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59-520: One version of the Big Board was used in the Xerox 820 . The Big Board was sold as an unpopulated printed circuit board with sockets for integrated circuits, with documentation and options to purchase additional components . The Big Board design was simple enough to build a system around that many people with no prior electronics experience were able to build and bring up a capable computer system of their own at

118-514: A print spooler . The Big Board II (1982) incorporated many of the most popular upgrades for the original Big Board into its design. It also featured a small breadboard area that allowed for many simple upgrades to be performed without the addition of daughter boards. The Big Board was designed primarily to run the CP/M operating system , version 2.2. It came with a monitor program in ROM called PFM-80 which

177-445: A river or other body of water. This is often done on whitewater or different degrees of rough water. Dealing with risk is often a part of the experience. This activity as an adventure sport has become popular since the 1950s, if not earlier, evolving from individuals paddling 10 feet (3.0 m) to 14 feet (4.3 m) rafts with double-bladed paddles or oars to multi-person rafts propelled by single-bladed paddles and steered by

236-484: A CPU daughter board. Andy Bakkers sold a 1 MB RAM Disk daughter board for Big Board II. Kenmore Computer Technologies (from Buffalo, NY ) offered the Ztime-I calendar/clock board kit and software. Calendar/clock circuits enabled early computers to time-stamp data and perform time-sensitive tasks with accuracy. Xerox 820 The Xerox 820 Information Processor is an 8-bit desktop computer sold by Xerox in

295-399: A Xerox 620 or 630 printer or compatible, and one intended for a modem), and two optional parallel ports which can be added via an internal pin header , usable with a Xerox or other cable. Keyboard: A bulky 96-character ASCII keyboard with a 10-key numeric keypad and a cursor diamond which otherwise defaults to Ctrl-A to Ctrl-D. It also includes HELP and LINE FEED keys, and

354-418: A bootstrap loader (i.e., for CP/M) from a floppy or the fixed disk. One can also access a "(T)ypewriter" mode for direct interface with the serial printer port and basic typing on screen. "(H)ost terminal" allows the 820-II to interface as a terminal via either of the serial ports, as specified, at up to 19.2 kbit/s. For low-end system operations, a user can manually read or write to memory, execute code at

413-621: A commercial rafting operator before signing on for that type of trip. The required equipment needed is essential information to be considered. Risks in white water rafting stem from both environmental dangers and from improper behavior. Certain features on rivers are inherently unsafe and have remained consistently so. These would include 'keeper hydraulics', 'strainers' (e.g. fallen trees), dams (especially low-head dams, which tend to produce river-wide keeper hydraulics), undercut rocks, and of course high waterfalls. Typical rafting injuries include trauma from striking an object, traumatic stress from

472-554: A cost far less than that of a fully assembled system of the time. In this way, the Big Boards anticipated the DIY PC clones that became popular later. In its most popular form, the fully assembled and tested Big Board need only be connected to a power supply, one or two eight inch floppy disk drives, a composite monitor , and an ASCII encoded keyboard in order to provide a fully functioning system. A serial terminal could be used in place of

531-418: A dealer had thousands of 820 motherboards for sale for $ 39 .95. Xerox discontinued the 16/8 and 820-II in early 1985; InfoWorld ' s article stated that "few will notice [their] demise". Yankee Group predicted that the company would introduce its own PC clone . White water rafting Rafting and whitewater rafting are recreational outdoor activities which use an inflatable raft to navigate

590-417: A disk drive, allowing a wide variety of configurations. Disk drives can be daisy-chained via a port on the back. Reference: 820-II Operation Manual The system can function to a limited extent without having to load a disk operating system : the system monitor in ROM allows, at boot-up, a variety of uses via one-letter commands followed by attributes. A user normally uses the "(L)oad" command to load

