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8bit ISA Clock Card

archeocomp

Experienced Member
Joined
Apr 29, 2012
Messages
397
Location
EU/SK
Hi, I am looking for an option to have real time clock on my Turbo XT PC. eBay search did not show anything cheap and pretty common or perhaps I do not know what to look for. I believe I need a card and a little exe to be able to set up system and card clocks. My location is Europe/SK.
 

mbbrutman

Associate Cat Herder
Staff member
Joined
May 3, 2003
Messages
6,240
I'd look for a Dallas DS1216E "no slot" clock chip. It fits under an existing ROM chip and it is basically invisible until you run the software to access it. My writeup of it is here:

http://www.brutman.com/PCjr/DS1216E.html

I use it in a PCjr. It was used in many other systems, including non-PC architectures.
 

archeocomp

Experienced Member
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Apr 29, 2012
Messages
397
Location
EU/SK
Hi, that's an interesting option. My BIOS socket is mapped between F000:E000-F000:FFFF and BASIC ROM socket is mapped between F000:6000-F000:DFFF. I hade once to grind package of one DS12887 and cut wire to internal lion battery and solder wires to external holder for a CR2032. I do believe with this chip I would have to face the same problem some time. It is really nice chip but Farnell wants 30Eur for one :confused:
 

mbbrutman

Associate Cat Herder
Staff member
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Yes, they are expensive. But the lifespan of the chip is also around 10 years. That's an expense I can handle once I consider how long it will last.


Mike
 

Trixter

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Aug 31, 2006
Messages
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Chicagoland, Illinois, USA
Here's an alternative: As I try to have a functional NIC in all of my vintage machines, I use mTCP's SNTP program to set the time on bootup, eliminating the need for a clock chip:

sntp -set 0.us.pool.ntp.org
 

Chuck(G)

25k Member
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Jan 11, 2007
Messages
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Pacific Northwest, USA
For years, I used one with a honest-to-gosh MC146816 CMOS chip, the same one that's in the 5170. So you also got a bit of CMOS SRAM at the same I/O port addresses as the 5170-and-above systems. I'm surprised not to see more of them kicking around.
 
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ibmapc

Veteran Member
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Apr 5, 2010
Messages
1,029
Location
Albany, OR USA
Here's an alternative: As I try to have a functional NIC in all of my vintage machines, I use mTCP's SNTP program to set the time on bootup, eliminating the need for a clock chip:

sntp -set 0.us.pool.ntp.org

I've also done this. Had to do some tweaking with the TZ environment variable though because the daylight savings time change date is not the same as it used to be and the default variable doesn't work right any more.
 

Chuck(G)

25k Member
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Jan 11, 2007
Messages
39,075
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Pacific Northwest, USA
You might also want to look for a "no slot clock" that's sandwiched between a BIOS chip and its socket.

Edit: Okay, I see that Mike said that back at the beginning. Just don't pick up one from the 1980s--batteries do have a fixed shelf life.
 
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Chuck(G)

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Jan 11, 2007
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39,075
Location
Pacific Northwest, USA
Here's another idea, but it's a maker project. Why not interface an external low-poer MCU to a spare port to provide a clock? I could even imagine a little in-line keyboard dongle that spit out the time of day when a certain key combination was pressed--or even spit out the DOS TIME and DATE commands...
 

archeocomp

Experienced Member
Joined
Apr 29, 2012
Messages
397
Location
EU/SK
That is a surprising and very interesting idea. I hope that key combination could be generated by little program too, called from autoexec. Even separate ISA card would be fine. I still have three free slots. I know Sergey used DS12885/DS12887 on his i8088 board.
 
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