Double your RAM:

Using, learning, programming and modding the Gigatron and anything related.
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at67
Site Admin
Posts: 651
Joined: 14 May 2018, 08:29

Re: Double your RAM:

Post by at67 »

Nice pics, discreet job like cde's, welcome to the club.
giobbi
Posts: 38
Joined: 11 Jul 2021, 22:12

Re: Double your RAM:

Post 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:
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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).
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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
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And here we have the 64k RAM chip installed:
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And of course the Gigatron liked it :-)
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Sugarplum
Posts: 94
Joined: 30 Sep 2020, 22:19

Re: Double your RAM:

Post by Sugarplum »

That's a neat way to do that.
veekoo
Posts: 123
Joined: 07 Jun 2021, 07:07

Re: Double your RAM:

Post 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_
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psergiu
Posts: 2
Joined: 02 Sep 2021, 22:33

Re: Double your RAM:

Post 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
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llevet
Posts: 2
Joined: 03 Jul 2022, 04:17

Re: Double your RAM:

Post 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.
renzo
Posts: 4
Joined: 06 Dec 2022, 23:51

Re: Double your RAM:

Post 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.
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bmwtcu
Posts: 145
Joined: 01 Nov 2018, 12:02

Re: Double your RAM:

Post 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
renzo
Posts: 4
Joined: 06 Dec 2022, 23:51

Re: Double your RAM:

Post 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.
Mephisztoe
Posts: 5
Joined: 22 Jun 2023, 10:48

Re: Double your RAM:

Post 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?
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