DOS 6.x’s INTERLiNK - (Works in Windows 95, too)
HOW TO BACKUP YOUR LAPTOP TO AN INTERNAL TAPE DRIVE ON A DESKTOP
By Fred Kagel

While many have raised concerns about DOS 6's DoubleSpace and MemMaker, little has been mentioned, positively or otherwise, about DOS 6.x’s INTERLiNK and its companion, INTERSerVeR. These pert little programs enable another PC, especially a laptop, to be "networked" to a desktop computer. Once connected with those new what's-it-for DOS 6 parallel cables (a.k.a. LapLink cables) and once the software is installed properly, files can be transferred back and forth between computers. The laptop, installed as a client, can also execute programs on the desktop server or vice versa if the setup is the other way around with the laptop as the server.

Many desktop users have internal tape drive backups given the size of today's hard drives. A question came up on how to backup the data from a laptop directly to the internal tape drive of the desktop. Actually, network programs have been around for years to do the job, but most single users do not own a network. Also, some of today's backup programs such as FastBack Plus 6.0 support laptop backups. Now, DOS 6.x has this little known capability built in. Here's how to do it:

1. Connect a LapLink or LL/DOS 6 Cable to the parallel ports of each computer.

2. Laptop

a. Laptop must act as server and must boot with DOS 6.

b. Type INTERSVR on the laptop or place the command in the Autoexec.Bat file; be sure Intersvr.Exe is in the path.

3. Desktop

a. Desktop must act as client; tape drives such as the Colorado system must be on a workstation.

b. Add the statements:

LASTDRIVE=x

DEVICE=path\INTERLINK.EXE /drives:n

to the Config.Sys, where x is the letter representing the last drive to be addressed on either system. For example, DoubleSpace defaults to drive H, so translating three additional drives require:

LastDrive = K.

Place Device statement after any other statements which would add drive letters such as double space, ramdisk, networks, etc. The parameter n can be used to increase the number of translated drives beyond the default of 3.

c. Reboot after changing the Config.Sys. Proceed with the tape backup once a connection is made using the proper drives; i.e., if the laptop server has a single floppy drive and the desktop client has two floppies and a hard drive, the laptop's hard drive will be addressed as the F drive.

4. The tape drive can now be operated from the desktop computer keeping in mind that drive F from the above scenario is being backed up. The laptop cannot access the tape drive.

What about transfer speed? 1.7 Megs was transferred in 2:22 minutes for a transfer rate of 700K per minute with compression. This seems to be about the right speed for transferring over the parallel port. The time includes tape start up and wind down times, so don't completely rely on this small sample size. At this rate, it would take approximately 1-1/2 to 2 hrs to backup 80 Megs. This compares with an expected maximum transfer rate of 4.4 MB/minute for the Colorado Jumbo 250 or roughly 20 minutes to backup up 80 Megs on a standalone system. In practice, the transfer speed will vary widely from system to system.

For extras, Interlink works with both Stacker and DOS's own DoubleSpace. Also, both DOSShell (Arghhh!) and Windows are Interlink-aware, meaning that you can use Dosshell or Windows' file manager to do your copying and moving about.

Your own favorite DOSSHELL may not work; QDOS III by Gazelle, for example, did not recognize the "network drives." LapLink by itself will not recognize another computer's drives as a different letter and, therefore, cannot use for tape backups. LapLink also will not run on top of Interlink. In spite of these incompatibilities (so what else is new?), Interlink is a welcomed addition to the DOS environment. [Copyrighted 1993-1999, Fred E. Kagel, Freehold Computer Training Center. All rights reserved. Permission is granted to republish in non-profit publications provided this notice appears in its entirety.]