• DIY Laplink cable results

    From kirkspragg@21:2/150 to All on Friday, August 15, 2025 21:15:35
    Hi everyone, hope your weekend has started off well & that your weekend is good to you.

    So i got round to putting together the 5m long laplink parallel port data transfer cable. I ended up using the 'Parallel Transfer Mode 0' cable schematics from docs.kernel.org/networking/plip.html and used 3 parallel runs of some cheap 4 core shielded speaker wire from our local hobby electronics store:
    https://www.jaycar.co.nz/4-core-round-screened-audio-cable/p/WB1510

    Soldering 12 wires from 3 different multi-core cables into the DB25 plugs was a bit of a hassle & with three runs of cable between the plugs. The cables barely fit in the plug housing -but they did fit with some light encouragement. I just tested it out & it works!

    Getting around 20KB/s between dosbox running on my main PC and my 386DX40 & I think that a reasonably speed to get form the old standard parallel port in my 386, I'm stoked!

    Supposed I should put together a serial null modem cable and try that out as well. I expect the speed will be quite a bit less.

    ... A friend asks only for your time, not your money.

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  • From poindexter FORTRAN@21:4/122 to kirkspragg on Sunday, August 17, 2025 07:58:03
    kirkspragg wrote to All <=-

    Soldering 12 wires from 3 different multi-core cables into the DB25
    plugs was a bit of a hassle & with three runs of cable between the
    plugs. The cables barely fit in the plug housing -but they did fit
    with some light encouragement. I just tested it out & it works!

    My first IT job had me soldering 100 DB25s onto some kind of shielded cable, forget what type. It was a pain, but at least it was one cable per
    connector!



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  • From kirkspragg@21:2/150 to poindexter FORTRAN on Monday, August 18, 2025 12:53:00
    My first IT job had me soldering 100 DB25s onto some kind of shielded cable, forget what type. It was a pain, but at least it was one cable per connector!

    That would have made it a bit easier, did you have a decent soldering setup to help you hold the connector & cable in place while soldering together?

    I kinda made do with my basic temp controlled iron and a single bench clamp to hold the plug.... next time i'll have 2nd clamp of some sort to hold the cables. Its far too fiddly and error prone otherwise - I only slightly melted the plastic of one of the plugs when I slipped with the iron. Man am I out of practice wielding a soldering iron!

    ... Help! I've fallen and I can't Hey! Nice carpet!

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  • From poindexter FORTRAN@21:4/122 to kirkspragg on Monday, August 18, 2025 13:14:47
    Re: Re: DIY Laplink cable results
    By: kirkspragg to poindexter FORTRAN on Mon Aug 18 2025 12:53 pm

    That would have made it a bit easier, did you have a decent soldering setup to help you hold the connector & cable in place while soldering together?

    A pair of vise-grips. :)
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  • From Bob Worm@21:1/205 to kirkspragg on Tuesday, August 19, 2025 19:48:31
    Re: DIY Laplink cable results
    By: kirkspragg to All on Fri Aug 15 2025 21:15:35

    Hi, kirkspragg.

    So i got round to putting together the 5m long laplink parallel port data transfer cable.

    I just tested it out & it works!

    I just wanted to let you know that you're my personal hero :)

    BobW
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  • From Retroswim@21:2/121 to kirkspragg on Wednesday, August 20, 2025 11:10:12
    Getting around 20KB/s between dosbox running on my main PC and my 386DX40 & I think that a reasonably speed to get form the old standard parallel port in my 386, I'm stoked!

    Hell yeah!

    What transfer software are you using? Back in the day, we used a package called "FastLynx", it could get around a megabit of throughport between 486es, using a standard LapLink parallel cable. I have to assume using some
    form of compression?

