Paper tape punch interfacing?

[Charles]

On Mon, 09 May 2005 12:07:36 -0500 (CDT), you wrote:

>I knew I had the Tally Model 420 manual somewhere, and amazingly it was 
>where I thought I'd put it....

Thanks very much, this is exactly the kind of information I
needed!

>Don't ask me where to get these lubricants....

It won't be punching miles of tape so sewing machine oil will
probably work in the mechanism (there is a sticker on the Lexan
cover that indicates the "light turbine oil").

>Having built a PC04 (well, converted a PC05 into one...) I seem to 
>remember that the DEC punch mechanism is a synchronous one. The motor 
>runs all the time, turnign the camshaft, you get a pulse per revolution

You recall correctly. I found the PC04/05 manual as well as the
PC8E interface schematics on bitsavers.org. I think your approach
to clock the interface card at slightly below the maximum punch
rate is a good one. I would use a one-shot to "reply" the sync
pulse to the PC8E but then it wouldn't have any way to start the
first character.

>Alas the manaul tells me that a mating connector is supplied with the 
>machine. Not a lot of help...

It seems that Continental Connector is still in business and that
25034 is a member of their 250 series power connector family. I'm
waiting for a reply from their sales dept. to find out where to
buy a single quantity...
thank goodness for the Web!

-Charles