CA1199436A - Display-attribute control for an alphanumeric color display - Google Patents

Abstract

DISPLAY-ATTRIBUTE CONTROL FOR AN ALPHANUMERIC
COLOR DISPLAY

ABSTRACT

An alphanumeric color display terminal translates an input set of monochrome display attributes into both a set of color display attributes and an overlapping output set of monochrome display attributes, and controls the color display in accordance with the color and the output monochrome attributes. Translation and control are performed with a ROM and control logic acting upon video signals.

Description

n~
~J~

DISPLAY-ATTRIBUTE CONTROL FOR ~N ALPH~NUMERIC
COLOR DISPL~Y

B~KGROUND

The present inyention concerns the display of alphanumeric data for data processing, and relates more spec~fically to methods and apparatus for displayin~
character ima~es in accordance with sets of display attributes.

Con~entional alphanumeric (~A/N~ data terminals ha~e pro~ision for attaching attributes to character data. In a general sense, attributescan specify any extrinsic property to be associated with one or more codes repre~enting character data to be displayed.
Some terminals, for example, allow certain characters to be designated as "protected fields"; character codes within these fields cannot be modified or replaced from the keyboard.

The present invention concerns one type of attributes, denoted "display attributes". Display attributes specify the manner in which character images are to be displayed. That is, they provide ~isually perceptibly di~ferent or d~stinct images each corresponding to the same character code in the terminal. (Protected fields, therefore, are not display attri~utes, since the associated characters ~ppear the same as in unprotected fields.) ~or the present purposes, di$play attributes are diYided into two species, color dtsplay attributes and monochrome display attribute$. ~IColor display attrlbutes" specify the colors in which c~aracter i~a~es and/or their back~r~und areas are to be shown. They are usually expresse~d in terms of intensitie$ of a set of three or more primary colors such as red, green, and blue.
"Monochrome display attributes`' (or "color-independent display attributes") affect the appearance of character '39~36 images irrespecti~e of color. That is, they would be ~isi~le in a black-and-white ima~e of the character image and its surround. Examples of monochrome display attributes are re~erse image ~dark character ima~es on light backgrounds~ and column separators ~yertical bars or dots on each side of the characters, to mark the extent of a data field~.

Color adds an entirely new dimension to data-entry terminals in electronic data processing applications, and high-quality color displays are becoming technically and economically feasible. Existing applications software, howe~er, is mostly designed for terminals with only monochrome attributes. It would be desirable to allow the use of color terminals without requiring any reprogramming of applications desiyned for monochro~e terminals. A strai~ht substitution of monochrome to color attributes is possible, but would produce garish or bizarre effects for some attribute com~inations. In addition, at leaist some monochrome attributes remain useful in a color environment.

SUMMARY

The present invention provides a meaningful enhancement of an alread~ defined input set of monochrome display attributes by translating them into both a set of color di5play attributes and an output set of monochrome display attributes, then controlling the display in accordance with both these sets. For example, a monochrome "blink" attribute by itsel~ is used to attract attention, and may appear in a color display as 30 a "red" image. ~n "intensify" attribute may appear as "white" (red plus green plus bluej in color~ A chaxacter ha~ing ~oth "blink" and "intensify", howe~er, appears as a blinking red image, for maximum attention value.

i`

119~9~36 Further, if the "column separators" attribute is actiYated~
"intensify" causes the character images to shift from cyan to ~ellow, although the column-separator shapes themselves appear in ~lue for both cases. The individual S monochrome display attributes may be the same ~or both the input and output sets, they may o~erlap, or one may be a $ubset of the other. The invention can ~lso be conceptualized as a translation or conversion of a smaller set of attributes includin~ only monochr~me 1~ display attributes to a lar~er set of attributes including both color and monochrome display attributes. The conYersion between sets of attributes are performed by an attri~ute transl-ator which may comprise a memory, and by monochrome and color logics for con~rolling the lS color display.

