CPU

Central Processing Unit (CPU)

CPU stands for Central Processing Unit, and refers to the main computational processor in use on a given computer system The CPU's used in all Atari TOS Family were variations of the 68000 family and is commonly written as 680x0 where the x is one of the numbers that mark the class of the CPU.

MC68000

The Atari ST and Atari Mega ST series of computer uses the 8 MHz 32-bits Motorola 68000 CPU while the Atari Mega STE uses the 16 MHz version. Variant of the CPU can be found here.

Motorola 68000 (MC68000) is the first member of 680x0 line of microprocessors. Internally the 68000 is a 32-bit microprocessor - it has 32-bit data and address registers. Externally the processor has 16-bit data bus and 24-bit address bus, which limits the size of addressable memory to 16 MB.

HMOS 68000 processors were manufactured at speeds up to 16 MHz. HCMOS 68000 microprocessors were manufactured (May 2007) at speeds up to 20 MHz.

MC68030

The Atari Falcon030 and Atari TT030 computers uses the 32-bits Motorola 68030 CPU. The Falcon uses the 16 MHz version while the TT uses the 32 MHz version. Variant of the CPU can be found here.

MC68060

Some hardware CPU accelerator uses this type of 32 bits CPU. Variant of the CPU can be found here.

Coldfire

The ColdFire is a microprocessor that derives from the Motorola 68000 family architecture, manufactured for embedded systems development by Freescale Semiconductor (formerly the semiconductor sector of Motorola). More information here.

Floating Point Unit (FPU)

The floating point processor is a specialized chip that is optimized to perform fast floating point arithmetic.

MC68881

The Atari ST series of computers can be modified to include the use of a FPU, the Motorola 68881. More information about the 68881 here.

MC68882

The Atari Falcon030 and Atari TT030 series of computers can be easily fitted with the Motorola 68882 as they come with sockets for an FPU. More information about the 68882 here.

Differences between 68882 & 68881

Motorola 68882 (MC68882) is an enhanced version of 68881 Floating Point Unit. The 68882 is pin- and object-code compatible with the 68881, and, like the 68881, it could work with Motorola 68020 and 68030 microprocessors. The architecture of the 68882 FPU is similar to the 68881. The FPU has 8 directly-addressable 80-bit registers. It supports seven data types: 8-bit, 16-bit and 32-bit integers, single, double and extended-precision floating point numbers, and packed decimal strings. The 68882 always converts external operands into internal extended-precision format, and performs all calculations in this format. The MC68882 has the same instruction set as the 68881 co-processor.

The 68882 FPU includes a few features that significantly improve its performance:

• The 68882 may execute more than one floating-point instruction at the same time.
• The MC68882 uses faster conversion method of external operands to/from FPU's internal format.

To get maximum performance from the co-processor the programs needs to be re-compiled specifically for the 68882. The 68882 may run re-compiled programs up to two times faster than the 68881 FPU. Performance gain for older applications, i.e. applications compiled for Motorola 68881 co-processor, is usually is not as impressive - the FPU may run these programs up to 15 - 25% faster than the 68881.
Source:CPU World

Digital Signal Processor (DSP)

A digital signal processor (DSP) is a specialized microprocessor with an architecture optimized for the fast operational needs of digital signal processing.

MC56001

The Atari Falcon030 uses the Motorola 56001 DSP chip. More information about the 56001 here.

Memory Management Unit (MMU)

MC68851

The 68851 is an external memory management unit (MMU) which is designed to provided page memory support for 68010 or 68020. More information available here.