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H EW LETT.PACKAFI D J O U FINAL
Technical Inlormation trom the Laboratories ot Hewlett-Packard Company
1981
MARCH 3
Volume r Number
32
Contents:
New Display Station Offers Multiple Screen Windows and Dual Data Communications
Ports, by Gary C. Staas tt'sfour terminals one, bringing new flexibility computerappli-
in to
cation sysfems.
Dispfay Station's User Interface ls Designed for Increased Productivity, by Gordon C.
Graham Easy access to an extensive feature set requiresa thorough,thoughtfulapproach
to the user interface.
Hardware and Firmware Support for Four Virtual Terminals in One Display Station' by
Srnlvas Sukumarand John D. Wiese The goalswere 26454 compatibility, improvedpricel
performanceand reliabitity, and ease of use, manufacturing,and service.
A sificon'on-sapphire Integrated video controller, by Jean-claude Roy Integration
was considered mandatory to make the display system practical and reliable.
SC-GutQuartz Oscillator Offers lmproved Performance,by J. RobertBurgoonand Robert
L. Wilson lt's more stableand /ess noisy, warms up fasfer, and uses /ess power.
The SC Cut, a Brief Summary, by Charles Adamsand John A. Kusters Firstintroduced
A.
in 1974, fhe stress compensated cut has many virtues.
Flexible Circuit Packaging of a Crystal Oscillator, by James H. Steinmetz Selectively
stiffenedflexibtecircuitry is a radical approach that meets tough obiectives.
New Temperature Probe Locates Circuit Hot Spots, by Marvin F. Estes and Donald
Zimmer, Jr. tt provides fast, accuratetemperaturemeasurementsfor design, diagnostic,
and testingaPPlications.
In this Issue:
The shiny rock on this month'scover is a pieceof cultured(laboratory-grown) quartz.The
thin transoarent disc mountedin its holderin front of the rock is a quartzcrystalof the type
used for frequencycontroland timing in many electronic devices,including quartzwrist-
the
watchesthat some of us wear (not all crystalsare as large as this one). When these thin
slices of quatlz arc subjectedto an alternating voltage,they vibrate,and they vibratemuch
more stronglyat one frequency than at any other.lt's this propertythat makesthem usefulas
-fi,
I frequencyand time references.
Y .
Quartz is a crystallinematerial,which means that its atoms line up in a regularpatternor
lattice.Thin crystaldiscsfor frequencycontrolare taken from largequartzrocksby slicingthe quartzat specific
anglesto the crystallattice.Different anglesproducedifferentsets of desirableproperties. The new HP crystal
oscillatordescribedin the articleon page 20 derives its frequencystability from a crystalthat has been cut to
make it relativelyinsensitive temperature
to variations.This propertyand some state-of-the-art circuitdesign
give the new oscillator,Model 10811lVB, betterstability,lower power consumption, and faster warmup than
earlierHP crystaloscillators. Model10811//B is designed serveas a highlystablef requency time reference
to or
in precision laboratoryinstruments, especiallythose that haveto operatefor long periodswithoutadjustment'
Pages3 through19of thisissuedescribe newcomputer
a terminal,Model26264Display Station, meetsa
that
needbt many computerusersfor a terminalthat can handlerelatively complexoperations. Internally 26264
the
can be set up to functionas up to four separate"virtual"terminals. The operatorcan see on the screenwhat's
happeningin one, two, three, or all four of these virtual terminalsat the same time, and can affect what's
happening one virtual
in terminal a time,usingthe keyboard. two virtual
at Any terminals communicate
can with
differentcomputers or the same computer at the same time. This kind of flexibilityopens up many new
possibilities computerapplicationsystems.
for
Wrappingup the issue is an articleaboutthe 100234Temperature Probe,a simpledevicethat helpscircuit
designers find and eliminatecircuithot spots that may indicateproblemsor likely failure sites'
R. P. Dolan
Editor,Fichard P. Dolan. AssociateEditor,KennethA. Shaw. Art Director,Photographer, Arvid A. Danielson
l l l u s t r a t o N a n c vS . V a n d e r b l o o m . d m i n i s t r a t i v ee r v i c e sT y p o g r a p h yA n n e S . L o P r e s te E u r o p e a n r o d u c t i o n a n a g e r D i c k L e e k s m a
r. A S , , i P M '
'98l @ Hewletl Packard Companv 1981 Pnnted n U S A
2 iE\ALF-'-DAchAqD Jo-RNA- N,4Aqcd
New Displ StationOffers Multiple
ay
ScreenWindowsand Dual Data
CommunicationsPorts
Thisversatile computerterminal
can act like four virtual
terminals. designedfor data entryand program
/f's
development.
