Simply using google to find a laplink parallel cable is quick, too.
http://www.nullmodem.com/LapLink.htm

Of course, even LapLink's "parallel" cable only transfers 4 bits
at a time vs. the 8-bits that are possible on an EPP port.

And LapLink does NOT run in the background (as does RIFS - Remote
Installable File Server, which, alas, uses a serial port and is
thus also much slower than a fully parallel port.)

I find it interesting: lots of people have suggested I do something
ELSE, but no one has answered the question itself. Obviously I
posted my question in the wrong newsgroups! Oh, well; nothing
ventured, nothing gained (and only a little time lost).

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor
Certified Instructor for the Kansas Concealed-Carry Handgun license

wrote in message ...
And I have several. Have you ever made a NIC work with DOS?
If so, I'd sure love to learn how you did it.

NICs work fine in DOS. At least back with Windows NT (and probably still
2000... possibly not XP anymore though) you could tell it to build you a "DOS
startup disk" which configured most everything you needed to connect to a
NetBEUI-based server (which is still supported in XP, etc.). Many network
cards still come with DOS drivers, and of those that don't, many really cheap
ones are still "NE2000 compatible" and generic drivers can be found. I'm sure
you can Google for the details -- I haven't done this in a number of years,
but very commonly what I used to do was make DOS network startup disks so that
I could connect to a server to pull over a complete hard drive image to set up
the machine using, e.g., Norton Ghost.

Linux may be free, but the aftermath of installing Linux would cost
YEARS of effort to "port" the:
801 FORTRAN programs I currently use
225 Pascal programs I currently use
452 DOS .BAT and Norton's DOS .BTM scripts I currently use.

There's a very good chance the vast majority of your programs would work under
WINE in Linux. That being said, Linux -- especially with the "popular"
desktops such as KDE -- has gotten to the point of requiring powerful enough
hardware that, if your PCs wouldn't "comfortably" run at least Windows 2000,
you probably shouldn't bother with Linux as you probably won't have a pleasant
experience if you just perform a "default" install of any contemporary
distributions.

---Joel

wrote in message ...
I find it interesting: lots of people have suggested I do something
ELSE, but no one has answered the question itself.

You might be better off in one of the "historical" computer groups (maybe
alt.folklore.computers); what you're wanting to do requires knowledge that's
simply obsolete by current standards, so you won't find that many people who
still possess it.

I did this back in 1984 when I got a Toshiba portable with the new 3"
floppies, just to get files back and forth.
Later somebody made some commercial products (pdq, lablink, ...)

In short I did:

Server end is a program that reads requeste from other pc, and reads or
writes disk sectors.

Client side has a device driver, disk type, so I now has a D: on that
computer.
I took the memdisk example from the tech books, and rewrote the read and
write sectors to go to other computer.

It works very nice. Only trashed a few disks when doing small
programming mistakes ;-)


Now the interface between the pc's, which first was tested for function
of rx/tx, like Send512Bytes(SomeData)

I had the old parallelport, so I had 5 bits and used 4 for data and 1
for strobe.
I did not use interrupts, as the server just sat there waiting for the
other end to start flipping the strobe bit.

Procedure SendHalfByte(Strobe,B: Byte);
begin
Port():= Strobe+ (B and $0F);
SleepShort;
Port():= (1 xor Strobe)+ (B and $0F);
SleepShort;
end;

Procedure Send1Byte(B: Byte);
begin
SendHalfByte($00,B);
SendHalfByte($80,B shr 4);
end;

The receiver end will do

Function Read1Byte: Byte;
var X: Byte;
begin
repeat until StrobeBit0;
X:=Port() and $0F;
repeat until StrobeBit=0;
Result:=X + (Port() shl 4);
end;

Use Send1Byte and Read1Byte, and you have data. Make some framing like
DataToSend:= LF + MyData + CR
and it is easy to check for correct reception.

I managed to put some 50KBytes between two PC's in 198x, at 8MHz I
guess.

PS: All coding above is out of my head, and was done in assembler back
then.

--
Christen Fihl
OZ1AAB
http://HSPascal.Fihl.net/

Have you thought about using PLIP to do tcpip over your parallel ports?



wrote:
Hope this isn't too far off-topic, but maybe somebody who has actually
done something homebrew like this can give me some pointers.

