Yes, Bryan – today’s modems will work on a Tandy 1000SL.
The Tandy 1000 SL is an XT-compatible, running at approximately 8 Mhz.
External modems will run to speeds up to 9600 bps reliably, so if you
want an external modem, getting a 14.4 and running at 9600 bps would
be a safe bet. [as 14.4’s are relatively cheap nowadays]
Internal modems are a better choice. I don’t have experience running
internal modems on an XT-compatible (I have a 286 – 1000 RLX :-> ), but
I suspect you can run an internal modem (as long as it has the 16550A UART
chip on it – look for it!!), you should be able to run the modem at the
speed its rated at.
Data compression is a different story – on my 286 here, even though my
modem says “57,600 with compression”, I can usually safely run the comm
port at 38,400, and always safely run it at 19,200. But one important thing
to remember: the difference in most transmissions is *small* between
using modem data compression and not using modem data compression.
Transferring binary files (.ZIP, .GIF, etc) will never run at 57,600,
38,400, or 19,200 on a 14,400 bps modem. They will transfer between
10,000 bps and 17,000 bps, depending on how good your connection is,
how fast your hard drive is, and the hard drive of the sender is, etc.
Hope this helps! My suggestion is: Get an internal modem – 14.4 or 28.8,
your choice. I know that the 14.4 will work great (there is at least one
SL owner on here (Yee Chang Lee) who runs a 14.4 at 19,200 and is pleased
with it. I don’t know for certain how a 28.8 would work, but I can’t
see why it wouldn’t run at at least 38,400.