by Gary C. Staas
EW DATA ENTRY and program development ca- play Station are reflected in many of the characteristics of
pabilities are provided by a new HP CRT terminal, the terminal. An important characteristic is compatibility
Model 2626A Display Station, which lets the user with the HP 2645A Terminal. Terminal drivers and applica-
display, compare, and combine data from two different tion programs that work with the 2645A will also work with
computers and four different memory workspaces simul- the 2626,4,,thereby protecting users' software investments.
taneously. The new terminal [Fig. 1) has dual data com- The new terminal is also reliable and is easy to build,
munications ports for connection to computers or periph- check out, and service. The reliability goal was 8,000 hours
erals and the user can divide both the display memory MTBF (mean time between failures). An extensive set of self-
and the display screen into as many as four independent tests is built into the terminal, and some of these tests can
work areas. Other features are line widths up to 160 char- isolate failures to the component level. One test, which
acters with horizontal scrolling, screen-labeled softkeys, repeatedly executes most of the other terminal tests, is used
an optional built-in thermal forms-copy printer, pro- after terminal assembly to spot failures in the factory. To
grammable tones for audio cues, and keys for interactive make the terminal easy to build, there are very few options
forms design. and the 2626A has many components in common with
DesignObjectives other terminals in the 262Xline. The factory does very little
Theobjectives guided design the 2626A
that configuration ofthe terminal. Since that is an easy process,
the of Dis-
Fig. 1. Model 26264 DisptaySta-
tion is a multi-workspace, multi-
wtndow computer terminal that
has dual data communications
porfs. /ts capabilities may be con-
figured dynamically as four logi-
cally independent vittual termi-
nals. The terminal can handle line
lengths up to 160 characters and
offers foreign language options
and an optional built-in pilnter.
I\,4ABCH
1981I-']EWLETT.PACKARO
.IOURNNT
3
it is almost totally left to the user. of softkey levels having similar functions.
User sophistication varies considerably, from the data
entry clerk to the very knowledgeable OEM customer. Each Workspaces and Windows
user needs to take advantageof a different set of features.A When the terminal is powered on, it partitions memory
department manager of a data entry operation, for example, into displayablelines of equal sizes.The user can select a
needs to configure the terminal for use by data entry clerks. length from B0 to 1.60characters line. Lines 132 charac-
per
The terminal provides configuration menus for this pur- ters wide, for instance,are useful for holding datato be sent
pose.On the other hand, theseconfiguration menus can be
locked out and made unavailable to the clerks to avoid
confusing them with details they don't need. Form 4
Among many new concepts embodied in the terminal is tl
the ability to handle more than one job at a time. Like
several sheetsof paper on a desk, each relating to a different Workspace4
task,the 2626ADisplay Station splits its display screeninto
as many as four windows, each with independent data. The
dual datacommports allow thesewindows to communicate
with more than one computer program at once.
The optional built-in thermal printer avoids the problems
of expensive,distant, large, and noisy impact printers. It
was considered essentialto be able to print whatever was on
the screen,such asforms and specialcharactersets,and the
integral printer makes this possible.
To allow a user to draw simple bar charts without
graphics capability, one of the terminal's character sets has
been expanded to include appropriate characters. The
forms-drawing keys make it easyto design data entry forms.
Foreign Ianguage support is an important goal in the
international marketplace.The 2626A provides six Euro-
pean languages, including mute and overshike characters.
The 26264 uses HP's silicon-on-sapphire (SOS) large-
scaleintegrated circuit process.This and other design fea- Data
tures make it possible to offer a terminal with a much
improved and expandedfeaturesetfor a cost comparableto Form 3 Form 4
an HP 2645A. tl
Softkeys Workspace 4
To allow easyaccess terminal functions, the 2626A has
to
eight softkeysthat do not have fixed functions. A two-row-
high label at the bottom of the screenjust aboveeachsoftkey
indicates its current function. A function key that indicates
Undisplayed
a terminal mode, such asREMOTHLOCAL, an asteriskon
has
Workspaces
its label when the corresponding function is on. The
softkeyscan be locked so the terminal stayswithin a group
Workspace 1 Workspace 2 80
1
-lt
Flg.3. (a) ln this example, the terminal has four workspaces,
Workspace 4 Bo
'I each holding a form. Workspace 1 is displayed in the
l keyboard window and the uset can type data into form 1.
Workspaces2,3, and 4 are not displayed in a screen window.