649-542: A full set of schematics , a document titled "Theory of Operation", the PFM-80 User's Manual, instructions for assembly and testing of the Big Board, a parts list, and addenda to these. The Theory of Operation described the details of the operation of the system, including the CRT controller , floppy disk controller , serial communications , memory bank switching , and connector pinouts . Big Board I Big Board II The success of

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708-526: A particular location in memory, read from or write to the system ports, or even read a sector from a disk. Further, (documented) calls to BOS subroutines allows a skilled user or program to restart the system, perform disk operations, take keyboard input, or write to the display. Reference: 820-II Reference Guide The Model 16/8 , introduced in May 1983, has dual CPUs, an 8-bit Z80 and 16-bit Intel 8086 , which can be booted jointly or separately. The operating system

767-407: A person at the stern, or by the use of oars . Rafting on certain sections of rivers is considered an extreme sport and can be fatal, while other sections are not so extreme or difficult. Rafting is also a competitive sport practiced around the world which culminates in a world rafting championship event between the participating nations. The International Rafting Federation , often referred to as

826-462: A rafting trip using proper precautions is low. Thousands of people safely enjoy rafting trips every year. Like most outdoor sports, rafting, in general, has become safer over the years. Expertise in the sport has increased, and equipment has become more specialized and improved in quality. As a result, the difficulty rating of most river runs has changed. A classic example is the Colorado River in

885-490: A reliably safe basis. Rafters can expect to encounter substantial whitewater, huge waves, huge rocks and hazards, and/or substantial drops that will impart severe impacts beyond the structural capacities and impact ratings of almost all rafting equipment. Traversing a Class 6 rapid has a dramatically increased likelihood of ending in serious injury or death compared to lesser classes. (Skill level: Full mastery of rafting, and even then it may not be safe) The overall risk level on

944-569: A small drop, but no considerable danger. May require significant maneuvering. (Skill level: Some experience in rafting) Class 4: Whitewater, medium waves, maybe rocks, maybe a considerable drop, sharp maneuvers may be needed. (Skill level: Exceptional rafting experience) Class 5: Whitewater, large waves, large volume, possibility of large rocks and hazards, possibility of a large drop, requires precise maneuvering. (Skill level: Full mastery of rafting) Class 6: Class 6 rapids are considered to be so dangerous that they are effectively unnavigable on

1003-455: Is 8-bit CP/M-80 and 16-bit CP/M-86 , and the computer was supplied with the WordStar word processor and dBase II database management system . It has double 8" floppy disk drives, a 12" monochrome monitor and a daisywheel printer . Later in 1984 double 5.25" floppy disk drives, a portrait-size blue monitor, and a laser printer were offered. The Model 16/8 is also called a Xerox 823. Flipping

1062-556: Is attached to the back of the CRT unit by a thick cable. Software: A typical 820-II comes with CP/M 2.2, diagnostic software, WordStar, and Microsoft 's BASIC-80 programming language . The Xerox 820-II is different from the 820: The Xerox 820-II's disk I/O capability is on one of two different cards: The 820-II has a processor expansion capability, which optionally supports a 16-bit Intel 8086 processor card with its own 128 KB or 256 KB of RAM (the 16-bit processor card uses

1121-905: Is generally more durable, longer-lasting, and just as easy to repair compared to older rubber rafts. Paddles and oars are the typical means of propulsion for rafts and come in many sizes and varieties with specific river conditions in mind. Paddles are a combination of layered wood, plastic, aluminium, carbon fiber, or other advanced composites. There are many types and combinations of these materials with lower-end entry-level paddles being composed of cheap aluminum and plastic. Higher-end models are constructed of high-end composites and mostly utilized by professional rafting guides, raft racers, and expedition paddlers. The basic paddle design for rafting consists of 3 parts: Paddles are typically utilized by rafters in smaller and lower volume rivers where rocks and other hazards can damage larger oars. Paddles are typically used by guests on commercial trips as well since it

