1、.”, _A. Y a a) b) t I a w - EIA 49A000 89 m 3234b00 00737b9 1 m - - EIA S P ECI FI CATION Sectional Specif ication for Full and Short Stroke Keyboards of Certified Quality EIA-498A000 JULY 1 0 ELECTRONIC IN DUSTRI ES ASSOCIATION ENGINEERING DEPARTMENT The NECQ Svstem EIA 498A000 89 = 3234600 0071770
2、 8 NOTICE EIA Engineering Standards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum
3、delay the proper product for his particular need. Existence of such Standards and Publications shall not in any respect preclude any member or non-member of EIA from manufacturing or selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Pub
4、lications preclude their voluntary use by those other than EIA members, whether the standard is to be used either domestically or internationally. Recommended Standards and Publications are adopted by EIA without regard to whether or not their adoption may involve patents on articles, materials, or
5、processes. By such action, EIA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Recommended Standard or Publication. This EIA Specification is considered to have international standardization implication, but the International Elec
6、trotechnical Commission activity has not progressed to the point where a valid comparison between the EIA standard and the IEC document can be made. This Specification does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the respons
7、ibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. (From EIA Standards Proposal No. 1735, formulated under the cognizance of the EIA P-13.3 Subcommittee on Non-Sensitive Pushbutton and
8、 Keyboard Switches.) (APPROVED FOR USE IN THE NECQ SYSTEM AS NQ-EIA-498A000.) Copyright 1989 Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Pennsylvania Ave., N.W. Washington, D.C. 20006 (Temporary Headquarters 1722 Eye St., N.W., Washlngton, D.C. 20006) PRICE: $10.00 All
9、 rights reserved Printed in U.S.A. _ _ _ EIA 498A000 89 m 3234b00 007L77L T m . EIA-498A000 Page 1 SECTIONAL SPECIFICATION FOR FULL AND SHORT STROKE KEYBOARDS OF CERTIFIED QUALITY 1.0 SECTION ONE - GENERAL 1.1 Scope This Sectional Specification covers alphanumeric keyboards having full stroke or sho
10、rt stroke key travel and intended for use in information handling systems by a trained operator. Both product qualification and capability approval requirements are included in this document. 1.2 Object The object of this specification is: (a) (b) (c) (d) to prescribe capability approval requirement
11、s and test (e) to prescribe a fixed sample Qualification Approval test to prescribe preferred ratings and characteristics, to prescribe the appropriate test procedures, to prescribe general performance requirements, schedules, schedule, and (f) to prescribe a Quality Conformance Inspection test sche
12、dule. 2.0 SECTION TWO - GENERAL 2.1 Related Documents The following documents of the issue in effect form a part of this specification to the extent specified herein: IEC 68-2-38 Test Z/AD: Composite temperature/humidity cyclic test. ANSI X3.64 Additional Controls for Use with the American National
13、Standard Code for Information interchange. ANSI/EIA 476 Marking, Source and Date Code ANSIIEIA 4980000 Generic specification for keyboard switches of certified quality 2.2 Units and Symbols In addition to the requirements of EIA-4980000, the units and symbols marked on the individual keys shall be,
14、when specified by the detail specification, in accordance with: ANSI X3.64 Additional Controls for Use with the American National Standard Code for Information Interchange. Units or symbols peculiar to a detail specification shall be defined by the detail specification. EIA 498A000 89 3234b00 007177
15、2 1 L EIA-498A000 Page 2 2.3 Terminology O The terminology shall be in accordance with the issue in effect of - EIA-4980000. Terminology peculiar to the products covered by this specification is defined below. Terminology peculiar to a detail specification shall be defined by the detail specif icati
16、on. Array The format in which the letters, numbers and control keys are organized. These include communication (typewriter), batch (with numerics in the center), block (sometimes used for stock market boards) and numeric (12 or 16 key). Codes The binary language used to translate key movement to inf
17、ormation. most common codes employed are: The two ASCII (American Standard Code for Information Interchange) - Consists of seven coding bits plus one parity bit. It is the most widely used code in the industry and is used primarily for communications terminals. EBCDIC (Extended Binary Coded Decimal
18、Interchange Code) - Consists of eight coding bits used primarily with data preparation keyboards and IBM 360 and 370 computers. e Data Key Idle Signal This signal is present at the keyboard output until one or more keys are depressed. Once a key is depressed, the signal changes to its off state prio