,,L
Flg.2. ln this example, portions of three 26264 workspaces
The host computer is connected to workspacelwindow 1. (b)
After the user presses the ENIEa key the host displays work-
space 2 in the keyboard window and workspace 1 is no longer
displayed. The host remains attached to workspace 1 and
are displayed in windows on the screen. Workspace 4 is not receives the data just entered while the user fills form 2 in
displayed. workspace 2.
4 rewurr-pnc FEBRUARY
JoURNAL
to a computer line printer. The user can group these lines and attaches the keyboard to it. The host program then
into workspaces,each with a fixed number of lines. For attachesitself to the first workspaceto receivethe datajust
example, the user could set up the terminal to have two entered on the form. The user continues entering data into
workspaces 80-character
of lines, workspacet with 40 lines the second form while this transfer is in progress.This
and workspace2 with 70 lines. Up to four workspacesare concurrency results in greater throughput and operator
allowed. Multiple workspacesare useful for doing several productivity.
different jobs on the terminal at the same time. To fine-tune a window configuration, the user can move
All workspacescan be displayed on the screen simul- the horizontal and vertical borders with softkeys.Another
taneously to give an overall view of what the terminal is softkey moves the cursor to the next screenwindow, and
doing. The screencan be divided into display windows that another displays the next workspace that is not currently
show all or part of the workspaces.To continue the above displayedon the screen. Wheneverthe line length is greater
example, workspace 1 might be viewed in a display win- than the screenwidth of a window, the datamav be scrolled
dow from the first through the tenth screenrows, and work-
space2 might be seenin a window from screenrows eleven
through twenty-four. Dotted lines separate windows on the
screento avoid confusion. The terminal also has a vertical
border on the screen to allow left and right windows. A COMPUTER
workspaceneed not be displayed to be functional. A work- PRINTER
spacethat is closed (i.e., has no display window) can re-
ceive and send data. Fig. z shows an example of a *)
PORT
S llo*t',
workspace/window configuration. 2 ...--i.\
To avoid ambiguity, all keyboard input affectsonly one ',;;;* ff+\f'l
workspace at a time, the one in which the cursor resides. \'
Typed data appears only in this keyboard workspace/ (a)
window, not in any other window. Local editing keys,such
as delete character,take effect only in this window, and so
on, The user can changethe keyboardwindow by meansof
a softkey. COMPUTER1
Each workspace operatesindependently, so that work-
spaces can be used to perform different tasks with a
computer. Most operating modes of the terminal are or can
be on a workspace basis. Some of the modes are always
associated with a workspace,such as FORMAT mode, which
allows a window to be used as a form, limiting the user to
]PORT2
typing data into unprotected fields. Other modes are
grouped into a terminal configuration,which may be freely
attached to workspaces.Supposethat in terminal config-
uration 1, REMOTE mode is on, and in terminal configura-
tion 2, REMOTE mode is off. If terminal configuration 1 is
used for both workspaces, 1 and 2, then both will have (b)
REMOTE If workspace 1 uses terminal configuration 1
on.
and workspace2 usesterminal configuration 2, then work-
spacet has REMOTE and workspace2 has REMOTE
on off.
There are four terminal configurations so that each work-
space can have its own configuration. This is desirable
when workspacesareto be used for different kinds of jobs.
The workspace/window configuration can be set locally
PORT1 COMpUTER
on a menu or remotely by escapesequences sent from the
host computer.
A datacommunicationsport can be attachedto any one of
the workspacesat a given time. Data flow is to and from that
sl lPORT
\-_-_-'
2
workspace only; other workspaces are unaffected. The data
entry examplein Fig. 3 illustrates how this feature is used. (c) \*t'tPs'
A data entry application program in the host computer first
creates four workspacesin the 2626,\ terminal and attaches
its host's data communications port to each workspace in
turn to transmit a form to it. After it sends all the forms, it
displays the workspace that has the first form and makes it Fig.4. Uses of the dual data communications ports. (a) port 1
the keyboardworkspaceso the user can begin entering data is attached to a computer. Port 2, when not rn use as a
into the form. When the user pressesthe ENTER key, the datacomm port, can be attached to a serial printer ot other
program displays the secondworkspacewith the next form RS-232-Cdevice. (b) Each port is attached to a different host
computer. (c) Both portsare attached to the samecomputer.
tvARcH1ggiHEWLETT,pAoKARo
lounlrnr 5
horizontally. If the vertical border were at screen column I]P 2626A BAR CHARTSEXAt'tPLE
BARI BAR2 VZII 8AR3
30, for example, a right window would have only 50 col- Ejjl W
.i0
umns displayed and horizontal scrolling would be neces- /r0
sary to view aII the data.
