Re: VIC-II DRAM refresh

From: Gerrit Heitsch <>
Date: Fri, 14 Oct 2016 13:12:47 +0200
Message-ID: <>
On 10/14/2016 12:52 PM, Francesco Messineo wrote:

> I agree that the vast majority of failed chips are MTs, but my other
> question is, how many MTs vs other brands were actually installed by
> Commodore factories to begin with? I have 2 boards with MT4164, so 1
> failed out of 16 chips so far and 2 boards one with Fujitsu (none
> failed) and one with Samsung (none failed) chips (not counting the
> repairs for others, since I didn't record the good chips, only a
> couple of failed MTs).
> Too bad I didn't record the failures in the '80s.
> Fujitsu chips (by memory) seems the second most used brand in C64s but
> that's me noticing them since the epoxy is darker and shiny and they
> look nicer than other brands., I've seen a few boards with Samsung
> too.

I have a board with Motorola RAMs, one with 3 makers mixed (Motorola, 
Oki, Mitsubishi), one with TI, 2 with Hitachi, one with Toshiba, 
Samsung, Fujitsu, Oki, Matsushita, NEC, Sharp. None of my personal 
systems has MT4264 in them. No, I didn't change them, they came that way.

Commodore used what was cheapest at the moment.

> By the way, if statistics were to be taken seriously, we should never
> leave any MOS ROM into CBM equipment :)

I don't if I can help it... All my 264 systems use 27C128 instead of the 
ROMs (which still work). Why? Replacing a mask ROM with a CMOS EPROM 
saves 50mA of power. 2 EPROMs = 500mW less heat. Combine with a 
switching regulator in a C16 or C116 instead of the 7805 and you have a 
system that produces a lot less heat which will hopefully prolong the 
life of TED and the CPU...


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Received on 2016-10-14 12:00:02

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