Commodore C16 RAM Upgrade

thecellartroll

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Recently my brother decided to complete my Commodore Breadbin collection by donating me a Commodore 16 that he found on ebay. The C16 was in non working condition, however I discovered (thanks to the Plus/4 that TC recently sent me), that the TED and CPU were working, but the TED socket was knackered. I replaced the socket, removed a very strange Datasette bodge that had been done and gave it a working power LED. Then I decided that it deserved to have 64K of RAM like its Plus/4 brother.

I followed the destructions here:
http://mcbx.netne.net/hacks/c16_64k/index.htm
and here:
http://www.commodore16.com/index.ph...9-how-to/148-upgrading-your-c16-to-64-kb.html

But I thought it would be good to get some more photos of the mod online. So here goes!

This is the patient...
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To do the mod you will need two 4464 ram chips. I put them in sockets to protect them from dodgy soldering.
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As you can see, in the beginning the machine was a standard C16
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The two chips highlighted in red are the ones that need to be changed.
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As you can see, I used the destructive method to remove the old RAM. Basically I cut the legs off.
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I then used tweezers and the soldering iron to heat each remaining leg stump and pull it gently from the board. This leaves all the solder holes covered in solder. My technique to clear the holes is to place a new blob of solder on each via and then heat and suck out the whole lot with a desolder pump. It works quite well. The 80s solder makes a mess of your soldering iron so you need to keep it clean!
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With all the solder holes clear, the chip sockets drop straight in without needing to be pushed. I put a bit of solder on the tip of my iron and tack two opposite corner pins in place to stop it falling out. Then I solder each pin in turn properly.
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The new RAM just pushes into the sockets. The right way round of course! Notches in the chip line up with notches printed on the board.
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At this point you can boot the C16 again. It will still display the standard ram, but it means you probably haven't broken anything yet.
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So now you have to attack the board and cut some tracks. First is pin 14 at U8. It is connected to the +5v rail and has to be disconnected. You can see the bridge at the tip of the blade.
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The next track is more difficult as it is hidden under the IC U7. It goes from Pin 2 to Pin 16 and is marked with an arrow. Cut it by sliding the tip of your knife between pin 2 and 16. Check with a multimeter that there is no longer a connection between pins 2 and 16.
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Now you need to solder new connections so that the CPU can see the extra RAM. U7 pin 2 to CPU pin 21 and U8 pin 14 to CPU pin 22 as pictured.
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This is the bit that I messed up as I managed a small short between pins 21 and 22 on the CPU. Don't do that; it took over an hour to find the mistake! :whistle:

Then you should have more tasty RAM to play with!
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Zetr0

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A most awesome thread!

its great to see some TEDy love =)
 

TheCorfiot

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Excellent, fantastic work, and many thanks for providing a tutorial too...(y)

What can I say, you made my evening....

TC ;)
 

protek

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Great work! (y) Interesting to see that the Basic doesn't hog third of the memory in the C16 as it does in C64.
 

stu232

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At last I've found a nice clear C16 tutorial!

Great work Cellartroll, I'm hoping to do this upgrade just as soon as I can source some 4464's.
 

protek

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Thanks once more for great tutorial, Cellar! My newly acquired C16 now joins the fold.
Edited_ImageEasyImageEditor_20141023_74.jpg Edited_ImageEasyImageEditor_20141023_73.jpg
 
Last edited:

SkydivinGirl

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A wonderful guide! I'll be doing this mod to my C16 in the near future. :)

Heather
 

craftsman1234

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Since everyone is showing off pictures. Say hello to my little friend. 64K and JiffyDos.



I used the guide here this week as well.

Here is another guide that I first used:

http://c128.com/comment/667#comment-667

I had problems with this guide and ended up going back to the one here but I believe failed to cut the trace on both lines as needed.

On my motherboard I could not see the line that needed to be cut on the top of the motherboard (74SL257) and ended up doing the wrong one. I ended up removing the IC and repaired the line from the bottom of the board.



If I had to do it over again I would go back to Callan's guide as it would be much easier to cut the 2 traces on the bottom of the board.
 

kaini

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Hi,i have a NEC D41464C-12NL is compatible for upgrade C16?
 

mjnurney

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Oh i like it , i must get my Plus4 working....that could be another Youtube vid

nice work.
 

johey

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Nice photos! I've successfully made this mod tonight. I think I have a newer motherboard revision with better pcb (not this thin foil traces or what to call them). I had problems cutting the trace under U7 as it was even more hidden than yours. I actually couldn't see the trace at all. I had to desolder pin 2 and forcefully pull it up through the hole in order to reach the trace. Then I cut the pin a little and had the wire go through the hole, attached to what remains of the pin.

A simpler solution would be just to cut the pin close to the pcb, then solder the wire in the component side. Then you wouldn't need to care about the trace at all. The same should apply for the other wire too. No need to harm the pcb but harming the chips instead. :) Next time, if ever, I'll do it that way I think.

Anyway, just in case someone will do it with the same motherboard revision as mine, it is a little tricky but doable.
 
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