30
:10
Dual Data Communications Ports !0
To further enhanceits multitasking capability, the 2626,{ 0
has two ports for data communication. When a port is at-
tachedto a workspace,it meansthat datareceivedfrom that
port is processed and/or displayed in that workspace.If the Fig. 6. New line drawingcharacters
make it easyto draw
user enters data in that workspace (by pressing ENTER high-quality charts.
bar
while that workspaceis the keyboard workspace/window,
for example) the terminal sends data through that port. A terminal modes for each workspace, and global terminal
port, workspaceand terminal configuration togethermake items.A host computer program can also setany configura-
up a virtual terminal entity. tion item on any menu. The terminal savesconfiguration
Fig. 4 shows different possibilities for using both ports. data in battery-powered RAM when ac line power is off. All
The two ports can be cabled to the same host or to two configurations can be locked to prevent local alteration in
different computers becauseeach port can use a different applications involving less sophisticatedusers. If the op-
data communications protocol. Fig. 5 shows an example tional thermal printer is presentor if an external printer is
using the two ports attached to two different computers. attachedto port 2, the usercan print the configuration menu
Both workspaces that are attachedto ports can be displayed for further backup.
on the screenat the sametime in two windows. To make the The 2626,4, provides both point-to-point and multipoint
terminal truly useful for handling multiple iobs, both data communicationsas standardfeatures.Data communi-
ports/workspaces can be receiving and sending data and a cation configuration is done by meansof six generalmenus
user can be entering data in a third workspacesimultane- that cover most full and half-duplex configurationsas well
ously. A useful single-host application is to use one port asmultipoint (multidrop bisynchronous)communications.
and workspacefor a consoleand anotheras a user terminal,
or a programmermight examinethe output of a compiler for Device Control
errors in one workspaceand edit the sourcefile in another The 26264 can copy data from one workspaceto one or
workspace. more other workspaces.If the receiving workspace is in
REMOTE mode, it will transmit the data just as if it were
Soft Configuration typed into that workspace.This allows data transfersfrom
The 26264 representsan advance over previous termi- one host to another.An externalprinter can be connectedto
nals in its flexibility and easeof configuration.Thereare no the seconddata communicationsport, which is a standard
hardware configuration switches inside the terminal. A RS-232-Cport when it is not used as a data communica-
user configuresthe terminal by choosing values on menus tions port.
built into the terminal. There are configuration forms for One of the 26264 options is a thermal printer integral to
workspace/windows,data communications for each port, the terminal. The printer is capableof printing all of the
terminal's charactersetsto give exact screencopies.It also
provides normal, expanded (40 characters/line), and com-
pressed (132 characters/line)printing modes. When RE-
PORT mode is on, the printer provides three blank lines at
the top ofeach page,60 lines oftext, and three blank bottom
lines to format standardBtlx11-inch sheets.
A datalogging mode enables terminal to record all the
the
datait receiveson a printer. When LoG TOPmode is on, the
terminal prints lines as they disappear from the top of a
workspace to the destination printer(s) when all display
lines for the workspaceare used up and the data would be
otherwise lost. LOG BOTTOMcauses the terminal to log
lines as they are received.
Ordinarily, one workspace at a time is copied to the
destinationdevice(s). SCREEN COPY copiesthe screento the
printer(s) exactly as it appears,so that all windows dis-
played are copied.
User-DefinableSoftkeys
Fig, 5. /n the top windowlworkspace, a user can examtne a
data baselisting from a computer attached to port 1, and in the
When they are not being used for terminal configuration
bottom windowlworkspace can get informationneeded fot a or control, the 2626A's softkeys can be used to perform
data entryprogram running on a second computer attached to user-definedfunctions. The user-definedfunctions are en-
port 2. abled by pressingthe USER KEYS key. Each softkey may be
l\,1ARcH
JoURNAL
6 nEwLEtt-pacrARD 1981
given a definition consisting of as many as B0 displayable French with mutes enabled,typing a circumflex displays it
characters. Subsequently, pressing a softkey has the same without moving the cursor. When the letter a is typed, the
effect as pressing all the keys in its definition. Two eight- characteris replacedby the letter a with a circumflex over it.
character rows on the screen label each softkey; the labels The terminal providesan eight-bit mode for the Hp 300A in
are defined by the user. Video and character set enhance- which characters shifted into the alternatecharacterset
are
ments may be embedded directly in the softkey labels and by setting the eighth bit. When the foreign charactersor
the B0-displayable-character key definitions. This allows Roman extensionset is selectedas the alternate,the termi-
eye-catching labels and more information in the defini- nal can operatewith an HP 300A doing foreign processing.
tions. The ENTER and RETURN keys are also softkeys.
