Default Where to locate firmware for Tab PC?

hi guys

i have recently recieved a old Tablet PC as new toy
Model number UM-A102, Build company unknown...
and these are the spec that was written on the little menu that came in the box
CPU processor speed 1.2GHZ
Memory 4GB-32GB
Tf card 128M-16G
it currently running Android 4.1.2

my question is
dose anyone know where i could find a newer firmware that might work with this unit?
have spent hours online digging but no luck so far
if anyone could point me at an right direction would be very very nice

thanks in advence~
Unit-00: Sony Xperia Z L36H C6602
System: Official Taiwan 4.4.2 KK 10.5.A.0.230 (Rooted with towelroot)
Unit-01: Galaxy Tab GT-P1000 GSM
System: CM11 - Android 4.4.4 20140627 Unofficial-P1
Unit-02: Galaxy S4 GT-I9505 (i think is LTE? it's running Australia Optus 4.3 Firmware)
System Official Australian Optus 4.3 JB I9505XXUEMK9