DECTape head problem

[Paul Koning]

> On Feb 8, 2022, at 4:04 PM, Ron Pool via cctech <cctech at classiccmp.org> wrote:
> 
>> So it sermsdectape heads are special. I don’t think Dec would have the desire to make them internally so they probably contractef with a company already set up to do that. Who were the big tape head manufacturers at that time? Does anyone know?
> 
> A photo of the back of a TU56 DECtape head can be seen at https://www.pdp8online.com/tu56/pics/head_label.shtml?small .
> The head has a label on it that reads:
>  Western Magnetics
>  Glendale Calif.
>  Record
>  7282
> 
> I've never seen a TU56 in person and have no idea if they have separate read, write, and erase heads or some other combo.  The "Record" notation on the above head's label hints to me this might be a write head.
> 
> I found that and other DECtape photos at https://www.pdp8online.com/tu56/tu56.shtml .

This picture https://www.pdp8online.com/tu56/pics/TU56_front.shtml?large shows the tape path clearly.  There is just one head assembly that performs reading as well as writing.  I don't know what "Record" refers to; the numbers near it look vaguely like a date code though not the usual year and week number.

The maintenance manual (on Bitsavers) speaks of a "read/write head" and has an illustration that shows one of the head elements with a "read/write coil".  So the implication is that (a) there isn't an erase head, and (b) the same head serves for read or write according to whether the coil is being driven or sensed.  Come to think of it, I think erase heads are an aspect of audio tapes, not relevant to computer tapes.

	paul