I hope I’m not too offtopic. I’ve got this old Pentium 120MHz which I sometimes use as an Impulse Tracker machine. It’s got a built-in soundcard but no joystick port so I can’t get MIDI out of it. I want to use it as a MIDI instrument. It’s an IBM Thinkpad 365XD, has parallel and serial ports. No USB also, it’s a very old machine. 
Any ideas? I’m not a solder guy, btw.
Not really a straight answer to your question but there are old midi-interfaces which communicate via serial-port. F.ex. I’m using an Emagic Unitor8 mk1 which works via the serial port.
I don’t get it though, why do you want to use your old laptop as a MIDI-instrument? Are you trying to control or sync Impulse Tracker via midi or what?
If so, I think that could get kinda tricky (if possible) and it would probably be easier to sample the track from Impulse Tracker and use it as a sample in Renoise, if there’s something in the sound from IT that appeals to you. You could also try to run Impulse Tracker on your new computer via dosbox (emulates a pc) or vdmsound (emulates a soundblaster) to sample the sound that way.
Impulse Tracker, yes and perhaps Edlib. It’s more about giving a use to this old machine than anything else. Thanks for your answer.
You want to have a MPU-401 link between two machines, this should be possible, though with the serial link you have to be carefull with the ground wire if you planned to solder the cable yourself, but AFAIK, the wiring is straight one on one (if you can find the schematics).
At least you can use an ordinary straight audio-DIN cable to connect your MIDI stuff with eachother through the DIN connectors.
Sorry, I didn’t understand. 
I need to solder two MPU-401s together?
No, two serial db connectors with wiring in between and connect the pc’s by plugging the wire in each pc’s serial/game port.
I don’t know if the very old stuff came with a game-port, usually you can configure the game-port as a MPU-401 device in the BIOS.