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From: rbj@icst-cmr (Root Boy Jim)
Newsgroups: net.lang.c
Subject: Re:  Questions about C on a Prime (primix)
Message-ID: <2473@brl-smoke.ARPA>
Date: Tue, 8-Apr-86 18:36:29 EST
Article-I.D.: brl-smok.2473
Posted: Tue Apr  8 18:36:29 1986
Date-Received: Thu, 10-Apr-86 08:28:07 EST
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	Any C implementation that insists on having the high bit set
	for normal character (char)s should also treat (char) as
	(unsigned char), or else there will be sign-propagation
	constants when (char)s are widened to (int).  Otherwise,
	this is a permissible (although unusual) implementation choice.

Both K&R & the ANSI standard say that a printing character is
guaranteed to be positive. If the implementation (hardware) insists on
characters with the high order bit set, then my guess is that it must
be done in very low level code, possibly within putc just before
the char is sent to the device. Varian 620i (sounds like a BMW)
aka V-7x's wanted this as I seem to recall.

In any case, the following program must print `positive', for any
printing character 'x'.

main()
{	char c;
	c = 'x'
	if (c > 0)
		printf("positive\n");
	else	printf("netative\n");
}
	
References:	K&R	page 183	sect 6.1
(4/30/85)	ANSI	page 16		sect C.1.2.5