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48-404: The RJE workstation is called a remote because it usually is located some distance from the host computer. The workstation connects to the host through a modem , digital link, packet-switching network or local area network (LAN). RJE is similar to uux and SSH , except that the workstation sends a complete job stream rather than a single command and that the user does not receive any output until

96-446: A digital modem  – one that connects directly to a digital telephone network interface, such as T1 or PRI – could send a signal that utilized every bit of bandwidth available in the system. While that signal still had to be converted back to analog at the subscriber end, that conversion would not distort the signal in the same way that the opposite direction did. The first 56k (56 kbit/s) dial-up option

144-762: A modem , is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more carrier wave signals to encode digital information , while the receiver demodulates the signal to recreate the original digital information. The goal is to produce a signal that can be transmitted easily and decoded reliably. Modems can be used with almost any means of transmitting analog signals, from LEDs to radio . Early modems were devices that used audible sounds suitable for transmission over traditional telephone systems and leased lines . These generally operated at 110 or 300 bits per second (bit/s), and

192-430: A choice of line printers between 280 and 1250 lines per minute (lpm), a 400 cards per minute (cpm) card reader , a 160 columns per second card punch , a paper tape reader, a 2.48 MB disk storage unit, and 7 and 9-track half-inch magnetic tape drives . An optional asynchronous terminal could be attached as a console. The system supported synchronous communications at up to 9600 baud, and usually served as

240-856: A different node. IBM has integrated NJE facilities into its mainframe software, and it is no longer available as separate products. However, the NJE support in JES3 requires the Batch Data Transmission (BDT) program product and the NJE support in z/VM requires the Remote Spooling Communications Subsystem ( RSCS ) program product. NJE supports Binary Synchronous Communications (BSC), Channel-to-channel adapter (CTCA), Systems Network Architecture (SNA) and TCP/IP connections among its nodes. Modem A modulator-demodulator , commonly referred to as

288-408: A given unit of time , usually expressed in bits per second (symbol bit/s , sometimes abbreviated "bps") or rarely in bytes per second (symbol B/s ). Modern broadband modem speeds are typically expressed in megabits per second (Mbit/s). Historically, modems were often classified by their symbol rate , measured in baud . The baud unit denotes symbols per second, or the number of times per second

336-518: A medium with less than ideal characteristics, such as a telephone line that is of poor quality or is too long. This capability is often adaptive so that a modem can discover the maximum practical transmission rate during the connect phase, or during operation. Modems grew out of the need to connect teleprinters over ordinary phone lines instead of the more expensive leased lines which had previously been used for current loop –based teleprinters and automated telegraphs . The earliest devices which satisfy

384-640: A protocol called HASP multileaving for use with HASP , and later, e.g., ASP, JES2 , JES3 , RSCS . The IBM System/360 Model 20 and 1130 , the Mohawk Data MDS 2400 and the UNIVAC 1004 , were popular. Later still RJE workstations switched to bit-oriented full duplex protocols such as IBM Synchronous Data Link Control , HDLC , or X.25 . The Internet Engineering Task Force has defined RFCs for internet remote job entry protocols, but they are now considered obsolete or legacy . The 200 USER Terminal

432-601: A series of popular modems for the S-100 bus and Apple II computers that could directly dial out, answer incoming calls, and hang up entirely from software, the basic requirements of a bulletin board system (BBS). The seminal CBBS for instance was created on an S-100 machine with a Hayes internal modem, and a number of similar systems followed. Echo cancellation became a feature of modems in this period, which allowed both modems to ignore their own reflected signals. This way both modems can simultaneously transmit and receive over

480-455: Is a component of OS/360 and OS/VS1 that provides job submission, job retrieval and editing for a user at an interactive terminal. Remote Entry Services ] (RES) is a component of OS/VS1 that provides RJE services. An RES workstation operator may have complete console control of the job flow between the workstation and mainframe, depending on local configuration and policy. Remote Spooling Communications Subsystem (RSCS) is, depending on

528-475: Is a remote batch terminal and protocol developed by the Control Data Corporation for their CDC 6000 series and CDC 3000 series mainframe computers in the 1960s. A 200 USER Terminal consisted of a low speed punched card reader, a line printer, and a CRT operators console. It typically communicated with a remote mainframe via synchronous modem. The software subsystem on the mainframe side

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576-438: Is near the theoretical Shannon limit of a phone line. While 56 kbit/s speeds had been available for leased-line modems for some time, they did not become available for dial up modems until the late 1990s. In the late 1990s, technologies to achieve speeds above 33.6 kbit/s began to be introduced. Several approaches were used, but all of them began as solutions to a single fundamental problem with phone lines. By