Another key sets the default values of the user softkeys. Terminal Tests and Error Messages
The 2626A offers a powerful set of internal tests.
Sketch Forms Facility Wheneverthe terminal is powered on, it performsa self-test
The HP 264X family of terminals has a line drawing to give the user an immediate indication of terminal mal-
character set to represent forms. The sketch forms facility of function. A more comprehensivetest is usedby production
the 2626,\ makes it much easier to use this set by providing during the burn-in time of the terminal. This test logs any
a set of keys to draw horizontal and vertical lines. The errorsfound into the battery-poweredRAM. The data com-
drawn lines do not overwrite text orfields. When horizontal munications test facility is menu-driven and allows a vari-
and vertical lines cross, the correct intersection character is ety oftestson eachport. The integral printer testprints a test
automatically selected. The user initially selects through pattern on the thermal printer. Each ROM in the terminal
softkeys the line type desired (single, double or bold) and has identification information that can be displayed on the
the video enhancement desired for the line. Another set of screen;this is useful to customerengineersin determining
keys automatically draws a box around either the margins the exact version of firmware in the terminal. All of these
(left, right, top and bottom) or the displayed data. tests can be invoked by softkeys and do not require
downloading a diagnostic into terminal memory. A cus-
Video Enhancements tomer can perform a test and pass on the results to a cus-
Video enhancements and character sets were previously tomer engineer over the telephone, making service calls
selected only by escape sequence.The 2626,{ user can also less frequent and more efficient.
select them with softkeys. The line-drawing, math, and All of the self-testsproduce error messagesindicating
Iarge-character sets have all been expanded to 96 charac- any problems found. Some user operations can also pro-
ters. With the new line-drawing characters, for instance, the duce enors, such ascertainillegal settingson the configura-
user can create bar charts as shown in Fig. 6. If a portion of tion menus. If a user attempts to set such a configuration,
the workspace has the new security enhancement, it dis- the terminal displays an explanatory message.All error
plays as blanks, no matter what data is there. This en- messagesappear on the bottom two lines of the screen
hancement is useful for password fields and for other secure replacing the softkey labels until the messageis cleared.
fields. For users who prefer black-on-white lettering, the The rest of the screenremains visible so the user can more
black background can be switched to inverse video. easily determine the error.
ForeignLanguages Additional Features
The2626.\hasISOcharacter for thefollowingEuro-
sets Among the 2626A'sfeaturesis a programmablebell with
pean languages: Swedish/Finnish, Danish/Norwegian, 15 tones,16 durations,and two volume levels.Severalnew
French, German, United Kingdom, and Spanish. Keyboards kinds of terminal statusare also offered.For example,win-
are available for all these languages. The terminal is set to dow status shows the current workspace/window config-
operate for a given language by making a selection on the
global configuration menu. AII the language capability is
built into the terminal; a user needs only the appropriate Gary C. Staas
keyboard with the special character keycaps and key Gary Staaswas born in Dayton,Ohio
placements and the extra character set ROM. and attendedthe University Dayton,
of
graduating 1969
in witha BSdegreein
Fig. 7 illustrates the new language option characters.
mathematics. 1971 he received
In his
Some of the languages provide a mute and overstrike capa-
MS degree in statisticsfrom Stanford
bility. For example, when the terminal is configured for University. threeyearsdeveloping
After
softwarefor hospitalinformationsys-
DECII\,4A1
VALUE tems,hejoinedHP'sDataTerminals Di-
LANGUAGE 35 64 91 92 93 94 96 123 124 125 126 vision,where his responsibilities
have
USASCII ,c t\ .t ) r
included of various
QA terminals,
data
Swedish/F nn sh tt fid Aii6:i o eii
'a
entrysystemdesign,and firmware de-
Danish/Norwegian ,Q [0 o t!
'c velopment and feature designfor the
French ta D d
26264 and other terminals.Gary is a
German rI A6 i A
it ii8
memberof the ACM and a resident ol
United Kingciom tc t\ ) !
Spanish ,Q
ScottsValley, He
California. Iistshis
iN L' ) !
Interests skiing,
as philosophy,
eastern running, backpacking, public
speaking,and humor.Recently leftHP to pursuehis careerwith
he
Fig. 7, Special characters,including overstrikecharacters,
anothercomputer firm.
are available.