Other objects a~d advantages of the present in~ention, as well as extensions and changes obvious to those skilled in the art, will become apparent from the following description of a preferred embodiment.

DRAWING

FIG. 1 is a high-level block diagram of an alphanumeric color display terminal according to the invention.

FIG. 2 is a more det~iled logic diagram of the color display control o ~i~. 1 for carryin~ out the inYention.

FIG. 3 is a logic diagra~ of a conventional ~ideo-si~nal serializer useful in the control oE Fi~. 2.

-DESCRIPTION

FIG. 1 is a block diagram of a microprocessor-controlled alphanumeric color-display terminal 10. A
con~entional parallel bus 11 contains address, data, 9~36 and control lines for interconnecting a microprocessor 12, read-onl~ memory ~OM~ 13 holding machine-language microcode for drivin~ the microprocessor, and read-write me~ory (RAM) 14 for holding working data of yarious types. Communications adapter 15 transfers data to and from a host data processor o~er a bit-serial communications link such as a t~inaxial cable.

Refresh buffer 16 contains a two-port RAM which receives data bytes from bus 11 under the contxol of microprocessor 12, and which also transmits these bytes to color display 20 in a predetermined sequence for maintaining the evanescent image on a cathode-ray tube (CRT). The mernory, timing and gating logic for buffer 16 are of conventional design. In the embodiment described herein, buffer 16 transfers a single data byte at a time to display 20. A data byte may represent either an alphanumeric character whose image is to be displayed, or a display attribute. The display attributes are of two kinds, color and monochrome. Color attributes specify the colors in which a character or its background are to be shown. In this embodiment, red, green and blue primaries have either of two intensities, on or off; thus seven colors tplus black~ are available.
Monochrome attributes affect the appearance of a character irrespective of color; that is, they would be visible in a black-and-white image o~ the character and its background area.

The set of five input monochrome attributes in this embodiment are those preyiously used in the IBM5250 family of monachrome data-entry workstation terminals.
The "column separator" (COLS) attribute marks the beginning and end of each character position, so that an operator entering data into a fixed-length field can see the field extent as characters are placed into it.

1~3g436 This attribute is displa~ed as two dots in the last raster scan of the character box, one dot just to the left of the character, the other just to the right.
The "blinkl' (BLNKl attribute causes the character image to blink on and off about two times per second.
"Underscore" ~UNSCI places a horizontal line in the - last scan o~ the character box. "Intensify" ~INT), sometimes called "highlis~t", brightens the entire character Lmage. "Reverse Yideo" (REY) chan~es the display from the normal light character on a dark field to a dark character on a light field. RE~ rçmains a monochrome attribute even in t~e environment of the present color display: it reverses the state of a single binary video signal having values representing "character" and 'Iback~round''; also, all of the color attributes can be controlled independently of REV.

Other monochrome display attributes could be included, such as italic or other fonts, and sub- or super-scripting. Obviously, other color display attributes could also be incorporated. Attributes other than display attributes could be utilized as well, if desired.
~ttributes other than display attributes do not enter into the present context; hence, the term "attribute"
by itself shall be taken to refer to display attributes only.

The remaining major components of FIG. 1 are inp~t/output tI/0) adapters 17 and a ke~board 18. The keyboard may ~e of any conventional desi~n, ha~ing either a parallel or serial interf~ce. Adapters 17 recçire character bytes or other codes from keyboard lB, and also inter~ace to other internal or e~ternal elements not relevant to the present invention, such as curser-position registers or dot-matrix printers. The lines from adapters 17 to display 20 specify certain operatin~ modes, explained below.

