Implementation of KERMIT for Version IV of the UCSD p-System
Kate MacGregor / Steven Pacenka
Cornell University
(Test) Version 0.1, May 1984
KERMIT-UCSD4 is a program which implements the KERMIT file-
transfer protocol for use under the Version IV.x UCSD p-System on
various computers. The distributed version has been developed on
an IBM Personal Computer under Network Consulting, Inc.'s
excellent adaptation of the p-System.
This implementation was done by Steven Pacenka, based largely
on an implementation by Kate MacGregor of Cornell Computing
Services for the Version II.0 p-System on a Terak 8510a.
USING KERMIT with the NCI p-SYSTEM on an IBM PC
You must have NCI release C1F or later to use this program.
Earlier releases suffered from bugs in the serial interface
support which caused incoming characters to be lost even at low
speeds.
You need to do two things with your boot diskette before
trying to execute the distributed .CODE file:
- Enable serial interrupts using the NCI CONFIG program; and
- Place the SYSTEM.SERIAL file on your boot disk.
You need to reboot to get these to take effect for the first
time. Then and thereafter just eX(ecute the KERM.CODE program.
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CONSTRUCTING A NEW KERMIT
The program consists of several Pascal source files which
need to be compiled. Also required is a REMUNIT.CODE to
interface with your computer's serial port.
The source files (and their short names on the distribution
tape) are:
UCSD Name KERMIT Contents
Distribution Name
-------------- ----------------- --------------------------------
KERMIT.DOC.TEXT UC4KRM.DOC This documentation
KERMIT.TEXT UC4KRM.PAS Main program
SETSEND.TEXT UC4STS.PAS Include file for KERMIT.TEXT
RECEIVER.TEXT UC4RCV.PAS UNIT Receiver (file receiving)
SENDER.TEXT UC4SND.PAS UNIT Sender (file sending)
HELPER.TEXT UC4KHP.PAS UNIT Helper (online help info)
KERMPACK.TEXT UC4PKT.PAS UNIT KermPack (packet utilities)
KERMUTIL.TEXT UC4KUT.PAS UNIT KermUtil (misc utilities)
KERMGLOB.TEXT UC4GLB.PAS UNIT KermGlob (declarations)
PARSER.TEXT UC4PRS.PAS UNIT Parser (command parsing)
KERM.CODE UC4NCI.COD p-code file that will run with
NCI p-system release C1F on IBM PC
The .PAS files are Pascal source files, and the .DOC file
(obviously) contains this user documentation, instructions for
building UCSD Pascal Kermit for the IBM PC, and hints on adapting
it to other machines. The .COD file is a p-code file for the NCI
p-System on an IBM PC.
All of the .PAS modules should compile and execute on any
adaptation of Version IV of the UCSD p-System, provided that an
equivalent of the REMUNIT.CODE unit is available for the
particular computer being used. (This file implements the UCSD
Pascal Users' Society (USUS) "standard remote unit.")
To generate a variant of this KERMIT for another computer
running the Version IV p-System:
1. Create or obtain a REMUNIT that implements the USUS
standard remote unit. Specifications and implementations
for a variety of different computers are available from
USUS. For communications above 300 baud, the incoming
characters to REMIN: should be processed in a buffered,
interrupt-driven mode. The buffer should be at least 256
characters long.
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2. Gather all of the source Pascal files onto your prefix
volume along with the REMUNIT.CODE file.
3. Compile the Pascal units in this sequence: 1--KERMGLOB
2--KERMUTIL 3--KERMPACK 4--PARSER 5--HELPER 6--SENDER
7--RECEIVER 8--KERMIT.
4. At this point you can use the standard p-System
LIBRARY.CODE program to combine the units (including
REMUNIT) into one code file for easier and faster loading,
or you can enter their individual .CODE file names into the
USERLIB.TEXT file on your root disk.
LIMITATIONS
1. No wild card designations of file names are allowed. Files
are transmitted and received individually.
2. No eight-bit character quoting is allowed. In practice,
this means that only text files can be transferred.
