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101-468: Floppy disk  via : PC via one of: The HP-41C series are programmable, expandable, continuous memory handheld RPN calculators made by Hewlett-Packard from 1979 to 1990. The original model, HP-41C , was the first of its kind to offer alphanumeric display capabilities. Later came the HP-41CV and HP-41CX , offering more memory and functionality. The alphanumeric LCD screen of

202-756: A computer or other device. The first floppy disks, invented and made by IBM in 1971, had a disk diameter of 8 inches (203.2 mm). Subsequently, the 5¼-inch (133.35 mm) and then the 3½-inch (88.9 mm) became a ubiquitous form of data storage and transfer into the first years of the 21st century. 3½-inch floppy disks can still be used with an external USB floppy disk drive. USB drives for 5¼-inch, 8-inch, and other-size floppy disks are rare to non-existent. Some individuals and organizations continue to use older equipment to read or transfer data from floppy disks. Floppy disks were so common in late 20th-century culture that many electronic and software programs continue to use save icons that look like floppy disks well into

303-411: A magnetic storage medium in a square or nearly square plastic enclosure lined with a fabric that removes dust particles from the spinning disk. The three most popular (and commercially available) floppy disks are the 8-inch, 5¼-inch, and 3½-inch floppy disks. Floppy disks store digital data which can be read and written when the disk is inserted into a floppy disk drive ( FDD ) connected to or inside

404-482: A PC (user). The final HP-41 model, the HP-41CX , included extended memory, a built-in time module, and extended functions. It was introduced in 1983 and discontinued in 1990. The HP-41C is keystroke programmable meaning that it can remember and later execute sequences of keystrokes to solve particular problems of interest to the user. These keystroke programs, in addition to performing any operation normally available on

505-596: A blinking zero; it could also specifically prompt the user for arguments (" ENTER RADIUS ") instead of just displaying a question mark. Earlier calculators needed a key, or key combination, for every available function. The HP-67 had three shift keys (gold "f", blue "g" and black "h" prefix keys); the competing Texas Instruments calculators had two ( 2nd and INV ) and close to 50 keys (the TI-59 had 45). Hewlett-Packard were constrained by their one byte only instruction format. The more flexible storage format for programs in

606-443: A button that, when pressed, ejects the disk with varying degrees of force, the discrepancy due to the ejection force provided by the spring of the shutter. In IBM PC compatibles , Commodores, Apple II/IIIs, and other non-Apple-Macintosh machines with standard floppy disk drives, a disk may be ejected manually at any time. The drive has a disk-change switch that detects when a disk is ejected or inserted. Failure of this mechanical switch

707-632: A customized operating system is used that has no drivers for USB devices. Hardware floppy disk emulators can be made to interface floppy-disk controllers to a USB port that can be used for flash drives. In May 2016, the United States Government Accountability Office released a report that covered the need to upgrade or replace legacy computer systems within federal agencies. According to this document, old IBM Series/1 minicomputers running on 8-inch floppy disks are still used to coordinate "the operational functions of

808-428: A disk can be accessed, the drive needs to synchronize its head position with the disk tracks. In some drives, this is accomplished with a Track Zero Sensor, while for others it involves the drive head striking an immobile reference surface. In either case, the head is moved so that it is approaching track zero position of the disk. When a drive with the sensor has reached track zero, the head stops moving immediately and

909-466: A disk, some 3½-inch drives (notably the Macintosh External 400K and 800K drives ) instead use Constant Linear Velocity (CLV), which uses a variable speed drive motor that spins more slowly as the head moves away from the center of the disk, maintaining the same speed of the head(s) relative to the surface(s) of the disk. This allows more sectors to be written to the longer middle and outer tracks as

1010-484: A fully remappable keyboard, I/O capabilities for storing and sharing programs, and alphanumeric support), led some users to propose a new name for the language, resulting in a competition that was won by "FOCAL" for "Forty One Calculator Language". As the name FOCAL was already in use by the Digital Equipment Corporation , the name was never formally adopted by HP. A large user community was built around

1111-444: A function vertically onto the narrow strip of printer paper. Instead of using the aforementioned printer, this module could be used to interface a thermal printer with an infrared interface, namely the HP 82240A and the HP 82240B . This allows for on-the-go printing without using cables - but the printer itself needs batteries as well. The optical wand was a barcode reader shaped like

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1212-546: A grand total of 319 registers. While this was considered huge for the time (a little more than 2 kilobytes ,) all expansion slots were used. User groups found a way to merge two memory chips in a single module, thus freeing two expansion slots. HP designed a module holding all four in one slot, the so-called Quad Memory Module . The later HP-41CV had the quad module built-in. The ROM -based application 'pac' modules added up to 4 kilobytes of read-only memory (some up to 8 kilobytes, but these were simply two independent 4K modules in

