"So as much as connecting a TPDD to a Z88 is a cool idea, my mass storage solution is to upload to either of my modern systems."
Typically the point of TPDD client software is not actually to connect to a real TPDD but to an emulator on a modern system. Which you should be able to do with the TPDD client. But as you say there are better supported ways to do that for the Z88. Plus the Z88 has excellent onboard permanent storage options. For the Z88 itself I REALLY wanted to like it. It's like a Model T with the display issues fixed and orders of magnitude advancement in programmability and onboard peripheral/storage options. I have a couple. But it is just way more crashy and likely to lose your work than the 100/102/200 which is frustrating. I always end up putting it down and going back to my Model Ts. -- John.
