Thanks Derek, I´ve already done that, I´ve built a protoype board with an 8052 basic chip running at 11.0592 MHz. , a 3 to 8 74hc373 chip and a 74hc138 address decoder for chip selects, I´ve configured SRAM at 0x2000 (6264 8kx8)as code mem (RAM´s RD attached to RD in the 8052 not PSEN), and nothing got going :=(. I don´t know what might be going wrong! When I pull EA low and use an external eprom programmed with a monitor, the chip works just fine. Then I´ve decided to program a 27C64 with BASIC-52, and use it on this chip, just to find out if the problem was the 8052basic internal rom, but I´ve got the same results, nothing happened. It´s frustrating I live in Argentina and it´s hard to find books about microcontrollers, not to mention the chips and other stuff. I´m lost, but with the hope to find the answer to my problem. Once again thanks.