The mysterious "L" port

[MattCarp]

On the back of the PCjr I was looking at the ports. I couldn't remember what the "L" port was for. I couldn't find it in the Tech Ref, Googled it, and found out it was a spare and not connected to anything on the system board?

Are there any thoughts about what was intended for this? Why label it "L". If it was a spare, I would have expected them to leave it blank...

[DoctorOctal]

There’s also an unused jack reserved for future expansion (labeled “L” for “Later,” explained an IBM spokesman).

— “Report on IBM’s New PCjr”, Compute!, January 1984, p. 48.

But I, too, would like to know what use IBM had in mind for a soldered-in connector that’s not electrically connected to anything on the motherboard except ground.

[Trixter]

I never looked at it -- I just assumed it was connected to some signal line. If it's really connected to only ground, that's pretty funny.

[monzamess]

I always thought it was a light pen port but never gave it much thought, not caring much for light pens.

[MattCarp]

That’s the LP port...

[Brutman]

The joke at the time was that "L" stood for "Later."

[toddvernon]

Pretty sure it's a Light Pen port.

[Brutman]

"LP" is for the light pen. "L" is just unused .. hence the "Later" joke.


Mike