[sci.electronics] 8bit to bcd

hughes@ee.rochester.edu (Tadd Hughes) (03/29/91)

		Hi, I think it would be easier to use an eprom
	using the address lines as the 8 bit input and the
	output lines as the bcd output.  These are extremely easy
	to program with a couple of components.  (one shot ....)

				Tadd
	  

ahill@hpdmd48.boi.hp.com (Andy Hill) (04/01/91)

Actually, this is a bit of overkill, since the 74185 is a six-bit-in,
eight-bit-out part, which would imply a 64x8 PROM.  I suppose fuse-programmed
PROMs that small still exist.  However, I guess if you're not limited by
board space, the venerable 2716 EPROM (or it's bigger descendents) would do
the job.  I guess I'm spoiled - my first thought, when I need a simple logic
function, is to reach for a 20V8 or 22V10 GAL...

                    Andy

deanr@sco.COM (Dean Reece) (04/04/91)

To convert 8 bit binary to BCD (10 bits, I assume), try using a few 74185
chips.  I'm not sure of the exact configurations, but the data sheet shows
how to cascade them to get wider convertors.  You'll probably need about
4 or 5 to get the width you need, but since they are only 16 pin DIPs, and
they need not be 'burned', I think the are a better solution that EPROM.

I think it is the National Semiconductor sheet that has all the
configurations for various widths; the TI sheet I have only shows the 6
bit configuration.  Also, for those who are interested, the '184 does
the reverse conversion (BCD to Binary).

Cheers, and happy hacking.
-deanr@sco.com