USB to RS232 are usually problematic as they are software driven and most people can't get them to connect.
I have a PCMCIA 1 adapter card like this one which works on my old Pentium 2 Sony Viao laptop with an RS232 LPG interface. The laptop does have it***8217;s own RS232 com port which I is the com port I usually use
I also have a 7 year old Toshiba Satellite Pro which doesn***8217;t have an RS232 com port but has a PCMCIA adapter slot and the card also works with this laptop.
For later laptops you will probably need a PCMCIA 2 adapter card as they are phisically sligthly dfferent.