624-818: Is the protocol developed by the Campus Computing Network at UCLA to deliver batch jobs to the Remote Job Service (RJS) on their IBM 360 Model 91 . This protocol was originally assigned to ARPANET Initial Connection Protocol sockets 71, 73, and 75, and later reassigned to Internet ports 71–74. RJS is a subsystem of OS/360 MVS written by UCLA to support remote batch from card-reader/printer terminals. Early RJE workstations were "dumb" (non-programmable) devices using byte-synchronous communications protocols such as IBM BISYNC or STR , or equivalents from other vendors. Later, programmable devices or small computers were used, and IBM developed

672-698: The VA3400 which performed full-duplex at 1,200 bit/s over a normal phone line. In November 1976, AT&T introduced the 212A modem, similar in design, but using the lower frequency set for transmission. It was not compatible with the VA3400, but it would operate with 103A modem at 300 bit/s. In 1977, Vadic responded with the VA3467 triple modem, an answer-only modem sold to computer center operators that supported Vadic's 1,200-bit/s mode, AT&T's 212A mode, and 103A operation. A significant advance in modems

720-757: The 1970s, independently made modems compatible with the Bell 103 de facto standard were commonplace. Example models included the Novation CAT and the Anderson-Jacobson . A lower-cost option was the Pennywhistle modem , designed to be built using readily available parts. Teletype machines were granted access to remote networks such as the Teletypewriter Exchange using the Bell 103 modem. AT&T also produced reduced-cost units,

768-520: The Multi-leaving protocol for BSC programmable work stations; this protocol is incompatible with that used by OS/360 RJE and is the basis for protocols used for job submission from programmable work stations for, e.g., Attached Support Processor (ASP), JES2 , JES3 , OS/VS1 Remote Entry Services (RES), VM RSCS , as well as the later protocols for Network Job Entry (NJE) in, e.g., JES2, JES3, VM RSCS. Conversational Remote Job Entry (CRJE)

816-576: The SAGE director centers scattered around the United States and Canada . Shortly afterwards in 1959, the technology in the SAGE modems was made available commercially as the Bell 101 , which provided 110 bit/s speeds. Bell called this and several other early modems "datasets". Some early modems were based on touch-tone frequencies, such as Bell 400-style touch-tone modems. The Bell 103A standard

864-521: The Smartmodem made communications much simpler and more easily accessed. This provided a growing market for other vendors, who licensed the Hayes patents and competed on price or by adding features. This eventually led to legal action over use of the patented Hayes command language. Dial modems generally remained at 300 and 1,200 bit/s (eventually becoming standards such as V.21 and V.22 ) into

912-619: The completion of the job.. The terms Remote Batch , Remote Job System and Remote Job Processing are also used for RJE facilities. Remote Job Entry (RJE) is also the name of an OS/360 component that provided RJE services. An RJE workstation operator may have complete console control of the job flow between the workstation and mainframe, depending on local configuration and policy. Houston Automatic Spooling Priority (HASP) initially supported job entry from terminals using Synchronous transmit-receive (STR); eventually HASP II supported only Binary Synchronous Communications (BSC), and added

960-510: The connection between devices was normally manual, using an attached telephone handset . By the 1970s, higher speeds of 1,200 and 2,400 bit/s for asynchronous dial connections, 4,800 bit/s for synchronous leased line connections and 35 kbit/s for synchronous conditioned leased lines were available. By the 1980s, less expensive 1,200 and 2,400 bit/s dialup modems were being released, and modems working on radio and other systems were available. As device sophistication grew rapidly in

1008-522: The definition of a modem may have been the multiplexers used by news wire services in the 1920s. In 1941, the Allies developed a voice encryption system called SIGSALY which used a vocoder to digitize speech, then encrypted the speech with one-time pad and encoded the digital data as tones using frequency shift keying. This was also a digital modulation technique, making this an early modem. Commercial modems largely did not become available until

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1056-417: The digitization itself placed constraints on the types of waveforms that could be reliably encoded. The first problem was that the process of analog-to-digital conversion is intrinsically lossy, but second, and more importantly, the digital signals used by the telcos were not "linear": they did not encode all frequencies the same way, instead utilizing a nonlinear encoding ( μ-law and a-law ) meant to favor

1104-507: The draft of a new 56 kbit/s standard V.90 with strong industry support. Incompatible with either existing standard, it was an amalgam of both, but was designed to allow both types of modem by a firmware upgrade. The V.90 standard was approved in September 1998 and widely adopted by ISPs and consumers. MDS 2400 The MDS 2400 was a small floor-standing computer manufactured by Mohawk Data Sciences Corporation . The machine

1152-432: The full spectrum of the phone line, improving the available bandwidth. Additional improvements were introduced by quadrature amplitude modulation (QAM) encoding, which increased the number of bits per symbol to four through a combination of phase shift and amplitude. Transmitting at 1,200 baud produced the 4,800 bit/s V.27ter standard, and at 2,400 baud the 9,600 bit/s V.32 . The carrier frequency

