Hazeltine 2000

Last updated
Hazeltine 2000
Manufacturer Hazeltine Corporation
Type Computer terminal
Release dateOctober 1970 (October 1970)
Display CRT 80x25 characters
Input Computer keyboard
Connectivity RS-232
Successor Hazeltine 1500

The Hazeltine 2000 is one of the first general-purpose "smart" computer terminals, [1] [lower-alpha 1] introduced in October 1970 at a price of $2,995 (equivalent to $20,900in 2021). While earlier terminal systems included "smart" editing features, notably the IBM 2260, the Hazeltine 2000 was the first that used a standard RS-232 interface and sent its control sequences in the data stream. It could be attached to any contemporary minicomputer or mainframe that had a serial port [2] and used ASCII-standard character sets.

Contents

One advanced feature of the design was the concept of "batch mode" that cached data being typed by the user and sent it all at once to the host. The system also had two display intensities, foreground and background (bright and dim). Data sent in background mode was independent and not sent back to the server. This allowed forms to be sent as text in background mode and then switch the terminal to foreground mode for data entry. This was used to create on-screen forms that could be filled out and cleared without having to re-send the background layout.

The base model displayed 27 lines of 74 characters, uppercase only, while an expansion added lowercase and 80-by-25 layout. In 1974 the expanded version became the only model and the price was lowered. The basic system was reimplemented several times using newer electronics as they became available during the 1970s. The Hazeltine 1500 was a lower-cost version introduced in 1977. The development team was unhappy with the support they received from the corporation, and the division was spun off to form Esprit Systems.

Description

Basic system

The system was an all-in-one unit with a 12" diagonal green phosphor screen with a 8.5" by 5.75" display area. The system weighed 62 pounds (28 kg) and required at least 24 inches (610 mm) of depth on a desk, and drew a massive 350 W in operation. It required 30 seconds to "warm up", and continually ran a fan to cool the system. [3] Later models first grew to 63 pounds (29 kg) before falling to 57 pounds (26 kg). [4]

In contrast to most glass terminals of the era, the 2000 offered only RS-232, lacking the common current loop based on the Teletype Model 33 that was widely used as an ad hoc terminal in the 1970s. Switches on the back of the case allowed the speed to be set to all common speeds between 110 and 9600 bit/s. A second switch, "CA", added additional Request To Send characters to sent data in order to turn around the communications channel in half-duplex modems like the WE202C. This also had the side-effect of reducing the speeds; when turned on the highest speed was 1200 bit/s, but it also supported a wider variety of speeds below that to match the variety of speeds seen with these modems, adding 150 and 600 bit/s. [5]

The system also had outputs for a printer, cassette storage, and the video signal so it could be mirrored on up to three additional screens. The connectors were complex, HDR panel mounts based on those used in avionics, Hazeltine's primary business. The RS-232 was connected via a hard-wired cable with a 25-pin connector at the end, not a rear-panel port. [6]

The keyboard could be detached, connecting to the terminal using a 5 foot (1.5 m) 54-pin HDR connector. [4] It had a 51-key typewriter layout main section, along with a numeric keypad to the right, and a cursor control section to the right of the numeric keypad. Running in a column down the extreme right hand side was a series of seven status lamps and pushbuttons with the on/off switch at the top of the column. [7]

Parity was selected using a rear-panel rotating switch, odd, even, always-1 or always-0. A parity error would cause the parity lamp to light, which could be cleared by pressing it. [8]

The base-model system had a character set of 64 characters covering the upper case ASCII set. These were drawn on-screen in a 5 by 7 dot matrix, allowing 27 rows of 74 characters per line. With the optional lower case option, the character matrix was expanded to 5 by 8, thereby allowing only 25 lines, although by adjusting the display slightly, they expanded to 80 columns wide. [9]

Batch mode

A key feature of the 2000 was its ability to be put into "batch mode", either by pressing the appropriate lamp/button on the right of the keyboard, or by sending the appropriate command as ASCII codes from the host computer. When the terminal was in this mode, the batch lamp/button was turned on. [10]

In batch mode, typing on the keyboard was not immediately sent to the host, but was instead buffered into the 2 KB of internal core memory. Buffered data was sent when the user pressed the return key. The data to be sent was normally everything on the line up to the cursor, but this could be modified by pressing holding down ⇧ Shift and pressing the special XMIT key in the cursor cluster. [11] This caused a second cursor to appear on-screen at the current location, and it will begin sending data from that position to the first carriage return it sees in the data. [12]

Foreground/Background

Batch mode was normally used in conjunction with a separate feature, foreground/background mode. This system allowed the text on the screen to be displayed at normal intensity, foreground, or a reduced intensity, background. The mode for every character on the screen was held in the buffer, so foreground and background data could be displayed anywhere on the screen. [13]

