As Mr. Karas had explained,

Giri, simply choose one of these:

1. use external RAM for buffering,
I think a 2kbyte chip is more than enough, you can either use address-data multiplexer chip (74LC573) in order to use MOVX, or wire all address to P0+P2 and data to P1 for alternative hardware design,

2. find other '51 derivative,
that equipped with onchip XRAM that fits your need
(It's very hard to find in Surabaya/Malang, I had to use AVR ATMEGA8 for that kind of task.... actually I had done it few months back ... woops I guest this one is not '51 after all)

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