1313-413: A hard-sectored disk, there are many holes, one for each sector row, plus an additional hole in a half-sector position, that is used to indicate sector zero. The Apple II computer system is notable in that it did not have an index hole sensor and ignored the presence of hard or soft sectoring. Instead, it used special repeating data synchronization patterns written to the disk between each sector, to assist

1414-420: A loaded disk can be removed manually by inserting a straightened paper clip into a small hole at the drive's front panel, just as one would do with a CD-ROM drive in a similar situation. The X68000 has soft-eject 5¼-inch drives. Some late-generation IBM PS/2 machines had soft-eject 3½-inch disk drives as well for which some issues of DOS (i.e. PC DOS 5.02 and higher) offered an EJECT command. Before

1515-613: A marginally different look (outer plastic parts in black, not brown, gray display frame) A badge-engineered version of the Sharp PC-1211 was marketed by Radio Shack as the original TRS-80 Pocket Computer. This was later referred to as the "PC-1" to differentiate it from subsequent entries (PC-2 onwards) in the TRS-80 Pocket Computer line . Introduced in July 1980, the "PC-1" measured 175 × 70 × 15 mm and weighed 170 g, and had

1616-524: A one-line, 24-character alphanumeric LCD . The TRS-80 Pocket Computer was programmable in BASIC , with a capacity of 1424 "program steps". This memory was shared with variable storage of up to 178 locations, in addition to the 26 fixed locations named A through Z. The implementation was based on Palo Alto Tiny BASIC . Programs and data could be stored on a Compact Cassette through an optional external cassette tape interface unit. A printer/cassette interface

1717-447: A real-time clock. The clock allowed use of real-world time in programs. The user could set alarms that triggered calls to user programs. The alarms were able to switch the calculator on, so it was possible to create programs that executed at some point during the day, then switch the calculator off until the next alarm. As the HP-41 was often used as a data-gathering device in labs, this allowed

1818-557: A recovery. The music and theatre industries still use equipment requiring standard floppy disks (e.g. synthesizers, samplers, drum machines, sequencers, and lighting consoles ). Industrial automation equipment such as programmable machinery and industrial robots may not have a USB interface; data and programs are then loaded from disks, damageable in industrial environments. This equipment may not be replaced due to cost or requirement for continuous availability; existing software emulation and virtualization do not solve this problem because

1919-492: A relatively small keyboard, and only one shift key, but provided hundreds of functions. Every function that was not assigned to a key could be invoked through the XEQ key (pronounced E XEQ TE  — "execute") and spelled out in full, e.g. XEQ FACT for the factorial function. The calculator had a special user mode where the user could assign any function to any key if the default assignments provided by HP were not suited to

2020-468: A selectable option and purchasable as an aftermarket OEM add-on. By January 2007, only 2% of computers sold in stores contained built-in floppy disk drives. Floppy disks are used for emergency boots in aging systems lacking support for other bootable media and for BIOS updates, since most BIOS and firmware programs can still be executed from bootable floppy disks . If BIOS updates fail or become corrupt, floppy drives can sometimes be used to perform

2121-505: A single hole in the rotating floppy disk medium line up. This mechanism is used to detect the angular start of each track, and whether or not the disk is rotating at the correct speed. Early 8‑inch and 5¼‑inch disks also had holes for each sector in the enclosed magnetic medium, in addition to the index hole, with the same radial distance from the center, for alignment with the same envelope hole. These were termed hard sectored disks. Later soft- sectored disks have only one index hole in

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2222-447: A small circle of floppy magnetic material encased in hard plastic. Earlier types of floppy disks did not have this plastic case, which protects the magnetic material from abuse and damage. A sliding metal cover protects the delicate magnetic surface when the diskette is not in use and automatically opens when the diskette is inserted into the computer. The diskette has a square shape: there are apparently eight possible ways to insert it into

2323-411: A small oblong opening in both sides to allow the drive's heads to read and write data and a large hole in the center to allow the magnetic medium to spin by rotating it from its middle hole. Inside the cover are two layers of fabric with the magnetic medium sandwiched in the middle. The fabric is designed to reduce friction between the medium and the outer cover, and catch particles of debris abraded off

2424-477: A specific application. For this mode, the HP-41C came with blank keyboard templates; i.e. plastic covers with holes for the keys, so the user could annotate customized keys. Hewlett-Packard even sold a version of the calculator where hardly any keys had function names printed on them, meant for users who would be using the HP-41C for custom calculations only (thus not needing the standard key layout at all); this version of

