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14.3 | SFRs for External Interrupt
As far as external interrupts of 8051 are concerned, there are three SFRs directly related with these. ey are
TCON, IE and IP. We will discuss only the related bits of these SFRs. Other bit functions of these SFRs
would be discussed in the following chapters on Timer interrupt and serial interrupt.
14.3.1 | TCON (bits 0, 1, 2 and 3)
TCON is a bit-addressable SFR with byte address 88H. Its bits may individually be designated as TCON.0,
TCON.1 and so on, with bit addresses, like 88H, 89H, etc., as shown in Fig. 14.2. Alternatively, these bits
may also be referred to as IT0, IE0 and so on. Out of 8 bits ...