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Thread: 2MB A600 CHIP RAM - Hack@Home

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    Ya' Like it Retr0? VIP Zetr0's Avatar
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    Default 2MB A600 CHIP RAM - Hack@Home

    Hello there my fellow AmiBayers,

    After a heap of stuff today I finally got round to this little bit of work for our dear chief maker of trouble JuvUK

    What you are about to see is a DIY 2MB CHIP hack for the A600 - this hack grants you an extra 1MB of precious CHIP RAM, to use and abuse as you see fit.

    Do not adjust you URL location =D


    Now, before we beging you must know that there is a con with this hack - after the modification, the trapdoor expansion port becomes (for the most part) redundant and unusable. (of course you can remove the modification and the expansion port is returned to normal operation).


    Tools Required:

    • A good quality solder (preferably silver bearing)
    • 20cms of Red and Blue 30AWG wire (single core jump wire)
    • 30watt soldering iron (preferably regulated / temp controlled)
    • Non-Corrosive / No-Clean flux
    • 2x (256Kx16) Memory Modules
    • Craft / Hobby Knife
    • Flat Bladed Plyers (no teeth)
    • Small Nail Clipers (optional)



    Skill & Level Required:

    • Soldering: Intermediate
    • Multimeter Use: Continuity Testing
    • Patience: LOTS




    Now that you are sitting comfortably.... let us begin... please turn to page 23 in your hackery books, if you missed the hand out come see me after class =)

    (loading part 1..... please wait....)


    Part 1: Preparing the extra RAM

    So lets have a look at what we need

    (click for super zoom)


    here we have the solder, the 30AWG (Kaynar) wire, and a couple of compatible 256x16 memory chips

    so lets get started eh?


    Taking our hobby knife we peal back the legs of the SOJ memory chip

    (click for super zoom)



    one by one, gently but firmly we bring them back so we can then do some work on them.

    Now we take our flat-headed plyers and straighten out the legs of the SOJ chip.

    (click for super zoom)



    We do this in two steps....

    step one is to draw out the leg curl at the bottom, the second step is flaten and align the pins straight using the pliers.

    Obviously you will need to do this for both sides of the SOJ chip

    Now, using the Hobby knife once more we align any legs that are slightly askewed or bent sidways.

    (click for super zoom)



    Part 2: Tinning the RAM


    Okay now that the SOJ chip legs are splayed out - we can now coat them in solder.

    First we use some flux: (no clean & non-corrosive)

    (click for super zoom)



    Be liberal with the flux - its there to make your next job easy so make sure theres plenty. If there is a trick to achieving a successful result with this mod then that trick is also solder the inside of the SOJ chip legs too, so get the flux in there as well


    Now let me introduce to you a technique called - Loading and Dagging, and no this is nothing to do with those types of parties on the weekend.

    First we load the soldering iron with some solder, not to to much by a reasonable blob =)

    (click for super zoom)


    Now that we have "Loaded" the iron we can now "Drag" this solder onto the legs of the SOJ chip

    (click for super zoom)



    Remember to always do the inside of the legs too

    (click for super zoom)



    Now you must perform the exact same thing on the otherside =D


    Part 4: Jump Wire Time



    Now this Hack uses the A600 motherboard to provide the nessasary addressing required access these new chips, however we must source two signals from the motherboard.

    UCAS (Upper Column Address Strobe)
    LCAS (Lower Column Address Strobe)

    we can source these signals from a variety of places but the best place to get this is from close to the expansion port =)

    so how do we get those signals to our new RAM chips?- Well that will be 30AWG Kaynar wire =D


    Cut a 10cm length of wire from your spool and then drawback the plastic coating.

    (click for super zoom)



    As you can see I use a small set of infant nail clippers, some skill is needed to know the right tension to use, but once you pick it up - you can really fly through the stuff.


    Now the two legs we need is pin [28] and pin [29] from the SOJ, to note this I bend the legs back-inward.

    (click for super zoom)



    I recommend to use a little flux and Load the soldering iron once again - press down on the leg and (RED) wire untill they unite in holy-smokey-soldery-matrimony

    (click for super zoom)


    it should look a bit like this

    (click for super zoom)


    Now we do the same for pin[29], its important to have different colour wire or you will be in for a minor nightmare and emotional breakdown later.

    Here we are using the blue 30AWG - its kinda fetching dontcha think?

    Anyway, as before we tack down the wire, dont be afraid to add a little flux it really will make light work for you.

    (click for super zoom)



    Yay!!! \o/ !!!

    The controll wires are complete and curled under the chip, now we just striaghten the legs to a vertical position.

    (click for super zoom)



    and this little puppy is done!!!

    now remember to pay close attention the legs, as they can get skewed and bent laterally as you perform your work, should this happen the just use your hobby knife and gently re-orientate them.

    Now that you have done this chip, you now need to perform all of this again on the other one =D



    [I]*notes

    Should that you get a solder bridge (thats two pins with solder between) then dont panic... move onto the next pins and keep "tinning the legs" come back and pick up the solder bridge with the iron once the solder on the tip runs low.

    I would also suggest a little extra flux should the bridge be a little stubborn.


