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GeoPort
GeoPort is a serial data system used on some models of the Apple Macintosh that could be externally clocked to run at a 2 Mbit/s data rate. GeoPort slightly modified the existing Mac serial port pins to allow the computer's internal DSP hardware or software to send data that, when passed to a digital-to-analog converter, emulated various devices such as modems and fax machines. GeoPort could be found on late-model 68K-based machines (the AV series) as well as many pre-USB Power Macintosh models and PiPPiN. Some later Macintosh models also included an internal GeoPort via an internal connector on the Communications Slot. Apple GeoPort technology is now obsolete, and modem support is typically offered through USB. Background AppleBus and LocalTalk Early during the development of the Apple Macintosh, Apple engineers decided to use the Zilog 8530 "Serial Communications Controller" (SCC) for most input/output tasks. The SCC was relatively advanced compared to the more common UARTs of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple Bandai Pippin
The Apple Pippin is a defunct open multimedia technology platform, designed by Apple Computer, and marketed as PiPP!N. According to Apple, Pippin was directed at the home market as "an integral part of the consumer audiovisual, stereo, and television environment." Pippin is based on the Apple Macintosh platform, including the classic Mac OS architecture. Apple built a demonstration device based on Pippin called "Pippin Power Player," and used it to demonstrate the platform at trade shows and to the media, in order to attract potential software developers and hardware manufacturers. Apple licensed the Pippin technology to third-party companies. Bandai Company Ltd. developed the ATMARK and @WORLD models, and focused them on the gaming and entertainment business in Japan, Canada and the United States. Katz Media developed the KMP 2000, and focused it on vertical markets throughout Europe and Canada. Naming The Apple Pippin platform was named for the Newtown Pippin, an apple cult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Macintosh
The Power Macintosh, later Power Mac, is a family of personal computers designed, manufactured, and sold by Apple Computer as the core of the Macintosh brand from March 1994 until August 2006. Described by ''MacWorld'' as "the most important technical evolution of the Macintosh since the Mac II debuted in 1987", it is the first computer with the PowerPC CPU architecture, the flagship product of the AIM alliance. Existing software for the Motorola 68k processors of previous Macintoshes do not run on it natively, so a Mac 68k emulator is in System 7.1.2. It provides good compatibility, at about two thirds of the speed of contemporary Macintosh Quadra machines. The Power Macintosh replaced the Quadra, and was initially sold in the same enclosures. Over the next twelve years, it evolved through a succession of enclosure designs, a rename to "Power Mac", five major generations of PowerPC chips, and a great deal of press coverage, design accolades, and controversy about performance cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serial Communications
In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels. Serial communication is used for all long-haul communication and most computer networks, where the cost of cable and synchronization difficulties make parallel communication impractical. Serial computer buses are becoming more common even at shorter distances, as improved signal integrity and transmission speeds in newer serial technologies have begun to outweigh the parallel bus's advantage of simplicity (no need for serializer and deserializer, or SerDes) and to outstrip its disadvantages (clock skew, interconnect density). The migration from PCI to PCI Express is an example. Cables Many serial communication systems were originally designed to transfer data over relatively l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Recovery
In serial communication of digital data, clock recovery is the process of extracting timing information from a serial data stream itself, allowing the timing of the data in the stream to be accurately determined without separate clock information. It is widely used in data communications; the similar concept used in analog systems like color television is known as carrier recovery. Basic concept Serial data is normally sent as a series of pulses with well-defined timing constraints. This presents a problem for the receiving side; if their own local clock is not precisely synchronized with the transmitter, they may sample the signal at the wrong time and thereby decode the signal incorrectly. This can be addressed with extremely accurate and stable clocks, like atomic clocks, but these are expensive and complex. More common low-cost clock systems, like quartz oscillators, are accurate enough for this task over short periods of time, but over a period of minutes or hours the drift in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadra 950
The Macintosh Quadra 950 (also sold with additional software as the Workgroup Server 95) is a personal computer designed, manufactured and sold by Apple Computer from March 1992 to October 1995. It replaced the Quadra 900 that was introduced several months earlier, increasing the CPU clock rate of its 68040 CPU from to , and improving the graphics support. The two computers were otherwise identical, including the price. With a Macintosh Processor Upgrade Card installed, this computer is known as the Power Macintosh 950. In 1993, the 950 was overtaken in performance by the less expensive Quadra 800 and 840AV. The newer Quadras had the addition of interleaved RAM, as well as an enhanced video system and SCSI bus. However, their more compact ( mini-tower) case offered less expansion capability, so the 950 (due to its mid-tower case allowing 6 slots to be supported) was kept in continued production for the server market, outliving the 800 and 840AV. Also, the Quadra 800 was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadra 900
