motorola 68000 by matt bachiochi, will lowrey, matt petrick, scott schenkein, and mark wade
TRANSCRIPT
Motorola 68000
by
Matt Bachiochi, Will Lowrey, Matt Petrick, Scott Schenkein, and Mark Wade
Registers
• About
• Status Bits
• Distribution
Registers: About
• General purpose register-based machine
• Every data register can be used as an accumulator or a temp register
• Data bytes are arranged with least-significant byte at the higher address
• This is known as the endian approach
Registers: Status Bits
• The M68000 has 10 status bits– T: Trace bit 15
– S: Supervisor Mode bit 13
– I2: Interrupt Mask 2 bit 10
– I1: Interrupt Mask 1 bit 9
– I0: Interrupt Mask 0 bit 8
– X: Sign Extend bit 4
– N: Negative bit 3
– Z: Zero bit 2
– V: Overflow bit 1
– C: Carry bit 0
Registers: Distribution
• Total number of registers is 19– 8 are general data– 7 are general address– 2 are stack pointers– 1 processor status word– 1 program counter
Addressing Modes
• The Motorola 68000 has 14 different addressing modes– Register Direct– Address Register Indirect– Absolute Data Register– Program Counter Relative– Immediate Data– Implied Addressing
Technology
• The 68000 was originally a 5 volt NMOS
dynamic construction
• Later updated to a CMOS
• CMOS-TTL bridged busses
• Bus Arbitration Control circuitry
Motorola 68000
Is a CISC!
With only one data pipe.
Speed
• Clock speed: 8 - 16 Mhz
• Dhrystones: – Raw processing benchmarks integer data– 2100 - 4376
• MIPS: – Millions of instructions per second– 1.2 - 2.5
The Motorola 68000 Processor
Historical Computers
The Apple LISA (1983)
• The Precursor to the Macintosh
• Local Integrated Software Architecture
• 1 Meg Ram, 10 Meg HDD
• Cost: $10,000
The Apple Macintosh (1984)
• Known as the “Mac-in-the-box”
• First to use MacOS• Had 128K RAM• No hard drive• Cost: $2500• Market for Radiation
Underwear
The Commodore Amiga (1985)
• The fastest commercial M68000
• Had 512K RAM• Capable of Color• Cost: $2,800