interesting problem of external memory interface

[sandeep_sggs]

Dear all,

i have tried to interface 256K bytes of external EEPROM to 89s52. following is the interface layout. when i touch the lines shown below, my memory is accessed properly. when i remove my finger from the indicated area, memory fails to be accessed. m observing some pre-stored pattern on LEDs.

m attaching the layout and schematic for this interface.
pls help me if anybody can!
thankx!

 

[bobcat1]

HI

Add series dumping resistor on the Address and data bus and pullup resistor on the A/D bus

Dupming resistor should be in the range of 33 ohm

All the best

Bobi

 

[sandeep_sggs]

the problem is solved eventually.

The problem was with the power supply. it was not giving adequate driving current for the board. I increased the rating and everything was OK after that.