    Part 5: Sticking it alltogether


    So here the technical bit -


    (image to go here)


    We are going to be taking these signals (in RED and BLUE) and re-routing them to another point on the A600 motherboard .... where might you ask... well just short of the trapdoor expansion port to be exact.





    Although there are alternate areas to use for these signals these vary from motherboard revision to motherboard revision, instead, I suggest you use pin 35 and 36 from the expansion socket as its both the simplest and quickest to use.

    Of course, you could buzz-out (continuity) with a multimeter where these signals meet under the FDD unit.

    (click to super zoom)



    Mounting (Piggy-backing) the Rams.


    Firstly I suggest that laying down some flux on the existing RAMs and lay on some solder to them as well, (similar to what we did earlier with the "Load and Drag" technique"

    once done we can slid the new ram on top and adjust its orientation appropriately. Once happy we can simply use the soldering iron to marry the two legs of each chip together.

    (click for super zoom)



    A fellow EAB'er recommends trimming the legs of the new chip so that you dont have to solder so far down, I have to admit thats a great idea and will certainly reduce your workload in this part of the modification.

    (click for super zoom)


    just make sure you have enough leg to make it to the shoulder of the bottom chip leg.


    (click for super zoom)



    As you can see here the UCAS(red) and LCAS(blue) are shared amongst the two chips, this is then tied to the motherboard expansion socket.


    (click for super zoom)



    Instead of going underneath the expansion port, I decided to use the VIA of pin 35 - which, as luck has it, just above pin 36 =D

    (click for super zoom)



    And that concludes the this part of the hackery, please turn to the last page of your hackery books for tonight's notes.


    *notes

    marrying the two chips can be tricky, If you are struggling getting the pins together - just relax, put on some enigma or enya and use some more flux. do take up Magno Boots suggestion of trimming the legs of the new RAM chip - this will help emensly.

    Remember flux before you solder and you will get the perfect weld, this goes for the motherboard too, when tying down wire to the expansion port or via, then be liberal with the flux =D
    Last edited by Zetr0; 12th July 2012 at 14:23.
    Flux Mastah' Zee
    50 L337 1'M W1R3FR4M3

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    Wink great

    Wow another great hardware hacking guide I enjoyed it with a fresh coffee.

    I need to improve my soldering skill so it was perfect.

    The ram on top is rather funny. lol.

    So the only route left is the pcmcia port or an accelerator to get extra mem?
    Proud on the classics: A1000-A500-A2000-A600-030-A1200 PPC -A3000D(basic)-A4000D(060)
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    Amibayer! LTAC's Avatar
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    EXCELLENT hack Zetr0, thank you very much.
    It only remains to find the Memory Modules and as jvdbossc writes: "we need to improve our soldering skill"
    It is unfortunate that we can't combine this hack with the trapdoor expansion port

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    Nice Zetr0,
    Also real good "pr0n" photo's.

    It's a joy to look at them.
    I have 2 left hands and a A600 with 1MB extra Chip so i don't need this hack.

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    Smoke me a Kipper, I'll be back for Breakfast Amibayer! bazzaq's Avatar
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    I really like to read these sort of threads.

    Nice hack.

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    Retro Girl Staff Moderator SkydivinGirl's Avatar
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    Wow! Simply amazing. Another wonderful hack, Zeets!



    Heather
    Promoted to Level II Solder Tech and Hackery Padawan

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    Ya' Like it Retr0? VIP Zetr0's Avatar
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    Thanks for you kind words guys,

    I would like to thank my padwan camera girl - my daughter - for her help in taking the pictures need for the expo =)
    Flux Mastah' Zee
    50 L337 1'M W1R3FR4M3

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    World Wide Suicide Amibayer! Mad_Cat_jr's Avatar
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    Quote Originally Posted by Zetr0 View Post
    Thanks for you kind words guys,

    I would like to thank my padwan camera girl - my daughter - for her help in taking the pictures need for the expo =)
    She made stunnin photo's, you could be proud on her.

  9. #9
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    Thanks and Greetz also to the guys over at a1k.org, who came up with this originally.

    It was originally translated from German into English (by yours truly ) over at EAB and then Zetr0 came up with the CAS and RAS lines that are guaranteed to work with any revision of A600.

    This photo sequence lays it all out a lot better than the original PDF we thrashed out.

    @ Zetr0

    How about some commentry on the subject of suitable sources for the 256x16 chips for this hack, along with compatible part numbers for chip manufacturers? That would really be putting a cherry on top of this cool How-To.

    Cheers
    Last edited by Merlin; 12th July 2012 at 18:55.
    The future's so Retr0bright, I gotta wear shades.....

    As rkauer said:-
    "Retro computers seems like an orgasm: it is always better to have a real one than fake it".

  10. #10
    Inactive Member skippy's Avatar
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    Smile

    @Zetr0:

    Can one safely assume that by routing UCAS / LCAS from the trapdoor Pin 35/36 to strobe the column addressing scheme this makes the expansion redundant?

    (IE: Similar to the re-routing technique used with an A500 1MB ChipRAM upgrade MOD and JP7A/Trace cut to expansion slot.)

    Regards,

    Skippy.

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