N/ARoH1981HEWLETT-pAOKARo
JouRNll 7
uration. and terminal ID identifies the terminal as a 2626A. Acknowledgments
Modify modesallow a user to modify a line on the screen I would like to acknowledgethe HP 26264 project man-
and retransmit it to the host. When the TAB : SPACES ager, Prem Kapoor, for his many helpful suggestionson
featureis on, pressingthe TABkey transmitsthe appropriate features and continual striving for excellence in the prod-
number of spaces to take the cursor to the next tab stop uct. Stan Telson contributed much to the self-test features
rather than sending a tab character.BACKTAB sends the and keyboardhardware.Productsof this complexity cannot
appropriatenumber of backspaces the previous tab stop.
to be realized without the active support of lab and marketing
This makesit easyto createtext files for applications that do management.I would like to thank Lance Mills, lab man-
not understand tab characters. ager, Tom Anderson, marketing manager,and Terry East-
ham and Ken Blackford, product managers, for their en-
couragementand support.
ls
Displ Station'sUserInterface
ay
Designed Increased
For Productivity
by GordonC. Graham
PRIMARY CONTRIBUTION of the HP 2626A Dis- Information Fresented to User. This is closely related to
play Station is its advanced user interface, which feedback. The central issueis how to display information in
allows quick accessto the many features of the ter- a manner that promotes the most effective interaction be-
minal. An important design goal in this project was to tween the user and the instrument. Both visual and audible
make the terminal easy to use. Becausethis terminal has meanscan be used.Generally,the form that visual informa-
more features than previous alphanumeric terminals tion takes must be tailored to the characteristicsof the
d e v e l o p e d b y H P , e a s y a c c e s sr e q u i r e d a t h o r o u g h , display.
thoughtful approach to the user interface. Application of these guidelines to the 26264 is mainly
reflected in two areas:screen-labeled softkevs and menu-
Elements of the User Interface driven configuration.
All user interfaceshave four elementsin common:
User Model. This is the mental model that the user of a Screen-Labeled Softkey
product forms as to how the equipment functions. If the Earlier terminals provided accessto their features by
product hasbeencarefully designed,the userautomatically means of function keys on the keyboard.These keys had a
developsa good understanding,or model, of how it works, fixed task associated with them, such as home the cursor or
and will use the product's features naturally instead of clear the display. This approach was satisfactory as long as
resorting to the operator'smanual every time a new situa- the function setwas small. Laterterminals, with many more
tion arises.This area is a very important part of the total functions,required the userto type in escape sequences (the
design. Each new feature and every change to an existing ESCkey followed by one or more other keystrokes) to exer-
feature must be carefully evaluated to ensure that it is com- cise many of the functions. These escapesequences were
pletely consistentwith the operation of all other features, designed for use by a host computer system driving the
and that its use is natural to the operator. terminal and so were designedfor compactness rather than
Command Language. The command language is closely ease of use. The result was that many of the advanced
related to the user model and is in fact a concreterepresen- featuresof theseterminals were used only by sophisticated
tation of it. It is by meansof the command languagethat the userswilling to memorize or look up the escape sequences.
user accesses the features of a product. The commands To solve theseproblems,more recent terminals have intro-
should all relate to each other in a consistent,systematic duced the concept of tree-structured, screen-labeled
way, and should include provisions for aborting commands softkeys.The 2626A has extended this approach.
and handling errors. Softkeysare keys that do not have a dedicatedfunction,
Feedback from the Instrument. Feedback from the instru- but instead perform many different functions depending
ment in response to commands tells the user about the upon the stateof the terminal. To indicate the current func-
completion statusof any command. Proper design of feed- tion ofa 2626A softkey,a visual representation ofthe key is
back mechanismsinspires confidence that the instrument displayed on the screen with a label describing the key's
is being used properly and is performing the desired func- current function (seeFig. 1). A softkeymay either perform a
tions. Feedback also usedto point out errorsto the user as
is terminal function or causea new set of softkey labels to be
soon as they are detected. displayedon the screen, thus assigninga new setoffeatures
I HEwlerr-pncrARD 1981
IMARcH
JoURNAL
Flg.2. Thetop levelof the softkey
trce. Eachkey causes
a
branchto a separatefunctionalareaof the termina!.
SETENHNCMNT key is pressedto propagate the selected
combination. To end the enhancement the cursor is placed
at the ending position and SET ENHNCMNT again pressed.
is
That's all there is to it. The softkey labels direct the user
through the entire operation. If a mistake is made when
selectingenhancements, pressingthe erroneouskey a sec-
ond time toggles the displayed asteriskoff, thus reversing
its selection.
