why only one serial port?

[geforceg4]

http://www.ebay.ca/itm/Vintage-Apple-Macintosh-PowerPC-G3-M3979-Computer-untested-OO2141-/331942654981?&_trksid=p2056016.m2516.l5255


looking at the image of this g3 desktop
why is one of the serial ports blocked/covered up?

[GaryN]

Probably because it has the then-optional 56k modem built in. That might be a cover plug over the port.

[geforceg4]

so does that mean the port is still there? functional? as long as u remove the modem?

[GaryN]

Somehow, I'm sure that somebody, somewhere, knows the answer to that question.

but it's not me…

[Texas_RangerAT]

Would the internal modem somehow use the same connector as the external modem (serial) port? That would be my only explanation, if the serial port is already used by the modem you couldn't use it for anything else. That seems odd to me though and besides it seems you'd need a special logic board without the second serial port to achieve that - I can't see how you could cram in a blanking plate between the connector and case!