The SCC68070 is a
Philips Semiconductors-branded,
Motorola 68000-based 16/32-bit processor produced under license. While marketed externally as a high-performance
microcontroller, it has been almost exclusively used combined with the Philips SCC66470 VSC (Video- and Systems Controller) in the
Philips CD-i interactive entertainment product line.
Instruction execution timing is completely different
Interrupt handling has been simplified
The SCC68070 has
MC68010 style bus-error recovery. They are not compatible, so exception error processing is different.
The SCC68070 lacks a dedicated
address generation unit (AGU), so operations requiring address calculation run slower due to contention with the shared ALU. This means that most instructions take more cycles to execute, for some instructions significantly more, than a 68000.
The MMU is not compatible with the
Motorola 68451 or any other "standard"
MotorolaMMU, so operating system code dealing with memory protection and address translation is not generally portable. Enabling the
MMU also costs a wait state on each memory access.
Even though the SCC68070 is a 32-bit processor internally, it has a 24-bit
address bus, giving it a theoretical 16MB maximum
RAM. However, this is not possible, as all of the on-board peripherals are mapped internally.