1180-535: Is little penalty associated with such segmented addressing, just as long as each individual data area does not exceed 64 KB, and most such data areas were intentionally designed so as not to exceed 64 KB. Much CP/M software uses the Xerox 820's disk format, and other computers such as the Kaypro II are compatible with it. The CRT unit contains the processor, and a large port on the back connected via heavy cable to

1239-605: Is located inside the CRT unit, and includes the Z80A, 64 KB of RAM and a boot ROM which enables booting from any of the supported external drives in 8-bit mode. Screen: The display is a 24-line, 80-character (7×10 dot matrix) white-on-black monochrome CRT, with software-selectable variations such as reverse video , blinking, low-intensity (equivalent to grey text), and 4×4-resolution graphics. Communication ports: These include two 25-pin RS-232 serial ports (including one intended for

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1298-464: Is seen as a more engaging way to enjoy the river trip. When paddles are used in a raft it is referred to as "paddling" or "paddle guiding". Oars are commonly made from the same materials as paddles. Wood, plastic, aluminum, and carbon fiber. Oars are designed for several different rivers with slightly different blade shapes built to handle varying river conditions. Wooden oars are typically built as one solid piece to help retain strength and resilience of

1357-579: The Chilko River in British Columbia , Canada. Like all outdoor activities, rafting must balance its use of nature with the conservation of rivers as a natural resource and habitat . Because of these issues, some rivers now have regulations restricting the annual seasons and daily operating times or numbers of rafters. Conflicts have arisen when commercial rafting operators, often in co-operation with municipalities and tourism associations, alter

1416-639: The Grand Canyon , which historically had a reputation far exceeding its actual safety statistics. Today the Grand Canyon sees hundreds of safe rafting trips by both do it yourself rafters and commercial river concessionaires. Rafting companies generally require customers to sign waiver forms indicating understanding and acceptance of potential serious risks. Both do-it-yourself and commercial rafting trips often begin with safety presentations to educate rafting participants about problems that may arise. Depending on

1475-565: The IBM PC to market, Xerox created little of the computer's design; it is based on the Ferguson Big Board computer kit and other off-the-shelf components, including a Zilog Z80 processor clocked at 2.5 MHz, and 64 KB of RAM . Xerox chose CP/M as its operating system because of the large software library —The 820 is compatible with all Big Board software —and sold a customized version of WordStar for $ 495, although by 1982

1534-790: The Snake River in Wyoming was planned. With no training, experience, or proper equipment, the river was found to be too difficult and dangerous. Hence, it was given the nickname "Mad River". On June 9, 1940, Clyde Smith led a successful trip through the Snake River Canyon. In 1843 lieutenant John Fremont introduced the first rubber raft in US. Later on in 1844 the further enhancements were made by Peter Halkett. These vessels greatly facilitated whitewater navigation. It lasted for many years, with improvements in craftsmanship and safety over time. Otherwise known as

1593-436: The riverbed by dredging and/or blasting in order to eliminate safety hazards or create more interesting whitewater features in the river. Environmentalists argue that this may have negative impacts to riparian and aquatic ecosystems , while proponents claim these measures are usually only temporary since a riverbed is naturally subject to permanent changes during large floods and other events. Another conflict involves

1652-401: The 8/16's console between 8 bit and 16 bit modes is accomplished by a simple keyboard control command. The 820 was codenamed The Worm because Xerox saw Apple Computer as its main competitor; InfoWorld reported that Apple delayed and redesigned a computer under development to better compete with the 820. While less expensive than dedicated word processors such as the Xerox 860, the 820

1711-457: The 8086 (and the 8088) offers only segmented addressing, with each segment limited to 64 KB. By effective utilization of the four available segment registers, Code, Data, Stack and Extra, the 512 KB address space possible with the modified 820-II 8086 processor card can be very effectively managed, although in 64 KB chunks. If each data area is identified with its segment and its offset, possibly starting with zero offset, then there