    Cheers,
    RetroSwim

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  • From Bob Worm@21:1/205 to Retroswim on Wednesday, August 20, 2025 21:04:57
    Re: DIY Laplink cable results
    By: Retroswim to kirkspragg on Wed Aug 20 2025 11:10:12

    What transfer software are you using? Back in the day, we used a package called "FastLynx", it could get around a megabit of throughport between 486es, using a standard LapLink parallel cable. I have to assume using some form of compression?

    Every time anyone mentions Laplink I go off into a mental rabbit hole and think that I might have to whip out the ol' logic analyser and sniff a Laplink connection to see how it works. My cheapo logic analyser only has 8 pins, though, so I guess it'll have to be serial. At a guess parallel would use the same protocol over the top.

    Maybe it would be easier to MitM it using a system with two serial ports. If it relies on hardware handshaking, though, I might have to bypass those through at first.

    Hmmmm...

    BobW
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  • From kirkspragg@21:2/150 to Bob Worm on Friday, August 22, 2025 22:11:20
    So i got round to putting together the 5m long laplink parallel port da transfer cable.

    I just tested it out & it works!

    I just wanted to let you know that you're my personal hero :)

    BobW
    Oh that so cool to hear!

    Seriously it wasn't exactly hard wire/solder everything up as a bit tedious and occasionally frustrating. You could do it yourself assuming you've got a decent soldering iron & a couple of bench vices to hold stuff in place.

    I've just finished making a 5m long null modem cable as well, did it "properly" with the hardware handshaking lines crossed over as per http://www.nullmodem.com/NullModem.htm. I was hoping that having hardware handshaking wired would enable me to use a baud rate > 9600 with my old 386.

    TLDR; Nope. The highest best rate that doesn't cause failures or crash the com port is 9600 baud. Turns out the UART in the multi-io card is a 16450 and so just can't do any better.

    ... All stressed out, and no one to choke.

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  • From kirkspragg@21:2/150 to Retroswim on Friday, August 22, 2025 22:18:43
    I think that a reasonably speed to get form the old standard parallel in my 386, I'm stoked!

    Hell yeah!

    What transfer software are you using? Back in the day, we used a package called "FastLynx", it could get around a megabit of throughport between 486es, using a standard LapLink parallel cable. I have to assume using some form of compression?

    Yea I'm using FastLynx. My past experience with laplink hasn't been so great as it tends to just die on long running transfers. Fastlynx on the other hand seems quite stable.

    Fastlynx can do compression (which I disabled for my benchmarking) so that would help. What speed 486es were they? anyting but a lowely 486sx25 should perform much better than my 386dx40, I wonder if that would lead to better parallel port data transfer rate?

    Also it is possible your 486es had 'proper' bi-diretional EPP parallel ports which would increase the speed quite a lot - but I think you need a different cable that the one I made for that but I'm not completely sure.

    ... Hear no evil, speak no evil, C:\NOEVIL

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  • From Bob Worm@21:1/205 to kirkspragg on Saturday, August 23, 2025 21:26:39
    Re: Re: DIY Laplink cable results
    By: kirkspragg to Bob Worm on Fri Aug 22 2025 22:11:20

    Hi, kirkspragg.

    TLDR; Nope. The highest best rate that doesn't cause failures or crash the com port is 9600 baud. Turns out the UART in the multi-io card is a 16450 and so just can't do any better.

    Eugh... mutli-I/O cards with 16450 UARTs really spoiled my day a few times back in the 90s. I (486SX-25 with 16550) used to play Duke 3D with my brother (486DX2-66 with 16450) over serial and it would regularly crash. Always my brother's computer pulled it down.

    I miss that Dell. On-board everything, really punched above its weight.

    BobW
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  • From Bob Worm@21:1/205 to kirkspragg on Saturday, August 23, 2025 21:31:45
    Re: Re: DIY Laplink cable results
    By: kirkspragg to Retroswim on Fri Aug 22 2025 22:18:43

    What transfer software are you using? Back in the day, we used a package called "FastLynx", it could get around a megabit of throughport between 486es, using a standard LapLink parallel cable. I have to assume using some form of compression?