11'39~3~

FIG. 2 shows the portions of color display 20 which pertain to the present invention. Other, con~entional ~unctions are not sho~n; these include, for example, raster-scan generation and timing t color-beam convergence, and yideo-signal amplification. sy way of background, the present Lmplementation employs a horizontal raster haYin~ interlaced "even'! ~nd "odd" scan fields, as in teleyision practice. Each character positicn is 12 scans high (S0-$11, six from each scan field) ~ith 9 possible dot positions along each scan, numbered T0-T8.
Most character images occupy dots Tl T7 of scans Sl-S9, the other dots and scans bein~ used for borders. Codes for character ima~es have values X40-XFF ("X" indicates hexadecimal notation~, while attributes have values X20-X3F. The attributes are coded as follows (bit 7 is the most significant bit of the code byte):

sit Attrlbute 7 Always = 0 for attribute codes~
6 Always = 0 for attribute codes.
Always = 1 for attribute codes.
4 Column separators (COLS) 3 Blink ~BLNK)

2 Underscore (UNSC) 1 Intensify (INT) 0 Re~erse image (RF,V~

Attributes themsel~es occupy a character position on the display, but no image is normally displayed for them; they appear as a blank or space char~cter. Thus, ~or example, the attribute code 0010 111~ (Y-X2E?
speçifies that the characters ~ollowing that posi~ion shall blink, haYe an underscore, and be intensified.

11~9~3~;

A new data byte is- input from refresh buffex 16 and is received on line 21 eac~ character time of e~ery scan in both scan fields. ~ conventional character generator 22 recei~es the data byte and a repetitive scan count 23, also as in conventional pr~ctice. Lines 24 contaln nine bits D~-D8 in parallel representing dot positions TQ-T8 of the current scan 23 of the character 21. t~ll attribute codes X20-X3F are normally blanked out by logic subsequent to ~enerator 22.1 Lines 24 are latched in register 25 by the previously mentioned clock 26 occurring every character time. Serializer 27 converts these parallel scan bits into serial ~ideo bits 28 ~y means of a dot clock 29 occurring nine times, T0-T8, during each character clock 26. In addition, a true/complement tT~C) input controls the selective inversion of the serial binary (li~ht or dark) video signals ~n line 28.

In this implementation, attributes apply to all character positions following them, in the same or succeeding rows of characters on the display. (These are termed "field attributes" in the art.~ Logic 30 ensures that the correct attribute code will be in force during each character time. Decoder 31 produces a signal 32 whenever an attribute code (i.e., X20-X3F) appears on data lines 21. This si~nal clocks the code on lines 21 into current-attribute reyister 33. When the ~ttribute code appears during the last scan (S10 in the even scan ~ield or $11 in the odd field~, AND
~ate 34 clocks the code into start-attrib1~te register 35 as well. The last o~ these attribute codes is retained in latches 33 and 35 until replaced at the ~ppropriate times for the next xow of characters.
These re~ister$ are selectively switched to output lines 36 by multiplexer 37, which is contr~lled by set/reset ~SR) latch 38. The presence of an attribute ~9~36 si~nal on line 32 causes latch 38 and multiplexer 37 to couple cuxrent regist~r 33 to line 36; at the ri~ht end of e~ery scan a standard horlzontal-retrace signal 39 resets latch 38, causin~ start re~ister 35 to feed lines 36 until latch 38 is again set by line 32. Thus as each scan proceeds from left to right across the display, each attribute code encountered along the way will be transmitted from register 33 to lines 36 to control the display of all characters to its ri~ht, until the next attribute code is encountered. Start register 35 operates only before the first attribute code of a scan is encountered, by retaining the last attribute of the preceding row of characters and transmitting it to lines 36 at the proper times.

Decoder 4Q provides scan-count or location signals used by several other elements of display 20. Specifically, odd-field location signal 41 is active during the six scans S1, S3, S5, S7, S9, Sll of the second scan field of each interlaced frame. (The even scan field contains scans numbered S0, S2, S4, S6, S8, S10.) Last-scan location signal 42 is active during the last scan of each scan field, i.e., during scans S10 and Sll.

