Kermit Software for the PDP-11
Digital Equipment Corporation's PDP-11 was (and is) a 16-bit
mini- and microcomputer system used in applications ranging from embedded
device control to general-purpose timesharing. Several different Kermit
programs are available for the PDP-11.
Kermit-11 is the Kermit software
for Digital Equipment Corporation PDP-11
operating systems: RT-11, RSX-11, RSTS/E, IAS, P/OS, and (not a DEC OS) TSX+.
Kermit-11 was written by Brian Nelson of the University of Toledo, Ohio,
circa 1984-89, in PDP-11 assembly language, Macro-11. Separate programs,
listed below, are available for other PDP-11 operating systems like UNIX
The Kermit-11 source code as well as prebuilt binaries for various
configurations are available at our
ftp site in the kermit/b subdirectory
as k11*.mac. There are also various utilities -- hex encoders and
decoders, etc -- written Macro-11, Fortran, and Basic in the same directory,
along with all the Kermit-11 text files, whose names all start with "k11".
Kermit-11 can operate in either remote or local mode; that is, it can
transfer files when it is on the far end, and it can make connections and
enter terminal mode (and transfer files) when it is on the "near end".
The documentation for Kermit-11 is based on Brian's last release (please note
that the ".doc" extension was used for plain-text documentation files
since long before Microsoft existed, so if your Browser thinks it's some kind
of rich-text document that needs a helper application to read it, tell it to
just load it directly as plain text, no helper needed).
- k11mit.doc -
PDP-11 Kermit User
Manual, plain text
(NOT Microsoft Word!)
- k11mit.ps - PDP-11 Kermit User Manual, PostScript.
Installation instructions are also available:
There are separate versions of Kermit-11 for each DEC OS, plus
distinct Kermit programs for other PDP-11 operating systems. Originally all
the Kermit-11 programs were all built from a common code base. After Brian
moved on, some of the Kermit-11 versions took on separate identities that,
we hope, will someday be brought back into alignment.
The PDP-11 Kermit programs are:
It is a goal of the Kermit Project to unify the divergent Kermit-11 versions,
bringing the RSX version up to date in the process but this will require some
volunteer effort by PDP-11 aficionados, and no promises can be made.
- RSX-11, RSX-11/M, RSX-11/M+, Micro/RSX, IAS, and P/OS
- Brian's last release, 3.60 from June 1989, is still current for RSX and
its cousins. RSX-11/M 4.1, RSX-11/M+ 2.1, P/OS 2.0 or IAS 3.1 or later is
required in most cases. This version has some bugs that prevent successful
transfers with more modern Kermits, which can usually be worked around by
telling one or both Kermit programs to "set attributes off".
- RT-11, Pro/RT, and TSX+
- A new version, 3.62, for the RT-11 family only, was produced by
Billy Youdelman in September 1993 and includes lots of bug fixes
and enhancements. Version 3.63 was released 27 September 1997.
RT-11 4.0, TSX-Plus 5.0, or Pro/RT 5.1 or later are required. All
of the source files are in the
kermit/b area as krt*.*.
file contains complete installation instructions for RT-11 and TSX-Plus.
- The RSTS version was further developed by John Santos in 1996, based on
Billy's version, and a test edition of John's improved RSTS version is
available. RSTS/E 8.0 or later is required. The source files are in the
area as krt*.*.
- 2.8, 2.9, 2.10, and 2.11 BSD
- The 2.xBSD versions are covered by
G-Kermit 1.00 and
C-Kermit 6.0 rather
than Kermit-11. (C-Kermit 7.0 or later, even in a minimal configuration, is
too large for the PDP-11 address space.)
- G-Kermit is
available for Ultrix-11 3.0.
- VENIX 1.0 and 2.0
- C-Kermit 4.x was buildable for VENIX on the Pro/350 and 380. Versions
5A and later were never tested there, but the C-Kermit makefile still contains
the appropriate entries.
- Bell UNIX V6 and V7
- G-Kermit can
probably be built for UNIX V6 or V7, but so far we have no reports about it.
- A version of Kermit for the MUMPS-11 PDP-11 operating system can also be
found at the Kermit archive. It is totally separate from Kermit-11 and
C-Kermit. It was written in MUMPS-82 at the New York State College of
Veterinary Medicine in 1984 and can be found in the
kermit/b area as mp*.*,
with documentation in the plain-text
Nothing has been heard about this version since 1984, when it was submitted;
It is completely unsupported. Reports would be welcome.
