Embedded Systems Design, 2nd Edition

Embedded processors 49

Bus interfaces

Many of the signals shown in the pin out diagram are the

same as those of the MC68000 — the function codes FC0–2,

interrupt pins IPL0–2 and the bus request pins, RESET*, HALT*

and BERR* perform the same functions.

With the disappearance of the M6800 style interface, sepa-

rate signals are used to indicate an auto-vectored interrupt. The

AVEC* signal is used for this function and can be permanently

asserted if only auto-vectored interrupts are required. The IPEND

signal indicates when an interrupt has been internally recognised

and awaits an acknowledgement cycle. RMC* indicates an indi-

visible read-modify-write cycle ...