From: utzoo!decvax!cca!Leonard@sri-unix
Newsgroups: net.micro
Title: Information needed on A/D interfacing for TRS-80 or Apple
Article-I.D.: sri-unix.2245
Posted: Fri Jul 23 03:25:48 1982
Received: Mon Jul 26 00:08:04 1982

I have a possible use for a micro, of either the TRS-80 or Apple
persuasion, for a scientific application.  The choice of which micro I
use is highly dependent on which can talk to an A/D converter that is
currently available (I have neither the time nor the desire to design
my own A/D converter for this application), and on price and
programming considerations if such a device is available for both
computers.

Specifically, I need information about a two-channel A/D converter
(one channel may do if I can get one bit of output to control an
analog switch to multiplex the A/D input, and more than two channels
aren't needed but will be tolerated if the only units come with more),
which generates one byte output (either signed or unsigned) in around
50 microseconds or less .  The input from the application will be on
the order of tenths of microvolts, but I expect to preamplify it to
whatever range the A/D converter requires, since I doubt that any
available for these computers can handle such low-level signals .

I need price, address, phone numbers, and descriptions of A/D hardware
for any micro of this sort, and I need to build this thing yesterday.

If no such device exists, suppliers of any parallel A/D converter
assembly (again, I don't want to have to start from just a chip unless
the design time will be very small) and parallel interfaces for either
micro would be greatly appreciated.

Any other information you throw in about the suitability of either
type of computer for this application (how easy it is to interface to,
how much equally configured systems including 48K or 64K RAM and two
5.5" drives cost relative to each other) would be appreciated but can
probably be obtained through other channels.

If anyone can give me some information, my undying gratitude!  And
thanx much, too!