1770-472: The 820, because "at last a recognized business-equipment manufacturer had brought out a standard CP/M" computer at a low price; dealers reportedly were also pleased to sell a computer from a well-known company. The Rosen Electronics Letter also unfavorably reviewed the 820 in June 1981, however, describing it as a disappointing, "me too" product for a leading technology company like Xerox. In November it stated that

1829-580: The 820-II's BIOS initialization code was developed to move the BIOS image up to the top of the 512 KB RAM area, thereby giving the applications maximum contiguous RAM. Otherwise, the 512 KB of the converted processor card is segmented into a lower 128 KB segment, and an upper 384 KB segment, but CP/M-86 was designed to handle such segmented RAM, so this BIOS modification is optional, although desirable. Unlike much later processors from Intel, and others, which offers both segmented and "flat" addressing,

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1888-423: The 820-II's console between 8-bit and 16-bit modes on an 820-II which is equipped with the optional 16-bit processor card is accomplished by a keyboard control command. Xerox 820-II component parts were available from Xerox outlet stores at quite reasonable prices, and it was not uncommon to convert surplus (but new) 128 KB 16-bit processor cards to 512 KB by the substitution of sixteen 41256 DRAM chips for

1947-539: The Big Board market. Paradise Valley Electronics of Moscow, ID sold a version of FORTH, as well as graphics upgrades and utility software for the Big Board. Several manufacturers, including JBW and Andy Bakkers sold SASI interface kits. Kuzara Enterprises of San Diego, CA (formerly Design Technology) sold printer interfaces that allowed the Big Board to use the full feature sets of the Xerox Diablo printers. Several manufacturers provided real time clock upgrades as

2006-512: The Big Board spawned Micro Cornucopia magazine. Many Big Board kits included a subscription flyer for the magazine. The magazine regularly featured user reports, hardware upgrade articles, and reviews of third party products. The magazine's publisher hosted the SOG (Semi Official Get-together) annually, where the magazine's readers would join staff and writers for white water rafting , potluck feasts , and technical discussions. The Xerox 820 computer

2065-713: The Big Board. SWP Microcomputer Products of Arlington, TX (formerly Software Publishers) provided the Bigboard Dual Density upgrade, which provided both hardware and software to allow the Big Board I to use dual density formats on its drives. Micro Cornucopia provided many products to enhance the Big Board computers, including speed upgrades, utility software and development tools both on ROM and on disk, and I/O enhancements. AB Computer Products sold enclosures, monitors, and pre-punched I/O panels targeted at Big Board users. D&W Associates of Rome, NY sold monitors, ASCII-encoded keyboards, and power supplies targeted to

2124-448: The IRF, is the worldwide body which oversees all aspects of the sport. Rafting equipment has continuously evolved and developed significantly from old rubber WW II era military surplus rafts. Modern whitewater rafts are typically made with advanced nylon or Kevlar infused plastics like PVC or urethane; though many of the more entry-level low-cost manufacturers still use a glued rubber. Plastic

2183-497: The International Scale of River Difficulty, below are the six grades of difficulty in white water rafting. They range from simple to very dangerous and potential death or serious injuries. Class 1: Very small rough areas, might require slight maneuvering. (Skill level: Very basic) Class 2: Some rough water, maybe some rocks, might require some maneuvering. (Skill level: Basic paddling skill) Class 3: Small waves, maybe

2242-522: The Xerox 820 lie mostly in its use of the Big Board design—its faults are, to a large extent, Xerox's own, and in no small measure due to its rush to get the system to market" before the IBM PC. The reviewer criticized the keyboard's contact bounce , slow disk access, and "pieced-together ... minimal" documentation, and warned customers against the Xerox-customized WordStar. He reported that three of

2301-403: The area, safety regulations covering rafting, both for the general do-it-yourself public as well as commercial operators, may exist in legislation. These range from the mandatory wearing of lifejackets, carrying certain equipment such as whistles and throwable flotation devices, to certification of commercial outfitters and their employees. It is generally advisable to discuss safety measures with