Contrast this to the older method. First there was no
indication to the occasionaluser that video enhancements
were available in the terminal (the enhance video key serves
this function in the 2626.\). Once aware, the user would
have to position the cursor to the desired starting position
and type in
escape d C
&
to propagatethe enhancement,then reposition the cursor
and type
escape d @
&
t o t e r m i n a t e i t . T h e s e e s c a p e s e q u e n c e sh a d t o b e
memorized or found by looking through the terminal refer-
Ffg.1. Ihe relationship
between eightsoftkeys their
the and encemanual, either of which requires a much higher level
screen labels. of sophistication than letting the softkey labels direct the
user's actions to the desiredresult. It should be noted that
to all ofthe softkeys.Eachset oflabels can be thought ofas a all 2626A features are still accessibleto the host system
node of a softkey tree, hence the name tree-structured, through escapesequences.The softkey tree is simply a
screen-labeled softkeys. user-orientedmeans of accomplishing the same thing.
Within the terminal family of which the 26264 is a The 2626A softkey tree is shown in Fig. 4. Each row of
member, a softkey labeling convention has been estab- softkey labels representsone level (or node) of the softkey
lished. A key that performs a function is labeled in capital tree and the labels within that level identify the functions
letters, while a key that performs a branch to a new set of available there. The auows between rows indicate the
softkeysis labeledin lower-caseletters.Fig. 2 indicatesthe transitions that are possible between levels using the
labelsdisplayedat the top level ofthe softkeytree.Theseare branching flower-case)keys.
all lower-case,so each branches to a separatefunctional Relating 2626A softkey operation to the four areasof user
area of the terminal. This is the functional choice level of interface design leads to the following conclusions.First,
the softkeytree, often referredto as the AIDSlevel. There is, extensive use of tree-structured,screen-labeledsoftkeys
in fact, a dedicated key labeled AIDSthat always displays significantly improves the user model by breaking the ter-
these labels when pressed,thus providing easy accessto minal feature set into smaller functionally related areas,
the top of the softkey tree. eachaccessible through branching keys. Second,the use of
An example will illustrate severalpoints. Supposeyou softkeys makes for a particularly simple command lan-
wish to enhancea certain section oftext on the CRT screen guage.All featuresare availablewith a few keystrokes(of-
by displaying it in blinking inversevideo. Pressing AIDS
the ten one) and there is virtually no syntax to learn or
key returns the terminal to the top of the softkeytree.Press-
ing the fifth softkey, labeled enhance video,then causesa
branch to the video enhancementlevel and displays the
labelsshown in Fig. S.The keyslabeledINVERSE VIDEO and
BLINKVIDEO and f6) can then be pressedto indicate the
(f5
desired combination of enhancements. responseto this,
In
asterisks appearin the lower right-hand cornersof thesekey
labels to indicate they have been selected.Next, the cursor
is positioned on the screenat the starting position for the
selected enhancements.When this is accomplished, the Fig, 3. Ihe video enhancement level of the softkey tree.
'1981
I\,4ARCH HEWLETI-PACKARO
IOUNINT 9
AIDS qF w w ry sF
DEVICE
CONTFOL
ffi ffi F W ry
DEVICE
FROM
ffi ffi rffi ry @
rF
DEVICE
f +tr ry
FUNCTIONS
GROUP TO
DEVICES @
DEVICE
MOOFS
[,4AFGIN]
T A BC O t
[m
ffi
ry @ ry ry
E ry ry @
SEFVICE W I I ry ry
WINDOW
C O NT F ] O L ffi ffiru ffi ffi
ry
ENHANCEMENTS I
ENHANCE
VlDEO
DEFINE
F ry
EH ffi
ffi
ffi
ffi
ffi
ffi
ffi
GROUP FI EL D S
MODJFY
CHARSET m gm I I ffi ffi Flg.4. 2626A softkey tree. Each
row of labels represenfs one level
SKETCiI
FORI\,,IS
F ffi ffi ffi ffi ffi of the tree and the labels within
that level identify the functions
FORMS DRAW
W ffi ffi ffi ffi ffim
GROUP
t LINES
DEFINE
LlNES ru 5H ffi H ffi ffiffi
available there. The arrows be-
tween rows indicate the transac-
tions that are possib/e using the
C O N FI ( ; ffi ffi ffi ffi ffi ffiffi branching (lower-case) keys.
memorize. Consistent labeling conventions further menu items displayed on the CRT screenduring configura-
simplify the command language by visually differentiating tion mode. This approachnot only improves the user inter-
between function softkeys and branching sof&eys. Third, face but also eliminates keyboard and internal switches.
the structure of the softkey tree presents several oppor- Thanks to the relative easeof this approach it is now feasi-
tunities for enhancing the display of information to the ble to reconfigurethe terminal quickly for different applica-
user. Since the softkeys are tree-structured,only relevant tions.