3. No character repeat counts are used in packets.
4. '?' and <esc> cannot be used when entering a command
line. Some versions of Kermit parse commands from the
keyboard character by character as they are entered. This
version interprets the line after it has been terminated by
a carriage return. Use the HELP command in place of '?',
and type out the command names in full.
5. No server communications are supported.
6. Instead of using a clock to time out when waiting for a
packet, KERMIT-UCSD has a limit on the number of times it
will look for a response before giving up.
7. All linefeed characters received during file transfer are
stripped from the local file that is being created, since
the p-System does not recognize them in text files. This
may cause difficulties in files received from certain other
computers which omit carriage returns at the ends of lines,
particularly blank lines.
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COMMANDS
The commands recognized by KERMIT-UCSD are listed below.
CONNECT To make a "virtual terminal" connection to a
remote system. The CONNECT command may be
abbreviated to 'C'. When in CONNECT mode, all
typed characters are sent to the serial interface
except the escape character (see SET ESCAPE,
below). The escape character may be followed by
another character which is interpreted as
follows:
c Break the connection and "escape"
back to the micro
b Send a "break" signal over the
communications line; this is only
useful on mainframes such as the IBM
3081/370/4341 et. al.
s Same as the "show all" command in
command mode; displays the current
parameter settings for the local
KERMIT.
? Displays the possible characters to
follow the escape code
<Escape char>
Two consecutive escapes are required
to send one such character to the
communications line
EXIT To return to main p-System command level.
HELP To get a list of KERMIT commands. HELP can be
followed by any command, in which case the help
will refer only to that command.
RECEIVE To accept a file from the remote system. Note
that ".TEXT" will be concatenated onto the end of
the received file name if it is not already
present.
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SEND To send a file to the remote system. Takes a
filename as a parameter. In creating a file name
for the remote Kermit, all periods in the name
except the rightmost are deleted. This is for
compatibility with most other operating systems.
SET To establish system-dependent parameters. The
SET options are as follows:
BAUD To set the communications baud rate
to 110, 300, 1200, 2400, 4800, or
9600 (default is 1200).
DEBUG To set debug mode ON or OFF (default
is OFF).
EMULATE To set DataMedia 1520A screen control
code interpretation ON or OFF
(default is OFF).
END-OF-LINE
To change the character used at the
end of packets to something other
than the default of CR. It must be a
digit between 0 and 31.
ESCAPE To change the escape sequence that
lets you return to the PC Kermit from
the remote host. The default is
CTRL-] c.
FILE-WARNING
ON/OFF, default is OFF. If ON,
Kermit will rename an incoming file
so as not to write over a file that
currently exists with the same name.
IBM ON/OFF, default is OFF. This flag
should be ON only when transfering
files between the PC and an IBM
VM/CMS system. It also causes the
parity to be set appropriately and
activates local echoing.
LOCAL-ECHO
ON/OFF, default is OFF. When on,
this causes characters typed at the
keyboard during connect mode to be
echoed to the screen.
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PARITY EVEN, ODD, MARK, SPACE, or NONE.
NONE is the default but if the IBM
flag is set, parity is set to MARK.
This flag selects the parity for
outgoing and incoming characters
during CONNECT and file transfer to
match the requirements of the remote
computer.
SHOW To see the values of parameters that can be
modified via the SET command. SHOW ALL shows all
parameters; SHOW followed by a parameter listed
under SET will show the value of only that
parameter.
WISH LIST FOR FUTURE VERSIONS
If anyone tries these, please consider portability and share
your work with the rest of the p-System community.
1. Increased memory buffering of sent and received packets.
Now only the standard 512 character buffers provided by the
operating system are utilized. On floppy disk systems the
throughput is slowed considerably by frequent disk access.
2. Timing of file transfers using the system clock to
determine the effective transmission rate.
3. More intelligent handling of received linefeed characters.
4. Implementation of the immediate '?' (help) and <esc>
(abbreviate) commands in the parsing routines;
5. A DIR command to list a local volume directory.
6. Text file capture with memory buffering, and XON/XOFF
protocol. (For remote computers not supporting Kermit.)
7. Text file transmission without protocol.
8. Eight-bit quoting for sending and receiving data and code
files.
9. Timeouts during send and receive using the hardware clock,
and a related SET TIMEOUT command.
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