Taking a stab here, looks to be one of the earliest models they released.
The 9V only powered ones were earlier, but the very earliest came with "PET" style keys, similar to the ones on the PETs:

Not the best to type on, but they look cool.
As for startup, should be able to just turn it on and go, though that particular variety seems to take a few seconds to show the BASIC screen (mine do, anyway.)