My machine only has 177kB (a 128k 1460 card, plus whatever is normally on the processor board I guess) of memory, so even running some fairly small HSM programs isn’t possible without drip feeding.
I’m using a Shoplink Flash 2.0 USB to RS232 converter on a 15 foot long RS232 cable (with a female to male converter on the end because Fadal is weird).
Transferring files using the normal transfer command (TA) seems to work fine up to 115,200 baud, but I couldn’t get DNC to work above 38,400. This is probably good enough, if I ever have any serious surfacing to do I guess I will find out if it can keep up.
One thing to keep in mind is that you need to reset the USB to RS232 converter if you stop a program in the middle, as the machine only sends ‘go’ commands (sequentially after every line it processes).