Subj : Cpu Display
To   : MIKE ROSS
From : JEFF GUERDAT
Date : Fri Sep 23 2005 07:58 am

On 09-22-05, MIKE ROSS said to ALL:

MR>I came across a funny cpu speed display in an old box with a newer
MR>board in it. It is a full 3 digit type but it has an IC marked F51231E
MR>and a small watch battery. At first I thought this was for a clock but
MR>on closer inspection the IC is seems to be a programmable 7 segment
MR>decoder and the watch battery is for backing up its data. There are
MR>also 3 transistors which are used as inverters for the digit decoding.
MR>The oddest thing is that in addition to the usual connection to the
MR>turbo switch it also has a connection to the reset switch.

MR>My question then is how is this thing programmed?

MR>These are the pin markings over the pcb header,
MR>Label:  L   T   H   R   R   +   -   S   S   T
MR>Connector:  nc  TB-LED  RESET   POWER   TB-SWITCH

MR>Any info is welcome.

Can't believe it!  I did a quick Google search on the chip marking you
provided and found a new thread that almost coincides with this question.
Start with http://www.eio.com/public/led/0312.html and click on the "next in
thread" link at the bottom of each message to go to the next one.  There's
various questions and comments so you prolly need to slog through the whole
thing.  There is a post about 6 posts in that speaks to programming but I
didn't look further.

Good luck!


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