The key feature of this concept is that common commands, like clear screen, could be issued to clear only the foreground or background data, and batch mode only sends the foreground characters. In practice, the host computer would send a stream of data in background mode to lay out a form, sending spaces in foreground mode to indicate input areas. Once the form was complete, it would switch back to foreground mode and turn on batch. [13]

Once sent up in this fashion, the user's input would only be into those portions of the screen that were in foreground mode, and only their entries would be sent back to the host. Additionally, the cursor keys and tab key skipped over background characters, allowing the user to easily move around the form from field to field. [13]

Sending commands

Like the wide variety of smart terminals that followed, the 2000 used an escape sequence to send commands to the terminal. For the 2000, the commands were indicated by Control-Shift-period, what they referred to as the "lead-in code". [14] The single character following the lead-in defines an action. These included SO (shift out) to trigger a transmit in batch mode, US (unit separator) to indicate following data was in foreground mode, EM (end of medium) to indicate background, FS (file separator) to clear the screen, or GS (group separator) to clear just the foreground. [15]

The command set also included basic editing and cursor positioning typical of other smart terminals. DC2 sent the cursor to the "home" position in the upper left, DC3 deleted the line, and SUB (substitute) inserted a blank line below the cursor position. [15] DC1 allowed the cursor to be sent to an indicated location on the screen by following it with two ASCII characters where the character code indicated a number. For instance, the NUL, ASCII code 0, would send the cursor to row or column 0. To avoid problems in transmission, the pattern repeated at 32, Space, so that the Y coordinate could be sent using the characters in the printable character range. The X coordinate was too large to fit in the printable range, so it repeated at character 96, although this did not allow the full range to be addressed in this manner. [16]

Notes

  1. ↑ da Cruz says "possibly" the first, but the Datapoint 3300 appears to have shipped months earlier with similar features.

Related Research Articles

In computing and telecommunication, a control character or non-printing character (NPC) is a code point in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly printing, printable, or graphic characters, except perhaps for the "space" character.

<span class="mw-page-title-main">Scroll Lock</span> Computer key

Scroll Lock is a lock key on most IBM-compatible computer keyboards.

<span class="mw-page-title-main">Terminal emulator</span> Program that emulates a video terminal

A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term terminal covers all remote terminals, including graphical interfaces. A terminal emulator inside a graphical user interface is often called a terminal window.

In computer science, an escape sequence is a combination of characters that has a meaning other than the literal characters contained therein; it is marked by one or more preceding characters.

<span class="mw-page-title-main">ANSI escape code</span> Method used for display options on video text terminals

ANSI escape sequences are a standard for in-band signaling to control cursor location, color, font styling, and other options on video text terminals and terminal emulators. Certain sequences of bytes, most starting with an ASCII escape character and a bracket character, are embedded into text. The terminal interprets these sequences as commands, rather than text to display verbatim.

<span class="mw-page-title-main">Computer terminal</span> Computer input/output device for users

A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The teletype was an example of an early-day hard-copy terminal and predated the use of a computer screen by decades.

<span class="mw-page-title-main">Tektronix 4010</span> Text and graphics computer terminals

The Tektronix 4010 series was a family of text-and-graphics computer terminals based on storage-tube technology created by Tektronix. Several members of the family were introduced during the 1970s, the best known being the 11-inch 4010 and 19-inch 4014, along with the less popular 25-inch 4016. They were widely used in the computer-aided design market in the 1970s and early 1980s.

ANSI.SYS is a device driver in the DOS family of operating systems that provides extra console functions through ANSI escape sequences. It is partially based upon a subset of the text terminal control standard proposed by the ANSI X3L2 Technical Committee on Codes and Character Sets.

<span class="mw-page-title-main">VT52</span> CRT-based computer terminal

The VT50 was a CRT-based computer terminal introduced by Digital Equipment Corporation (DEC) in July 1974. It provided a display with 12 rows and 80 columns of upper-case text, and used an expanded set of control characters and forward-only scrolling based on the earlier VT05. DEC documentation of the era refers to the terminals as the DECscope, a name that was otherwise almost never seen.

<span class="mw-page-title-main">Teletype Model 33</span> 1963–1981 ASCII communications/computer terminal device

The Teletype Model 33 is an electromechanical teleprinter designed for light-duty office use. It is less rugged and cost less than earlier Teletype machines. The Teletype Corporation introduced the Model 33 as a commercial product in 1963; the machine had originally been designed for the United States Navy. There are three versions of the Model 33:

<span class="mw-page-title-main">HP 2640</span> Serial computer terminal

The HP 2640A and other HP 264X models were block-mode "smart" and intelligent ASCII standard serial terminals produced by Hewlett-Packard using the Intel 8008 and 8080 microprocessors.