2360-409: The boat called an "oar frame". Oars connect to the frame by either a pin and clip system or a system called oarlocks . Either system connects to the frame via oar towers on either side of the frame. Pins are referred to as "thole pins" or "oar pins". A large metal clip attaches to the oar and clips onto the pin. The top of the pin has a rubber or plastic stopper that prevents the oar from slipping over

2419-585: The card's usual sixteen 4164 DRAM chips (both are 16-pin DIPs—pin 1 is unused on a 4164 and becomes A8 on a 41256), plus the addition of two ICs (one 74F02 and one 74F08, or two user-modified PALs ) for controlling the 41256's 9th address row and column (not found on 4164s), thereby achieving a four-times increase in RAM without the use of a "daughter" card (which can only achieve a two-times increase in RAM). A simple modification to

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2478-475: The clock divider, with no software modifications or changes to the ICs on the board.) There was also a minor industry in user-installable system upgrades such as real time clocks , 4 MHz upgrades, double density floppy upgrades, character enhancements for the display (reverse video, blinking, etc.), and the addition of hard disk interfaces such as SASI and SCSI . Most of these upgrades were accomplished through

2537-502: The company "gets it act together" and fix the keyboard and other problems, he suggested that potential customers consider building a similar computer at a lower price around the Big Board. Xerox was the second Fortune 500 company after Tandy Corporation , and first major American office-technology company, to sell a personal computer. It had experience with large customers, unlike Apple or Tandy. InfoWorld ' s reviewer stated that he and his colleagues were glad when Xerox announced

2596-452: The company offered the standard version for the same price. By 1984, surplus 820 mainboards were available from Xerox for about $ 50 each, and one of these could be combined with other surplus components to build a working system for a few hundred dollars. The Xerox 820-II followed in 1982, featuring a Z80A processor clocked at 4.0 MHz. Pricing started at US$ 3,000 (equivalent to $ 9,500 in 2023). Hardware: The processor board

2655-534: The distribution of scarce river permits to either the do-it-yourself public or commercial rafting companies. Rafting by do-it-yourself rafters and commercial rafting companies contributes to the economy of many regions which in turn may contribute to the protection of rivers from hydroelectric power generation, diversion for irrigation , and other development. Additionally, white water rafting trips can promote environmentalism . Multi-day rafting trips by do-it-yourself rafters and commercial rafting companies through

2714-453: The early 1980s. The computer runs under the CP/M operating system and uses floppy disk drives for mass storage. The microprocessor board is a licensed variant of the Big Board computer. Xerox introduced the 820 in June 1981 for $ 2,995 with two 5 + 1 ⁄ 4 -inch single-density disk drives with 81K of capacity per diskette, or $ 3,795 with two 8-inch drives with 241K capacity. To beat

2773-442: The four computers' disk-drive units his company had purchased had problems, and "strongly recommend an 820 owner get a service contract". The reviewer concluded that while the 820 "could be a fine office computer, its faults are so egregious that they indicate a basic lack of attention to detail on the part of Xerox". While noting the 8" model's low price and Xerox's strong field service and "prestige nameplate", and expressing hope that

2832-607: The interaction of the paddler's positioning and equipment and the force of the water, overuse injuries , submersion/environmental injuries, and non-environmental injuries due to undisclosed medical conditions (such as heart problems). Studies have shown that injury rates in rafting are relatively low, though they may be skewed due to a large number of unreported incidents. Fatalities are rare in both commercial and do-it-yourself rafting. Meta-analyses have calculated that fatalities ranged between 0.55 – 0.86 per 100,000 user days. A rare accident with five fatalities occurred in 1987 on

2891-445: The monitor and keyboard, further simplifying assembly. The only tool required for basic assembly was a screwdriver for the terminal block power connections. The design was also simple to modify for the sake of system expansion and enhancement. Many different modifications to increase the system clock speed were possible, including some that required nothing more than jumpers (e.g. the 3.5 MHz speed upgrade obtained by jumpering

