17 Oct
2016
17 Oct
'16
10:20 p.m.
From: Ian S. King
> Does anyone know anything about the status of the
plans to open-source
> it?
I've made some inquries, stay tuned....
OK, thanks!
> Can you briefly describe what it was?
I'm still curious about what it was: was it a stand-alone board with a
separate power supply, or did it plug into some sort of backplane? Did it use
something like SD cards for storage? And what was the MASSBUS connection
like: a set of 3 Berg headers into which one plugged the flat cables, or was
there some oddball connector that wound up connected to a standard MASSBUS
connector?
Noel
18 Oct
18 Oct
1:58 a.m.
On Mon, Oct 17, 2016 at 10:20:58PM -0400, Noel Chiappa wrote:
I recall seing a picture of it long ago in someones online album. It was a
separate 19 inch box a few RUs high with at least one pcb and a jumble of
wires :) Obviously in some sort of development stage and I'm not sure it
was working at that point.
I think it might even be the compaq rackbox shown here:
http://www.panix.com/~alderson/LivingComputerMuseum/07_Storage_comparison_i…
Of course this is just speculation :)
/P
From: Ian S.
King
> Does anyone know anything about the status of
the plans to open-source
> it?
I've made some inquries, stay tuned....
OK, thanks!
> Can you briefly describe what it was?
I'm still curious about what it was: was it a stand-alone board with a
separate power supply, or did it plug into some sort of backplane? Did it use
something like SD cards for storage? And what was the MASSBUS connection
like: a set of 3 Berg headers into which one plugged the flat cables, or was
there some oddball connector that wound up connected to a standard MASSBUS
connector?
Noel 
2:18 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Pontus
Pihlgren
Sent: Tuesday, October 18, 2016 1:58 AM
To: General Discussion: On-Topic and Off-Topic Posts
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)
On Mon, Oct 17, 2016 at 10:20:58PM -0400, Noel Chiappa wrote:
open-source
I recall seing a picture of it long ago in someones online album. It was a
separate 19 inch box a few RUs high with at least one pcb and a jumble of
wires :) Obviously in some sort of development stage and I'm not sure it was
working at that point.
I think it might even be the compaq rackbox shown here:
http://www.panix.com/~alderson/LivingComputerMuseum/07_Storage_comparison_in
_open_space.jpg
Of course this is just speculation :)
/P
------
Maaaaaybe there are three ribbon cables back there ....
What is the big white disk (platters plus heads?) near the front end of the
table?
-----
paul
From: Ian S.
King
>> Does anyone know anything about the status of the plans to
> it?
I've made some inquries, stay tuned....
OK, thanks!
> Can you briefly describe what it was?
I'm still curious about what it was: was it a stand-alone board with a
separate power supply, or did it plug into some sort of backplane? Did
it use something like SD cards for storage? And what was the MASSBUS
connection
like: a set of 3 Berg headers into which one plugged the flat cables,
or was there some oddball connector that wound up connected to a
standard MASSBUS connector?
Noel 
2:26 p.m.
From: Noel Chiappa
Sent: Monday, October 17, 2016 7:21 PM
> From: Ian S. King
>> Does anyone know anything about the status of
the plans to open-source
>> it?
> I've made some inquries, stay tuned....
OK, thanks!
>> Can you briefly describe what it was?
I'm still curious about what it was: was it a
stand-alone board with a
separate power supply, or did it plug into some sort of backplane? Did it
use something like SD cards for storage? And what was the MASSBUS
connection like: a set of 3 Berg headers into which one plugged the flat
cables, or was there some oddball connector that wound up connected to a
standard MASSBUS connector?
There have been 2 generations of Massbus Disk Emulator (MDE) at LCM. The
one of which people have seen pictures was the first generation, created
when there were only 2 people working on the collection which became the
museum years later.
This was a breadboarded prototype which supported 4 emulated RP06 disks,
represented by directories of track files, each representing 20 sectors of
128 36-bit words. These mimicked the physical layout of the data on disk,
where each 18 bits of data has an associated parity bit; this was stored as
3 8-bit bytes (3rd byte being 2 data + overall parity). The MDE itself was
made up of a Rabbit and 3 PICs; the driver/receiver portion of the board
terminated the Massbus. Standard Massbus cables connected it to the 2065
running Tops-10. Data was transferred via FTP over a 100baseT crossover
cable connected to a Slackware server; the Rabbit was able to keep up with
4 drives at this speed, but a 5th drive (MDE could in theory represent an
entire 8-drive string) would cause data dropouts on all units.
Various improvements were attempted on this (work with Unibus on a 2020, for
example), but it was never quite stable enough.
