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From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.electronics
Subject: Re: Help identify Motorola SC prefix chips
Message-ID: <1991May24.211332.6810@milton.u.washington.edu>
Date: 24 May 91 21:13:32 GMT
References: <13711@pasteur.Berkeley.EDU>
Organization: University of Washington, Seattle
Lines: 25

In article <13711@pasteur.Berkeley.EDU> atn@cory.Berkeley.EDU (Alan Nishioka) writes:
>I need help identifying some Motorola chips. 
>Found in a Radio Shack Color Computer 2:
>
>SC77527P	16 pin	8423 date code		seems to be a voltage regulator
>SC77526P	20 pin	8329 date code

	These are special-purpose ICs, which only Radio Shack can help
you with.  Fortunately, they are field-replaceable units (socketed),
and Radio Shack offers service (i.e. you can buy spares).  

	One is "U3", and is a DAC of sorts.  Inputs are pins 13-16, connected
to the joystick connector, and addressed by the PIA chip via two
analog select lines, pins 11 and 12.  The cassette output and
sound drivers are also on this chip.  It includes a comparator,
so that the DAC output can be compared with an input (so you can
measure input voltages this way).  This is a 20-pin chip.
	The other, "U1" is called the SALT chip (supply and level
translator) and includes voltage regulation and the cassette READ
circuitry.  This is a 16-pin chip.
	
	If you want full information, contact Radio Shack and ask about
the Color Computer II Service Manual.

	John Whitmore