[HECnet] Slightly OT: DECTape support in SIMH VMS?

[Mark Pizzolato - Info Comm]

On Thursday, October 03, 2013 at 9:39 AM, Johnny Billquist wrote:
On 2013-10-03 17:24, Paul_Koning at Dell.com wrote:

On Sep 29, 2013, at 9:18 AM, Johnny Billquist <bqt at softjar.se> wrote:

On 2013-09-29 14:48, Sampsa Laine wrote:
I noticed that the SIMH PDP-11 distribution contains emulation of
TC11/TU56 DECtape drives. My questions are:

	- How hard would these be to port to the VAX SIMH emulation?
	- Do modern VMS (e.g > 7.0) OSes support DECtapes?

I figure it would be a nice way to transfer files between a PDP-11 and
VAX system for example..

VMS have never supported DECtape, as far as I know...

Not officially.   But I know it was done as a "midnight project", by Andy
Goldstein if I remember correctly.   That supposedly even included
overlapped seek support, just as TOPS-10 did.

Why am I not surprised he would be involved...

You might just turn it on and see if it works "out of the box".

I would assume the file structure used is the same as what RSX uses,
whatever that is.

That would be normal Files-11 in that case. It might be a single directory file;
structure, though. Like for floppies.

It would be easy enough to add the TC11/TU56 to a simh Unibus VAX system. 

I think that the hard part would be getting the "Midnight project" device driver which may have been written back then.   

The driver doesn't seem to be included in VMS:

$ mc sysgen
SYSGEN>   CONF
DEVICE> tc11
DEVICE>   Exit
Device: TC11       Name: DTA               CSR: 777340         Vector: 214       Support: no

Notice the "Support: no".

- Mark