The Casio CFX-9850G series is a series of graphing calculators manufactured by Casio Computer Co., Ltd . from 1996 to 2008.
65-453: The back of the device shows a slightly protruding battery case cover, which slides out to reveal the compartment for the four AAA alkaline batteries used for primary power , and a CR2032 lithium button cell used for memory backup when primary power is down or being changed. The device consumes power at the rate of 0.06 W , and turns itself off automatically after about 6 minutes of time spent without any keypad activity. Battery life for
130-614: A DTE ( data terminal equipment ) such as a computer terminal or PC , and a DCE ( data circuit-terminating equipment or data communication equipment ), such as a modem . The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pinout of connectors. The current version of the standard is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange , issued in 1997. The RS-232 standard had been commonly used with serial ports and serial cables . It
195-639: A graphics resolution of 127 by 63 pixels (the first row and column of pixels are unusable in graphing), and a character resolution of 21 columns by 8 lines. The bottom line is reserved for function key menu tips, and the rest is available for the graphics and character display. The calculators includes program capacity of 26 kilobytes . This is divided among storage blocks for programs, statistics, matrices, lists, static and dynamic graphs and their associated settings, functions, recursions , equations , financial data , and variables (all of which are global). These can be cleared individually or completely in
260-467: A loopback capability used for testing. When enabled, signals are echoed back to the sender rather than being sent on to the receiver. If supported, the DTE can signal the local DCE (the one it is connected to) to enter loopback mode by setting Local Loop (LL, pin 18) to ON, or the remote DCE (the one the local DCE is connected to) to enter loopback mode by setting Remote Loop (RL, pin 21) to ON. The latter tests
325-426: A router ) as an alternative to monitoring over Ethernet. In RS-232, user data is sent as a time-series of bits . Both synchronous and asynchronous transmissions are supported by the standard. In addition to the data circuits, the standard defines a number of control circuits used to manage the connection between the DTE and DCE. Each data or control circuit only operates in one direction, that is, signaling from
390-486: A "high" or "low" signaling rate. The rates, as well as which device will select the rate, must be configured in both the DTE and DCE. The prearranged device selects the high rate by setting the Data Signal Rate Selector (DSRS, pin 23) signal to ON. Sometimes called Data Rate Select (DRS), this signal should not be confused with the more commonly used Data Set Ready (DSR, pin 6). Many DCE devices have
455-514: A 25-pin D-sub connector does not necessarily indicate an RS-232-C compliant interface. For example, on the original IBM PC, a male D-sub was an RS-232-C DTE port (with a non-standard current loop interface on reserved pins), but the female D-sub connector on the same PC model was used for the parallel "Centronics" printer port . Some personal computers put non-standard voltages or signals on some pins of their serial ports. The standard does not define
520-409: A DTE to the attached DCE or the reverse. Because transmit data and receive data are separate circuits, the interface can operate in a full duplex manner, supporting concurrent data flow in both directions. The standard does not define character framing within the data stream or character encoding. The RS-232 standard defines the voltage levels that correspond to logical one and logical zero levels for
585-453: A cable that connects the corresponding pins according to the table below. Cables with 9 pins on one end and 25 on the other are common. Manufacturers of equipment with 8P8C connectors usually provide a cable with either a DB-25 or DE-9 connector (or sometimes interchangeable connectors so they can work with multiple devices). Poor-quality cables can cause false signals by crosstalk between data and control lines (such as Ring Indicator ). If
650-421: A common ground limits RS-232 to applications with relatively short cables. If the two devices are far enough apart or on separate power systems, the local ground connections at either end of the cable will have differing voltages; this difference will reduce the noise margin of the signals. Balanced, differential serial connections such as RS-422 or RS-485 can tolerate larger ground voltage differences because of
715-518: A computer (FA-122 and FA-123 (serial) and FA-124 (USB) interface unit and cables) or to another calculator (SB-62 cable) to transfer data, such as programs, equations, graphs etc. It can also connect to a Casio label printer (SB-62 cable). Transmission speed is stated as 9600 byte/s . The calculator can be connected to the EA-100 data logger which is used to read data such as temperature, light intensity, force, voltage, loudness, pH and other such data in