MDE 2.0 was created by a different engineer with lots of resources thrown at
him. He replaced the Rabbit and PICs with a Mesa 5i22 Anything I/O card
(includes a Xilinx Spartan-III FPGA) that plugs directly into the PCI bus in
a server-class X86-64 box, and used a revision of a separate driver/receiver
card designed for MDE 1.0 to connect to the Massbus, still via standard
cables. An outside contractor wrote a control program for the PC side which
runs under Windows 2008/2012 Server.
MDE 2.0 supports SimH-format RP07 and RP06 disk drive images. There is also
a variant for tape drive emulation called the MTE, which reads and writes to
SimH-format tape files.
We currently run the DECSYSTEM-2065 (public Tops-10 v7.04), DECsystem-1070
(public Tops-10 v6.03A), PDP-11/70 (public Unix v7), and DECSYSTEM-1095
(under development: WAITS operating system from Stanford Artificial
Intelligence Laboratory) using MDEs. The two KL-10 systems also have an MTE
apiece; we haven't needed tape service on the KI-10 or the 11/70 so far.
Rich
Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
19 Oct
19 Oct
2:44 a.m.
New subject: 2020 Power consumption [Was: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)]
On Tue, Oct 18, 2016 at 06:26:06PM +0000, Rich Alderson wrote:
There have been 2 generations of Massbus Disk Emulator (MDE) at LCM. The
one of which people have seen pictures was the first generation, created
when there were only 2 people working on the collection which became the
museum years later.
Ah, thanks for clarifying :)
Somewhat related, how much power does a 2020 draw on average?
/P
3:08 a.m.
New subject: 2020 Power consumption [Was: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)]
That should be in the site prep documents, or the installing documentation.
On Wed, Oct 19, 2016 at 1:44 AM, Pontus Pihlgren <pontus at update.uu.se>
wrote:
On Tue, Oct 18, 2016 at 06:26:06PM +0000, Rich
Alderson wrote:
There have been 2 generations of Massbus Disk Emulator (MDE) at LCM. The
one of which people have seen pictures was the first generation, created
when there were only 2 people working on the collection which became the
museum years later.
Ah, thanks for clarifying :)
Somewhat related, how much power does a 2020 draw on average?
/P
3:24 a.m.
New subject: 2020 Power consumption [Was: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)]
On Wed, Oct 19, 2016 at 02:08:37AM -0500, Paul Anderson wrote:
That should be in the site prep documents, or the
installing documentation.
Certainly, I think I've even looked it up. But I was curious if LCM has
measured their specific configuration.
/P
5:39 a.m.
New subject: 2020 Power consumption [Was: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)]
On Wed, Oct 19, 2016 at 7:44 PM, Pontus Pihlgren <pontus at update.uu.se> wrote:
On Tue, Oct 18, 2016 at 06:26:06PM +0000, Rich
Alderson wrote:
Bye some enormous coincidence I was just looking through some DEC
pdp-10 brochures I have.
DEC advertised the 2020 as drawing no more power that a hairdryer; the
quoted figure was 1400w as I recall.
Mike
http://www.corestore.org
'No greater love hath a man than he lay down his life for his brother.
Not for millions, not for glory, not for fame.
For one person, in the dark, where no one will ever know or see.'
There have been 2 generations of Massbus Disk Emulator (MDE) at LCM. The
one of which people have seen pictures was the first generation, created
when there were only 2 people working on the collection which became the
museum years later.
Ah, thanks for clarifying :)
Somewhat related, how much power does a 2020 draw on average?
/P 
2:41 p.m.
New subject: 2020 Power consumption [Was: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)]
In the US, the 2020 was sold with a NEMA 5-20P plug, so 120V at less than
20A, but likely more than 15A for a maximum configuration.
Of course, that's only for the actual 2020 box, and does not include disk
and tape drives, terminals, printers, card readers or punches, etc.
4:44 p.m.
New subject: 2020 Power consumption [Was: Re: MASSBUS disk emulator (Was: Unibus controller for MFM disks)]
On Oct 19, 2016, at 2:41 PM, Eric Smith <spacewar
at gmail.com> wrote:
In the US, the 2020 was sold with a NEMA 5-20P plug, so 120V at less than
20A,
Less than 16, in fact. NEC requires branch circuits to be loaded to at most 80% of the
circuit breaker setting, so 16 amps on a "20 amp" circuit.
paul
2880
days inactive
2881
days old
9 comments
8 participants
participants (8)
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jnc＠mercury.lcs.mit.edu -
paulkoning＠comcast.net -
pbirkel＠gmail.com -
pontus＠Update.UU.SE -
RichA＠LivingComputerMuseum.org -
spacewar＠gmail.com -
tmfdmike＠gmail.com -
useddec＠gmail.com