2525-498: A thick pen, and was designed to read lines of HP-proprietary standard barcodes into the calculator memory. The barcodes, printed in e.g. HP solutions books, could consist of programs, numeric or alphabetical constants, and even keypresses (letting the calculator be operated without using the keyboard) — useful for diagnosing calculators where the keyboard was suspected to be faulty. The Extended Functions module added many functions which had long been requested by users, such as

2626-475: Is a common source of disk corruption if a disk is changed and the drive (and hence the operating system) fails to notice. One of the chief usability problems of the floppy disk is its vulnerability; even inside a closed plastic housing, the disk medium is highly sensitive to dust, condensation and temperature extremes. As with all magnetic storage , it is vulnerable to magnetic fields. Blank disks have been distributed with an extensive set of warnings, cautioning

2727-451: Is correctly aligned. For a drive without the sensor, the mechanism attempts to move the head the maximum possible number of positions needed to reach track zero, knowing that once this motion is complete, the head will be positioned over track zero. Some drive mechanisms such as the Apple II 5¼-inch drive without a track zero sensor, produce characteristic mechanical noises when trying to move

2828-428: Is still used by software on user-interface elements related to saving files even though physical floppy disks are largely obsolete. Examples of such software include LibreOffice , Microsoft Paint , and WordPad . The 8-inch and 5¼-inch floppy disks contain a magnetically coated round plastic medium with a large circular hole in the center for a drive's spindle. The medium is contained in a square plastic cover that has

2929-683: The HP-34C and the HP-15C ). Among others, the standard function set offered no integration or root-finding capabilities and lacked support for matrices and complex numbers; these extra functions could be added by an extension module. Another module, known as the Interface Loop allowed for connection of more peripherals: larger printers, microcassette tape recorders, 3 1 ⁄ 2 -inch floppy disk drives, RS-232 communication interfaces, video display interfaces, etc. The Interface Loop could also be used with

3030-556: The HP-71B , HP-75 and HP-110 computers. HP-41 extension (or expansion) modules allowed the user of an HP-41 programmable calculator to extend the functionality of the machine. The HP-41 had room for up to four expansion modules at the back of calculator. The HP-41 was not the only calculator of its generation that allowed expansion modules. The TI-58 and TI-59 also had pluggable ROM modules. The HP-41 modules were however much more versatile. Memory modules added RAM main memory to

3131-510: The National Air and Space Museum in Washington, D.C. HP-41Cs with some special hardware configurations (the addition of Velcro strips, pre-production time module, and louder beeper, as well as the removal of parts whose outgassing could cause contamination) were carried on early Shuttle missions for the purpose of performing mundane but necessary calculations, such as calculating the change to

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3232-464: The TI-59 allowed combining more keys into one instruction. The longest instruction required eleven keypresses, re-using the shift keys four times. The TI-59 also made use of the Op key followed by two digits to access another 40 different functions, but the user had to remember the codes for them. Clearly, a more convenient and flexible method of executing the calculator's instructions was needed. The HP-41C had

3333-547: The Type 1 Diskette in 1973, the industry continued to use the terms "floppy disk" or "floppy". In 1976, Shugart Associates introduced the 5¼-inch floppy disk drive. By 1978, there were more than ten manufacturers producing such drives. There were competing floppy disk formats , with hard- and soft-sector versions and encoding schemes such as differential Manchester encoding (DM), modified frequency modulation (MFM), M FM and group coded recording (GCR). The 5¼-inch format displaced

3434-398: The 1990s were non-networked, and floppy disks were the primary means to transfer data between computers, a method known informally as sneakernet . Unlike hard disks, floppy disks were handled and seen; even a novice user could identify a floppy disk. Because of these factors, a picture of a 3½-inch floppy disk became an interface metaphor for saving data. As of 2024 , the floppy disk symbol

3535-469: The 21st century, as a form of skeuomorphic design . While floppy disk drives still have some limited uses, especially with legacy industrial computer equipment , they have been superseded by data storage methods with much greater data storage capacity and data transfer speed , such as USB flash drives , memory cards , optical discs , and storage available through local computer networks and cloud storage . The first commercial floppy disks, developed in

3636-409: The 67. Magnetic cards could be write-protected, and programs saved as private: once loaded back, the source code for the program could not be displayed. This made magnetic cards an obvious choice for program distribution. However, the electric motor put a heavy strain on the calculator batteries, and the price tag for blank cards put an even heavier strain on the user's wallet. The time module added

