6 Nov
2008
6 Nov
'08
8:53 a.m.
Hi Paul,
You also have what looks very much like a DecMate in the bottom, left of:
http://hisdeedsaredust.com/pdp/04112008377.jpg
Of course, that's another pdp-8! I have a DecMate III which I picked
up at a Radio Rally, but it doesn't have an RX50, so I can't get
it to do anything, apart from display its bios screen.
-cheers from julz @P
7 Nov
7 Nov
1:28 p.m.
New subject: DECmateIII (was Re: PDP-8/e and terminals in West Sussex, UK)
On Thu, Nov 06, 2008 at 05:53:03AM -0800, Julian Skidmore wrote:
Hi Paul,
You also have what looks very much like a DecMate in the bottom, left of:
http://hisdeedsaredust.com/pdp/04112008377.jpg
Of course, that's another pdp-8! I have a DecMate III which I picked
up at a Radio Rally, but it doesn't have an RX50, so I can't get
it to do anything, apart from display its bios screen.
I haven't tried it personally, but if you don't have an RX50 handy,
you might try strapping a Teac FD55-GFR 5.25" drive to the RX33
settings and see if it works. You might be able to at least boot
something up and watch it go.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 7-Nov-2008 at 18:20 Z
South Pole Station
PSC 468 Box 400 Temp -36.2 F (-37.9 C) Windchill -63.5 F (-53.0 C)
APO AP 96598 Wind 10.8 kts Grid 11 Barometer 681.7 mb (10564 ft)
Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
1:38 p.m.
New subject: DECmateIII (was Re: PDP-8/e and terminals in West Sussex, UK)
Ethan Dicks wrote:
On Thu, Nov 06, 2008 at 05:53:03AM -0800, Julian
Skidmore wrote:
> Hi Paul,
>
> You also have what looks very much like a DecMate in the bottom, left of:
> http://hisdeedsaredust.com/pdp/04112008377.jpg
The grey box there ? It looks like a tk50, or just scsi drive enclosure.
There is an SCSI terminator on it ...
2:20 p.m.
New subject: DECmateIII (was Re: PDP-8/e and terminals in West Sussex, UK)
I don't think so. That's a standard DEC enclosure for various small computer
systems. DECmate 3 rings a bell, but I think it was also used for various VAXen.
VAX2100?
paul
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] On Behalf
Of e.stiebler
Sent: Friday, November 07, 2008 1:39 PM
To: On-Topic and Off-Topic Posts
Subject: Re: DECmateIII (was Re: PDP-8/e and terminals in West Sussex, UK)
Ethan Dicks wrote:
On Thu, Nov 06, 2008 at 05:53:03AM -0800, Julian
Skidmore wrote:
> Hi Paul,
>
> You also have what looks very much like a DecMate in the bottom, left of:
> http://hisdeedsaredust.com/pdp/04112008377.jpg
The grey box there ? It looks like a tk50, or just scsi drive enclosure.
There is an SCSI terminator on it ...
8 Nov
8 Nov
6 a.m.
New subject: DECmateIII (was Re: PDP-8/e and terminals in West Sussex, UK)
Ethan Dicks wrote:
You're right, it is a TK50. I accidentally responded off-list to Julian.
On Thu, Nov 06, 2008 at 05:53:03AM -0800, Julian
Skidmore wrote:
>
> You also have what looks very much like a DecMate in the bottom, left
> of:
> http://hisdeedsaredust.com/pdp/04112008377.jpg
The grey box there ? It looks like a tk50, or just scsi drive enclosure.
There is an SCSI terminator on it ...
9:13 a.m.
New subject: DECmateIII (was Re: PDP-8/e and terminals in West Sussex, UK)
paul at frixxon.co.uk wrote:
Thanks for clearing this up, Paul.
I was already thinking about taking pictures of the "behinds" of the
various Vax2000, TK50, DecmateIII, SCSI-enlcosures" for comparison ;-)
Ethan Dicks
wrote:
You're right, it is a TK50. I accidentally responded off-list to Julian. On Thu, Nov 06, 2008 at 05:53:03AM -0800, Julian
Skidmore wrote:
> You also have what looks very much like a DecMate in the bottom, left
> of:
> http://hisdeedsaredust.com/pdp/04112008377.jpg
The grey box there ? It looks
like a tk50, or just scsi drive enclosure.
There is an SCSI terminator on it ... 
7 Nov
7 Nov
4:07 p.m.
Of course, that's another pdp-8! I have a DecMate
III which I picked
up at a Radio Rally, but it doesn't have an RX50, so I can't get
it to do anything, apart from display its bios screen.
I assume you realise that an RX50 is just a pair of 80 cylinder single
head floppy drives with a common disk spindle and common head stepper.
The 34 pin interface cable is essentially the standard pinout. The only
trap for the unwary (if I am reading the schematic correctly) is that if
side select is asseted (this would select the other side of a double-head
drive, of course), then the RX50 _disables_ its track 00 output. I think
at least one machine used that feature to detect a real RX50.
-tony
6:39 p.m.
On 07/11/2008 21:07, Tony Duell wrote:
I assume you realise that an RX50 is just a pair of 80
cylinder single
head floppy drives with a common disk spindle and common head stepper.
The 34 pin interface cable is essentially the standard pinout. The only
trap for the unwary (if I am reading the schematic correctly) is that if
side select is asseted (this would select the other side of a double-head
drive, of course), then the RX50 _disables_ its track 00 output. I think
at least one machine used that feature to detect a real RX50.
I found that out the many years ago, trying to get non-DEC drives to
work on several variants of the RQDX1 and RQDX2. I came up with a
little 1-LSTTL circuit to kludge the effect. I've a feeling that may be
how an RQDX3 tells the difference between RX50 and RX33 drives. ISTR
there's also something about the index pulse that meant some drives
didn't work, something up the way the controller checks the drive is up
to speed. Ah, yes, see below.
Other differences:
1) The RX50 doesn't use or need the HeadLoad/InUse signal on pin 4.
2) The RX50 will only respond to step pulses if it is selected *and*
Motor On is valid; many SA400-type drives will step even if MotorOn is
de-asserted.
3) The Ready signal on Pin 34 is asserted whenever the drive is
selected, has a disk in it, and the door is closed. Most drives only
assert Ready when the drive is up to speed (often by timing the interval
between index pulses).
The inherent delay on non-genuine-RX50s means that some RQDX controllers
don't see the drive is Ready immediately, and take it offline.
--
Pete Peter Turnbull
Network Manager
University of York
5740
days inactive
5742
days old
7 comments
7 participants
participants (7)
-
ard＠p850ug1.demon.co.uk -
emu＠e-bbes.com -
ethan.dicks＠usap.gov -
julianskidmore＠yahoo.com -
paul＠frixxon.co.uk -
Paul_Koning＠Dell.com -
pete＠dunnington.plus.com