Panda Display Panel

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Build or Buy Your Own

Assembly Hints

Once upon a time, Ken Harrenstein wrote a an emulator for the DEC KS10 and KL10 processors, along with the associated peripherals.  As an ex-36 bit programmer (See What is JFCL, anyway?) I can tell you that this was no small task, and we're fortunate that Ken was kind enough to share his emulator, KLH10, with the world.  Mark Crispin got TOPS20 running on KLH10, and put it together with a small Linux kernel on a bootable CD, which is available to any interested hobbyist.  To this day Mark maintains a pseudo-DECSYSTEM-20 running on PC hardware.

The only problem with KLH10 and a PC is that it lacks the lights and switches of the original hardware.  Well, admittedly the KL and KS10 processors had no lights and switches, but the KI and KA models did, and you'll just have to use your imagination.  In any case, after Mark bought one of the Spare Time Gizmos PDP-8 replicas,  he approached me about the possibility of creating a pseudo front panel for KLH10.  A realistic replica of a KI or KA panel was financially, mechanically and physically beyond our means , but a simple blinking LEDs panel was easy to do.

The result was the Panda Display Panel that you see here.  The Panda display contains 40 LEDs (because LED bars are sold in multiples of 8, not 6!) and four discrete status LEDs.  In Mark's modified version of KLH10, 36 of the 40 LEDs emulate a KI style lights register and three of the remaining LEDs indicate processor load.  The four discrete LEDs are used to indicate virtual Disk, Tape, and Network activity as well as the simulated processor run state.

The Panda Display Panel is designed to replace a blank cover over a standard 5 1/4" drive bay. The Panda Display receives power thru a standard floppy/hard disk drive power cable and the Panda Display plugs into a standard parallel (aka LPT) port for control and data. The display logic uses eight standard 74HC series ICs along with one 16V8 GAL and occupies two small PC boards. The two PC boards are designed to stack together, back to back, and the entire assembly pretty much fits inside a blank cover for a 5 1/4" drive bay. If you're really into blinking lights, it is possible to daisy chain as many as four Panda Displays on the same parallel port. Each display is individually selectable by a unique two bit address.

Build or Buy Your Own

Mark Crispin's "DECSYSTEM-20" box, linglingThe schematic and parts list for the Panda Display Panel are available free from Spare Time Gizmos. All of the parts are readily available from mail order sources source as Mouser, Digi-Key and Jameco, and it's fairly easy to assemble for anyone who has experience building small electronic gizmos. If you have a small, 25W soldering pencil or (better yet) a temperature controlled soldering station and you're comfortable reading a schematic and using it to stuff parts in a PC board then you probably won't have any trouble with assembly.

If you decide to build your own, Spare Time Gizmos can sell you a set of bare PC boards to make your life easier and we can also sell you a pre-programmed GAL. All the other parts can be ordered from the sources given in the parts list and you should have no trouble obtaining them. This is a low volume kit for use and we're sorry to say that we just don't have the resources to provide a complete instruction or assembly manual, and the schematics, parts list and a few assembly hints are all the documentation you'll get. Please download and read these documents and be sure you're comfortable with that before ordering parts.

If you don't feel comfortable building your own, then Spare Time Gizmos will sell you a completely assembled and tested unit, ready to install in your PC.


Please read the Spare Time Gizmos store policies before ordering.  Shipping charges shown are for the US only - international customers please inquire before ordering.  Sales tax must be charged on all shipments to California addresses.

P/N Description Price
  Panda Display Schematics, Parts List and Firmware FREE!  
PANDA-1B Panda Display PC Boards Only
Set of two - logic and display - PC boards.
PANDA-GAL Preprogrammed 16V8 GAL for the Panda Display
Available only with the purchase of a PC board.
PANDA-ASM Assembled and Tested Panda Display
Ready to install in your PC.

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