3737-518: The 720 KB double density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and the 1.44 MB (1,474,560 bytes) high-density version with the IBM Personal System/2 (PS/2) line in 1987. These disk drives could be added to older PC models. In 1988, Y-E Data introduced a drive for 2.88 MB Double-Sided Extended-Density (DSED) diskettes which was used by IBM in its top-of-the-line PS/2 and some RS/6000 models and in

3838-530: The 8-inch one for most uses, and the hard-sectored disk format disappeared. The most common capacity of the 5¼-inch format in DOS-based PCs was 360 KB (368,640 bytes) for the Double-Sided Double-Density (DSDD) format using MFM encoding. In 1984, IBM introduced with its PC/AT the 1.2 MB (1,228,800 bytes) dual-sided 5¼-inch floppy disk, but it never became very popular. IBM started using

3939-514: The Extended Functions module as standard. Extended memory modules added more extended memory to the HP-41C. They required an extended functions module to be present, or the HP-41CX version of the calculator. Floppy disk A floppy disk or floppy diskette (casually referred to as a floppy , a diskette , or a disk ) is a type of disk storage composed of a thin and flexible disk of

4040-417: The HP-41C revolutionized the way a pocket calculator could be used, providing user friendliness (for its time) and expandability (keyboard-unassigned functions could be spelled out alphabetically). By using an alphanumeric display, the calculator could tell the user what was going on: it could display error messages, such as showing (" DATA ERROR ") upon attempting to divide by zero instead of simply displaying

4141-434: The HP-41C. One of the discoveries of the community was that, because some FOCAL instructions were stored in memory as more than one byte , it is possible to exploit a bug in the program editor to assign strange functions to keys. The most important function was known as the byte jumper or byte grabber , a way to step partially through programming instructions and edit them in ways that were not otherwise allowed. The use of

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4242-650: The HP-41C. Enthusiasts around the world found new ways of programming, created their own software (such as a codebreaking game, and a version of Hunt the Wumpus ) and expansion modules, and sped up the clock (see overclocking ). Most of these activities were coordinated by the PPC club and its president, Richard J. Nelson. The PPC club published the PPC Journal and produced the PPC ROM, a collection of highly optimized low-level programs for

4343-469: The Sony design, introduced in 1983 by many manufacturers, was then rapidly adopted. By 1988, the 3½-inch was outselling the 5¼-inch. Generally, the term floppy disk persisted, even though later style floppy disks have a rigid case around an internal floppy disk. By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks. During this time, PCs frequently came equipped with drives of both sizes. By

4444-636: The United States' nuclear forces". The government planned to update some of the technology by the end of the 2017 fiscal year. Use in Japan's government ended in 2024. Windows 10 and Windows 11 no longer come with drivers for floppy disk drives (both internal and external). However, they will still support them with a separate device driver provided by Microsoft. The British Airways Boeing 747-400 fleet, up to its retirement in 2020, used 3½-inch floppy disks to load avionics software. Sony, who had been in

4545-433: The X register and passed as an input parameter when the program is run. The program takes up two registers, which is ≈14 bytes. Though the programming language used on the 41 series is a version of the keystroke programming languages used in all preceding programmable HP calculators, the range of technologies, and programming-related usability and extensibility features available in 41 series models (notably keyboard overlays,

4646-409: The ability to programmatically assign functions to keys, repartition memory, etc. But the most important new function was the management of extended memory: while the HP-41C could theoretically access up to 1024 registers, the early design limited main memory to 319 registers only. The Extended Functions module added instructions to manage a bank of additional memory in the available addressing space of

4747-433: The author concluded that it was "maybe not quite" a pocket computer. In the next issue, another author wrote that "The HP-41C ... is among the programmable calculators that lie closest to the computer borderline. It comes close enough for the jargon of computers to be useful in describing it", and praised the simplicity and reliability of the card reader and compatibility with HP-67 and HP-97 software. The review criticized

4848-407: The calculator to read data from monitored devices at specific times every day, without having to remain fully powered up in between readings (thus saving battery capacity). The HP-41CX had the time module built in. The printer used rolls of thermal paper to print lines of up to 24 characters. The thermal paper provided for a bluish printout, but was somewhat unstable, as the printout could vanish or

4949-444: The calculator was colloquially known, within HP's Corvallis calculator team, as a "Blanknut" (because the development code name for the HP-41C's processor was known as the "coconut"). Alphanumeric display also greatly eased editing programs, as functions were spelled out in full. Numeric-only calculators displayed programming steps as a list of numbers, each number generally mapped to a key on

5050-458: The calculator, allowing more programming steps and/or more data registers. The original HP-41C had a main memory of 63 registers of 7 bytes each. Each register could hold either a number, a 6-character string, or up to seven program steps in the FOCAL language (program steps used a variable number of bytes). Each memory module added 64 registers, and the calculator could hold up to four of them, for