1200-710: The late 1950s, when the rapid development of computer technology created demand for a method of connecting computers together over long distances, resulting in the Bell Company and then other businesses producing an increasing number of computer modems for use over both switched and leased telephone lines. Later developments would produce modems that operated over cable television lines , power lines , and various radio technologies , as well as modems that achieved much higher speeds over telephone lines. A dial-up modem transmits computer data over an ordinary switched telephone line that has not been designed for data use. It

1248-601: The late 1980s, many modems could support improved standards like this, and 2,400-bit/s operation was becoming common. Increasing modem speed greatly improved the responsiveness of online systems and made file transfer practical. This led to rapid growth of online services with large file libraries, which in turn gave more reason to own a modem. The rapid update of modems led to a similar rapid increase in BBS use. The introduction of microcomputer systems with internal expansion slots made small internal modems practical. This led to

1296-418: The late 1990s and the emergence of smartphones in the 2000s led to the development of ever-faster radio-based systems. Today, modems are ubiquitous and largely invisible, included in almost every mobile computing device in one form or another, and generally capable of speeds on the order of tens or hundreds of megabytes per second. Modems are frequently classified by the maximum amount of data they can send in

1344-431: The late 1990s, telephone-based modems quickly exhausted the available bandwidth , reaching 56 kbit/s. The rise of public use of the internet during the late 1990s led to demands for much higher performance, leading to the move away from audio-based systems to entirely new encodings on cable television lines and short-range signals in subcarriers on telephone lines. The move to cellular telephones , especially in

1392-466: The lengthy introduction of the 28,800 bit/s V.34 standard. While waiting, several companies decided to release hardware and introduced modems they referred to as V.Fast . In order to guarantee compatibility with V.34 modems once a standard was ratified (1994), manufacturers used more flexible components, generally a DSP and microcontroller , as opposed to purpose-designed ASIC modem chips. This would allow later firmware updates to conform with

1440-824: The market around February 1997; although problems with K56Flex modems were noted in product reviews through July, within six months the two technologies worked equally well, with variations dependent largely on local connection characteristics. The retail price of these early 56k modems was about US$ 200 , compared to $ 100 for standard 33k modems. Compatible equipment was also required at the Internet service providers (ISPs) end, with costs varying depending on whether their current equipment could be upgraded. About half of all ISPs offered 56k support by October 1997. Consumer sales were relatively low, which USRobotics and Rockwell attributed to conflicting standards. In February 1998, The International Telecommunication Union (ITU) announced

1488-518: The market when V.32bis was standardized, which operated at 14,400 bit/s. Rockwell International 's chip division developed a new driver chip set incorporating the V.32bis standard and aggressively priced it. Supra, Inc. arranged a short-term exclusivity arrangement with Rockwell, and developed the SupraFAXModem 14400 based on it. Introduced in January 1992 at $ 399 (or less), it was half

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1536-469: The mid-1980s. Commodore's 1982 VicModem for the VIC-20 was the first modem to be sold under $ 100, and the first modem to sell a million units. In 1984, V.22bis was created, a 2,400-bit/s system similar in concept to the 1,200-bit/s Bell 212. This bit rate increase was achieved by defining four or sixteen distinct symbols, which allowed the encoding of two or four bits per symbol instead of only one. By

1584-602: The modem sends a new signal. For example, the ITU-T V.21 standard used audio frequency-shift keying with two possible frequencies, corresponding to two distinct symbols (or one bit per symbol), to carry 300 bits per second using 300 baud. By contrast, the original ITU-T V.22 standard, which could transmit and receive four distinct symbols (two bits per symbol), transmitted 1,200 bits by sending 600 symbols per second (600 baud) using phase-shift keying . Many modems are variable-rate, permitting them to be used over

1632-400: The nonlinear response of the human ear to voice signals. This made it very difficult to find a 56 kbit/s encoding that could survive the digitizing process. Modem manufacturers discovered that, while the analog to digital conversion could not preserve higher speeds, digital-to-analog conversions could. Because it was possible for an ISP to obtain a direct digital connection to a telco,

1680-428: The originate-only 113D and the answer-only 113B/C modems. The 201A Data-Phone was a synchronous modem using two-bit-per-symbol phase-shift keying (PSK) encoding, achieving 2,000 bit/s half-duplex over normal phone lines. In this system the two tones for any one side of the connection are sent at similar frequencies as in the 300 bit/s systems, but slightly out of phase. In early 1973, Vadic introduced

1728-564: The price of the slower V.32 modems already on the market. This led to a price war, and by the end of the year V.32 was dead, never having been really established, and V.32bis modems were widely available for $ 250 . V.32bis was so successful that the older high-speed standards had little advantages. USRobotics (USR) fought back with a 16,800 bit/s version of HST, while AT&T introduced a one-off 19,200 bit/s method they referred to as V.32ter , but neither non-standard modem sold well. Consumer interest in these proprietary improvements waned during

