Re: N3101 RAM for Missile Command

Open collector is needed when you are driving colour video output
resistors. You have to have an output gate that floats when it is not
pulling down the output resistor. You should be able to get the same result
if you use an isolation diode on each output gate, otherwise all the
colours will be the same intensity and you won't get that lovely 16/32/?
colours potential of these old timers...just a nine colour palette.

John :-#)#

At 01:28 AM 31/01/2004, Rodger Boots wrote:

>The N3101 is a Signetics number
>(<http://www1.cedar-rapids.net/00000028/IHS/N3101.pdf>datasheet here) that
>directly crosses to a 74S289
>(<http://www1.cedar-rapids.net/00000028/IHS/74s289.pdf>datasheet here),
>and for completeness I'm including the Intel 3101 datasheet
><http://www1.cedar-rapids.net/00000028/IHS/3101.pdf>here.
>
>So far we have chips that are all open collector output and are
>obsolete. That being said, I see no reason why you need open collector
>outputs, it's probably just what was available when they designed the
>game. A 74S189 (Jameco has them
><http://www.jameco.com/cgi-bin/ncommerce3/ProductDisplay?prmenbr=91&prrfnbr=1817&cgrfnbr=582&ctgys=502;508;582;>here)
>should work fine.
>
>The 3101 is NOT compatible with the 5101 or 2102 or anything else. It is
>a very fast, very small RAM. 64 bits arranged as 16 x 4.
>
>
>MyPearl wrote:
>>
>>Hello group,
>>
>>I found that the COLOR RAM (at L7) of my missile command has litterary
>>cracked open. Weird thing is it, still works, but becomes unstable now and
>>then and triggers the Watchdog.
>>
>>The partnumber on the chip is 'N3101'
>>
>>I cannot find a datasheet for this part, nor a source, or a cross to a
>>replacement on the web...
>>
>>Does anyone know where I could get this RAM, or equivalent?
>>
>>Hope someone knows...
>>
>>Thanks
>>
>>Mendel Pearl
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>>
>>
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Received on Sat Jan 31 12:50:21 2004