    Yea I'm using FastLynx. My past experience with laplink hasn't been so great as it tends to just die on long running transfers. Fastlynx on the other hand seems quite stable.

    The intrusive thoughts finally got the better of me so I DOSBox'd two copies of LapLink3 and sniffed the traffic going between them. I don't understand all the messages yet but it doesn't look ridiculously complicated - if I ever get the free time I could probably write an implementation of it for my Acorn, which would make copying files back and forth much easier. I would need to mangle file names (Acorn allows longer filenames, uses . as a directory separator and has file type as a file system attribute) but it would make a fun project.

    I've never tried FastLynx, a couple of people have told me it's better, though.

    BobW
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  • From kirkspragg@21:2/150 to Bob Worm on Saturday, August 23, 2025 17:55:59
    Eugh... mutli-I/O cards with 16450 UARTs really spoiled my day a few
    times back in the 90s. I (486SX-25 with 16550) used to play Duke 3D with my brother (486DX2-66 with 16450) over serial and it would regularly crash. Always my brother's computer pulled it down.

    Lol! I have similar memories of playing the settlers 1 & 2 as well as the original warcraft over a null modem connection with a mate who has a 486 & my 386dx40. It mostly worked but had to keep baud rate down at something pitiful or it would all fall apart.

    These days trying to find ISA multi-io cards with 16550 uarts is difficult :/ the type of UART a card has its not something the ebay vendors selling vintage PC cards advertise.

    I'd love to try out an ISA EPP printer port to see how much faster that would be vs a standard one, but how do you find an ISA EPP printer card? ISA Parallel port cards are there but how do you tell if its standard SPP or the faster EPP parallel port?

    ... The neophyte knows the rules; the expert, the exceptions

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  • From kirkspragg@21:2/150 to Bob Worm on Saturday, August 23, 2025 18:05:13
    The intrusive thoughts finally got the better of me so I DOSBox'd two copies of LapLink3 and sniffed the traffic going between them. I don't understand all the messages yet but it doesn't look ridiculously complicated - if I ever get the free time I could probably write an implementation of it for my Acorn, which would make copying files back
    and forth much easier. I would need to mangle file names (Acorn allows longer filenames, uses . as a directory separator and has file type as a file system attribute) but it would make a fun project.

    Well if you do get round to making an implementation for Acorn, I'm sure the folks here would be interested so let us know if you do. It would be a pretty cool project.

    I've never tried FastLynx, a couple of people have told me it's better, though.

    I think laplink can be stable if both ends are roughly the same speed, otherwise it just tends to get unstable and either crash completely or fail part way through a transfer.

    Thats said, i've never had much luck running it in dosbox at one end and connected to a 'rea' pc at the other. It works for small transfers but once I try > 10 MB or so it either locks up or craps out mid way through the transfer. I've tried messing with various dosbox settings, increasing and reducing the speed ect, but it never seems to be stable.

    Fastlynx seems to be a bit more reliable, though I have noticed if your doxbox machine is considerably faster than the PC at the other end it tends to drop the connection. That is easy enough to fix though, simply by reducing the number of cycles (effectively the emulation speed) it fixes it.

    ... Those butts are ripe for kicking - Mike

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  • From Bob Worm@21:1/205 to kirkspragg on Sunday, August 24, 2025 17:37:40
    Re: Re: DIY Laplink cable results
    By: kirkspragg to Bob Worm on Sat Aug 23 2025 18:05:13

    Hey, k!

    Well if you do get round to making an implementation for Acorn, I'm sure the folks here would be interested so let us know if you do. It would be a pretty cool project.

    I shall keep you informed (if I ever get around to it).

    I constantly hear complaints about unreliable transfers on Laplink - I wonder if there's an element of emulation issues because I used to constantly send stuff between 386 & 486 laptops, probably a 286 desktop, I don't remember ever having a single failure.