In computer data, a substitute character (␚) is a control character that is used to pad transmitted data in order to send it in blocks of fixed size, or to stand in place of a character that is recognized to be invalid, erroneous or unrepresentable on a given device. It is also used as an escape sequence in some programming languages.

<span class="mw-page-title-main">IBM 2741</span>

The IBM 2741 is a printing computer terminal that was introduced in 1965. Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter operation, interchangeable type fonts, and both upper and lower case letters.

<span class="mw-page-title-main">ADM-3A</span> Early video display terminal

The ADM-3A was an influential early video display terminal, introduced in 1976. It was manufactured by Lear Siegler and had a 12-inch screen displaying 12 or 24 lines of 80 characters. It set a new industry low single unit price of $995. Its "dumb terminal" nickname came from some of the original trade publication advertisements. It quickly became commercially successful because of the rapid increase of computer communications speeds, and because of new minicomputer systems released to the market which required inexpensive operator consoles.

<span class="mw-page-title-main">Sixel</span> Bitmap graphics format

Sixel, short for "six pixels", is a bitmap graphics format supported by terminals and printers from DEC. It consists of a pattern six pixels high and one wide, resulting in 64 possible patterns. Each possible pattern is assigned an ASCII character, making the sixels easy to transmit on 7-bit serial links.

<span class="mw-page-title-main">Termcap</span>

Termcap is a software library and database used on Unix-like computers. It enables programs to use display computer terminals in a device-independent manner, which greatly simplifies the process of writing portable text mode applications. Bill Joy wrote the first termcap library in 1978 for the Berkeley Unix operating system; it has since been ported to most Unix and Unix-like environments, even OS-9. Joy's design was reportedly influenced by the design of the terminal data store in the earlier Incompatible Timesharing System.

VS/9 is a computer operating system for the UNIVAC Series 90 mainframes, used during the late 1960s through 1980s. The 90/60 and 90/70 were repackaged Univac 9700 computers. After the RCA acquisition by Sperry, it was determined that the RCA TSOS operating system was far more advanced than the Univac counterpart, so the company opted to merge the Univac hardware with the RCA software and introduced the 90/70. The 90/60 was introduced shortly thereafter as a slower, less expensive 90/70. It was not until the introduction of the 90/80 that VS/9 finally had a hardware platform optimized to take full advantage of its capability to allow both interactive and batch operations on the same computer.

The POSIX terminal interface is the generalized abstraction, comprising both an application programming interface for programs, and a set of behavioural expectations for users of a terminal, as defined by the POSIX standard and the Single Unix Specification. It is a historical development from the terminal interfaces of BSD version 4 and Seventh Edition Unix.

<span class="mw-page-title-main">Waveform graphics</span>

Waveform graphics is a simple vector graphics system introduced by Digital Equipment Corporation (DEC) on the VT55 and VT105 terminals in the mid-1970s. It was used to produce graphics output from mainframes and minicomputers. DEC used the term "waveform graphics" to refer specifically to the hardware, but it was used more generally to describe the whole system.

<span class="mw-page-title-main">Hazeltine 1500</span> Computer terminal

The Hazeltine 1500 was a popular smart terminal introduced by Hazeltine Corporation in April 1977 at a price of $1,125. Using a microprocessor and semiconductor random access memory, it implemented the basic features of the earlier Hazeltine 2000 in a much smaller and less expensive system, less than half the price. It came to market just as the microcomputer revolution was taking off, and the 1500 was very popular among early hobbyist users.

References

Citations

  1. ↑ da Cruz 2001.
  2. ↑ "The Hazeltine 2000 Terminal". Columbia University Computing History. Retrieved 14 January 2020.
  3. ↑ Manual 1975, p. 3.
  4. 1 2 Manual 1975, p. 26.
  5. ↑ Manual 1975, pp. 22.
  6. ↑ Manual 1975, p. 2.
  7. ↑ Manual 1975, p. 5.
  8. ↑ Manual 1975, p. 24.
  9. ↑ Manual 1975, p. 25.
  10. ↑ Manual 1975, pp. 7, 11.
  11. ↑ Manual 1975, p. 7.
  12. ↑ Manual 1975, p. 13.
  13. 1 2 3 Manual 1975, p. 14.
  14. ↑ Manual 1975, p. 16.
  15. 1 2 Manual 1975, p. 17.
  16. ↑ Manual 1975, p. Appendix IV.

Bibliography

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.