I'd like to connect two PC's with EPP ports so they could "talk" to each
other (mono-directional at any instant but reversible -- probably by
passing a "token" back and forth -- and preferably NOT using interrupts

kl7r wrote:
Have you thought about using PLIP to do tcpip over your parallel ports?



Check out :

http://www.crynwr.com/ for DOS packet drivers
http://tldp.org/HOWTO/PLIP-9.html for information on DOS/LINUX PLIP
connections

wrote:

Simply using google to find a laplink parallel cable is quick, too.
http://www.nullmodem.com/LapLink.htm

Of course, even LapLink's "parallel" cable only transfers 4 bits
at a time vs. the 8-bits that are possible on an EPP port.

You asked how to connect tow parallel ports. The link gives two examples.
The examples are ones that worked with commercial software. (Hint: that
means they would probably work for you. It may also meet your criteria for
reliability.)


And LapLink does NOT run in the background (as does RIFS - Remote
Installable File Server, which, alas, uses a serial port and is
thus also much slower than a fully parallel port.)

Your original post made no mention of specific software being a restriction.
It did say this was a one-off job without out a speed requirement.


I find it interesting: lots of people have suggested I do something
ELSE, but no one has answered the question itself.

The link answered the question in the subject.

Obviously I
posted my question in the wrong newsgroups! Oh, well; nothing
ventured, nothing gained (and only a little time lost).


Your fault the time was lost. Simple google searches would have given you
what you wanted.

The search to find the earlier link was on "laplink parallel cable".

If you do a search on "connecting epp ports", one of the links will be this
page.

http://www.lvr.com/jansfaq.htm

Scroll down to the bottom to see a problem with connecting all data bits.
(You did say you wanted a reliable solution.)

Yes, this may have been the wrong newsgroup. That is not the fault of anyone
who replied to you.

wrote in message ...
Neither do the computers I'm working with have Ethernet or USB.

16-bit NICs are $10 apiece, and likely free for the asking from almost any
office's dead PC junk heap.

And I have several. Have you ever made a NIC work with DOS?
If so, I'd sure love to learn how you did it.

Wollongong. Beame and Whiteside. To name two.

But that's going backwards. With one foot in the grave already, you need to
keep moving forward, not back. If it runs DOS, it'll run Linux.



Besides, there's always the fun of doing it, and that much time
difference should even "pay" for the programming effort.

Seems to me your time would be better spent on things with lasting value.
Linux is free....

Linux may be free, but the aftermath of installing Linux would cost
YEARS of effort to "port" the:
801 FORTRAN programs I currently use
225 Pascal programs I currently use
452 DOS .BAT and Norton's DOS .BTM scripts I currently use.

It boots off the CD. I know I mentioned that. It's worth mentioning a second
time. And a third: It boots off the CD. No installing, no configuring...
Just boot it, FTP your files, and get on with whatever it is you're trying
to do.


No, converting to Linux is NOT free, especially at my age!

Yeah, I know just what you mean. About the age thing, that is. Time's
wasting; best get to it.

wrote:

I find it interesting: lots of people have suggested I do something
ELSE, but no one has answered the question itself. Obviously I
posted my question in the wrong newsgroups! Oh, well; nothing
ventured, nothing gained (and only a little time lost).

Maybe it was the wrong *question*. Kindly refrain from
criticizing a forum like this for not being your personal
research staff.

As the discussion showed, what you really want to do
is transfer files. Fine. If you want to transfer files, a null
modem cable (an off the shelf item) and a couple of
copies of kermit (ditto) will transfer a lot of data. I
transferred a Windows 95 CD to a laptop once that way.

Laura Halliday VE7LDH "That's a totally illegal,
Grid: CN89mg madcap scheme. I like it!"
ICBM: 49 16.05 N 122 56.92 W - H. Pearce

As the discussion showed, what you really want to do is transfer files.
....[snip]....

That may be what the DISCUSSION showed, but that's NOT what my QUESTION
asked (which was how one might connect two EPP ports so they could "talk"
with each other bidirectionally).

Others "answered" the question by suggesting alternative solutions
(And there is/was nothing wrong with that!),
but only a very few actually addressed the original question,

And I hereby thank them.
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor
Certified Instructor for the Kansas Concealed-Carry Handgun license