- MOS Technology 6502
- Motorola 6800
- MOS Technology 6502
- Full Face Respirator Mask Sizing
MOS Technology 6502The had 46 instructions, using only 2, transistors in a pin DIP. It ran at a clock rate of kHz eight clock cycles per CPU cycle of The was an enhanced version of theadding 14 instructions, larger 8 level stack, 8K program space, and interrupt abilities including shadows of the first 8 registers. Should Pioneer 10 and Pioneer 11 ever be found by an extraterrestrial species, the will represent an example of Earth's technology. S Navy qualifies as the "first microprocessor". Although interesting, it was not a single-chip processor, and was not general purpose - it was more like a set of parallel building blocks you could use to make a special purpose digital signal processor from in the form of one or more data pipelines in parallel. It's only included here because at least two people asked me about it. It was bit serial to reduce connections between chips, with highly parallel design and high clock rate to compensate. Words were 20 bits required by the precision of the sensor and control values and ALU units could perform operations on input bits as they were read in, while bits of the previous result was read out. Bits read serially from the ROMS eight banks with bit words, each with its own program counter directed the data movement and unit operations, but had to be synchronized with data movement making programming difficult basically microcode. Programming consisted of using the SLs to direct instruction and data words to the function units, which could be hooked to other function units in a pipeline, along with other pipelines in parallel. A separate set of eight ROMs could be used for data. It took until to declassify a paper on the design. Although impressively elegant, it probably didn't warrant that length of secrecy. It also featured an innovative feature to add custom instructions to the CPU. It included a 4-bit accumulator, 4-bit Y register and 2 or 3-bit X register, which combined to create a 6 or 7 bit index register for the 64 or nybbles of on chip RAM. A 1-bit status register was used for various purposes in different contexts. There was also a 6-bit subroutine return register and 4-bit page buffer, used as the destination on a branch, or exchanged with the PC and page registers for a subroutine amounting to a 1-element stack, branches could not be performed within a subroutine. An interesting feature of the PC is it was incremented using a feedback shift register, not a counter, so instructions were not consecutive in memory, but since all memory was internal, this was not a problem. Instructions were 8 bits with twelve hardwired, and with a 31X16 element PLA allowing 31 custom microprogrammed instructions. All hardwired instructions were single cycle, and no interrupts were allowed. The was the successor to the Aprilintended as a terminal controller, and similar to the
The design team had formerly worked at Motorola on the Motorola project; the is essentially a simplified, less expensive and faster version of that design. When it was introduced inthe was, by a considerable margin, the least expensive microprocessor on the market. It initially sold for less than one-sixth the cost of competing designs from larger companies, such as the or Intel Its introduction caused rapid decreases in pricing across the entire processor market. Along with the Zilog Z80it sparked a series of projects that resulted in the home computer revolution of the early s. Soon after the 's introduction, MOS Technology was purchased outright by Commodore Internationalwho continued to sell the microprocessor and licenses to other manufacturers. In the early days of theit was second-sourced by Rockwell and Synertekand later licensed to other companies. In its CMOS form, the 65C02which was developed by the Western Design Center WDCthe family continues to be widely used in embedded systemswith estimated production volumes in the hundreds of millions. The was designed by many of the same engineers that had designed the Motorola microprocessor family. The chip layout began in latethe first chips were fabricated in February and the full family was officially released in November Motorola's "total product family" strategy did not focus on the price of the microprocessor, but on reducing the customer's total design cost. They offered development software on a timeshare computer, the " EXORciser " debugging system, onsite training and field application engineer support. Peddle, who would accompany the salespeople on customer visits, found that customers were put off by the high cost of the microprocessor chips. At that time, Motorola's new semiconductor fabrication facility in Austin, Texas, was having difficulty producing MOS chips, and mid was the beginning of a year-long recession in the semiconductor industry. Also, many of the Mesa, Arizona, employees were displeased with the upcoming relocation to Austin. Motorola's Semiconductor Products Division management was overwhelmed with problems and showed no interest in Peddle's low-cost microprocessor proposal. Eventually Peddle was given an official letter telling him to stop working on the system. The new group vice-president John Welty said, "The semiconductor sales organization lost its sensitivity to customer needs and couldn't make speedy decisions. Peddle began looking outside Motorola for a source of funding for this new project. Sevin, but Sevin declined and later admitted this was because he was afraid Motorola would sue them. While Peddle was visiting Ford Motor Company on one of his sales trips, Bob Johnson, later head of Ford's engine automation division, mentioned that their former colleague John Paivinen had moved to General Instrument and taught himself semiconductor design. He had since moved on and was doing some very interesting work on calculator chipsets at a new company he formed in Valley Forge, Pennsylvania. Allen-Bradleya supplier of electronic components and industrial controls, acquired a majority interest in Mike Janes joined later. Of the seventeen chip designers and layout people on the team, seven left. The goal of the team was to design and produce a low-cost microprocessor for embedded applications and to target as wide as possible a customer base. Chips are produced by printing multiple copies of the chip design on the surface of a "wafer"a thin disk of highly pure silicon. Smaller chips can be printed in greater numbers on the same wafer, decreasing their relative price. Additionally, wafers always include some number of tiny physical defects that are scattered across the surface of the disk. Any chip printed in that location will fail and has to be discarded. Smaller chips mean any one is less likely to be printed on a defect. For both of these reasons, the cost of the final product is strongly dependant on the size of the chip design.
MOS Technology 6502
We believe in the long term value of Apple hardware. You should be able to use your Apple gear as long as it helps you remain productive and meets your needs, upgrading only as necessary. We want to help maximize the life of your Apple gear. The earlier from could only address 16 KB. But there was a parallel path, a new CPU family that Motorola launched in Although the and were designed more or less simultaneously, they had some different goals. The had more registers which were bit but each could be used as two 8-bit registerswhile the had fast access to the first bytes of RAM and supported direct memory access, which allowed another device such as a disk controller to write data directly to system memory. Despite the difference in clock speed, the and performed comparably because the instructions took more cycles to process. Motorola later produced a 2 MHz version of the The was short-lived, because Motorola sued over it being pin-compatible with its CPU. The went on to power many different home computers. Another benefit is that the was easier to program than the or The was initially available in 1 MHz, 1. Motorola engineers considered the so well designed that there was no further room for improvement. Apple originally planned to build the Macintosh around the — until the design team determined that what they wanted to do could not be accomplished within 64 KB of memory. Then they moved to the Motorola CPU. Hitachi was a licensee of thebut its CMOS was more than a clone of the The was available at higher clock speeds 3. Low End Mac is funded primarily through donations. All of our advertising is handled by BackBeat Media.