- Others for which no Kermit programs are known to exist
- Early RSX-11 versions (e.g. RSX-11/M 2.x and 3.x).
- DEC DOS-11.
- SITS (Small ITS, MIT's Incompatible Time Sharing system, a small
version for the PDP-11).
Kermit-11 File Organization
As noted, all the text files, including source code, documentation, utilities,
and so on, are in the
kermit/b directory of the
Kermit software archive, all sharing the filename prefix "k11". The newer
RT/TSX version is in the same directory, but with prefix "krt". The RSTS/E
test version is in
Binaries are in
Here they are. More detailed descriptions can be found in the installation
How to get Kermit-11 onto your PDP-11 if it doesn't already have Kermit
or FTP, and nobody can send you a binary on the required media? The precise
answer depends on your PDP-11 operating system (RT, RSTS, RSX, etc), but
basically involves "capturing" a copy of the appropriate "hexified" binary
(next section) onto your PDP-11 disk, as well as a copy
of the dehexifying program, and then running the latter on the former.
- Kermit-11 3.60 for RSTS/E 8.0 or later, linked to RMSRES
- As above but with I&D space
- RSTS, but not linked with RMSRES
- A test 3.62 version for RSTS, requires I&D space
- Kermit-11 3.60 for RSX11M+ or Micro/RSX with I&D Space
- Kermit-11 3.60 For RSX11M+, Micro/RSX, or P/OS.
Reportedly, this one might also work on RSX 3.x.
- Kermit-11 3.60 for RSX, not linked with RMSRES
- Kermit-11 3.60 RSX11M, small executable, tightly overlaid
- Kermit-11 3.60 for IAS 3.1
- Kermit-11 3.60 for IAS
- Kermit-11 3.60 for RT-11XM and TSX+.
- Kermit-11 3.60 for RT-11FB and TSX+.
- Kermit-11 3.63 for RT-11FB/SB/SJ and TSX+.
- Kermit-11 3.62 for RT-11FB/SB/SJ minimal version
- Kermit-11 3.63 for RT-11XB/XM/ZB/ZM and TSX+.
For example in RT-11
get the following files in text mode:
And then read the instructions are at the top of the krthex.mac file.
These are "hex" encoded (i.e. printable text) versions of the executable
programs. They are useful if you don't have any way to get binary files onto
your PDP-11. Hex files can be "bootstrapped" as indicated in the
previous section, or sent by email, etc.
- krtmin.abs - A short abstract describing KRTMIN
- krtmin.doc - Documentation (krt.doc is the complete version if need be)
- krtmin.hex - A HEX encoded copy of the Kermit executable image
- krtmin.hlp - The HELP command text file
- krtmin.ini - A sample init file
- krthex.mac - The HEX to executable image conversion program
- Corresponds to k11.tsk.
- Corresponds to k11i31.tsk.
- Corresponds to k11nrs.tsk.
- Corresponds to k11pos.tsk.
- Corresponds to k11rsx.tsk.
- Corresponds to k11rt4.sav.
- Corresponds to k11xm.sav.
- Corresponds to krt.sav.
- Corresponds to krtmin.sav.
- Corresponds to krttsx.sav.
Native media -- RX01, RX50, RK05, DECtape, who knows what else -- might be
available from the DECUS library, 219 Boston Post Road, BP02, Marlboro, MA
01752-1850. Write, or call (800) 332-8755, or send Internet e-mail to
for further info.
The Kermit Project has no PDP-11s in house to make PDP-11-specific formats.
We can make ANSI-format 9-track tapes, which are supported by some PDP-11 OSs,
and we can make VMS BACKUP format TK50s as well more common non-DEC formats
like DOS diskettes, etc (but not RX50s).
When you can't get PDP-11 Kermit on native media, you probably can still
bootstrap the appropriate hexified binary onto your PDP-11, along with the
dehexifying program, and then use the latter to decode the former. See the
Binaries section above.
"Beware File" -- Assorted Hints, Tips, Cautions, and Reports (plain text).
Kermit-11 3.60 File List - Detailed notes on what's what, as of February, 1987
Kermit-11 Edit History (plain text).
Kermit-11 Help File (plain text).
- Kermit for the PDP-10
(DECsystem-10 and DECSYSTEM-20).
Note: .HLP and .DOC are original 1960s and -70s DEC
filetypes. If your browser insists on treatming them as Windows Help or
Microsoft Word documents, your browser lacks a sense of history.
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Kermit for the PDP-11 / Columbia University /
firstname.lastname@example.org / 4 August 2001