information is presented.The use of sixteen charactersto The terminal's feature set is broken into four smaller
label key functions exceedswhat can be placed on a normal areas,eachwith its own configuration menu. The four areas
keytop and thus makes it easier to understand the function are: global configuration, window configuration, terminal
of the key. configuration, and datacomm configuration. Since the
2626A can act like four virtual terminals, there are four
Menu-Driven Configuratlon terminal configuration menus. Similarly, there are two
Early terminals were designedfor specific purposesand datacomm configuration menus to accommodatethe two
their featuresetsdid not have a great deal ofbreadth. Later datacommports.
designsoffered featuresthat coveredlarger portions ofthe Global Configuration. Contains configuration items global
total terminal market. Some of these featureswere added as to all four virtual terminals. Examples are the terminal
optional extras, while some were available as strap options language (USASCII or one of the six international lan-
within the terminal. Straps usually took one of two forms, guages)and frame rate (50 Hz or 60 Hz).
either a physical switch on a printed circuit board or some Window Configuration. Containsall items associated with
type of wire jumper. The terminal could be made to exhibit the window/workspace relationships within the terminal.
a different feature set simply by modifying the arrangement This configuration menu is used to partition the terminal's
of internal straps. The user became aware of the straps and memory into workspacesand to partition the CRT screen
their related meaningsby reading the referencemanual for into windows.
the terminal, To alter the strapsthe user had to unplug the Terminal Configuration. Contains all items specific to a
terminal, open the case, locate the board containing the given virtual terminal, i.e., virtual terminal modes (remote,
strap, remove it, locate the strap, make the adjustment, block, format, etc.),handshakingrequirements,and choice
reassemble terminal, turn it on, and verify the operation
the of alternatecharactersets.
of the terminal with the modified strap. Datacomm Configuration. Contains all datacomm items.
Strapping the terminal in this way, and setting a few
external switches, such as the baud rate and duplex con-
trols for data communications, is called configuring
the terminal.
To enhance the user interface in this area and make the
full terminal feature set accessible to all users rather than
just the skilled few, the 2626A uses a menu approach to
accomplish the same result. There are no physical shaps
inside the 2626A,so a userwill never haveto open the case.
All configuration items are selected simply by choosing Ffg. 5. Ihe configuration level of the softkey trce.
10 i-iewrerr-pncKARD tvARcH
JoURNAL 1981
One first chooses from a set of menus describing the various with either the default values stored in ROM or the power-
datacomm protocols supported by the terminal and then on values stored in nonvolatile RAM.
fills out the configuration items for that particular protocol. Let's review the above featureswith respectto the four
An example will best illustrate the use of configuration guidelines for designing user interfaces. As with the
menus. Suppose that the terminal language is to be changed softkeys,the configuration menus enhancethe user model
from USASCII to Danish. Like all other features the config- by dividing the entire terminal function set into smaller
uration menus are accessed through the softkeys. Pressing related groups. All items associatedwith each functional
the AIDS key returns the terminal to the top softkey level. areaare presentedon the sameconfiguration menu, while
Then, pressing config keys (f8) causes a branch that displays unrelated items are always contained on other menus.This
a set of softkey labels allowing access to all of the configura- helps the user develop an understandingof the terminal by
tion menus in the terminal (Fig. 5). Since the terminal understanding its subfunctions.
language is a global item, pressing f1 (global config) brings The command language used to configure the 26264 is
up the appropriate menu (see Fig. 6). Note that the first very simple. Oncethe appropriatemenu is displayed,items
configuration item on the second line of this menu is the to be modified are selectedwith the cursor and the user
language specification. either types in the new value or selectsfrom a predefined list
To change this the cursor is positioned in the field and the of values. Again, there is no syntax to learn or remember.
softkey labeled NEXT cHoICE (f3) is used to scroll through a Feedbackto the usei takes several forms during config-
list of all available languages. Each depression of this key uration. When using the NEXTCHOICE/PREV CHOICE keys
displays the mnemonic associated with one of the lan- the value of eachchoice is fed back via an English-language
guages supported by the terminal. For our example, two mnemonic in the selectedfield. When values are entered
depressions are required to display the desired mnemonic, directly from the keyboard, the range of each value is
DANSK/NORSK (Danish/Norwegian). At this point any other checked and the consistencyof all menu items is verified.
changes required in the global configuration menu can be When erroneousentriesaredetectedthe useris informed by
made using a similar approach. When all changes have error messages the softkey label area,and the cursor is
in
been completed and the SAVE CONFIGkey (fl) pressed, all placed in the offending field to aid in correcting the error.
changed items are activated. Typically, this is all that is It is particularly in the areaof presenting information to
required to change any configuration item in the terminal. the user that the configuration menus make a large con-
Once again, the softkey labels combined with English- tribution. In t