14 Apr
2016
14 Apr
'16
1:28 p.m.
From: Josh Dersch
> They are 12 sector 2315 packs. You have to
duplicate it on a two drive
> Alto, since the format is unique.
we're able to duplicate packs and write new ones
out from disk images.
(At the moment it's kind of cumbersome -- involving a PDP-11/44 with a
3mbit Ethernet board, a seriously hacked 2.11BSD kernel and a bit of
luck
You mean the RK11 controller can write packs that the Alto disk controller
can read? (As in, the low-level format - preamble, sector header, sector
checksum, etc, etc are all identical?)
Wow, I never knew that - that would have been a useful thing to know BITD -
we had both at MIT (we got the Altos as part of the 3-university Xerox
grant), and although I'm not sure we really needed to be able to transfer
bits from one kind of machine to another, it might have been useful for
something or other.
We did send a lot of files over the network to an Alto, but it was the Dover
printer spooler machine - using a disk pack for that function wasn't really an
option! :-)
Noel
14 Apr
14 Apr
1:32 p.m.
On Apr 14, 2016, at 12:28 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
Not only that, but we used Diablo Drives on RK05 Controllers. If you had a mix
of Diablo and RK05 drives, the order and termination was a bit tricky but it worked.
From: Josh Dersch
> They are 12 sector 2315 packs. You have to
duplicate it on a two drive
> Alto, since the format is unique.
we're able to duplicate packs and write new
ones out from disk images.
(At the moment it's kind of cumbersome -- involving a PDP-11/44 with a
3mbit Ethernet board, a seriously hacked 2.11BSD kernel and a bit of
luck
You mean the RK11 controller can write packs that the Alto disk controller
can read? (As in, the low-level format - preamble, sector header, sector
checksum, etc, etc are all identical?)
Wow, I never knew that - that would have been a useful thing to know BITD -
we had both at MIT (we got the Altos as part of the 3-university Xerox
grant), and although I'm not sure we really needed to be able to transfer
bits from one kind of machine to another, it might have been useful for
something or other.
We did send a lot of files over the network to an Alto, but it was the Dover
printer spooler machine - using a disk pack for that function wasn't really an
option! :-)
Noel 
1:34 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Noel
Chiappa
Sent: Thursday, April 14, 2016 10:28 AM
To: cctalk at classiccmp.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: Xerox Alto on eBay
No, they're as different as can be. The key is that we have a Xerox UNIBUS 3Mbit
Ethernet board in the 11/44 (kindly provided by Al.)
I modified the 2.11BSD kernel to support the 3Mbit board (there's already technically
a driver but it was incredibly broken and I'm not sure it ever actually ran on a
PDP-11), added support for reading/writing raw Ethernet packets using BSD sockets (and
added support for that to the DEUNA/DELUA driver as well) and wrote a rough implementation
of PUP BSP and the Alto CopyDisk protocol on top of all of that. It was fun!
So we copy disk images to/from the PDP-11/44 over 3Mbit Ethernet to the Alto :).
- Josh
From: Josh Dersch
> They are 12 sector 2315 packs. You have to
duplicate it on a two drive
> Alto, since the format is unique.
we're able to duplicate packs and write new
ones out from disk images.
(At the moment it's kind of cumbersome -- involving a PDP-11/44 with a
3mbit Ethernet board, a seriously hacked 2.11BSD kernel and a bit of
luck
You mean the RK11 controller can write packs that the Alto disk controller can
read? (As in, the low-level format - preamble, sector header, sector
checksum, etc, etc are all identical?)
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jnc＠mercury.lcs.mit.edu -
JoshD＠LivingComputerMuseum.org -
jsw＠ieee.org