DMT, Peek, PeekSum
This documentation describes the operation of three related Alto
Subsystems: DMT, the Memory/Control Ram diagnostic; Peek, the program
to which DMT reports its findings; and PeekSum, the program which
summarizes the reports collected by Peek.
1. Creating a Peek Disk
You should devote a separate disk to Peek. Boot files can take up a
lot of space and the Peek report file can get quite large over a long
holiday weekend if your network has many hosts. To avoid coming in on
Monday and discovering your Peeker in Swat out of disk space, clean the
disk out regularly. Peek automatically keeps its network directory and
boot files up-to-date, so building a new peek disk amounts to building
an bare disk (OS, Exec, Ftp, Empress, perhaps Bravo), getting Peek and
PeekSum and just running it: it does the rest. I have written a canned
procedure for building a Peek disk from scratch:
1) Boot an OS from the net and respond 'Yes' when it asks if you
want the long installation dialog, and 'Yes' when it asks if
you want to ERASE the disk.
2) When the erase procedure finishes, retrieve
[Maxc]<Alto>PeekDisk.cm and invoke it by typing to the Exec:
>@PeekDisk.cm@
3) When the smoke clears, install your printer's name in the
[HardCopy] section of user.cm and re-install Bravo. If you
aren't on the west coast, change the ZONE parameter (e.g to
+5:00 if you are on the east coast).
2. History
Chuck Thacker made DMT (early 1973) by combining many small diagnostics
which he had developed to stress main memory using certain emulator
instructions. There were originally two versions: PMT (Printer Memory
Test) which logged statistics on the Diablo printer; and DMT (Display
Memory Test) which used the display. Later (late 1973), an Ethernet
driver was added to DMT, Bob Metcalfe wrote Peek, and Chuck wrote
PeekSum. At this point, development and maintenance of PMT stopped.
Still later (mid 1975), David Boggs added a Control Ram test to DMT,
rewrote the Ethernet driver and took over maintenance. Nate Tobol, who
designed the Alto II memory system, wrote the Alto II memory test (mid
1976) which was merged into DMT. David rewrote Peek and took over its
maintenance. Doug Clark extended PeekSum, and took over its
maintenance (early 1977).
------------
Copyright Xerox Corporation 1979
DMT, Peek, PeekSum February 12, 1979 2
3. DMT
DMT is written in the Alto BCPL-compatible variant of machine language
and is distributed as a type-B boot file (see the BuildBoot
documentation for more details).
When DMT is running, the Alto screen is black with a white cursor
changing position once each time through the main loop. For Alto I the
cursor flips at random intervals; for Alto II the interval is about 1
second. On Alto IIs with extended memory, the cursor contains a number
between 0 and 3 indicating which bank it is currently testing. DMT
contains a TeleSwat server. The key combination <Control><Left-
Shift><Swat> causes DMT to stop and enter the debugger.
3.1. Statistics
If the 'S' key is depressed, DMT will display (and transmit on the
Ethernet) the statistics it has accumulated. The display looks
something like this:
DMT of 25 Dec 78, Alto II XM 241. 456 blocks, testing 17341 to 176777
0 bad main memory chips
0 bad control memory chips
If there are errors, a line describing each type of error will be
displayed, and then, if the errors can be resolved to a particular
chip, the Card, Row and Column (for Alto I), or the Card and Chip
number (for Alto II) will be displayed. This display will stay up as
long as the "S" key is depressed. Periodically the statistics are
automatically broadcast on the Ethernet and appear briefly on the
screen.
3.2. Booting in Response to Packets
If DMT receives a request-for-connection (RFC) Pup and DP0 is ready,
then it boots the Operating system and passes it a message of type
eventRFC. If the Executive section of user.cm contains an entry of the
form:
eventRFC: <arbitrary command line>
then the executive will consume the event and execute the command line.
<< If DMT receives an EFTP data packet with sequence number 0 and DP0
is ready then it boots the OS and passes it a message of type
eventEFTP. This is included so that printers (which use the EFTP
protocol) can drop into DMT when nobody is using them, and
automatically wake up when someone wants to print. >> If DMT receives
a Kiss-of-Death Pup for socket 4 (miscellaneous services), then it
EtherBoots the file whose ID is contained in the low 16 bits of the Pup
ID.
4. Peek
DMT, Peek, PeekSum February 12, 1979 3
Peek opens several windows on the display. The top window is for user
commands. There is currently only one: Quit. The next window displays
the release date of the program, a digital clock, the Pup internetwork
address of the machine, and the number of free pages on the disk. The
next window is opened by the Peek Server and displays DMT reports as
they arrive.
Peek loads special Ethernet microcode so that it can receive Peek
reports directed to host 376b as well as conduct business as itself.
If it can't load the ram, it runs the Ether interface promiscuously and
filter packets in software. More diagnostic reports will be lost and
booting may be slower, but things should still work.
Peek has a lot of options, and reads User.cm to find out what to do.
An example of the Peek slice of a User.cm file is given below. In
addition, it contains a host of network servers:
4.1. Peek Server
If there is a line of the form "Peek <filename>" in User.cm, Peek will
start up a Peeking process which will listen for raw Ether packets of
type PeekReport and write them on <filename>. The filename should be
'Peek.reports' since PeekSum, described below, assumes this (I was just
feeling general the day I wrote that code).
