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Dual Systems -  CLK24C Clock Board

There were a few different versions/revisions of this board. The picture below is the first Rev A version. Later versions used a circular battery holder.

Dual Systems RTC Board

The heart of the CLK-24 was the OKI MSM5832, which can be read by the computer to give the current time or date. The CMOS integrated circuit uses so little power that with one small battery it could keep time for over three years with the   computer power off.
The CLK-24C  was easy to use. The time and date may be set or read from either BASIC, assembly language, or any other language that allows access to the I/O ports. Programming examples were included in the manual.

For critical timing applications or operating system requirements the CLK-2M could generate vectored interrupts on intervals of minutes, seconds, 1/64 second and 1/1024 second. This was useful if, for example, you wish to display the current time every second or minute, concurrent with normal system operation.

The board was very similar to the the CompuTime clock board using the same chip.
It looks like there are at least two versions of this board. I actually have an earlier version, shown below.  As far as I can tell both boards are the same from a software point of view.

Dual Syatems RTC board-2

The manual for this board may be obtained here.

Other Dual Systems S-100 Boards
68000 CPU    256K RAM    Clock Board   CMEM-RAM    Digital-to-Analog    Analog-to Digital    4SIO    EPROM


This page was last modified on 10/25/2013