To:	All PC Pursuit Users
From:	Bob Freed
Date:	October 17, 1986
Subj:	Documentation for PCPCK.COM

PCPCK.COM is a simple program which checks a CP/M file to 
determine if it contains the Telenet (PC Pursuit network) local 
command escape sequence.  Such files cannot be uploaded to a 
remote system with XMODEM (or YMODEM) file transfer protocol, 
unless a special Telenet command is first issued to disable 
recognition of the escape sequence.  Details of this problem and 
its solution may be found in the previously-published messages, 
PCP-WARN.MSG and PCP-FIX.MSG, which are included in this library.

To use this program, simply supply the unambiguous file name of 
the (single) file to be checked.  For example:

	A>PCPCK B:TEST.LBR
        File is ok!

Note that the specified file name should not contain wildcard 
characters (? or *), although this is not treated as an error 
(and will cause the first matching file on disk to be checked).  
If no file name is supplied, a short help message is generated.

The above example illustrates the program's response if the 
escape sequence is not detected.  This implies that the file 
should be safe to upload.  (See note below, however.)

If the escape sequence is detected in the middle of a 128-byte 
record, the program terminates immediately with the following 
message (nnn is the decimal record no. containing the escape 
sequence):

	File will fail in record # nnn!

If the (three-byte) escape sequence crosses a record boundary, it 
is possible that the file will upload successfully using 128-byte 
transmission blocks (XMODEM protocol) but will fail using 1024- 
byte blocks (YMODEM protocol).  In this case, the program issues 
the following message and continues checking the file:

    Warning: File will fail in record # nnn! (with 1K blocks)

If only the above such (warning) conditions are detected, the 
following final message will appear:

	File is ok! (with 128-byte blocks)

In this case, the file is safe to upload using XMODEM protocol 
but not YMODEM (1K) protocol.

                              NOTE

	It is possible that a file will pass the PCPCK
	program's check and still not upload properly.  
	This may happen if a part of the Telenet escape
	sequence occurs at the beginning or end of a
	record and is completed by the additional bytes 
	which are inserted by the XMODEM protocol (record
	no. or checksum/CRC bytes).  Determination of
	such a (highly unlikely) condition is beyond the
	scope of this simple program.

I originally wrote this program two months ago (at the time the 
above-mentioned message files were generated).  I have not used 
it since.  (Nor have I encountered an aborted file upload 
situation since then, which illustrates just how rare an 
occurrence that is.)  I am releasing it now at the request of 
Gary Inman, sysop of the West Los Angeles RCP/M.  It is 
completely public domain.  The source program uses Zilog 
mnemonics but does not implement any Z80-specific instructions, 
and it should be usable on any CP/M system.

				Bob Freed
				Newton Centre, MA
				October 17, 1986