Need more than two external interrupts in 8051
One option is to use an I/O expander such as the MCP23017 or MCP23S17 (I²C or SPI).  These chips can record an interrupt on any of 16 pins and report it over a single (additional) pin.  Reading two 8-bit registers will tell you which of the 16 pins sent the interrupt.  This chip is also available in an 8-port version (MCP23008 or MCP23S08).