate Jumper 2 (JP2) Between the CPU
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A :: -| C |- | JP2 and the ROM chip (just above and left of
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N :: -| 6 |- 2| _ the ROM chip.) The jumper consists of three
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S :: -| 8 |- =| |= solder "pads". See how Fig 1 has these pads
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I P:: -| 0 |- 3| =|R|= numbered. When your computer arrived, pads
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O O:: -| 0 |- =|O|= 2 and 3 should have been set. We are about
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N R:: -| 0 |- =|M|= to change this. Now take your razor blade
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T:: -| |- =| |= or Xacto knife and just the trace between
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:: -|____|- =|_|= pad 2 and 3. Make sure, and check with a multi-
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++ meter or magnifying glass that there is no
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connection between these two pads. Now take
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your HOT soldering iron and solder, and
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connect pads 2 and 1, just like the jumper
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= depicted in Fig 1. Make sure it is a solid
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= Fig 2 connection and not a cold joint.
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=
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=
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= 14. Now it is time to locate the other jumper,
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JP7A = which is just left of the connector to the
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= trapdoor (where the A501 goes). Search for
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1| = Trapdoor another three-padded jumper, labeled "JP7A"
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= or JP7. Now cut the trace which was connecting
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2| = pads 2 and 3. Make sure it is a clean, solid
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= cut. This jumper should be left open, and no
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3| = pad should be soldered to another.
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=
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=
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=
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15. Now check and make sure all connections are firm and clean, and replace
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the RF cover. Then push down the metal tabs and make sure the cover is
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secure at those points.
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16. Now replace the grounding plate and CAREFULLY screw the two Torx screws
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in. These are special screws- so as soon as it feels firm, no NOT turn
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ANY further! This can strip the screwholes and damage your case perm-
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enantly. Remember to put each screw in it's dedicated position.
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17. Now replace the other two Torx screws and once again screw them in just
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until secure. Remember once again to put each screw in it's dedicated
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position.
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18. Replace the keyboard and set it in the special slots so it is secure.
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Carefully replace the keyboard cord, and make SURE it is inserted the
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correct way. If it is not then I cannot guarantee your system will boot
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up and work correctly.
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19. Now snap the top case of the A500 back on. Make sure it is perfectly
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aligned and all.
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20. Now carefully flip over the A500, and remember not to grab the edge-
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connector! I have never seen this incedent happen but I'm sure it has.
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Such a simple mistake could cost you a whole new computer/motherboard.
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21. Now insert each Torx screw. And once again remember to put each screw
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in it's dedicated position. (whew!)
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22. Now return the A501 to the trapdoor, close it up and flip the Amiga
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over. (and now I KNOW you know not to grab the edge-connector :-)
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23. Plug all other peripherals and cords back in, and turn the machine on.
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24. If it boots up O.K, then hopefully you're in buisness. Now run a program
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like SysInfo or PerfMon to make sure you have 1024k of chip ram (1mb)
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25. Have fun! It is now possible to load large large mods, have more graphic
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data in memory at once, play better demos, and, in short, fit along with
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the rest of the world! :-) Good luck!
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*** If you are having any problems I encourage you to check all of these
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steps and make sure nothing was left out or improperly done.
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Stay Cool with your new 1mb of Chip Ram,
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Bill The Cat (wjhun@oswego.edu)
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(Will Jhun)
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