4.2. Event Report Server
Peek implements the Pup Event Report protocol. For each line of the
form "ERP <number> <filename>" in User.cm, Peek will instantiate an
event report process which will listen on socket <number> and write
event reports on <filename>. The default address which the OS uses is
Maxc, so I don't expect many people will use this, however it might be
helpful for an Alto site that isn't connected to the Parc Internet.
4.3. Pup Echo Server
Peek contains a Pup Echo server running continuously in the background.
PupTest and GateControl contain Echo users with which you can poke it.
4.4. Raw Ether Echo Server
Peek also contains a raw Ethernet Echo server. This is the echo
protocol used by EDP and NEDP, the diagnostic programs for the Alto and
Nova Ethernet interfaces.
4.5. Boot Server
Peek implements the protocols necessary to be an Alto boot file server.
For each line of the form "Boot <number> <filename>" in User.cm, Peek
will send <filename> when it receives a Mayday packet requesting
bootfile <number>. If the file isn't on the disk, or if Peek discovers
a neighboring Boot server with a later version, your Peek will aquire
it. The more boot files you tell Peek to keep, the less space there is
for Peek reports.
DMT, Peek, PeekSum February 12, 1979 4
4.6. Name Server
PeekSum consults the file 'Pup-Network.Directory' to get the owner and
location of Altos. Peek contains a name lookup server and in addition
to answering lookup requests, keeps its copy of the directory current.
4.7. Time Server
Peek also has a time server. Alto time is based on Greenwich Mean
Time, and local users must know their local time zone and the beginning
and ending days of Daylight Savings Time to convert to local time.
Time servers are the source of this information, so it is important
that the time parameters in User.cm be correct. "Zone +8:00" means
that the peek disk is 8 hours west of Greenwich -- in the USA Pacific
Time zone. The standard User.cm contains this, so you must edit it if
you live elsewhere. The Daylight Savings Time parameters are set by
the line "DST 121,305", and only change when Congress messes with time.
Keep an eye on your local CongressPerson.
4.8. User.cm Example
Below is an example of the Peek part of a User.cm file. In this
example DMT statistics go to the file 'Peek.reports', Event reports
addressed to socket 30 (swat error reports) go to the file 'Swat.ERP',
and some maintenance-type boot files are available for diagnosing
Altos. Notice that all characters between a semicolon and a carriage
return are considered to be comments and ignored by Peek (this is not
true for all programs that use User.cm).
[EXECUTIVE]
...executive stuff...
[PEEK]
; Syntax:
; Boot <boot file number> <filename>
; ERP <socket number> <filename>
; Peek <filename>
; Correction <seconds per day> (decimal) [positive makes clock go faste
; DST <beginning day> <ending day> (decimal)
; Probe <hours> (decimal)
; Zone <sign><hours>:<minutes> (decimal, plus is west of Greenwich)
Peek Peek.reports ; for PeekSum.run
ERP 30 Swat.erp ; Swat Error reports
Zone +8:00 ; USA Pacific Time Zone
DST 121,305 ; DST begins on day 121 and ends on day 305
Boot 0 DMT.boot
Boot 5 CRTTest.Boot
Boot 6 MadTest.Boot
Boot 10 NetExec.boot
Boot 11 PupTest.boot
Boot 12 EtherWatch.Boot
Boot 13 KeyTest.boot
Boot 15 DiEx.Boot
Boot 17 EDP.Boot
DMT, Peek, PeekSum February 12, 1979 5
Boot 20 BFSTest.Boot
[BRAVO]
...bravo stuff...
Peek writes the contents of User.cm into the Command window as it reads
through the file. If the file has bad syntax, Peek will call Swat with
a description of its complaint (e.g. "[ReadNumber] - number contains
illegal characters" if it is expecting a number and reads something
other than 0-7). Typing <ctl>-U will restore the user display. The
last item in the Command window is what Peek is having trouble with.
The source code for most of the servers in Peek is borrowed from the
gateway program, and so there are some more specialized commands which
you can ignore and which default to reasonable actions. I mention
there here for completeness. "Correction +20" means the Alto's clock
looses 20 seconds per day, and the time server should correct by
gaining 1 second at 20 equally spaced times during a day. "Probe 1"
means attempt to locate newer versions of boot files and the network
directory once an hour.
5. PeekSum
PeekSum reads the file "Peek.Reports" (the output of Peek) and
constructs a summary of the errors reported by DMT (see above) for each
Alto. PeekSum writes on the file 'PeekSummary.Tx' a tabulation of the
error reports, together with the owner's name and the machine's
location, retrieved (if possible) from the file "Pup-
Network.Directory", which is maintained by Peek, as described above.
As Peek is started and stopped, it writes short messages to this effect
on Peek.Reports; these messages are reproduced at the beginning of
PeekSummary.Tx. The number of the local network is also written. If
Peek.Reports contains multiple reports from a single Alto (which is
usually the case), PeekSum will record the largest number of errors of
each type, over all such reports.
PeekSum will complain and then gracefully stop execution if the files
Peek.Reports or PeekSummary.Tx are unopenable for some reason. If Pup-
Network.Directory is unopenable or absent, the ouput file
PeekSummary.Tx will not include names and locations of Altos, but will
contain error reports grouped by Alto host number.
To run PeekSum, just type:
>PeekSum
and the program will go about its business. When it has finished,
PeekSummary.Tx should be printed on your local printer.