5151-547: The center of gravity due to fuel consumption. The HP-41C was also programmed to handle calculations usually performed by the main on-board computer, such as determining ignition times for re-entry, in the case of a main computer failure. The functions of the calculator could be expanded by adding modules at the top of the machine. Four slots were available to add more memory, pre-programmed solution packs containing programs covering engineering, surveying, physics, math, finance, games, etc. As such, an HP-41 could in fact be tailored to

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5252-409: The computer in finding and synchronizing with the data in each track. The later 3½-inch drives of the mid-1980s did not use sector index holes, but instead also used synchronization patterns. Most 3½-inch drives used a constant speed drive motor and contain the same number of sectors across all tracks. This is sometimes referred to as Constant Angular Velocity (CAV). In order to fit more data onto

5353-406: The corresponding sensor; this was mainly a hardware cost-saving measure. The core of the 3½-inch disk is the same as the other two disks, but the front has only a label and a small opening for reading and writing data, protected by the shutter—a spring-loaded metal or plastic cover, pushed to the side on entry into the drive. Rather than having a hole in the center, it has a metal hub which mates to

5454-399: The current is reversed the magnetization aligns in the opposite direction, encoding one bit of data. To read data, the magnetization of the particles in the media induce a tiny voltage in the head coil as they pass under it. This small signal is amplified and sent to the floppy disk controller , which converts the streams of pulses from the media into data, checks it for errors, and sends it to

5555-446: The data into memory. As the HP-41C had non-volatile memory (user programs and data were not wiped out when power was off) there was no absolute need for a permanent storage device, so the card reader was optional. Each card held two strips of 112 bytes each, that could hold 16 data registers or up to 112 program steps. This limited capacity resulted in typical programs requiring five or more magnetic cards to be saved. A full backup of

5656-399: The disk media, an action originally accomplished by a disk-load solenoid. Later drives held the heads out of contact until a front-panel lever was rotated (5¼-inch) or disk insertion was complete (3½-inch). To write data, current is sent through a coil in the head as the media rotates. The head's magnetic field aligns the magnetization of the particles directly below the head on the media. When

5757-442: The disk shell are not quite square: its width is slightly less than its depth, so that it is impossible to insert the disk into a drive slot sideways (i.e. rotated 90 degrees from the correct shutter-first orientation). A diagonal notch at top right ensures that the disk is inserted into the drive in the correct orientation—not upside down or label-end first—and an arrow at top left indicates direction of insertion. The drive usually has

5858-466: The disk to keep them from accumulating on the heads. The cover is usually a one-part sheet, double-folded with flaps glued or spot-welded together. A small notch on the side of the disk identifies whether it is writable, as detected by a mechanical switch or photoelectric sensor . In the 8-inch disk, the notch being covered or not present enables writing, while in the 5¼-inch disk, the notch being present and uncovered enables writing. Tape may be used over

5959-569: The display of uppercase letters, digits, and a few punctuation characters (the FOCAL character set ), some designs needed to be twisted arbitrarily (e.g. to distinguish S from 5) and lowercase letters were unreadable (HP only provided display of lowercase letters a through e). HP's competitor Sharp , when introducing the PC-1211 , used a dot matrix of 5×7 dots and displayed the characters in principle as we see them today on computer screens (and, in fact, many LCD screens on various embedded systems ); this

6060-406: The eight ways one might try to insert the diskette, only one is correct, and only that one will fit. An excellent design. A spindle motor in the drive rotates the magnetic medium at a certain speed, while a stepper motor-operated mechanism moves the magnetic read/write heads radially along the surface of the disk. Both read and write operations require the media to be rotating and the head to contact

6161-687: The existing 3½-inch designs was the SuperDisk in the late 1990s, using very narrow data tracks and a high precision head guidance mechanism with a capacity of 120 MB and backward-compatibility with standard 3½-inch floppies; a format war briefly occurred between SuperDisk and other high-density floppy-disk products, although ultimately recordable CDs/DVDs, solid-state flash storage, and eventually cloud-based online storage would render all these removable disk formats obsolete. External USB -based floppy disk drives are still available, and many modern systems provide firmware support for booting from such drives. In

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6262-555: The flexibility of floppy disks combined with greater capacity, but remained niche due to costs. High-capacity backward compatible floppy technologies became popular for a while and were sold as an option or even included in standard PCs, but in the long run, their use was limited to professionals and enthusiasts. Flash-based USB thumb drives finally were a practical and popular replacement, that supported traditional file systems and all common usage scenarios of floppy disks. As opposed to other solutions, no new drive type or special software

