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From: gordon@sage.cs.reading.Ac.Uk (Simon Gordon)
Newsgroups: net.micro.atari16
Subject: Re: Power supply
Message-ID: <171@sage.cs.reading.Ac.Uk>
Date: Fri, 16-May-86 19:57:21 EDT
Article-I.D.: sage.171
Posted: Fri May 16 19:57:21 1986
Date-Received: Fri, 23-May-86 22:36:04 EDT
References: <8605100658.AA12747@ucbvax.Berkeley.EDU> <3407@ukma.UUCP>
Reply-To: gordon@sage.UUCP (Simon Gordon)
Organization: Comp. Sci. Dept., Reading Univ. UK. (sage)
Lines: 26

In article <3407@ukma.UUCP> knnngt@ukma.UUCP (Alan Kennington) writes:
>
>
>        So, the plot thickens. That explains why my new TOS ROMs blew - perhaps.
>When I replaced the old 2 chips with 6 new ones, one (or more) of the new
>ones blew. And everything worked okay again with the old ones.
>        And at the time I thought logically that increased power drain meant
>lower voltage, and therefore lower current per chip. The note this
>note follows explains that actually a higher power drain means more
>current per device. I hope that this new engineering concept will be
>explained to novices like myself in due course. How can the MMU be blown
>by extra chips on the board???
>        Respectfully,   ak.

Some people seem to get their facts twisted.

There seem to be two problems
1) Some of the older power supplies cannot supply enough power if you have
the extra 16 ram chips to give 1 meg ( my one is black with a lead out of
each end, ive been using it for a month since the 1 meg upgrade and rom upgrade
which i had done at the same time)
2) With twice as many ram chips, the MMU must do extra work    holding the
inputs to the ram chips at their normal voltage. The resisters are therefore
pull ups and do this job instead.

Simon Gordon @ Sibly Hall Reading University UK