Things to do with a PDP8 No.1243, Flashing Christmas Tree Lights

[DaveH]

http://www.youtube.com/watch?v=B1MDYYvw0cY


Not maybe the optimal engineering solution but fun, also gives me an excuse to " pop out to the workshop to check on the 8 " from time to time over the festive break.
Dave

 

[tradde]

Very cool. Nice looking Lab 8e too.

 

[Marty]

Hi All;
Dave what was the basic circuit ?? The 8 controlling a few relays which turned the lights on and off, OR something more exotic ??
THANK YOU Marty

 

[RSX11M+]

I noticed that 8e has a blade key - not an ACE type. Is this common?

 

[DaveH]

I noticed that 8e has a blade key - not an ACE type. Is this common?

No its not, its a bit of a cheat on my part, when I originally got the Lab8 , in the 80es, it did not have the key so I removed the existing ACE switch and substituted a blade type that I happened to have. I have more spares now including 3 keys and sometime intend to go back to the original switch.

Marty, the actual interface is quite simple, when I first did this, 20 or so years ago I did use relays, with a driver transistor to interface from the TTL to relay, to low voltage incandescent lamps. My wife however did not appreciate the "click, clank" of the relays so now we have LED lamps and just 6 x NPN's as interface, only 40ma per string.

The program is a little more complicated than just a bit shift as it has a data block "array" with initial starting patterns, speed and shift direction and the program cycles through these.

 

[NeXT]

That is one of the most modern yet practical thing I have seen a lab/8 do in....ever.

 

[NF6X]

Delightful!

 

[daver2]

Dave,

Very cool!

What can we expect next year?

Dave

 

[Marty]

Hi All;
Next Year, He'll have ALL of His House lights controller by the "8".. Year after that all the House Security.. Either that or He'LL have bought a Dog for House security..
THANK YOU Marty

 

[tradde]

Next year will have music played by the 8. As long as it has core memory. I was always amazed by how people used the RFI from the core to make tones and
thus play music. Was really cool.

 

[RSX11M+]

I noticed that 8e has a blade key - not an ACE type. Is this common?

No its not, its a bit of a cheat on my part, when I originally got the Lab8 , in the 80es, it did not have the key so I removed the existing ACE switch and substituted a blade type that I happened to have. I have more spares now including 3 keys and sometime intend to go back to the original switch...

That answer is quite a relief - Thank you.

I think your DEC Christmas Light Controller is the very best defense against PDP obsolescence a home could have. You've got me trying to think up ways I can inextricably tie all my Vintage Computers to every essential household function possible.

 

[cruff]

\My wife however did not appreciate the "click, clank" of the relays so now we have LED lamps and just 6 x NPN's as interface, only 40ma per string.

Apparently you failed to provide the proper mood music at a suitable volume to drown out the relay noise.

 

[NF6X]

With some remote switches, you could toggle in a program from your living room, using the Christmas tree as the display.

 

[pontus]

Very nice Lab8/e. What is the TTY brand? ITT?

That slight squeaky noise, is it coming from the left TU56?

 

[leeb]

"They call him
Merlin Jones, the scrambled egghead,
Merlin Jones, the campus kook,
But her heart's whirlin,
She's the girl in love with
Merlin Jones"

That was fantastic! Thanks for the looksie and the lulz!

 

[dave_m]

so now we have LED lamps and just 6 x NPN's as interface, only 40ma per string.

Wonderfully useful application!

Some questions: You seem to load two tapes, one must be the program and the other? Also, you plug in one patch cord to control six strings?
-Dave

 

[DaveH]

Thanks to everyone for the comments, I'm pleased its been of interest.
Marty, sorry to disappoint but cant afford the power to run the 8 7-24 so security is gonna have to be a dog.

pontus,
the TTY is a "Data Dynamics" on the case but its a standard ASR33 inside, had been sitting for 25 years or so, needed a clean , lube and the
obligatory type hammer replacement but now seems basically ok.
Yes the squeak is from drive 0, the left , though both will do it now and again, seems to be the tape just touching the inside of the spool when you are at the 50 50 point as it were.

Dave,
Left hand drive, set as drive 0 has the system tape and is used to boot and run the operating system ,OS 8.
The other drive, set as 1, has a data tape on it, and the light flashing program is on this tape, I could have put this program on the system tape but loading would have taken a lot longer.
The tapes themselves are 40 years old, the system tape I reformatted and rebuilt last year but that data tape had the lights program written to it in 1982 !!, these DECtapes are pretty long lived.
The "patch cord" is a cat 5 but i'm just using it as 8 singles, well 6 TTL and a ground. I tend to use cat5 for other stuff not just networking, its handy for general control as here or for CCTV using a balum, you just gotta check VERY carefully before you plug in the RJ45
Dave