Ademco 685

Ademco 685 Digital Alarm Receiver

the stealth S-100 chassis

Provision for battery backup

This alarm is built on a S-100 Chassis. It comes with a California Computer Systems (CCS) 2810 2 / 4 mhz switchable Z80 CPU. It doesn't have the CMOS EPROM installed however I burnt one from a copy of my existing CCS system, changed a couple jumpers and there we go a nice auto bauding serial console with a ROM Monitor. Get a feel for the size of the enclosure for this if not rack mounted. This is the chassis after I striped it of an unnecessary wiring harness. The chassis removed from the enclosure weights in at 20 pounds where a CompuPro desktop weights 32 pounds. I measured the DC supply at 9.18, 14.22 and -15.8 I see a bunch on ePay and have seen them on Craigslist too.

I installed a set of CCS boards and successfully booted from 8" FDD at both 2 and 4 mhz. I tried a CompuPro set without success. Interesting that I haven't made the CCS board set work on the CompuPro chassis. Buss termination needs more experimentation.

Cabinetry

Inside

If you look closely you'll see that the S-100 edge connector spacing is not consistent. I didn't measure, but a board set fits in the slots that are closer together.

I've cut away the wire harness. There is a single purple wire to leave between the aluminum supply within the main supply that goes to the PCB mounted against the outer wall of the chassis.

Power supply detail

Leave this purple wire.

Rear view

Front face

Cover

The inner box does have a cover.

A standard rack mount plate can easily replace the front panel. Drill 4our holes to attach to chassis.

Salvagable

I like the VFD. I looked around on the boards for a VFD controller which I didn't find. There are a couple 27C256 EPROMs too.

Vacuum Fluorescent Display

Boards

Aside from the CCS CPU the unit I dissembled had these boards.