TechWhirl (TECHWR-L) is a resource for technical writing and technical communications professionals of all experience levels and in all industries to share their experiences and acquire information.
For two decades, technical communicators have turned to TechWhirl to ask and answer questions about the always-changing world of technical communications, such as tools, skills, career paths, methodologies, and emerging industries. The TechWhirl Archives and magazine, created for, by and about technical writers, offer a wealth of knowledge to everyone with an interest in any aspect of technical communications.
Subject:Network two PCs without a LAN adapter From:jrose on BIX <jrose -at- BIX -dot- COM> Date:Mon, 1 Aug 1994 17:19:22 GMT
NETWORK TWO PCs WITHOUT LAN ADAPTERS
By John B. Rose
Copyright 1994 by Rose Business Systems Inc. All rights reserved.
This article may be redistributed provided that the article and this
notice remain intact. This article may not under any circumstances be
resold or redistributed for compensation of any kind without prior written
permission from Rose Business Systems Inc.
If you have any questions about these terms, please telephone (516)
726-4711, or send e-mail to jrose -at- bix -dot- com or CompuServe ID 72357,346.
----
Do you frequently need to transfer large amounts of data from one PC to
another? If so, you'll want to consider a high-speed connection between
them so that one computer's disk and diskette drives and printers appear as
extra resources on the second machine.
This sure beats the tedious method of backing up one machine (on dozens
of diskettes) and restoring to the other. And it's a lot cheaper than a
portable tape backup unit.
Unlike a regular local area network (LAN), there's no need to purchase
expensive Network Interface Cards (NICs) -- just use the parallel or serial
ports built into both computers.
Likewise, you won't need coaxial cable between the two machines.
Instead, you can build a null-modem cable (or a special bidirectional
parallel cable) using standard DB-25 and/or DB-9 connectors available from
electronics parts retailers.
Typically, you'd use this method when you're upgrading a client to a
new computer (the "client") and you want to transfer the directories,
programs, and data files from the old one (the "host").
At least one of the computers has to be running MS-DOS 6.0 or higher.
Here's what you do.
1. PHYSICALLY CONNECT THE TWO COMPUTERS
Build one of the following cables. If you have INTERSVR.EXE, the
server program, already on the host machine, or you have a way to get it
there (such as compatible diskette drives), we recommend the BIDIRECTIONAL
PARALLEL CABLE; it has a very fast transfer speed, and it doesn't interfere
with modems and mouse drivers. It's a little harder to build, and it
occupies the printer port, so choose this one only if you don't want to use
the host's printer remotely. You can get away with using a THREE WIRE NULL
MODEM CABLE if both machines have COM ports available.
HOWEVER, if the host is running a version of DOS earlier than 6.0, AND
the two computers don't have mutually compatible diskette drives, you HAVE
to build the SEVEN WIRE NULL MODEM CABLE just to transfer the server program
from the client to the host. Also, the host computer must have an available
COM1 or COM2 -- higher numbered COM ports won't work.
BIDIRECTIONAL PARALLEL CABLE: Two DB-25 male connectors, and cable
with at least ELEVEN conductors. If you can't find the multi-conductor
cable, get thin stranded hookup wire and spiral cable wrap (Radio Shack
#278-1638). Connect pins as follows:
PC #1 PC #2
-------------------------------------
2 <-----------------------> 15
15 <-----------------------> 2
SEVEN WIRE NULL MODEM CABLE: Two DB-25 or DB-9 female connectors
(depending on the physical plugs you find connected to working COM ports on
each computer), and cable with at least SEVEN conductors. Connect pins as
follows:
THREE WIRE NULL MODEM CABLE: Same as the SEVEN WIRE CABLE above; omit
the RTS-CTS and DSR-DTR leads.
2. INSTALL THE SERVER SOFTWARE ON THE HOST.
Typically, you'll want to transfer files from an older, slower PC to a
newer, faster one that will be replacing it. The older machine, or "host",
will be running an earlier version of DOS -- say, MS-DOS 3.3. If the two
computers have compatible diskette drives, just copy INTERSVR.EXE from the
newer PC's \DOS directory, via diskette, to the older machine.
