home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Cream of the Crop 21
/
Cream of the Crop 21 (Terry Blount) (October 1996).iso
/
os2
/
sio157.zip
/
VMODEM.TXT
< prev
next >
Wrap
Text File
|
1996-08-27
|
40KB
|
905 lines
VMODEM
Technical Reference Manual
Copyright (c) 1995 by Raymond L. Gwinn
26 Tanager Place
Beckley, West Virginia 25801
All Rights Reserved
August 15, 1996
CompuServe: 72662,3547
InterNet: ray@gwinn.com
Voice: 1-304-255-7900
FAX: 1-304-255-7902
BBS: 1-304-255-7903 or vmbbs.gwinn.com
WEB http://www.gwinn.com
INTRODUCTION
The Virtual Modem is a concept that the author believes will change
the way serial data communications is done and thought of. It is
going to bring the Internet alive more then ever before. Perhaps it
will not be this implementation of a Virtual Modem, but the concept
will remain and be used for a long time. The concept of the Virtual
Modem was born from the desire to make the SIO support BBS available
via Internet. In only a few minutes, I was convinced the Virtual
Modem was a solution of a multitude of problems that Internet access
poses.
The Virtual Modem removes most of the complexities and mysteries of
the Internet by allowing common, well understood, programs to be used
to access the Internet highway. Users can use programs like PmComm
and TE/2 to download files from a BBS (across the Internet) using
common protocols like ZMODEM. The dialing directories of terminal
programs can contain Internet addresses instead of phone numbers for
easy access to remote sites.
BBS SysOps can simply declare one or more of their BBS's
communications ports as a Virtual Modem and users can then "dial" in
over the Internet and no BBS software changes should be necessary. Is
your BBS ready for 20 million new users that can access it without
making a long distance call? This Virtual Modem implements protocols,
including a Telnet server which allows most anyone on Internet to
access your system.
Users transferring large volumes of data across phone lines (like
FidoNet echomail) can now use the Internet highway instead. Again,
software changes should be minimal, if any at all.
Vmodem is unique in that it has a dual personality of both Server and
Client. The Server/Client personality is determined by the direction
of the connection (outgoing or incoming).
ii
TABLE OF CONTENTS
WHAT IS VMODEM . . . . . . . . . . . . . . . . . . . . . . . . . 1
DISTRIBUTION, ORDERING AND SUPPORT . . . . . . . . . . . . . . . 2
Distribution and Ordering . . . . . . . . . . . . . . . . . 2
SIO Distribution and Support BBS . . . . . . . . . . . 2
Support . . . . . . . . . . . . . . . . . . . . . . . . . . 2
GETTING IT GOING . . . . . . . . . . . . . . . . . . . . . . . . 5
TCP/IP Required . . . . . . . . . . . . . . . . . . . . . . 5
TCP/IP Sockets . . . . . . . . . . . . . . . . . . . . 5
The default port number . . . . . . . . . . . . . . . . 5
The SIO.SYS command line . . . . . . . . . . . . . . . . . . . . 5
THE VIRTUAL MODEM . . . . . . . . . . . . . . . . . . . . . . . . 7
AT Commands Supported . . . . . . . . . . . . . . . . . . . 7
S Registers Supported . . . . . . . . . . . . . . . . . . . 8
Result Codes . . . . . . . . . . . . . . . . . . . . . . . . 8
NO CARRIER . . . . . . . . . . . . . . . . . . . . . . 8
NO DIALTONE . . . . . . . . . . . . . . . . . . . . . . 8
. . . . . . . . . . . . . . . . . . . . . . . . . . . 8
BUSY . . . . . . . . . . . . . . . . . . . . . . . . . 8
CONNECT 57600/ARQ/VMP . . . . . . . . . . . . . . . . . 8
CONNECT 57600/ARQ/TEL . . . . . . . . . . . . . . . . . 8
RING . . . . . . . . . . . . . . . . . . . . . . . . . 9
RINGING . . . . . . . . . . . . . . . . . . . . . . . . 9
Caveats . . . . . . . . . . . . . . . . . . . . . . . . . . 9
SECURITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 10
Vmodem's Implementation . . . . . . . . . . . . . . . . . . 10
Developers Information . . . . . . . . . . . . . . . . . . . 10
DIALING EXAMPLES . . . . . . . . . . . . . . . . . . . . . . . . 11
Telnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
IBM's Telnet Client . . . . . . . . . . . . . . . . . . . . 12
Development and Debugging Tools . . . . . . . . . . . . . . . . . 13
Vmodem's Semaphores . . . . . . . . . . . . . . . . . . . . 13
The Poor Man's Line Monitor (PMLM.EXE) . . . . . . . . . . . 13
VIEWPMLM.EXE . . . . . . . . . . . . . . . . . . . . . . . . 14
SIO's Utility (SU.EXE) . . . . . . . . . . . . . . . . . . . 14
IRQs that currently free for use . . . . . . . . . . . 14
Appendix A, Hardware Port and IRQ Assignments . . . . . . . . . . 15
Addresses and IRQs for COM1 and COM2 . . . . . . . . . . . . 15
Defacto standard for COM3 and COM4 . . . . . . . . . . . . . 15
Addresses and IRQ for COM3 through COM8 on the PS/2 . . . . 15
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1
WHAT IS VMODEM
Vmodem is a software implementation of a modem, referred to as a
Virtual Modem. Basically, it attempts to fake out other software
(like terminal programs) into believing they are accessing a real
modem. Vmodem will turn any Terminal into a Telnet Client, and any
BBS into a Telnet Server.
Normal (real) modems provide an interface that allows terminal
programs to pass digital information across telephone lines. Vmodem
does the same thing from the application (terminal) program's point of
view. However, the other side of Vmodem is not a phone line, but a
digital network like Internet. Thus, Vmodem allows the hoards of
communications programs to pass information across Internet instead of
using phone lines.
In addition to acting as a Telnet server, Vmodem uses a newly designed
protocol for communications networks, called the Virtual Modem
Protocol (VMP). At this time, no other programs have implemented VMP,
thus Vmodem is required on both ends of the connection to use the VMP.
However, VMODEM.EXE will accept inbound Telnet connections from any
system, meaning a BBS under vmodem can be accessed by just about
anyone with an Internet connection.
Future implementations of Vmodem may access networks other than
Internet and use TCP/IP implementations other than IBM's. The current
implementation of Vmodem works only on Internet, using the Internet
Access Kit (IAK) that is included with OS/2 V3 and IBM's TCP/IP (for
OS/2) version 2.0, with the August 1994 CSD applied.
A single invocation of Vmodem can service all of the Internet ports
defined in the SIO command line.
2
DISTRIBUTION, ORDERING AND SUPPORT
Distribution and Ordering
Vmodem is a part of a larger package collectively known as SIO. The
entire package collectively known as S