6363-457: The floppy disk business since 1983, ended domestic sales of all six 3½-inch floppy disk models as of March 2011. This has been viewed by some as the end of the floppy disk. While production of new floppy disk media has ceased, sales and uses of this media from inventories is expected to continue until at least 2026. For more than two decades, the floppy disk was the primary external writable storage device used. Most computing environments before

6464-512: The general population, floppy disks were often used to store a computer's operating system (OS). Most home computers from that time have an elementary OS and BASIC stored in read-only memory (ROM), with the option of loading a more advanced OS from a floppy disk. By the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were an estimated five billion standard floppy disks in use. An attempt to enhance

6565-431: The greater capacity, compatibility with existing CD-ROM drives, and—with the advent of re-writeable CDs and packet writing—a similar reusability as floppy disks. However, CD-R/RWs remained mostly an archival medium, not a medium for exchanging data or editing files on the medium itself, because there was no common standard for packet writing which allowed for small updates. Other formats, such as magneto-optical discs , had

6666-407: The heads past the reference surface. This physical striking is responsible for the 5¼-inch drive clicking during the boot of an Apple II, and the loud rattles of its DOS and ProDOS when disk errors occurred and track zero synchronization was attempted. All 8-inch and some 5¼-inch drives used a mechanical method to locate sectors, known as either hard sectors or soft sectors , and is the purpose of

6767-450: The host computer system. A blank unformatted diskette has a coating of magnetic oxide with no magnetic order to the particles. During formatting, the magnetizations of the particles are aligned forming tracks, each broken up into sectors , enabling the controller to properly read and write data. The tracks are concentric rings around the center, with spaces between tracks where no data is written; gaps with padding bytes are provided between

6868-414: The inaccuracies in calculations from the lack of guard digits ; "There is something absurd about the world's fanciest calculator not being able to give results accurate to more than seven or eight decimal places". Hewlett-Packard responded that the alleged imprecision was inherent to arithmetic on any computer with finite precision. An HP-41C that flew on nine early Space Shuttle missions is on display in

6969-618: The keyboard, can also make use of conditional and unconditional branching and looping instructions, allowing programs to perform repetitive operations and make decisions. The HP-41C also supports indirect addressing ( computed goto ) with which it is possible to implement a Universal Turing machine and therefore the programming model of the HP-41C can be considered Turing complete . The combination of indirect addressing and gotos easily led to spaghetti code . Program steps are numbered starting from 1, but this numbering has no intrinsic meaning and changes as new instructions are added or removed in

7070-434: The keyboard, often via row and column coordinates. Encoding functions to the corresponding numeric codes, and vice versa, was left to the user, having to look up the function–code combinations in a reference guide. The busy programmer quickly learned most of the codes, but having to learn the codes intimidated the beginners. In addition to this, the user had to mentally keep function codes separate from numeric constants in

7171-499: The late 1960s, were 8 inches (203.2 mm) in diameter; they became commercially available in 1971 as a component of IBM products and both drives and disks were then sold separately starting in 1972 by Memorex and others. These disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates , and Burroughs Corporation . The term "floppy disk" appeared in print as early as 1970, and although IBM announced its first media as

7272-494: The machine's 319 memory registers plus internal data required 11 magnetic cards (each card had to be inserted twice.) The card reader could read magnetic cards from the earlier model HP-67 . HP-67 programs were translated into HP-41C instructions, as the HP-67 and HP-41 share the same programming model and operation stack. Some instructions however were specific to the HP-67, and the card reader provided additional instructions to emulate

7373-424: The machine, only one of which is correct. What happens if I do it wrong? I try inserting the disk sideways. Ah, the designer thought of that. A little study shows that the case really isn't square: it's rectangular, so you can't insert a longer side. I try backward. The diskette goes in only part of the way. Small protrusions, indentations, and cutouts prevent the diskette from being inserted backward or upside down: of

7474-536: The machine. As this memory was not directly addressable by user programs, it was seen as a set of named files containing either programs or data. Programs and data registers could be copied back and forth from the extended memory to the main memory, where they could be accessed as usual. Extended memory could also hold ASCII files, and a rudimentary text editor was added also. The Extended Functions module contained 124 registers of Extended memory. More could be added by ... Extended Memory modules. The HP-41CX contained

7575-399: The media. In some 5¼-inch drives, insertion of the disk compresses and locks an ejection spring which partially ejects the disk upon opening the catch or lever. This enables a smaller concave area for the thumb and fingers to grasp the disk during removal. Newer 5¼-inch drives and all 3½-inch drives automatically engage the spindle and heads when a disk is inserted, doing the opposite with

