Well, I found the problem with the sis900 driver.

If you look in the source file sis900.inc, you will find these lines at the end of the transmit code:

;****make sure packet transmitted successfully****
mov esi,10
call delay_ms

There are your 10ms :o)

I cannot test removing or reducing this delay, but you might like to experiment yourself, until I hear back from the author.

Mike.

Dear Mike,

many thanks for revisiting the SIS900.INC driver.

Commenting the lines 1034, 1035 etc
;****make sure packet transmitted successfully****
; mov esi,10
; call delay_ms

SOLVES THE SIS900.INC driver problem.

Now Realtek 8029, Realtek 8139 and SiS900 based drivers behaved similar. Time delay between two UDP packets cca 85 microseconds with MIKE.ASM test program. <For others see above for download>

Viktor

hey, how can u count on RDTSC? it is not present on 486 and oldre processors, and how do you determine the divisor? - the accurate cpu frequency, i give u an advise: use pit timer directly
MATRIX

Look at Intel HW manuals. Shortly newer processors all have RDTSC 64long binary couter, which counts CPU clock frequency RDTSC => EAX = LSB EDX => MSB.

This is the most precise timing at CPU.

Viktor

look at my other thread about timing
http://board.flatassembler.net/topic.php?t=2207

MATRIX