The physical PDP-11/44 is not connected to the outside world at the moment. So we install "Kermit", in a two-phase boostrap process.

We do this still under SimH!

But there remain some problems to be solved!

About Kermit

Kermit is the well-known communication program. It transfers files over serial connection.

For 2.11BSD on PDP-11, there are two precompiled version:

A big C-Kermit (so named because it’s sources are all in C), and a small “G-Kermit” (Gnu license).

For c-kermit, see

For g-kermit, see

Bootstrap small G-Kermit

To transfer a kermit image to PDP-11 the first time, do this:

  1. Convert the binary image in to a text representation on PC side:
    uuencode gku100.pdp11-bsd-2.11 gku.txt
  2. On PDP-11 side,
    # cd /usr/bin
    # cat gku.txt
  3. On PC side, let your terminal emulator send “gku.txt”, as if it is typed-in by hand.
  4. On PDP-11 side, hit ^D.
    Konvert the text back to a binary image:
     uudecode gku.txt 
  5. Done, the original “gku100.pdp11-bsd-2.11” is there
  6. chmod a+x gku100.pdp11-bsd-2.11

Bootstrap big C-Kermit with G-Kermit

mkdir /usr/local/src
mkdir /usr/local/src/cku211
mkdir /usr/local/bin

Set SimH to 8bit transmission and telnet.

sim> set tti 8b
sim> set tto 8b
sim> set cons telnet=23

Execute G-kermit in receive mode, inhibit streaming mode (slow over telnet)

# gku* -r -S

Unexpected trouble

Well so much for theory!

I worked with kermits 15 years ago and rememberd it as very reliable. So I was surprised by the problems I experienced now:

  • Kermit to SimH on the same WinXP machine over telnet made a big hang up in the fast streaming mode.
    If I called gkermit as “gku100 -r -S” with streaming mode inhibited, I got an unusable slow connection: typical 85 chars/per second! Over TCP/IP on a local machine! THis is because the telnet protocol has same delay heuristics in it, the kermit manual warn about this
  • I was unable do get any transfer started, if SimH’s tti and tto were in 7bit mode.
  • Worst of all: I could not start any transfer on the real 11/44!

I bought the C-Kermit manual, I hope they have same debugging hints.