WAITS: Getting data in and out

If you are looking to download files from the existing disk image, for example the manual for the COPY command in COPY.RPH[S,DOC], the easiest way is to get these from saildart.org. Simply prepend https://www.saildart.org/ to the file you want to get and open it in a browser or download via wget or curl. Note that the file you get is in HTML, so characters like < will be encoded as <.

If the file you want to get is a binary file rather than a text file, saildart will automatically output it in octal format. Each line of the file will be a 36-bit word encoded as octal digits.

To force a text file to be encoded as binary, add _octal to the end of the URL, eg https://www.saildart.org/COPY.RPH[S,DOC]_octal.

The file you get will be the most recent version in the DART archive. Sometimes you want an earlier version, eg to ensure you are viewing a manual from 1974. To check this, open the directory listing for the file you want, eg https://www.saildart.org/[S,DOC]. Here you can see there are several different versions, from 1972 to 1976:

File detector on saildart.org. Source: Rupert Lane. License: CC0.

Note the version number after the directory name, so here I've selected version 8 which is dated 1974-07-24. To get this file directly you would go to https://www.saildart.org/COPY.RPH[S,DOC]8.

There is one quirk - for the latest version of the file you should not provide the version number, so if you wanted version 11 from 1976 you should request https://www.saildart.org/COPY.RPH[S,DOC]. If you try to fetch https://www.saildart.org/COPY.RPH[S,DOC]11 it will fail.

Using the virtual line printer is a good way to get text files - either system files or your own files - out of the system.

First you need to attach a text file to the virtual printer so you can view the output on your PC. For the quckstart this is done for you already and the file used will be printer.txt. Otherwise you will need to press Control-E in the simh window and enter commands:

sim> at lpt -n printer.txt
%SIM-INFO: LPT: creating new file: printer.txt
sim> cont

The -n switch creates a new printer text file each time simh starts. If you want to keep previous output and append to the file, change this to -a.

Then in WAITS, use the LIST command to send files to the printer, eg

.list hworld.f4

This takes wildcards like other COPY-class commands.

If you then look at your printer file on your PC you will see the file (it may take several seconds) with a header like this:

26-JUL-74    0955            HWORLD.F4  1,REL            PAGE 1-1

LIST sends files directly to the printer. On the real system you would normally use the spooler by typing PRINT instead, but this is not running on the emulated system.

If you want to extract several files from WAITS, here is a method using emulated tapes and the WAITS DART program - the same program that produced the backup tapes on saildart.org.

You will first need to get the dart utility from Lars Brinkhoff's set of PDP-10 tools:

$ git clone https://github.com/larsbrinkhoff/pdp10-its-disassembler/
$ cd pdp10-its-disassembler/
$ make dart

Copy the dart executable file to somewhere on your PATH.

Next, on the simh console, we will create a blank tape file on your PC backup.tap and attach it to the emulated tape drive MTA0.

Press Control-E to enter simh command mode and then type the following. Note that MTC0 on simh maps to MTA0 on WAITS.

sim> at mtc0 backup.tap
%SIM-INFO: MTC0: creating new file
%SIM-INFO: MTC0: Tape Image 'backup.tap' scanned as SIMH format
sim> cont

Switch to your WAITS login and run R DART, then at the * prompt type dump and the files you want to save. Type exit when done.

.r dart

*dump *.f4
HWORLD F4      1,REL
SECOND F4      1,REL
*exit

EXIT
^C
.

On your host PC, use the dart command you compiled earlier with the -tf option to view what's on the tape.

$ dart -tf backup.tap 

DART VERSION 5  TAPE HEADER
RECORDED 1974-07-26 10:10,  BY [  1,REL] USER CLASS
   DSK:    HWORLD.F4 [  1,REL]        256   1974-07-26 19:02
   DSK:    SECOND.F4 [  1,REL]          3   1974-07-26 19:52
END OF TAPE (NO TRAILER)

Use the -xf option to extract files. It will create directories in reverse order to store the files, ie HWORLD.F4[1,REL] will go to rel/1/hworld.f4.

$ dart -xf backup.tap
$ ls rel/1/
hworld.f4  second.f4

To upload files from your PC to WAITS, we can use the same technique bur in reverse. First, use dart with the -cf option to create a upload tape file. Here we create the tape upload.tap containing two Lisp files one.lsp and two.lsp intended for [1,REL] by placing them in the reverse directory structure shown above.

$ ls rel/1/
one.lsp  two.lsp
$ dart -cf upload.tap rel/1/*

Switch back to the simh console, press Control-E and attach the new file.

sim> at mtc0 upload.tap
%SIM-INFO: MTC0: Tape Image 'upload.tap' scanned as SIMH format
sim> cont

Go to your WAITS login and use DART with the RESTORE command to get all the files in the archive. You can specify which files to restore but here we choose to restore everything:

.r dart

*restore *.*[*,*] _ *.*[*,*]
DART VERSION 5  TAPE HEADER
RECORDED  11:02 20-Jul-126,  BY [DMP,SYS] USER CLASS
ONE    LSP     1,REL
TWO    LSP     1,REL
DART VERSION 5  TAPE TRAILER
RECORDED  11:02 20-Jul-126,  BY [DMP,SYS] USER CLASS
MT READ ERROR. MT STATUS = 200610
MT READ ERROR. MT STATUS = 200610
...

When it reaches the end of the tape it will repeatedly say MT READ ERROR. MT STATUS = 200610; just press Control-C to quit and then verify your files have been transferred.

.dir *.lsp

26-JUL-74  1104
FILNAM  EXT   SIZE LAST WRITTEN

   [1,REL]
ONE     LSP      2  31-JUN-71
TWO     LSP      2  31-JUN-71
        TOTAL=     4

The WAITS DART tape backup command is described in DART.REG[UP,DOC].

Lars Brinkhoff is working on getting simh and the WAITS image to provide Arpanet functionality via emulation at sailing-on-arpanet; once this is fully running it may be possible to upload and download files via ftp.

I welcome any questions or comments, and also especially any corrections if I have got something wrong. Please email me at rupert@timereshared.com and I will add it here and update the main text.