Well the equipment is a kind of batch counting device - and uses 9 numbers common cathode type 7 -segment LED displays. ( 9 digits )

The segments of all the 9 digits are driven by the output of 9 numbers DM74LS573. The inputs of all these octal latches are driven by the P2 port of the P89c51.

OK so what is the problem ? When the equipment was referred to me for a problem of random display jitter, I looked at the circuit and found there was no driver like 74244 for the common segment bus.

The data sheet for P89c51 - P2 pin High Level output current says :
VOH @ VCC = 4.5V and IOH = -30 microAmp.

The data sheet for DM74LS573 says for High Level Input current :
IOH = 20 microAmp ( and 9 such were being driven by the 89c52!)

The question is, without the driver how did the set up work at all ? How do I explain THAT to the guy ? Or am I missing something ?

Raghu