I see it more of a 2068 with addons.
And with a much better keyboard, judging from the pictures.
Timeword is probably on a "SCLD memory bank" as well as TT3000 ROM.
I am not sure what would an "SCLD memory bank" mean, but TimeWord (and TT3000 ROM as well) works fine as a main ROM, where in TC2048 normally is Basic ROM.
I assume there is a 27512 (64Kx8) EPROM, divided in 4 banks 16K each:
- main bank with:
- boot menu,
- TOS routines (around 4 KB, as M397's ROM),
- TEC routines (including 64/85 column printing, RAM disk, hi-res DRAW!/PLOT! - I'd say 8-10 KB),
- Standard Basic bank, so 16 KB,
- TimeWord+ (the version for TC2068 is also 16 KB),
- 80-column CP/M Terminal bank (TT3000 ROM also takes 16 KB).
Invoking TEC commands seems pretty standard - you have TOS commands suffixed with "*"and new RAM disc/graphic/sound commands suffixed with "!". In both cases, Basic tries to print an error using
RST 8 command, so that's the best way to switch from Basic to TEC ROM.
As I wrote before, there must be an additional memory page register, for both ROM and RAM. It would take 2 bits to control ROM pages (if the bit 7 of the port 255/#FF is not used, otherwise one bit would do). Another 2 bits of this register would choose a 64K RAM block, becoming available when setting a desired bit (or bits) to 1 in the port 244/#F4. Block 0 is the Basic 48 main RAM, i.e. available on boot without any need to set in the port 244.
Two more bits of the memory bank register would allow to expand RAM to 1 MB. Remaining 2 bits must be used for some other purposes - like enabling/strobing TENET chip (probably an Intel '31 or '51 MCU, as in the TENET prototype).
That's a nice bunch of speculations, isn't it?

But this is how I would design it, given the old SCLD and not much funds for the project.