    I'll do more testing :)

    BobW
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  • From kirkspragg@21:2/150 to Bob Worm on Sunday, August 24, 2025 19:58:44
    Hi Bob!
    I constantly hear complaints about unreliable transfers on Laplink - I wonder if there's an element of emulation issues because I used to constantly send stuff between 386 & 486 laptops, probably a 286 desktop,
    I don't remember ever having a single failure.

    I'll do more testing :)

    You make a good point there. I did use laplink quite a bit in the 90s to transfer stuff between various computers and I don't recall it being that unreliable either.

    Must be dosbox. Or maybe nostalgia has me remembering things as better than they were....

    Let us know how you testing pans out.

    ... If you throw mud, you will have dirty hands.

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  • From Mortar M.@21:2/101 to kirkspragg on Wednesday, August 27, 2025 13:44:03
    Re: Re: DIY Laplink cable results
    By: kirkspragg to Retroswim on Fri Aug 22 2025 22:18:43

    ... Hear no evil, speak no evil, C:\NOEVIL

    The code-monkey's credo. :)
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  • From Mortar M.@21:2/101 to kirkspragg on Wednesday, August 27, 2025 14:12:26
    Re: Re: DIY Laplink cable results
    By: kirkspragg to Bob Worm on Sun Aug 24 2025 19:58:44

    Must be dosbox. Or maybe nostalgia has me remembering things as better than they were....

    I would check it against another VM like VirtualBox of 86box. That'll tell if it's an emulation or host issue.
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  • From Bob Worm@21:1/205 to Mortar M. on Wednesday, August 27, 2025 22:32:17
    Re: Re: DIY Laplink cable results
    By: Mortar M. to kirkspragg on Wed Aug 27 2025 14:12:26

    Hi, Mortar M.

    Must be dosbox. Or maybe nostalgia has me remembering things as better than they were....

    I would check it against another VM like VirtualBox of 86box. That'll tell if it's an emulation or host issue.

    I have a sneaking suspicion that hardware handshaking might be something to do with this. I have been trying to push Laplink III from DOSBox to a laptop running FreeDOS. The remote bootstrapping process on the laptop seems to insist on hardware handshaking and isn't getting it from either DOSBox or the cheap USB to serial adaptor I'm using. Could also be the cable, I suppose. I need a little spare time to poke at it with an oscilloscope and figure out what's up.

    I could probably just copy it on via x/y/zmodem using the FreeDOS bundled terminal emulator - that works fine (to the extent that you can type one end and it appears on the terminal at the other). Possibly it's just the bootstrap that doesn't work.

    I'm away tomorrow but I'll try to find some time to do this when I get back.

    BobW
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  • From kirkspragg@21:2/150 to Mortar M. on Thursday, August 28, 2025 00:34:19
    I would check it against another VM like VirtualBox of 86box. That'll tell if it's an emulation or host issue.

    Last time I checked, neither allowed you to pass through VMs parallel port to a 'real' parallel port on the host machine, at least not when the host machine is running windows.

    Dosbox-x does all this which is why I use it, that and the parallel port transfer speed it much faster than com port with null modem.

    Though if you've got suggestions for other visualization options I should try, pass them on & i'll have a look and try them out.

    ... He's one bit short of a byte.

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  • From Mortar M.@21:2/101 to All on Thursday, August 28, 2025 09:44:55
    Re: Re: DIY Laplink cable results
    By: kirkspragg to Mortar M. on Thu Aug 28 2025 00:34:19

    ... He's one bit short of a byte.

    Word!
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  • From kirkspragg@21:2/150 to Mortar M. on Thursday, August 28, 2025 15:38:42
    ... He's one bit short of a byte.

    Word!
    Nice to see we are on the same page.

    Took me a while to register what you were saying there, I almost JMPed to the wrong conclusion!

    ... Anti-Windows Taglines - Windows Errors!

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