7676-400: The medium, and sector position is determined by the disk controller or low-level software from patterns marking the start of a sector. Generally, the same drives are used to read and write both types of disks, with only the disks and controllers differing. Some operating systems using soft sectors, such as Apple DOS , do not use the index hole, and the drives designed for such systems often lack

7777-419: The memory of the HP-41C, and four available slots. The internal architecture prohibited the addition of more memory, so HP designed an extended memory module that could be seen as secondary storage. The data could not be access directly, but it was possible to transfer data to and from main memory. To the calculator (and the user), data located in the extended memory looked like files on a modern hard disk do for

7878-493: The mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. The advantages of the 3½-inch disk were its higher capacity, its smaller physical size, and its rigid case which provided better protection from dirt and other environmental risks. Floppy disks became commonplace during the 1980s and 1990s in their use with personal computers to distribute software, transfer data, and create backups . Before hard disks became affordable to

7979-479: The mid-1990s, mechanically incompatible higher-density floppy disks were introduced, like the Iomega Zip disk . Adoption was limited by the competition between proprietary formats and the need to buy expensive drives for computers where the disks would be used. In some cases, failure in market penetration was exacerbated by the release of higher-capacity versions of the drive and media being not backward-compatible with

8080-411: The middle of a program. A special LBL instruction is used to create a label that is then referenced by the user to invoke the program, or by the program itself as target of a GTO (unconditional goto) or XEQ (execute) instruction. Here is a sample program that computes the factorial of an integer between 1 and 69 (70! needing an exponent greater than 99, the calculator's maximum). The integer is entered in

8181-526: The notch to change the mode of the disk. Punch devices were sold to convert read-only 5¼" disks to writable ones, and also to enable writing on the unused side of single-sided disks for computers with single-sided drives. The latter worked because single- and double-sided disks typically contained essentially identical actual magnetic media, for manufacturing efficiency. Disks whose obverse and reverse sides were thus used separately in single-sided drives were known as flippy disks . Disk notching 5¼" floppies for PCs

8282-485: The old format, including a rigid case with a sliding metal (or later, sometimes plastic) shutter over the head slot, which helped protect the delicate magnetic medium from dust and damage, and a sliding write protection tab, which was far more convenient than the adhesive tabs used with earlier disks. The large market share of the well-established 5¼-inch format made it difficult for these diverse mutually-incompatible new formats to gain significant market share. A variant on

8383-492: The original drives, dividing the users between new and old adopters. Consumers were wary of making costly investments into unproven and rapidly changing technologies, so none of the technologies became the established standard. Apple introduced the iMac G3 in 1998 with a CD-ROM drive but no floppy drive; this made USB-connected floppy drives popular accessories, as the iMac came without any writable removable media device. Recordable CDs were touted as an alternative, because of

8484-408: The personal needs of the user. Hardware extensions included a thermal printer , a magnetic card reader (HP-67 compatible via converter software), and a barcode "wand" (reader). Extension modules could also add new instructions to the machine. The standard set of mathematical functions of the 41-series was somewhat limited when compared to the functionality of some contemporary HP calculators (notably

8585-409: The press of the eject button. On Apple Macintosh computers with built-in 3½-inch disk drives, the ejection button is replaced by software controlling an ejection motor which only does so when the operating system no longer needs to access the drive. The user could drag the image of the floppy drive to the trash can on the desktop to eject the disk. In the case of a power failure or drive malfunction,

8686-412: The program listing. The HP-41C displayed each character in a block consisting of 14 segments that could be turned on or off; a so-called fourteen segment display (similar to the much more common seven segment displays , which can be used to display digits only). The HP-41C used a liquid-crystal display instead of the ubiquitous LED displays of the era, to reduce power consumption. While this allowed

8787-403: The read operation; other errors are permanent and the disk controller will signal a failure to the operating system if multiple attempts to read the data still fail. After a disk is inserted, a catch or lever at the front of the drive is manually lowered to prevent the disk from accidentally emerging, engage the spindle clamping hub, and in two-sided drives, engage the second read/write head with

8888-644: The resulting instructions was called synthetic programming . Through synthetic instructions, a user could access memory and special status flags reserved for the operating system, and do very strange things, including completely locking the machine. It was possible to create sounds or display characters, and create animations not officially supported by the operating system. The system flags were also accessed as low-level shortcuts to Boolean programming techniques. Hewlett-Packard did not officially support synthetic programming, but neither did it do anything to prevent it, and eventually even provided internal documentation to

8989-537: The same box). Most modules held dozens of programs written in the HP-41C programming language, FOCAL. Programs in the ROM modules could be called from a user program, using the ubiquitous XEQ function. In the program code, XEQ appeared as " XROM " when it was used to call a ROM program. The card reader was a device able to read and write small rectangular plastic cards with two magnetic strips. The card reader could copy contents of memory onto magnetic cards, and later read back