2950-565: The new IBM PC was much more attractive; "we think the bulk of the sales will go to IBM". They did choose the PC, introduced one month after the 820; Yankee Group said after the latter's discontinuation that it "sort of got blown away right then and there by the IBM announcement". Xerox hoped to sell 100,000 820s in two years, but reportedly failed to do so in four; Micro Cornucopia reported in October 1983 that

3009-517: The oar while it is strained under a load. Composite or metallic oars typically are made in three parts: All of these parts are interchangeable and can be upgraded and altered in many ways to make rowing more enjoyable. Oars are generally used on wider flatter rivers of higher volume to facilitate moving more efficiently across long slow-moving pools, though anglers will often use shorter oars on smaller rafts in low volume rivers to help them maintain an advantageous upstream position while anglers cast from

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3068-413: The on-mainboard Z80A for all peripheral I/O operations, therefore the 8086 behaves more like a co-processor ). The 820-II's 16-bit processor card features a true 16-bit 8086 processor, not an 8/16-bit 8088 processor as on the contemporary IBM PC. The 16-bit processor card is, however, limited to 128 KB of DRAM (256 KB, maximum, if incorporating a rather rare RAM "daughter" card). Flipping

3127-478: The person using the oars to continue downstream. Oarlocks look like a pin topped with a U-shaped metal flange. The oars slide into the gap between the U-shaped metal pieces and can be held in place with a plastic stopper called an oarlock. The oarlock allows the oar to maintain its position on the oar at a correct length for rowing. Whitewater rafting can be traced back to 1811 when the first recorded attempt to navigate

3186-424: The raft. When a raft utilizes oars it is called "rowing" though many people typically incorrectly refer to this as "oaring" or "oar framing", however, these terms are incorrect and often suggest inexperience when used in conversation with members of the rafting community. Oars typically use one of 2 systems to attach to the boat, but in either case, they interface with the boat through a large metallic frame strapped to

3245-443: The top of the pin. The bottom of the pin connects to an oar tower designed to hold the pin in place. This system is an older system though it is useful for certain types of river running namely big, dangerous Class 5 rivers that require your oars to stay in place as much as possible. Oarlocks or locks are a more common form of attachment for oars as they allow the rower to "feather" the oar back and forth as they row making it easier on

3304-456: The use of daughter boards that plugged into existing IC sockets on the board, with the original IC either replaced by a more capable IC or placed into a socket on the daughter board. It was possible to upgrade the memory to 256 KB , which was extremely large for the time. While not directly supported by CP/M, the extra memory could be used to implement a ram disk , caching of the operating system image (to greatly improve warm boot time), or

3363-433: Was based on the Big Board; InfoWorld stated that its "considerable virtues ... lie mostly in its use of the Big Board's design". Shugart Associates was a common source of floppy disk drives, as was Tandon Corporation . Taylor Electric Company provided the "Better Board", including floppy disk drive interface enhancements, enhancements to PFM, and corrections to the original assembly and testing instructions bundled with

3422-469: Was expensive and slow compared to personal computers; one month after its release, the $ 1,795 Osborne 1 —faster, portable, and with bundled software worth more than $ 1,000 —appeared, while Xerox charged $ 200 for the required CP/M software. The 820 did not use Xerox PARC 's sophisticated technology that influenced the Apple Macintosh . InfoWorld in 1982 stated that "The considerable virtues of

3481-426: Was the "software front panel" of the system. The source code listing of PFM was a feature of the first and second issues of Micro Cornucopia . PFM featured many well-documented routines that could be employed in user code. The board featured 3 spare 2K ROM sockets that allowed for the addition of additional firmware . Popular additions were Tiny BASIC , FORTH , and enhanced versions of PFM. The Big Board came with

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