While the 68000 family has a 32-bit design, the 68000 used in several early models is generally referred to as 16-bit.

The 68000 has a 23-bit external address bus and two byte-select signals " replaced " A0.

The 68000 did not meet the Popek and Goldberg virtualization requirements for full processor virtualization because it has a single unprivileged instruction " MOVE from SR ", which allowed user-mode software read-only access to a small amount of privileged state.

The 68000 does provide a bus error exception which can be used to trap, but it does not save enough processor state to resume the faulted instruction once the operating system has handled the exception.

The 16-bit PDP-11 instruction set has been very influential, with processors ranging from the Motorola 68000 to the Renesas H8 and Texas Instruments MSP430, inspired by its highly orthogonal, general-register oriented instruction set and rich addressing modes.

A large DIP package ( such as the DIP64 used for the Motorola 68000 CPU ) has long leads inside the package between pins and the die, making such a package unsuitable for high speed devices.

The 68000 line of processors has been used in a variety of systems, from modern high-end Texas Instruments calculators ( the TI-89, TI-92, and Voyage 200 lines ) to all of the members of the Palm Pilot series that run Palm OS 1. x to 4. x ( OS 5. x is ARM-based ), and even radiation hardened versions in the critical control systems of the Space Shuttle.

After the mainline 68000 processors ' demise, the 68000 family has been used to some extent in microcontroller / embedded microprocessor versions.

The 68000 and video controller take turns accessing DRAM every four CPU cycles during display of the frame buffer, while the 68000 has unrestricted access to DRAM during vertical and horizontal blanking intervals.

For those running on a Motorola 68000 processor ( like the TI-89 ), C programming ( possible using TIGCC ) has began to displace assembly.

In its history, Stratus has offered hardware platforms based on the Motorola 68000 microprocessor family (" FT " and " XA " series ), the Intel i860 microprocessor family (" XA / R " series ), the HP PA-RISC processor family (" Continuum " series ), and the Intel Xeon processor family (" V Series ").

S-Net has also been called NetWare 68, with the 68 denoting the 68000 processor.

ARexx is written in 68000 Assembly, and cannot therefore function at full speed with new PPC CPUs, a version of ARexx has not been rewritten for them and is still missing in MorphOS 3. 0.

The home system featured two CPUs: the 16-bit Motorola 68000 main processor running at 12 MHz and the 8-bit Zilog Z80 coprocessor running at 4 MHz.

The main CPU is a 12. 5-MHz 16-bit Motorola 68000 processor.

* CPU: a 16-bit Motorola 68000, the same as the Mega Drive.

The 32016 was also very similar to the Motorola 68000, which also used 32-bit internals with a 16-bit data bus and 24-bit address bus.

Generation 1 68000 CPUs primarily competed against the 16-bit 8086 / 8088 and 80286.

The original 68000 had a 24-bit address bus and a 16-bit data bus.

The centerpiece of the machine was a Motorola 68000 microprocessor connected to a 128 kB DRAM by a 16-bit data bus.

Like the 128K Macintosh before it, the 512K contained a Motorola 68000 connected to a 512 kB DRAM by a 16-bit data bus.

* Atari released Quantum, an early arcade game to use a 16-bit 68000 CPU, for more detailed and smoother graphics.

The early 1980s saw the first popular personal computers, including the IBM PC / AT with an Intel 80286 processor using 24-bit addressing and 16-bit general registers and arithmetic, and the Apple Macintosh 128k with a Motorola 68000 processor featuring 24-bit addressing and 32-bit registers.

As early as 1981, laser printers such as the Imagen Imprint-10 were controlled by external boards equipped with the 68000.

It is a version of the Motorola 68000 with an 8-bit external data bus, as well as a smaller address bus.

A PDP-10, a PDP-8, an Intel 386, an Intel 4004, a Motorola 68000, a System z mainframe, a Burroughs B5000, a VAX, a Zilog Z80000, and a 6502 all vary wildly in the number, sizes, and formats of instructions, the number, types, and sizes of registers, and the available data types.

In the end, the 68000 did retain a bus protocol compatibility mode for existing 6800 peripheral devices, and a version with an 8-bit data bus was produced.

This was a 68000 with an 8-bit data bus and a smaller ( 20 bit ) address bus.

The previous 68000 and 68010 processors could only access word ( 16 bit ) and longword ( 32 bit ) data if it were word-aligned ( located at an address that is evenly divisible by 2 ).

An 8-bit data bus version of the 68000 ( i. e., the 68008 ) was intended for use in future 8-bit designs.

Numerous versions included Apple II, TI 99 / 4a, DEC PDP-11, Zilog Z80 and MOS 6502 based machines, Motorola 68000 and the IBM PC ( Version II on the PC was restricted to one 64K code segment and one 64K stack / heap data segment ; Version IV removed the code segment limit but cost a lot more ).

With the exception of the split of general purpose registers into specialized data and address registers, the 68000 architecture is in many ways a 32-bit PDP-11.

The expansion of the memory space caused an issue for any programs that used the high byte of an address to store data, a programming trick that was successful with those processors that only have a 24-bit address bus ( 68000 and 68010 ).

Because of its smaller data bus, it was only about half as fast as a 68000 of the same clock speed.

Except for its smaller data and address buses, the 68008 behaved identically to the 68000 and had the same internal organization and microarchitecture.

The general rule of thumb is a 286, 386SX, 68000 or low-end 68020 / 68030 ( e. g. Atari, Mac LC ) system ( using a 16 bit wide data bus ) would require two 30-pin SIMMs for a memory bank.

Some processor architectures, such as the Motorola 68000, Motorola 6809, WDC 65C816, Knuth's MMIX, ARM and x86-64 allow referencing data by offset from the program counter.

Autoconfig requires the 68000 data and address bus to be available to all devices on the bus.

Many 32-bit computers ( such as 68000, ARM, or PowerPC ) have more than one register which could be used as a stack pointer — and so use the " register autoincrement indirect " addressing mode to specify which of those registers should be used when pushing or popping data from a stack.

There was a so-called 68070 processor, produced by Signetics ( Philips ), and was a modestly improved 68000 series processor, with a simple, on-chip MMU and I²C bus support.

The processor is upgraded not by replacing the 68000, but rather by fitting a connector over the CPU, which allows the upgraded CPU to commandeer the system bus.

VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI / IEEE 1014-1987.

In 1979, during development of the Motorola 68000 CPU, one of their engineers, Jack Kister, decided to set about creating a standardized bus system for 68000-based systems.

The bus signals were simple to create using an 8080 CPU, but increasingly less so when using the Z80 and even more unrelated processors like the 68000.

The amount of physical main memory available is limited by the number of address bits on the address bus that connects the CPU to main memory — for example, the 68000 CPU, and the i386SX CPU,