Yep!! It was a bad Dallas DS12887A chip.
I called Digikey, and told them the Dallas chip died and they sent me
a new one within a few days. It was a $9 chip so I figured Digikey
would replace it. Yep, they are very good and fast too. Even payed
for the shipping and didnt even ask for the old one back. Nice people.
I put it in the ELF2000 Disk board and it worked right of the bat, no
problem. Being that it is a special custom like module, I guess
someone didnt solder the oscillator correctly. Who knows, this stuff
can happen from time to time. Always listen to STG's ELF monitor!! It
checks itself out very thoroughly.
Anybody want a small RAM chip with a dead clock, hehe. I wonder if
the battery still works!. I guess well never know.
(CO)mplementary (S)ilicon (M)et(A)l oxide (C)onductor
--- In firstname.lastname@example.org
, "saturn5tony" <saturn5tony@...>
> Wow, this is wierd,
> I just finished building the DISK/UART/RTC board for the ELF2000.
> it worked great!! I checked SHOW DATIME and it recognized the RTC
> clock chip perfectly, no errors, just wrong numbers, its new. I
> bought the Dallas DS12887A a week ago from Digikey, brand new. I
> tried the SET DATIME to 04/22/2008 17:00:00 and bingo, my 1802 can
> now tell time. weeee!!
> I even checked it an hour later before I turned everything off for
> the night and yes Show datime said 4/22/2008 18:02:56. cool...
> Well, I shut the system off for the night, woke up the next day and
> powerd up the ELF2000 with the RTC board and wham!, I got a POST 75
> error on the LEDs. What happened?? I checked the manual thinking
> battery in the dallas chip died overnight, and I see that 75
> means "RTC clock not ticking" not the post code 74 which is "RTC
> battery fail" Hmmmm. What happened overnight since the machine was
> powered off? Nothing!! Just a new power on with the ELF2K.
> I checked the board for missing solder on some pins, bad PC board
> connections and nothing. Its fine. I have a scope and I could see
> that all the signals are going to and from the dallas chip were
> Anybody ever come across this? It seems very strange that the chip
> worked fine one day and now the crystal clock is gone??
> I even tried to reset the chip. I have the "A" version of the
> clock, so the JP5 jumper will work on the RTC board. nope, didnt
> Did the Dallas crystal just die over night?? Seems weird.
> (CO)mplementary (S)ilicon (M)et(A)l oxide (C)onductor