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#1732797619012780-461: A few of the twenty signals specified in the standard, so connectors and cables with fewer pins are sufficient for most connections, more compact, and less expensive. Personal computer manufacturers replaced the DB-25M connector with the smaller DE-9M connector. This connector, with a different pinout (see Serial port pinouts ), is prevalent for personal computers and associated devices. Presence of
845-496: A given cable will not allow a data connection, especially if a gender changer is in use, a null modem cable may be necessary. Gender changers and null modem cables are not mentioned in the standard, so there is no officially sanctioned design for them. The following table lists commonly used RS-232 signals (called "circuits" in the specifications) and their pin assignments on the recommended DB-25 connectors (see Serial port pinouts for other commonly used connectors not defined by
910-416: A maximum open-circuit voltage of 25 volts: signal levels of ±5 V, ±10 V, ±12 V, and ±15 V are all commonly seen depending on the voltages available to the line driver circuit. Many RS-232 driver chips have inbuilt charge pump circuitry to produce the required voltages from a 3 or 5 volt supply. RS-232 drivers and receivers must be able to withstand indefinite short circuits to
975-502: A maximum cable length, but instead defines the maximum capacitance that a compliant drive circuit must tolerate. A widely used rule of thumb indicates that cables more than 15 m (50 ft) long will have too much capacitance, unless special cables are used. By using low-capacitance cables, communication can be maintained over larger distances up to about 300 m (1,000 ft). For longer distances, other signal standards, such as RS-422 , are better suited for higher speeds. Since
1040-453: A minimum diameter of 4.3 mm (0.17 in). Alkaline AAA batteries weigh around 11.5 grams (0.41 oz), while primary lithium AAA batteries weigh about 7.6 g (0.27 oz). Rechargeable nickel–metal hydride (NiMH) AAA batteries typically weigh 14–15 g (0.49–0.53 oz). AAA batteries are most often used in small electronic devices, such as TV remote controls, MP3 players and digital cameras. Devices that require
1105-972: A multi-level grayscale display, in that altering the contrast of a pixel changes its color. A light contrast displays orange, then as the contrast increases, the color becomes blue, then green at a dark contrast. The calculators include program capacity of 28 to 64 kilobytes of memory depending on model: The CFX-9850GB PLUS and CFX-9950GB PLUS models have a built-in software library , consisting of programs that perform complicated calculations and data processing . For example, operations on differential equations , digital caliper measurements, capacitor charge curves, figure rotations and Riemann sums . These are organized into six sub-libraries, five of them for mathematical computations , and one for scientific instrumentation . A number of financial operations such as interest compounding and amortization are also provided. Changes from CFX-9950GB PLUS include: AAA battery The AAA battery (or triple-A battery )
1170-424: A reduced voltage. Some manufacturers therefore built transmitters that supplied +5 V and −5 V and labeled them as "RS-232 compatible". Later personal computers (and other devices) started to make use of the standard so that they could connect to existing equipment. For many years, an RS-232-compatible port was a standard feature for serial communications , such as modem connections, on many computers (with
1235-449: A short-range, point-to-point, low-speed wired data connection is fully adequate. The Electronic Industries Association (EIA) standard RS-232-C as of 1969 defines: The standard does not define such elements as the character encoding (i.e. ASCII , EBCDIC , or others), the framing of characters (start or stop bits, etc.), transmission order of bits, or error detection protocols. The character format and transmission bit rate are set by
1300-709: A special section for advanced conic section graphing. Dynamic graphing provides all the functionality of regular graphing, but allows the binding of a variable in the graph equation to time over a value range. Up to 36 lists can be stored and manipulated in various ways in the list manager. The lists can also be used to feed data into inbuilt statistics operations, producing various statistical figures, performing regression analysis , and generating graphs like scatter and box and whisker plots , among others. Tables can be generated from functions , recursive series can be generated, and equations can be solved - both simultaneous and polynomial. The device can link up by cable to
1365-461: A specialized DTE called a bit error rate tester (or BERT). Some synchronous devices provide a clock signal to synchronize data transmission, especially at higher data rates. Two timing signals are provided by the DCE. Pin 15 is the transmitter clock (TCK), or send timing (ST); the DTE puts the next bit on the transmit data line (pin 2) when this clock transitions from OFF to ON (so it is stable during