19、r to strobe coming true. The data key idle signal may be logically compared with strobe to produce a warning to an operator of a two-key down condition. . Encoding The process of generating a binary coded signal when a key is depressed. The common methods rely on TTL or MOS memory circuits. Inter lo
20、ck An electronic means of preventing error due to actuating more than one key at a time. Phantom Key - An erroneous code that may be sensed when three or more keys are operated, within any one scan period, on an unprotected mechanical contact keyboard with a scanned matrix switch array. Phantom Key
21、Lockout - Prevents the entry of erroneous codes from a sensed phantom key when three or more keys are operated on a mechanical contact keyboard with a scanned matrix switch array. a Two-Key Rollover (3 key lockout) - When the first key is depressed, the switch closure is encoded. While the first key
22、 is still active, a second key is depressed and the switch closure is encoded, If a third key is depressed, the third key is not encoded until either the - EIA 498A000 89 M 3234600 0073773 3 M EIA-498A000 Page 3 first or second key is released. This is called two-key rollover with 3 key lockout. If
23、two keys are depressed at the same time and the switch closures are detected during the same scan period, the switch closure encountered first in the scan period will be encoded first, followed by the second switch closure encountered (i.e., both keys will be encoded). 235 Key Rollover - The first k
24、ey depressed is encoded. The second key depressed without releasing the first key is also encoded. When the third key is depressed without releasing the first or second key, a third and possible fourth key closure may be s.ensed because of an electrical path which can occur through the closed switch
25、es. This is a phantom key closure and neither the third nor fourth switch closure can be considered a valid key depression. If no “Phantom Key“ is detected, then the third key will be encoded (i.e. the third key may or may not be encoded depending on where it is in the scan matrix). A fourth key dep
26、ressed while three others are still depressed will never be encoded. N-Key Rollover (NKRO) - It is a multiple key electronic interlock that memorizes each keys code on the down stroke. Thus, the operator is not constrained by the need to release one key before depressing the next. An MOS memory is u
27、sed to keep the signals in stroked sequence. The application advantages are in high throughput data entry, word processing and typesetting equipment. Error Signal An error tag bit may be specified which can be used within the system for error indication of undesirable key depressions. This signal ma
28、y be used to detect undesirable key depressions in the shifted mode or numeric protected mode. The signal may be used in conjunction with the keyboard inhibit feature to block keyboard outputs until the error is removed and the keyboard reset. Flip-Flop Inhibit This option permits external control o
29、f the one-character storage flip- flops within the MOS pack. This is useful for systems which require the data bits to remain stable until the system acknowledges that it has read the data. The data bits remain true until the acknowledge signal is received from the system, even though the operator m
30、ay have depressed the next key. Keyboard Inhibit With this option, two or more keyboards can be wired in parallel into one system, and the system can select the keyboard from which data will be received. Multi-Character Buffer (silo-store) An option that permits uninhibited keyboard entry speeds wit
31、hout data loss. It is designed to circumvent the missed character syndrome resulting from burst speed typing and feeds directly into a slow system. O EIA 498A000 89 E 3234600 8073774 5 E EIA-498A000 Page 4 One-Character Storage An option that allows one character to be held in a keyboard output regi
32、ster until the next key depression or until the system reads out the data. Parallel-to-Serial Converter A useful option when the keyboard is used for transmitting data over communication lines. Keyboard information is entered in parallel form, requiring several transmission lines to send data out. T
33、he converter sends information one bit at a time over a single line. It generates start and stop signals for synchronizing the receiving system, Parity A coding check against false signals caused by an extra or a missing pulse, Pulses are added to code block to make the total number of bits an odd o
34、r an even number. Failure to have odd or even parity indicates an error. Repeat Electronic simulation or repeated key depression. Three means of achieving repeat are : Bi-level: A two position operation. Depression past normal key travel operates the repeat function. Found in keyboards for offices.
