//
TH----timer high
TL----timer low
//
TMOD----timer mode
//
TCON----timer control
TF----timer overflow flag
TR----timer run
IE----interrupt enable
IT----interrupt trig mode
//
IE----interrupt enable
EA----enable all
ES----enable serial
ET----enable timer
EX----enable external
//
SCON----serial control
TI----transmit interrupt
RI----receive interrupt
