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Although a capable design, it was eclipsed by more powerful designs, such as the Zilog Z80 , and less powerful but faster designs, such as the MOS As the sales prospects of the dimmed, Motorola began a totally new design to replace it. The MACSS aimed to develop an entirely new architecture without backward compatibility with the It ultimately did retain a bus protocol compatibility mode for existing peripheral devices, and a version with an 8-bit data bus was produced.
However, the designers mainly focused on the future, or forward compatibility , which gave the design a head start against later bit instruction set architectures. In the mid s, the 8-bit microprocessor manufacturers raced to introduce the bit generation. Arriving late to the bit arena afforded the new processor more transistors roughly 40,[ citation needed ] active versus 20, active in the , bit macroinstructions, and acclaimed general ease of use.
Formally introduced in September ,  initial samples were released in February , with production chips available over the counter in November.
Rhines wrote that thus "Motorola, with its superior technology, lost the single most important design contest of the last 50 years". The was used in the first generation of desktop laser printers , including the original Apple Inc.
In , the received a minor update to its ISA to support virtual memory and to conform to the Popek and Goldberg virtualization requirements. The updated chip was called the To support lower-cost systems and control applications with smaller memory sizes, Motorola introduced the 8-bit compatible MC , also in This was a with an 8-bit data bus and a smaller bit address bus.
After , Motorola devoted more attention to the and projects. These included Hitachi HD , who shrank the feature size to 2. Encrypted variants of the , being the Hitachi FD and FD, store decryption keys for opcodes and opcode data in battery-backed memory and were used in certain Sega arcade systems including System 16 to prevent piracy and illegal bootleg games. Apple selected the 68HC for use in the Macintosh Portable. Thus, like the , it could be used in systems with cheaper 8-bit memories.
The later evolution of the focused on more modern embedded control applications and on-chip peripherals. When run in Supervisor Mode, there was no difference. More recently, with the Sendai fab closure, all 68HC, , , and parts have been discontinued, leaving only the 68SEC in production. In , Motorola introduced the MC communications processor. Unix systems rapidly moved to the more capable later generations of the 68k line, which remained popular in that market throughout the s. By the mids, falling production cost made the viable for use in personal and home computers , starting with the Apple Lisa and Macintosh , and followed by the Commodore Amiga , Atari ST , and Sharp X On the other hand, the Sinclair QL microcomputer was the most commercially important utilisation of the , along with its derivatives, such as the ICL One Per Desk business terminal.
The multi-processor Atari Jaguar console used a as a support chip, although some developers used it as the primary processor due to familiarity. As early as , laser printers such as the Imagen Imprint were controlled by external boards equipped with the Other printer manufacturers adopted the , including Apple with its introduction of the LaserWriter in , the first PostScript laser printer.
The continued to be widely used in printers throughout the rest of the s, persisting well into the s in low-end printers. The also saw success in the field of industrial control systems. Among the systems benefited from having a or derivative as their microprocessor were families of programmable logic controllers PLCs manufactured by Allen-Bradley , Texas Instruments and subsequently, following the acquisition of that division of TI, by Siemens.
Users of such systems do not accept product obsolescence at the same rate as domestic users, and it is entirely likely that despite having been installed over 20 years ago, many based controllers will continue in reliable service well into the 21st century.
The XX microcontrollers, based on the architecture, are used in networking and telecom equipment, television set-top boxes, laboratory and medical instruments, and even handheld calculators. The MC and its derivatives have been used in many telecom products from Cisco, 3com, Ascend, Marconi, Cyclades and others. AlphaSmart uses the DragonBall family in later versions of its portable word processors. Early versions of these used a specialized microcontroller with a static 68EC core; later versions use a standard MC68SEC processor.
COMPUTER ORGANIZATION AND THE MC68000 PDF
Computer organization and the MC68000