16 Oct
2015
16 Oct
'15
4 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Johnny
Billquist
Sent: 16 October 2015 11:38
To: cctalk at classiccmp.org
Subject: Re: Contents of DEC 8" floppies
On 2015-10-16 10:08, Dave Wade wrote:
You might be right. I partly based that comment on the RSX P.S.I product.
Not
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of
> Johnny Billquist
> Sent: 16 October 2015 09:07
> To: cctalk at classiccmp.org
> Subject: Re: Contents of DEC 8" floppies
>
> On 2015-10-16 08:14, Mark J. Blair wrote:
>> I have some unused 3M blank preformatted RX02 diskettes. Would
those
be usable
in an RX01 drive?
Yes. The RX01 and RX02 is the same format. It's only the data part of
the sector that differs.
> I don't know what the VAX PSI software is, but I'm guessing it must
> be
for
the 11/780 based on the media type. I have zero
use for it, but the
thought
of 11/780 bits being returned to the entropy pool
disturbs me a bit.
:)
Can
anybody fill me in on what these disks likely
contain, to help me
decide whether I might like to trade blank floppies for them?
Yes, most likely a distribution intended for people with an 11/78x.
The software was probably available on several different media.
PSI is (as others have mentioned) the packetswitch interface software.
So X.25 for DECnet.
From what I remember it does not need DECnet.... sure how you'd handle this without DECnet, but I
obviously don't the know
any VMS specifics. In RSX, you can certainly communicate over X.25 without
the DECnet overhead, but you use NCP to configure your
X.25 links. So you need at least the CEX subsystem, but not the full
DECnet
stack.
From what I remember VAX PSI has its own programs to
configure the X.25
links.
Certainly in the early days the only connectivity that was supported was
X.3, X.28 and X.29 terminal access.
So there was an X.29 terminal program, and you could connect to the VAX from
an X.29 PAD.
The problem was as the VAX kind of insists on sending one character per
packet the overhead was horrendous.
In the UK we had coloured book protocols that ran on top of X.25 to provide
mail and file transfer.
I think Reading University wrote the VAX version but Digital marketed it.
https://en.wikipedia.org/wiki/Coloured_Book_protocols
The poor performance due to the character mode terminals and other aspects
of the software meant it was pretty much universally hated by DEC lovers as
this tirade shows...
https://groups.google.com/forum/#!topic/comp.os.vms/QU1svFCgAkM
In fact DEC had little option. If they had not provided the X.25 software
they would have been unable to sell large machines to UK Universities as
support of Janet was required to get central government funding.
Johnny
Dave
G4UGM