If you haven't the luxury of compatible diskette drives, INTERSVR can
install a copy of itself on a remote machine. Connect the two computers via
the SEVEN WIRE NULL MODEM CABLE. On the client, enter the command:
INTERSVR /RCOPY
The program will prompt you for the COM port number of the OTHER (host)
machine. Highlight either COM1 or COM2 and press Enter.
On the host machine, enter the commands:
MODE COM1:2400,n,8,1,p
CTTY COM1
Replace 'COM1' with 'COM2' above as necessary.
The INTERSVR program will copy itself to the host machine.
3. EXECUTE THE SERVER PROGRAM ON THE HOST.
You can specify options, such as a maximum data transfer rate, which
disk drives to omit, and which COM or LPT port to use for transfer. Enter
"INTERSVR /?" for a list of all the options.
On the host machine, enter the command:
INTERSVR
The host is now ready to act as a file server to the client PC.
4. INSTALL THE INTERLNK PROGRAM ON THE CLIENT COMPUTER.
You can specify which COM or LPT port to use for data transfer, the
number of host drives to address, and other options. Enter "HELP
INTERLNK.EXE" for a list of all the options.
On the client machine, enter the command:
EDIT C:\CONFIG.SYS
... or use your favorite text editor to add a line to the CONFIG.SYS
file to read as follows:
DEVICE=C:\DOS\INTERLNK.EXE
Also, if a line containing the text "LASTDRIVE" is already in the file,
raise the drive letter it specifies, if necessary, so that you can add as
many extra drives as there are drives on the host. Usually, that's three.
For example, if the client computer already has diskettes A: and B:, a hard
disk C:, and a RAM disk D:, LASTDRIVE must be at least G: to accommodate the
new E:, F:, and G: drives, which are known on the host as A:, B:, and C:.
In this example, the line looks like this:
LASTDRIVE=G
If LASTDRIVE is already set high enough, you don't need to change it.
Save the file, exit the editor, and reboot the computer (Ctrl-Alt-Del).
If the connection is working properly, the server screen will display the
additional drive letters that now appear as additional drives on the client.
5. USING THE LINKED COMPUTERS
The host computer's disk and diskette drives and printers are now
available as additional drives (and, maybe, printers) on the client
computer. For example, if the host has drives A:, B:, and C:, they may
become known to the client as E:, F:, and G:. Programs such as the Windows
File Manager, the DOS Shell, Xtree (tm), and ProFinder (tm) will let you
copy to and from, move, rename, and delete files, on host drives
interchangeably with your local drives.
To copy an entire directory, including all subdirectories and files,
from the host's hard disk to the client's, substitute the correct drive
letters and directory name in the following commands:
MD C:\WP51
XCOPY G:\WP51\*.* C:\WP51 /S
6. CLEANING UP AFTERWARD
When you're finished using the host's disks, you can stop the server
program by pressing Alt-F4 on the host keyboard.
On the client computer, edit CONFIG.SYS and delete the INTERLNK command
line. It's generally OK to leave LASTDRIVE set to a high value. Save the
file, exit the editor, and reboot.
7. READY-MADE CABLES
You can save the time and uncertainty of building your own cables by
purchasing factory-made ones. If your retail store is out of them, we'll
cheerfully ship the following on receipt of your check or money order.
#219: 4-head 7-wire null modem cable (female DB-9 & DB-25 each end) US$19.95
#310: Bidirectional parallel cable (male DB-25 each end) $19.95
#248: 6-head cable, use for parallel or serial $29.95
Cables are guaranteed to work, or return them for a refund. Priority
Mail postage to U.S. locations is included; NY AND NJ ADDRESSEES ADD YOUR
LOCAL SALES TAX. Add US$5.00 to Canada or Mexico; $10.00 for other
international destinations. Prices are valid through December 31, 1994.
ROSE BUSINESS SYSTEMS INC.
Since 1976
511 Head-of-Pond Road
P.O. Box 630
Water Mill, NY 11976-0630 USA
