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Re: Double your RAM:

Posted: 24 Feb 2021, 05:24
by at67
Nice pics, discreet job like cde's, welcome to the club.

Re: Double your RAM:

Posted: 27 Aug 2021, 15:42
by giobbi
hi all,

I finally made the 64k upgrade. I decided for a different solution, I put a socket that can be used for both 32k and 64k chips.

Since I hadn't a 32 pin socket (and frankly I'm too lazy to remove a 28 pin socket if I can avoid it :lol:) I decided for a Frankenstein socket: I cut a portion of the socket (pins 1,2,3 and 26,27,28) and I removed it. Then I built the replacement in a MacGyver way:
IMG_20210819_090710.jpg
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I lowered the 4 (2+2) extra pins with the Dremel, so they don't touch the board (I checked it out later passing a piece of paper between the pins and the board: the papel have to pass freely behind the pins to be sure they're far enough from the board to prevent any unwanted contact).
IMG_20210819_090700.jpg
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The red wire (A15 line) comes from an old, burnt pinball coil; it's very well insulated (it's hard to remove the red coating) and thin enough to pass between two socket pins
IMG_20210827_120524.jpg
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And here we have the 64k RAM chip installed:
IMG_20210827_120623.jpg
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And of course the Gigatron liked it :-)
IMG_20210827_120739.jpg
IMG_20210827_120739.jpg (708 KiB) Viewed 4330 times

Re: Double your RAM:

Posted: 28 Aug 2021, 07:17
by Sugarplum
That's a neat way to do that.

Re: Double your RAM:

Posted: 24 Feb 2022, 15:45
by veekoo
Time to do 64K RAM upgrade mod. I did it from the top of chip.

Now that I have 64K RAM, what are the top applications benefitting from more memory?

btw. I've tested most of the programs marked _64k_

Re: Double your RAM:

Posted: 26 May 2022, 07:02
by psergiu
Upgrade worked fine with a generic 128k x 8 TTL SRAM: MT62C1024P-70L
Could not find a 32-pin socket in parts bin so I soldered AWG30 wires under the RAM chips

Re: Double your RAM:

Posted: 16 Jul 2022, 12:14
by llevet
You can also replace the HM628128LP-7 (128Kx8) by a TC551001CP-70L or better speed TC551001CP-55L
The advantage for TC551001CP over HM628128LP is it only have half of the power consumption and it exist also in 55ns.

Re: Double your RAM:

Posted: 10 Dec 2022, 01:01
by renzo
Hello,
to expand the RAM size I installed the Alliance AS6C1008 chip.It is a 128Kx8 as the other one listed in the previous posts.
I connected pin 30 and 32, pin 31 to A15 signal on pcb, and pin 2 to pin 16 (GND).

Since pin2 is fixed to low level state (let's say low half 64k), I expected to see 64KB on the boot screen, insted I get "Gigatron 128K".
Probably I made something wrong even if wiring seems to be correct.

Re: Double your RAM:

Posted: 11 Dec 2022, 04:59
by bmwtcu
renzo wrote: 10 Dec 2022, 01:01 Since pin2 is fixed to low level state (let's say low half 64k), I expected to see 64KB on the boot screen, insted I get "Gigatron 128K".
This is a known issue with ROMv5a. https://forum.gigatron.io/viewtopic.php?p=3182

Re: Double your RAM:

Posted: 11 Dec 2022, 18:22
by renzo
Hi bmwtcu,

many thanks for the reply. I serched on the forum for a possible bug somewhere, but probably I didn't type the tricky words.

Re: Double your RAM:

Posted: 22 Jun 2023, 11:22
by Mephisztoe
I am kinda late for the party and actually didn't modify my GT (yet). However,... I wanted to ask why no one tried to simple wire everything on the solder side of the PCB? In my understanding there should be no difference anyway... except that you don't have to fiddle around with the socket at all - which sounds like a good thing to me. Or am I missing something?