9090-651: The second-generation NeXTcube and NeXTstation ; however, this format had limited market success due to lack of standards and movement to 1.44 MB drives. Throughout the early 1980s, limits of the 5¼-inch format became clear. Originally designed to be more practical than the 8-inch format, it was becoming considered too large; as the quality of recording media grew, data could be stored in a smaller area. Several solutions were developed, with drives at 2-, 2½-, 3-, 3¼-, 3½- and 4-inches (and Sony 's 90 mm × 94 mm (3.54 in × 3.70 in) disk) offered by various companies. They all had several advantages over

9191-502: The sectors and at the end of the track to allow for slight speed variations in the disk drive, and to permit better interoperability with disk drives connected to other similar systems. Each sector of data has a header that identifies the sector location on the disk. A cyclic redundancy check (CRC) is written into the sector headers and at the end of the user data so that the disk controller can detect potential errors. Some errors are soft and can be resolved by automatically re-trying

9292-413: The small hole in the jacket, off to the side of the spindle hole. A light beam sensor detects when a punched hole in the disk is visible through the hole in the jacket. For a soft-sectored disk, there is only a single hole, which is used to locate the first sector of each track. Clock timing is then used to find the other sectors behind it, which requires precise speed regulation of the drive motor. For

9393-408: The spindle of the drive. Typical 3½-inch disk magnetic coating materials are: Two holes at the bottom left and right indicate whether the disk is write-protected and whether it is high-density; these holes are spaced as far apart as the holes in punched A4 paper, allowing write-protected high-density floppy disks to be clipped into international standard ( ISO 838 ) ring binders . The dimensions of

9494-528: The track length increases. While the original IBM 8-inch disk was actually so defined, the other sizes are defined in the metric system, their usual names being but rough approximations. Sharp PC-1211 A badge-engineered version of the PC-1211, the TRS-80 Pocket Computer (model PC-1 ), was marketed by Radio Shack in July 1980 as the first iteration of the TRS-80 Pocket Computer with just

9595-464: The user groups. In its December 1980 issue, BYTE magazine described the HP-41C as "the most versatile machine ever". The author praised HP's documentation as "among the best in the industry", and reported that the calculator was " much easier to program and debug" than the TI-59. Stating "I found the HP-41C far more pleasurable to program and use than its predecessors" because of its alphanumeric display,

9696-442: The user not to expose it to dangerous conditions. Rough treatment or removing the disk from the drive while the magnetic media is still spinning is likely to cause damage to the disk, drive head, or stored data. On the other hand, the 3½‑inch floppy disk has been lauded for its mechanical usability by human–computer interaction expert Donald Norman : A simple example of a good design is the 3½-inch magnetic diskette for computers,

9797-475: The whole paper turn blue due to excessive heat. The printer had some graphical capabilities, to allow the user to design character shapes, or even turn on or off individual pixels. However, the buffer memory could not hold sufficient information to print a whole line in graphic mode, and could not alter line spacing, so it was impossible to print continuous graphics in horizontal mode. The printer, nevertheless, provided some printing utilities that were able to graph

9898-409: Was generally only required where users wanted to overwrite original 5¼" disks of store-bought software, which somewhat commonly shipped with no notch present. Another LED/photo-transistor pair located near the center of the disk detects the index hole once per rotation in the magnetic disk. Detection occurs whenever the drive's sensor, the holes in the correctly inserted floppy's plastic envelope and

9999-536: Was later used by HP with the HP-71B handheld computer. Many users had used all four ports for memory expansion, leaving no room for other modules. HP designed the Quad Memory Module with four times the amount of memory, providing the maximum available memory and leaving three empty ports available. The HP-41CV (V being the Roman numeral for 5) included this memory module on the main board, thus providing five times

10100-468: Was little financial incentive to omit the device from a system. Subsequently, enabled by the widespread support for USB flash drives and BIOS boot, manufacturers and retailers progressively reduced the availability of floppy disk drives as standard equipment. In February 2003, Dell , one of the leading personal computer vendors, announced that floppy drives would no longer be pre-installed on Dell Dimension home computers, although they were still available as

10201-443: Was required that impeded adoption, since all that was necessary was an already common USB port . By 2002, most manufacturers still provided floppy disk drives as standard equipment to meet user demand for file-transfer and an emergency boot device, as well as for the general secure feeling of having the familiar device. By this time, the retail cost of a floppy drive had fallen to around $ 20 (equivalent to $ 34 in 2023), so there

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