I do not remember year, but ...:
some year in USA born another Sinclair clone.
It was designed to be compatible, and even exceed orginal sinclair 48!
so it born. 
Shiny new Timex 2048.
It failed to be 100% compatible...
specification:
like sinclair 48 
plus
New plastic keyboard with rubber contacts, like in TV remote.
keys are better than in 48... when Timex is new. then they fuck up
like keys in TV remote. You can simply fix it, but then keys will 
repeat too quickly - just cut "confetti" from aluminium foil, and 
use two sided adhesive tape to place them on each rubber. 
this will fuck up anyway, but then just do the same. in hard use (like coder
stuff) it will last for about half of year. If you are not a coder, 
and 4 eg a musican, you can make most used keys on "microswitch" like in
a lot of mouses, or CD equipment. Just soldier this microswitch to timex
key-board, and use. At start it is hard to use, but will last for years.

anyway
in keyboard SPACE is full-sized.
Ula is placed in square SMD chip, so it is practically unfixable.
Ula holds - xtra vidmodes (below) irq generating (can be stopped trough
software) and memory managment (can hook off memory)
Timex is differ timed. i do not remember exactly how, but i think
it have moved all scren by 6 tacts (longer upper border by 6 tacts).
In IN 254 unused bits have random value, so some games does not work.
they can be fixed by simple and, or invert controlled unused bits.

Also small changes in rom (below).

Timex also have KEMPSTON joy... but! there is NO +5V on Kempston, so 
such things as Autofire or Mouse will NOT work :( it can be simply fixed :)

FIX

Timex do not have +12, -12, -5 volts on Edge connector, and 
also do not have video signals on edge connector, exepting composite video.
A! and timex have xtra CHINCH monitor output.

                                TIMEX 2048
as described you dumb :)
                                TIMEX 2068
all the same, exepting BIG changes in rom (best thing is to buy 
EPROM) which are so stupid, as STICK basic command, who 
controlls joystick. On the case the plastic (this thing, which is 
sticked onto keyboard, and for example colors are printed on it...
excuse my engish...) appearing new commands and instead of
2048 there is 2068. 
I Heard also about T/S 2068... It had silver case, but i do not know
what is difference between Timex 2068 and T/S 2068. Maybe only case,
maybe not only case... Info welcome (i have Timex 2068, but NO
T/S 2068... Maybe it is T/S 1000 ?)

(actually i found out, that T/S 2068 have AY interface built in (timex 2068 have not) but

hooked up to strange ports.)

                                TIMEX 2128
this timex have 128 kb of ram, and a AY sound interface.
banks & ports are organized as in 182+2.
there is NO speed change, or such things. 
I do not know how to write it... all is same as in 2048,
but banks, sound, 2nd screen, is like on +2. IT IS 128 compatible.
Also Slow-Fast banks (even and odd)
Sound is reachable trough small stereo jack output. ABC stereo ofcoz.
BTW. in 128 mode all capablities of 2048 are achieved, 
so you can for example:
switch 2 timex vidscreens, and also swith 2 128 vid screens, so you have
 4 SCREENS!!! 
also extra modes are doubled, so you have 2 screens of multicolour
 (interlaced multicolour... HUH!) and 2 screens of 512*192 
 (interlace!! 512*384... i saw few pictures... even Pentagon does not
  have those!!!!!)
Malyrules

                           TIMEX 2048 and above 
1. Graphic modes:
  All graphics modes are reachable trough OUT 255,nr  Also state of 
this port can be read by IN 255
 At power-up always ZX Spectrum vidmode is set, port 255 have value = 0.
It is hardware provided, but for insure, or warm reset (JP 0) 
there is one and only change in rom at adresses 4762 and 4763
where insteado of 10,12 (#OA,#OC) values, whih jumps to procedure printing:
 "(C) 1982 Sinciair..." 
is adress to end of basic interpreter, where are three new instructions:

14446 #386E #D3 #FF OUT (#FF),A ; send 0 to #ff
14448 #3870 #CD #OA OC CALL #OCOA ; "sinclair..."
14451 #3873 #C9 RET- ; "(C)", return to 4764

Extra vidmodes:

O  - Spectrum mode;  memory at 16384 to 22527 (#4000-#57FF) - 256*192
                               22528 do 23295 (#5800-#5AFF) - attributes

1  -  same as above, but videoram starts from 24576 (#6000)
                                   attributes 30720 (#7800),
2  -  Multicolor
 data starts from  16384 (#4000) 
 but there are also ATTRIBUTE FOR EACH BYTE on the screen 8192 bytes higher.
 
6 -  Hi-res. Will be described below.

SO BITS MEAN:

0UT  255, 7 6 5 4 3 2 1 0

bit  0 - Set - ULA makes picture taking data from #6000

bit  1  - Set - ULA takes attributes from #6000-#7AFF

bit  2  - Set - Hi-res on. (512*192)
 In columns 0,2,4,6, and so on - data
 In cols    1,3,5,7  and so on - attributes

bits 3,4 & 5 setting ink colour (for whole screen) in hi-res mode.

  3 4 5 colour

0 0 0 0 black
1 0 0 1 blue
2 0 1 0 red
3 0 1 1 purple
4 1 0 0 green
5 1 0 1 cyan
6 1 1 0 yellow
7 1 1 1 white

EXAMPLES:

OUT  255,6 - full hi-res mode. 
0,2,4,... cols - data from #4000
1,3,5,... cols - data from #6000
Ink - black
Paper - white

bit 6 - set - interrupts disabled

bit 7 - NOT USED

Marek Sawicki/ Translated by Malyrules.

There is also 244 port! This port is designed to cut off ram.
each bit of this port represents one 8K cluster (8*8=64)
Set- disabled.
This port is NOT cleared by reset, so if you disable ROM you
must power down your machine to run.
In orginal T2048 and T2128 disabled RAM or ROM go to 255 value.
It can be easily used to do RAM or ROM upgrade, cause switched 
off RAM data lines are in high Z.
Malyrules