35、Repeat Key: One key controls repeat function for any other key when both are depressed; used in high speed data entry. Timed Repeat: Any key repeats if held for a longer than specified time (at least 1/2 second). Used in interactive keyboard applications where a limited number of keys are needed to
36、repeat. Shif tlock A means of generating twice the number of characters with a key, as with lower case and upper case letters on a typewriter. Secretary Shift: Duplicates the traditional typewriter shift found in general office applications. Can be furnished left side only or both sides. Alternate,A
37、ction: The alternate action key, when operated, drops below the level of the unoperated keys on the keyboard. Operating the alternate action key a second time returns the keyboard to the unshifted mode. Electronic Shiftlock: An electronic duplication of the mechanical function. Used in interactive d
38、isplays, this method often incorporates an operator light to indicate mode. Strobe A signal that indicates valid key depression. Its function is to synchronize the keyboard. EIA-49 8AO0 Page 5 Strobe Enable The data strobe can be controlled by the system or .by internal circuits. This permits contro
39、l of oqe-character memory for applications where the keyboard is temporarily disabled or where the keyboard output timing is not synchronized with system scanning rates. System Control Provision for the system selecting the keyboard operating mode. Used in addition to manual selection. Throughput Th
40、e maximum rate of keyboard error-free data entry. 2.4 Preferred Ratings and Characteristics 2.4.1 Preferred Electrical Ratings The electrical ratings shall be specified by the detail specification. (a) Applied Voltage: The following voltages are preferred: 5 Vdc, 12 Vdc, 24 Vdc, 28 Vdc 2.4.2 Preferr
41、ed Environmental Characteristics The operat ional and non-operational environmnt a characteristics shall be specified by the detail specification. The following environmental characteristics are preferred for keyboards intended for normal indoor usage: Operating Temperature 0C to 52C Storage Tempera
42、ture -40C to 60C Humidity 5% to,95% noncondensing Shock 15 Gs, 11 ms, half-sine Vibration 10-55 Hz at .O05 inch D.A. 2.4.3 Electrical Characteristics The electrical characteristics shall be specified by the detail specification: (a) Power input (voltage and current) (b) Logic convention (define volt
43、age of Logic O and 1) (c) Output signals (data and clock outputs) (d) Input signals (DATA, CEN and CLOCK) (e) Interface connector (identify pin functions?) 2.4.4 Mechanical Characteristics The mechanical characteristics shall be specified by the detail specification: (a) Key force (b) Key displaceme
44、nt (c) Physical dimensions ELA-498A000 Page 6 (d) Termination (arrangement per ANSI standards?) (e) Key arrangement (per ANSI standards preferred?) (f) Threads (metric and/or U.S. standard threads?) (g) Enclosure (h) Sealing 2.5 Marking Additional markings may be applied to the keyboard provided the
45、y do not interfere with, obscure, or confuse the required markings. 2.4.4.1 The preferred range for the key force values are .9 ounce (.25 N) to 5.3 ounces (1.47 N) when rapid “touch-typing“ operation is intended. 2.4.4.2 The preferred range for key displacement values are .O50 inch (1.27 mnt) to .2
46、50 inch (6.35 mm) when rapid “touch-typing“ operation is intended. 2.4.5 Functional Characteristics The functional characteristics shall be specified by the detail specification: (i.,) Encoding (b) Interlock (c) Automatic Repeat (d) Buffering (e) Audible Feedback 2.5.1 Identification Marking: The ke
47、yboards shall be legibly marked with the following information: (a) manufacturers name (b) identifying number (IECQ part number, EIA part number, or users part number) (c) manufacturers part number i (d) date code per RS-476 e 2.5.2 Terminal Marking: When specified by the detail specification, the t
48、erminals shall be legibly marked with the terminal identification specified in the detail specification. 2.5.3 Keytop Marking: information specif.ied by the detail specification. Each keytop shall be legibly marked with the 2.6 Detail Specification 2.6.1 General. Environmental characteristics: opera
49、tional and non- operational environmental characteristics shall be specified in detail specifications. 2.6.2 Detail specifications shall be derived from the instructions given in EIA 498BA00 and shall contain all required infor- mation directly or by reference, Detail specifications shall not specify requirements inferior to those of the generic or EIA 498A000 89 3234600 0071777 O EIA-498A000 Page 7 sectional specifications. .When more severe requirements are included they shall be listed in the detail specification and indicated in the te
