31 Oct
2010
31 Oct
'10
8:48 p.m.
On Sat, Oct 30, 2010 at 8:17 AM, Dan Roganti <ragooman at gmail.com> wrote:
On Sat, Oct 30, 2010 at 8:02 AM, Dan Roganti <ragooman at gmail.com> wrote:
4 chip solution, 74247, 74138, 7407, 4066
No rule against using diodes ;)
http://www.vintagecomputer.net/ragooman/files/schematics/hexdec/hexdecoder1…
You have to take the ol' "ouside the box" approach.
I call it the Kobayashi Maru hack ;)
Since the '247 already provides 15 decodes already, I just tweak the ouputs
for A-F
I use the lowercase 'c' since it saves a chip versus a uppercase 'C'
eh-hem, and don't let programmers design hardware :D
=Dan
--http://www.vintagecomputer.net/ragooman/
On Sat, Oct 30, 2010 at 3:52 AM, Vincent Slyngstad <
v.slyngstad at frontier.com> wrote:
little typo - early in the morning you know
7403 should be 7409 -- gotta love that Negative Logic ;)
On Sat, Oct 30, 2010 at 2:31 PM, Vincent Slyngstad <vrs at msn.com> wrote:
From: "Brent Hilpert": Thursday,
October 28, 2010 3:55 PM
OK, I claim three solutions:
only 4 chips ;)
74138
74247
7407
7403
and 4 pullups
only 4 chips ;)
74138
74247
7407
7403
and 4 pullups
OK, I admit that I'm not seeing it.
Are you using the funky 247 outputs for 10-15? Or are you disabling the
247 somehow (wouldn't that require an inverter from somewhere)?
Vince
(I have attached my schematic, in case you are interested.) 