28 Oct
2010
28 Oct
'10
7:47 a.m.
On Thu, Oct 28, 2010 at 12:13 AM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
Then there was National's oddball inverse-function
IC: 7-segment input
converted to BCD out.
I have one of those in a binary clock kit. The clock chip is one of
the standard National Semiconductor 1970s-era alarm clock IC, meant to
directly drive a multiplexed multi-digit 7-segment module. The clock
itself is more-or-less the reference design with that 7-segment-to-BCD
between the clock IC and a grid of 12mm LEDs.
I bought mine in 1994. Once the supply of those decoder chips dried
up, the kit manufacturer switched the design to a PIC-based design.
The clock I bought as a gift ten years later was the newer design.
-ethan