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#17327976190121430-418: A synchronization preamble to the receiver when they are re-enabled. The DTE asserts RTS to indicate a desire to transmit to the DCE, and in response the DCE asserts CTS to grant permission, once synchronization with the DCE at the far end is achieved. Such modems are no longer in common use. There is no corresponding signal that the DTE could use to temporarily halt incoming data from the DCE. Thus RS-232's use of
1495-484: A weight reading, or a GPS receiver that periodically sends position, if no configuration via RS-232 is necessary). When only hardware flow control is required in addition to two-way data, the RTS and CTS lines are added in a 5-wire version. The EIA-232 standard specifies connections for several features that are not used in most implementations. Their use requires 25-pin connectors and cables. The DTE or DCE can specify use of
1560-632: Is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange , issued in 1997. Changes since Revision C have been in timing and details intended to improve harmonization with the CCITT standard ITU-T/CCITT V.24 [ de ] , but equipment built to the current standard will interoperate with older versions. Related ITU-T standards include V.24 (circuit identification) and ITU-T/CCITT V.28 [ de ] (signal voltage and timing characteristics). In revision D of EIA-232,
1625-480: Is a standard size of dry cell battery . One or more AAA batteries are commonly used in low-drain portable electronic devices. A zinc–carbon battery in this size is designated by IEC as R03 , by ANSI C18.1 as 24 , by old JIS standard as UM-4 , and by other manufacturer and national standard designations that vary depending on the cell chemistry. The size was first introduced by The American Ever Ready Company in 1911. In China, they are called #7 batteries,
1690-453: Is a signal sent from the DCE to the DTE device. It indicates to the terminal device that the phone line is ringing. In many computer serial ports, a hardware interrupt is generated when the RI signal changes state. Having support for this hardware interrupt means that a program or operating system can be informed of a change in state of the RI pin, without requiring the software to constantly "poll"
1755-840: Is faster, uses lower voltages, and has connectors that are simpler to connect and use. Disadvantages of USB compared to RS-232 are that USB is far less immune to electromagnetic interference (EMI) and that maximum cable length defined by standards is much shorter (15 meters for RS-232 versus 3–5 meters for USB, depending on the USB version and use of active cables). RS-232 cable lengths of 2000 meters are possible with appropriate line drivers. In fields such as laboratory automation or surveying, RS-232 devices continue to be used. Some types of programmable logic controllers , variable-frequency drives , servo drives , and computerized numerical control equipment are programmable via RS-232. Computer manufacturers have responded to this demand by re-introducing
1820-940: Is still widely used in industrial communication devices. A serial port complying with the RS-232 standard was once a standard feature of many types of computers. Personal computers used them for connections not only to modems, but also to printers , computer mice , data storage, uninterruptible power supplies , and other peripheral devices. Compared with later interfaces such as RS-422 , RS-485 and Ethernet , RS-232 has lower transmission speed, shorter maximum cable length, larger voltage swing, larger standard connectors, no multipoint capability and limited multidrop capability. In modern personal computers, USB has displaced RS-232 from most of its peripheral interface roles. Thanks to their simplicity and past ubiquity, however, RS-232 interfaces are still used—particularly in industrial CNC machines, networking equipment and scientific instruments where
1885-476: Is used beyond the original purpose of interconnecting a terminal with a modem, successor standards have been developed to address the limitations. Issues with the RS-232 standard include: In the book PC 97 Hardware Design Guide , Microsoft deprecated support for the RS-232 compatible serial port of the original IBM PC design. Today, RS-232 has mostly been replaced in personal computers by USB for local communications. Advantages compared to RS-232 are that USB
1950-531: Is used by some older uninterruptible power supplies (UPSs) to signal a power failure state to the computer. Certain personal computers can be configured for wake-on-ring , allowing a computer that is suspended to answer a phone call. The Request to Send (RTS) and Clear to Send (CTS) signals were originally defined for use with half-duplex (one direction at a time) modems such as the Bell 202 . These modems disable their transmitters when not required and must transmit
2015-476: The DE-9M connector on their computers or by making adapters available. RS-232 ports are also commonly used to communicate to headless systems such as servers , where no monitor or keyboard is installed, during boot when an operating system is not yet running and therefore no network connection is possible. A computer with an RS-232 serial port can communicate with the serial port of an embedded system (such as
Casio 9850 series - Misplaced Pages Continue
2080-715: The CFX-9850G Plus, Ga Plus, GB Plus, and GC Plus. The CFX-9850GB Plus includes a built-in software library, and the CFX-9850GC Plus increases memory from 32k to 64k. Two other models were sold alongside the CFX-9850G series, the CFX-9950G series, which has 64k of memory, and the CFX-9970G, which has symbolic algebra. The series was discontinued with the CFX-9850GC Plus in 2008. There are French versions where
2145-561: The D-subminiature connector was formally included as part of the standard (it was only referenced in the appendix of RS-232-C). The voltage range was extended to ±25 volts, and the circuit capacitance limit was expressly stated as 2500 pF. Revision E of EIA-232 introduced a new, smaller, standard D-shell 26-pin "Alt A" connector, and made other changes to improve compatibility with CCITT standards V.24, V.28 and ISO 2110. Specification document revision history: Because RS-232
2210-407: The DTE. Unlike the original use of RTS and CTS with half-duplex modems, these two signals operate independently from one another. This is an example of hardware flow control . However, "hardware flow control" in the description of the options available on an RS-232-equipped device does not always mean RTS/CTS handshaking. Equipment using this protocol must be prepared to buffer some extra data, since
2275-579: The MEM menu. When saving files, a file name uses 17 bytes of memory. A command consumes 1 or 2 bytes. Graphs can be drawn with split-screen viewing of graphs as well as tables or zooms . Graphed areas can be shaded in customizable colors. The graph viewport can be resized and shifted (these settings can be saved for later retrieval), and points along the graph curves can be traced. Graph solver tools can also be used to find useful points, such as maxima/minima and intersection points. The calculator also has
2340-460: The ON to OFF transition when the DCE registers the bit). Pin 17 is the receiver clock (RCK), or receive timing (RT); the DTE reads the next bit from the receive data line (pin 3) when this clock transitions from ON to OFF. Alternatively, the DTE can provide a clock signal, called transmitter timing (TT, pin 24) for transmitted data. Data is changed when the clock transitions from OFF to ON, and read during
2405-409: The ON to OFF transition. TT can be used to overcome the problem of propagation delay in a long cable. ST must traverse a cable of unknown length and delay, clock a bit out of the DTE after another unknown delay, and return it to the DCE over the same unknown cable delay. When sending data at high speed, the data bit may not arrive in time for the ON to OFF transition of ST. Since the relation between
2470-421: The RS-232 device, can send data onto the bus. Modern communications environments use full-duplex (both directions simultaneously) modems. In that environment, DTEs have no reason to deassert RTS. However, due to the possibility of changing line quality, delays in processing of data, etc., there is a need for symmetric, bidirectional flow control . A symmetric alternative providing flow control in both directions
2535-414: The RS-232 interface, and provide sufficient current to comply with the slew rate requirements for data transmission. Because both ends of the RS-232 circuit depend on the ground pin being zero volts, problems will occur when connecting machinery and computers where the voltage between the ground pin on one end, and the ground pin on the other is not zero. This may also cause a hazardous ground loop . Use of
2600-454: The RTS and CTS signals, per the older versions of the standard, is asymmetric. This scheme is also employed in present-day RS-232 to RS-485 converters. RS-485 is a multiple-access bus on which only one device can transmit at a time, a concept that is not provided for in RS-232. The RS-232 device asserts RTS to tell the converter to take control of the RS-485 bus so that the converter, and thus
2665-512: The United States. In Japan as of 2011, 28% of alkaline primary batteries sold were AAA. In Switzerland as of 2007, AAA batteries totaled 30% of primary battery sales and 32% of secondary battery (rechargeable) sales. RS-232 In telecommunications , RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between
Casio 9850 series - Misplaced Pages Continue
2730-592: The ab/c and EXP buttons are labelled differently. (French versions: 9750=Graph 30,35,fx-8930GT; 9850,9950=Graph 60,65,CFX-9930GT,9940,9960; 9970=Graph 80) Power consumption is same as fx-9750. Battery life for the primary battery ranges from 320 hours (LR03 battery) to 180 hours (R03 battery) for continuous display of main menu. For continuous operation (5/55 minutes calculation/display), battery life ranges from 280 hours (LR03 battery) to 160 hours (R03 battery). CFX models are capable of displaying three colors : orange , blue and green . The colors are handled much like
2795-403: The communications link, as well as both DCEs. When the DCE is in test mode, it signals the DTE by setting Test Indicator (TI, pin 25) to ON. A commonly used version of loopback testing does not involve any special capability of either end. A hardware loopback is simply a wire connecting complementary pins together in the same connector (see loopback ). Loopback testing is often performed with
2860-408: The companies was "PC-Link". It has a 2.5mm stereo phono plug on one end, the patented electronic circuit inside the plastic bump and a DE-9F on the other for connecting to the serial port of a PC. The circuit converts low voltage low power signals of the handheld device to be compatible with the levels and power of a PC's RS-232 serial port. Versions of the circuit were used by many companies from
2925-457: The computer acting as the DTE). It remained in widespread use into the late 1990s. In personal computer peripherals, it has largely been supplanted by other interface standards, such as USB. RS-232 is still used to connect older designs of peripherals, industrial equipment (such as PLCs ), console ports, and special purpose equipment. The standard has been renamed several times during its history as
2990-403: The data transmission and the control signal lines. Valid signals are either in the range of +3 to +15 volts or the range −3 to −15 volts with respect to the "Common Ground" (GND) pin; consequently, the range between −3 and +3 volts is not a valid RS-232 level. For data transmission lines (TxD, RxD, and their secondary channel equivalents), logic one is represented as a negative voltage and
3055-610: The differential signaling. Unused interface signals terminated to the ground will have an undefined logic state. Where it is necessary to permanently set a control signal to a defined state, it must be connected to a voltage source that asserts the logic 1 or logic 0 levels, for example with a pull-up resistor . Some devices provide test voltages on their interface connectors for this purpose. RS-232 devices may be classified as Data Terminal Equipment (DTE) or Data Circuit-terminating Equipment (DCE); this defines at each device which wires will be sending and receiving each signal. According to
3120-553: The early 1990s to bridge the RS-232/TTL voltage/power gap. Changes from fx-9750G include: The Casio CFX-9850G was introduced in 1996. As a higher-end version of the FX-9750G series, The CFX-9850G introduced a number of enhancements over that series, the most noticeable being a color LCD display capable of displaying orange, green, and blue. The CFX-9850G was later replaced with updated models that added features and fixed bugs,
3185-417: The ground or to any voltage level up to ±25 volts. The slew rate , or how fast the signal changes between levels, is also controlled. Because the voltage levels are higher than logic levels typically used by integrated circuits, special intervening driver circuits are required to translate logic levels. These also protect the device's internal circuitry from short circuits or transients that may appear on
3250-500: The name originating from the Burgess Battery Company designating his AAA batteries "Number 7". An AAA battery is a single cell that measures 10.5 mm (0.41 in) in diameter and 44.5 mm (1.75 in) in length, including the positive terminal button, which is a minimum 0.8 mm (0.031 in). The positive terminal has a maximum diameter of 3.8 mm (0.15 in); the flat negative terminal has
3315-430: The original DCEs were (usually) modems. When electronic terminals (smart and dumb) began to be used, they were often designed to be interchangeable with teletypewriters, and so supported RS-232. Because the standard did not foresee the requirements of devices such as computers, printers, test instruments, POS terminals , and so on, designers implementing an RS-232 compatible interface on their equipment often interpreted
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#17327976190123380-442: The primary power cells ranges from 300 hours (LR03 battery) to 200 hours (R03 battery) for continuous display of main menu. Backup cells last up to about 2 years each. The calculators weigh about 190 grams including batteries , and measure about 19.7 mm x 83 mm x 176 mm. Features include scientific calculations , including calculus , graphing and programming , statistics and matrix operations. The display has
3445-405: The remote system may have begun transmitting just before the local system de-asserts RTR. A minimal "3-wire" RS-232 connection consisting only of transmit data, receive data, and ground, is commonly used when the full facilities of RS-232 are not required. Even a two-wire connection (data and ground) can be used if the data flow is one way (for example, a digital postal scale that periodically sends
3510-577: The same fashion as the Texas Instruments Computer Based Laboratory and various data loggers for use with the Hewlett-Packard calculators; Sharp also makes such a tool. The serial link cable was designed and U.S. patented (5504864) by Larry Berg of Purple Computing. It was manufactured by Traveling Software (AKA Laplink.com) and later by Purple Computing for Casio. The common name for the cable used by
3575-400: The same pin as RTS (Request to Send), and that when 133 is in use, RTS is assumed by the DCE to be asserted at all times. In this scheme, commonly called "RTS/CTS flow control" or "RTS/CTS handshaking" (though the technically correct name would be "RTR/CTS"), the DTE asserts RTS whenever it is ready to receive data from the DCE, and the DCE asserts CTS whenever it is ready to receive data from
3640-577: The same voltage, but have a higher current draw, are often designed to use larger batteries such as the AA battery type. AA batteries have about three times the capacity of AAA batteries. With the increasing efficiency and miniaturization of modern electronics, many devices that previously were designed for AA batteries (remote controls, cordless computer mice and keyboards, etc.) are being replaced by models that accept AAA battery cells. As of 2007, AAA batteries accounted for 24% of alkaline primary battery sales in
3705-566: The serial port hardware, typically a UART , which may also contain circuits to convert the internal logic levels to RS-232 compatible signal levels. The standard does not define bit rates for transmission, except that it says it is intended for bit rates lower than 20,000 bits per second. RS-232 was first introduced in 1960 by the Electronic Industries Association (EIA) as a Recommended Standard . The original DTEs were electromechanical teletypewriters , and
3770-439: The signal condition is called "mark". Logic zero is signaled with a positive voltage and the signal condition is termed "space". Control signals have the opposite polarity: the asserted or active state is positive voltage and the de-asserted or inactive state is negative voltage. Examples of control lines include request to send (RTS), clear to send (CTS), data terminal ready (DTR), and data set ready (DSR). The standard specifies
3835-496: The sponsoring organization changed its name, and has been variously known as EIA RS-232, EIA 232, and, most recently as TIA 232. The standard continued to be revised and updated by the Electronic Industries Association and since 1988 by the Telecommunications Industry Association (TIA). Revision C was issued in a document dated August 1969. Revision D was issued in 1986. The current revision
3900-553: The standard definitions are not always correctly applied, it is often necessary to consult documentation, test connections with a breakout box , or use trial and error to find a cable that works when interconnecting two devices. Connecting a fully standard-compliant DCE device and DTE device would use a cable that connects identical pin numbers in each connector (a so-called "straight cable"). " Gender changers " are available to solve gender mismatches between cables and connectors. Connecting devices with different types of connectors requires
3965-411: The standard idiosyncratically. The resulting common problems were non-standard pin assignment of circuits on connectors, and incorrect or missing control signals. The lack of adherence to the standards produced a thriving industry of breakout boxes , patch boxes, test equipment, books, and other aids for the connection of disparate equipment. A common deviation from the standard was to drive the signals at
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#17327976190124030-440: The standard). The signals are named from the standpoint of the DTE. The ground pin is a common return for the other connections, and establishes the "zero" voltage to which voltages on the other pins are referenced. The DB-25 connector includes a second "protective ground" on pin 1; this is connected internally to equipment frame ground, and should not be connected in the cable or connector to signal ground. Ring Indicator (RI)
4095-585: The standard, male connectors have DTE pin functions, and female connectors have DCE pin functions. Other devices may have any combination of connector gender and pin definitions. Many terminals were manufactured with female connectors but were sold with a cable with male connectors at each end; the terminal with its cable satisfied the recommendations in the standard. The standard recommends the D-subminiature 25-pin connector up to revision C, and makes it mandatory as of revision D. Most devices only implement
4160-492: The state of the pin. RI does not correspond to another signal that carries similar information the opposite way. On an external modem the status of the Ring Indicator pin is often coupled to the "AA" (auto answer) light, which flashes if the RI signal has detected a ring. The asserted RI signal follows the ringing pattern closely, which can permit software to detect distinctive ring patterns. The Ring Indicator signal
4225-463: Was developed and marketed in the late 1980s by various equipment manufacturers. It redefined the RTS signal to mean that the DTE is ready to receive data from the DCE. This scheme was eventually codified in version RS-232-E (actually TIA-232-E by that time) by defining a new signal, "RTR (Ready to Receive)", which is CCITT V.24 circuit 133. TIA-232-E and the corresponding international standards were updated to show that circuit 133, when implemented, shares
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