1776-647: The release, a component of or extra cost product in VM that provides RJE services. The RSCS in the free VM/370 only supported BSC; IBM added support for Systems Network Architecture (SNA), NJE and TCP/IP over several chargeable versions. Network Job Entry (NJE) is Store and forward networking for transmitting, e.g., card files, jobs, printed output, among peers. The initial versions of NJE for JES2, JES3, VSE POWER and VM RSCS used BSC multileaving, but IBM quickly added support for Channel-to-channel adapters . IBM later added support for SNA and, ultimately, TCP/IP . NETRJS

1824-467: The standards once ratified. The ITU standard V.34 represents the culmination of these joint efforts. It employed the most powerful coding techniques available at the time, including channel encoding and shape encoding. From the mere four bits per symbol ( 9.6  kbit/s ), the new standards used the functional equivalent of 6 to 10 bits per symbol, plus increasing baud rates from 2,400 to 3,429, to create 14.4, 28.8, and 33.6 kbit/s modems. This rate

1872-423: The time technology companies began to investigate speeds above 33.6 kbit/s , telephone companies had switched almost entirely to all-digital networks. As soon as a phone line reached a local central office, a line card converted the analog signal from the subscriber to a digital one and conversely. While digitally encoded telephone lines notionally provide the same bandwidth as the analog systems they replaced,

1920-499: Was 1,650 Hz in both systems. The introduction of these higher-speed systems also led to the development of the digital fax machine during the 1980s. While early fax technology also used modulated signals on a phone line, digital fax used the now-standard digital encoding used by computer modems. This eventually allowed computers to send and receive fax images. In the early 1990s, V.32 modems operating at 9,600 bit/s were introduced, but were expensive and were only starting to enter

1968-469: Was a proprietary design from USRobotics , which they called "X2" because 56k was twice the speed (×2) of 28k modems. At that time, USRobotics held a 40% share of the retail modem market, while Rockwell International held an 80% share of the modem chipset market. Concerned with being shut out, Rockwell began work on a rival 56k technology. They joined with Lucent and Motorola to develop what they called "K56Flex" or just "Flex". Both technologies reached

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2016-517: Was an interest in a peer-to-peer transfer of, e.g., submitted jobs, printer output. Following customer requests, IBM developed a suite of facilities, derived from BITNET and VNET , known as Network Job Entry. As part of that software, IBM provided commands to transmit datasets among nodes (complexes of computers with a collective name). NJE allows a batch job to control where it would run and where its output would be processed; similarly, NJE allows an interactive user to send printed or punched output to

2064-589: Was called Export-Import 200, and later, the Remote Batch Facility (RBF). Other remote batch terminals using the UT200 protocol included the CDC 731, 732, and 734. Software emulators for the UT200 protocol were also written for a number of minicomputer systems. RJE is well suited to organizations that had a single large central computer center. However, in large organizations with multiple data centers, there

2112-458: Was integrated into devices from many other manufacturers. Automatic dialing was not a new capability—it had been available via separate Automatic Calling Units , and via modems using the X.21 interface —but the Smartmodem made it available in a single device that could be used with even the most minimal implementations of the ubiquitous RS-232 interface, making this capability accessible from virtually any system or language. The introduction of

2160-412: Was introduced by AT&T in 1962. It provided full-duplex service at 300 bit/s over normal phone lines. Frequency-shift keying was used, with the call originator transmitting at 1,070 or 1,270  Hz and the answering modem transmitting at 2,025 or 2,225 Hz. The 103 modem would eventually become a de facto standard once third-party (non-AT&T modems) reached the market, and throughout

2208-548: Was once a widely known technology, mass-marketed globally dial-up internet access . In the 1990s, tens of millions of people in the United States alone used dial-up modems for internet access. Dial-up service has since been largely superseded by broadband internet , such as DSL . Mass production of telephone line modems in the United States began as part of the SAGE air-defense system in 1958, connecting terminals at various airbases, radar sites, and command-and-control centers to

2256-532: Was originally developed by Atron Corporation as the Atron 501 Datamanager, introduced in 1969. It was marketed primarily for remote job entry applications and promoted as The Peripheral Processor . Two related models from Mohawk were the 1200 and the 2300. The system had a base memory of 4 KB of core memory with a 2 μs cycle time, expandable to 32 KB. It supported one to four input/output channels with up to 16 devices per channel. It offered

2304-536: Was the Hayes Smartmodem , introduced in 1981. The Smartmodem was an otherwise standard 103A 300 bit/s direct-connect modem, but it introduced a command language which allowed the computer to make control requests, such as commands to dial or answer calls, over the same RS-232 interface used for the data connection. The command set used by this device became a de facto standard, the Hayes command set , which

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