The 8-bit Fairchild F8 (also known as the 3850) microcontroller was Fairchild's first processor. It had no stack pointer, no program counter, no address bus. It did have 64 registers (the first 8 of which could be accessed directly) and 64 bytes of "scratchpad" RAM. The first F8s were multichip designs (usually 2-chip, with the second being ROM). The F8 was released in a single-chip implementation (the Mostek 3870) in 1977.
Where is it now?
The F8 was used in the company's Channel F Fairchild Video Entertainment System in 1976. By the end of the decade, Fairchild played mostly in niche markets, including the "hardened" IC market for military and space applications, and in Cray supercomputers. Fairchild was acquired by National Semiconductor in the 1980s, and spun off again as an independent company in 1997.
The first multi-chip 16-bit microprocessor was introduced by either Digital Equipment Corporation in its LSI-11 OEM board set and its packaged PDP 11/03 minicomputer, or by Fairchild Semiconductor with its MicroFlame 9440, both released in 1975. The first single-chip 16-bit microprocessor was the 1976 TI TMS 9900, which was also compatible with the TI 990 line of minicomputers and was used in the TM 990 line of OEM microcomputer boards.
Where are they now?
The DEC chipset later gave way to the 32-bit DEC VAX product line, which was replaced by the Alpha family, which was discontinued in 2004.
The aptly named Fairchild MicroFlame ran hot and was never chosen by a major computer manufacturer, so it faded out of existence.
The TI TMS 9900 had a strong beginning, but was packaged in a large (for the time) ceramic 64-pin package which pushed the cost out of range compared with the much cheaper 8-bit Intel 8080 and 8085. In March 1982, TI decided to start ramping down TMS 9900 production, and go into the DSP business instead. TI is still in the chip business today, and in 2004 it came out with a nifty TV tuner chip for cell phones.
Probably the most popular microprocessor of all time, the Zilog Z-80 was designed by Frederico Faggin after he left Intel, and it was released in July 1976. Faggin had designed or led the design teams for all of Intel's early processors: the 4004, the 8008, and particularly, the revolutionary 8080.
This 8-bit microprocessor was binary compatible with the 8080 and surprisingly, is still in widespread use today in many embedded applications. Faggin intended it to be an improved version of the 8080 and according to popular opinion, it was. It could execute all of the 8080 operating codes as well as 80 more instructions (including 1-, 4-, 8-, and 16-bit operations, block I/O, block move, and so on). Because it contained two sets of switchable data registers, it supported fast operating system or interrupt context switches.
The thing that really made it popular though, was its memory interface. Since the CPU generated its own RAM refresh signals, it provided lower system costs and made it easier to design a system around. When coupled with its 8080 compatibility and its support for the first standardized microprocessor operating system CP/M, the cost and enhanced capabilities made this the choice chip for many designers (including TI; it was the brains of the TRS-80 Model 1).
The Z-80 featured many undocumented instructions that were in some cases a by-product of early designs (which did not trap invalid op codes, but tried to interpret them as best they could); in other cases the chip area near the edge was used for added instructions, but fabrication methods of the day made the failure rate high. Instructions that often failed were just not documented, so the chip yield could be increased. Later fabrication made these more reliable.
Where are they now?
In 1979, Zilog announced the 16-bit Z8000. Sporting another great design with a stack pointer and both a user and a supervisor mode, this chip never really took off. The main reason: Zilog was a small company, it struggled with support, and never managed to bank enough to stay around and outlast the competition.
However, Zilog is not only still making microcontrollers, it is still making Z-80 microcontrollers. In all, more than one billion Z-80s have been made over the years -- a proud testament to Faggin's superb design.
Faggin is currently Chairman of the Board & Co-Founder of Synaptics, a "user interface solutions" company in the Silicon Valley.
In 1976, Intel updated the 8080 design with the 8085 by adding two instructions to enable/disable three added interrupt pins (and the serial I/O pins). They also simplified hardware so that it used only +5V power, and added clock-generator and bus-controller circuits on the chip. It was binary compatible with the 8080, but required less supporting hardware, allowing simpler and less expensive microcomputer systems to be built. These were the first Intel chips to be produced without input from Faggin.
In 1978, Intel introduced the 8086, a 16-bit processor which gave rise to the x86 architecture. It did not contain floating-point instructions. In 1980 the company released the 8087, the first math co-processor they'd developed.
Next came the 8088, the processor for the first IBM PC. Even though IBM engineers at the time wanted to use the Motorola 68000 in the PC, the company already had the rights to produce the 8086 line (by trading rights to Intel for its bubble memory) and it could use modified 8085-type components (and 68000-style components were much more scarce).
In 1979, Motorola introduced the 68000. With internal 32-bit registers and a 32-bit address space, its bus was still 16 bits due to hardware prices. Originally designed for embedded applications, its DEC PDP-11 and VAX-inspired design meant that it eventually found its way into the Apple Macintosh, Amiga, Atari, and even the original Sun Microsystems® and Silicon Graphics computers.
Where is the 68000 now?
As the 68000 was reaching the end of its life, Motorola entered into the Apple-IBM-Motorola "AIM" alliance which would eventually produce the first PowerPC® chips. Motorola ceased production of the 68000 in 2000.
No comments:
Post a Comment