Carl's and AJR's contributions have advanced the state of the Alphatronics emulation in wide leaps ... I will post disk images tomorrow that match the drivers and may help.
The P2 series now shows signs of life after the provision of a HSYNC signal from the TMS9927 driver.
All you need is a little patience, as it takes a while for the MOS prompt to show up.
From here you can boot into two regions on the disk using the B (in the case of this disk a BASIC dialect) and B1 (here shown with a disk utility) commands.
A speciality of the TA P2 and P2S is the existence of a CP/M with a TPA at 0x4300 that uses no bankswitching and keeps the MOS ROM below.
The P2U has the same bank switching logic as the P3 and can boot a "full" 64K CP/M
In MAME, the P2 varieties and P3 share most of their code, so at the moment even the lowly P2 can boot the 64K CP/M.
The Alphatronics' cursor moves back to line 1 (and then down the screen again) if you go beyond line 24 of the text screen.
So at the moment the next challenges are (and help is again most welcome)
* fix the cursor movement
* give the P2 line its proper video chip, the 5527 instead of the 5537
* seperate the P2 models better (single sided vs. double sided, remove bank switching in P2 and P2S but keep for P2U)
* check why video using the HSYNC is slowing down the system
* fix data exchange between P3 and P2
I thought I could get around the double stepping problem by allowing the P3 to switch to a DSDD drive, but even then I get a BDOS error if I try to access P2 disks via the pseudo drive P: