Re: Laser128/NoSlotClock

[dempson@swell.actrix.gen.nz (David Empson)]

In article <2kfikd$h92@rbse.Mountain.Net> quinn@Mountain.Net
(Quinn Avery) writes:
> 
> I have an SMT No Slot Clock and a Laser 128ex.  Apparently the only
>  way to use the clock is to piggyback the ROM on top of it.

Yep.  The No Slot Clock is a "SmartWatch/ROM", part DS1216E, made by
Dallas Semiconductor.  It is designed to work transparently under a ROM
(8KB, 16KB or 32KB) by watching for a particular pattern of address
accesses to the ROM.  Subsequent READ cycles to the ROM cause the time
to be fed out serially via one of the data bus pins.  (Setting the time
requires a series of reads to particular ROM locations.)

In a IIe, you have the option of placing this chip under a motherboard
ROM (CD or EF ROM) or under any similarly sized ROM in a card in any
slot.  This isn't an option with the Laser unless you happen to have
an appropriate card in the external slot.

Dallas Semiconductor also make RAM versions of the SmartWatch, such as
the DS1216C, which sits under an 8k or 32k static RAM chip.  It
provides battery backup for the RAM as well as holding the time.

The No Slot Clock software wouldn't work with this type of SmartWatch
without a reasonable amount of modification.

> Unfortunately, on a Laser this means that the ROM is gonna stick out
>  the bottom.  I've got to raise the case with two sticks of wood or
>  something.  Is there somewhere else I can install this clock so I
>  don't have to keep this thing on blocks for the rest of its life?

Sorry, I think you're out of luck in this case.

If you were really keen, you could make up your own circuit using the
clock chip itself (DS1215 "Timechip"), a 32.768 kHz crystal, a
battery, and a few wires to hook it onto the ROM chip in the
appropriate places.  This would work with the existing No Slot Clock
software.

> Someone mentioned earlier that they had their NS-clock in the printer
>  port?  How would I do that?

They were probably talking about a IIe printer card with a 28-pin ROM
on it, in which case the No Slot Clock can go under the ROM on the card.
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz                                                
Snail mail: P.O. Box 27-103, Wellington, New Zealand