The Macintosh Quadra 900 is a personal computer designed, manufactured, and sold by Apple Computer from October 1991 to May 1992. It was introduced alongside the Quadra 700 as the first computers in the Quadra family of Macintosh computers using the Motorola 68040 processor. It is also the first computer from Apple to be housed in an 18.6 inch (47 cm) tall mid-tower form factor, which by 1991 had gained momentum with PC manufacturers as a suitable design for departmental servers. The Quadra 900 had a short lifespan; it was discontinued about six months after the first shipments in favor of the more powerful Quadra 950. Hardware The Quadra 900 was more expandable than the Quadra 700 but cost US$7,200. The Quadra 900 could be upgraded to 256 megabytes of RAM, an astronomical amount for the time, when a typical midrange system would come equipped with 2–4 MB. The standard, as-shipped configuration for the 900 was 4 MB. The high RAM and storage capacity, alon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SCSI
Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interfaces. The SCSI standard defines command sets for specific peripheral device types; the presence of "unknown" as one of these types means that in theory it can be used as an interface to almost any device, but the standard is highly pragmatic and addressed toward commercial requirements. The initial Parallel SCSI was most commonly used for hard disk drives and tape drives, but it can connect a wide range of other devices, including scanners and CD drives, although not all controllers can handle all devices. The ancestral SCSI standard, X3.131-1986, generally referred to as SCSI-1, was published by the X3T9 technical committee of the American National Standards Institute (ANSI) in 1986. SCSI-2 was published in August 1990 as X3.T9.2/86-109 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Memory Access
Direct memory access (DMA) is a feature of computer systems and allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU). Without DMA, when the CPU is using programmed input/output, it is typically fully occupied for the entire duration of the read or write operation, and is thus unavailable to perform other work. With DMA, the CPU first initiates the transfer, then it does other operations while the transfer is in progress, and it finally receives an interrupt from the DMA controller (DMAC) when the operation is done. This feature is useful at any time that the CPU cannot keep up with the rate of data transfer, or when the CPU needs to perform work while waiting for a relatively slow I/O data transfer. Many hardware systems use DMA, including disk drive controllers, graphics cards, network cards and sound cards. DMA is also used for intra-chip data transfer in multi-core processors. Computers that have DMA channels can trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOS 6502
The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small team led by Chuck Peddle for MOS Technology. The design team had formerly worked at Motorola on the Motorola 6800 project; the 6502 is essentially a simplified, less expensive and faster version of that design. When it was introduced in 1975, the 6502 was the least expensive microprocessor on the market by a considerable margin. It initially sold for less than one-sixth the cost of competing designs from larger companies, such as the 6800 or Intel 8080. Its introduction caused rapid decreases in pricing across the entire processor market. Along with the Zilog Z80, it sparked a series of projects that resulted in the home computer revolution of the early 1980s. Popular video game consoles and home computers of the 1980s and early 1990s, suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh IIfx
The Macintosh IIfx is a personal computer designed, manufactured and sold by Apple Computer from March 1990 to April 1992. At introduction it cost from to , depending on configuration, and it was the fastest Macintosh available at the time. The IIfx is the most powerful of the 68030-based Macintosh II family and was replaced at the top of Apple's lineup by the Macintosh Quadra in 1991. It is the last Apple computer released that was designed using the Snow White design language. Overview Dubbed "Wicked Fast" by its Product Manager, Frank Casanova – who came to Apple from Apollo Computer in Boston, Massachusetts, where the Boston term "wicked" is commonly used to denote anything extreme – the IIfx runs at a clock rate of 40 megahertz, has 32 KB of Level 2 cache, six NuBus slots, and includes a number of proprietary ASICs and coprocessors. Designed to speed up the machine even further, these chips require system-specific drivers. The 40 MHz speed refers to the main l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mac Plus
The Macintosh Plus computer is the third model in the Macintosh line, introduced on January 16, 1986, two years after the original Macintosh and a little more than a year after the Macintosh 512K, with a price tag of US$2,599. As an evolutionary improvement over the 512K, it shipped with 1 MB of RAM standard, expandable to 4 MB, and an external SCSI peripheral bus, among smaller improvements. Originally, the computer's case was the same beige color as the original Macintosh, Pantone 453; however, in 1987, the case color was changed to the long-lived, warm gray "Platinum" color. It is the earliest Macintosh model able to run System Software 5, System 6, and System 7. Overview Bruce Webster of ''BYTE'' reported a rumor in December 1985: "Supposedly, Apple will be releasing a Big Mac by the time this column sees print: said Mac will reportedly come with 1 megabyte of RAM ... the new 128K-byte ROM ... and a double-sided (800K bytes) disk drive, all in the standard Mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flow Control (data)
In data communications, flow control is the process of managing the rate of data transmission between two nodes to prevent a fast sender from overwhelming a slow receiver. Flow control should be distinguished from congestion control, which is used for controlling the flow of data when congestion has actually occurred. Flow control mechanisms can be classified by whether or not the receiving node sends feedback to the sending node. Flow control is important because it is possible for a sending computer to transmit information at a faster rate than the destination computer can receive and process it. This can happen if the receiving computers have a heavy traffic load in comparison to the sending computer, or if the receiving computer has less processing power than the sending computer. Stop-and-wait Stop-and-wait flow control is the simplest form of flow control. In this method the message is broken into multiple frames, and the receiver indicates its readiness to receive a fra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