From a logical standpoint, the o~erall functions o~ attribute translator 5a ~ color logic 60, and monochrome logic 70 are: (a~ to translate an input set of m~nochrome display attributes into both a set of color attributes and an output set of monochrome attrlbutes, (b~ to produce color si~nals in accordance ~ith the set of color attributes, and ~cl to modif~ the Yideo si~nals in accordance with the subset of output monochrome attributes. In practice, each of the elements 50, 60, 70 may perform portions of more than one of these functions, in order to reduce the o~erall cost of the implementation.

~39436 As pre~iously explained, the fi~e monochrome attributes inPut to the system are column separators (COLS), blink (BLNK), underscore (UNSC~, intensify (INT~, and re~erse video (REV~. The subset of these which are actually used by the display are COLS, sLNK, UNSC and REV. In addition, another output monochrome attrihute, "non-display" (NOND~ is produced from certain combinations of the input attributes. NOND causes all following characters to be blanked out, i.e., to appear as spaces. The color atrri~utes may be considered to be either the three separate primary-color si~nals or the seven actual colors produced by combinations of these si~nals. The pximary-color signals are denominated as green (G), red (R) and blue (B). However, the CRT
phosphers are somewhat different from the normal television standard colors, to avoid eyestrain and to produce a more pleasing palette with a limited number of colors.
The actual colors are: pink (R+s), red (R), yellow (R+G), light green (G), turquoise ~G+B~, light blue or azure (~), and white (R+G+B). Black, of course, is the absence of all three primary signals. Table I summarizes the overall translation of the monochrome input attribute set to the monochrome output attribute set and the primary-color attribute set. For each vertical column in the table, an attribute code (X20-X3F~ is first expanded in terms of the input monochrome attributes it specifies, shown as "1" entries in the table. Then, the ~ i entries below the horizontal line specify the corxesponding output monochxome and primary color attributes.

~0981-010 ~1~943~
0 10 ~1 860 rl r~l rl r~
~7 Cl r-i r-l r~ I r~ r-l r~ ~1 C ) r-l r~l ~J r-l r-l r-l r-l r l r-l r-l ~1 ~
~I r l ~7 ~ r-l r-l ~ r~l r I r-l c~ r~ r~ r~ 1 rl r-l r-l rl t~ 1~ r-l rl r-l r I r-l r I r-l ~ Lr) ,1 ~I r-l r~ ~ r l r-t~ ~ r~ r~ 1 r-l r l tr~ rl r~l r l r I r-l ~I r-( 1 r-l rl r-l r-l r~l ~1 r l r-l r~l r l r-l r-l r1 O r~ r~ 1 r-l N h r~ ri r-l r~
t~ ~ r-l r~l r-l rl r l r l HN ~ -1 r-l ~I r-l r~ r-l C_) r-l r-l r-l r1 mN m .~ r1 rl rJ ~-1 rl r-l r-l a~ r-l r-l r-l r-l ~1 CD ~--I r l N 1~ r-l r-l r-l r-l D r-l r l r~ r I r J r l r-l r-l r-l r t r-l r-l r l t~l ~) r~ 1 r-l r-l r-l r l N r~ r~l r-l r l ~J r-l -1 r l r-l O r~

O
~: h O O
a) o Z U~ ~ Z
.~ ~o~æz~ ~o~z~o o m :~ H P~ ) m :~ ~ z ~ m ~ O
H O p~

1~99436 The major purpose of attribute translator 50 is to tr~nslate the set of input mono~hrome attributes on lines 36 into signals 51-55 representin~ the set of output monochrome output attributes and into urther signals 56-58 for t~e pximary color attributes. Translator 50 may conveniently be implemented as the lo~er half of a lQ24-byte ~y 8-bit-wide ROM integrated-circuit module having addr~ss lines A~ tleast signi~icant bit, LSB~
through A8 (most si~nificant bit, MS~). The attribute lines 51-58 xepresent the ei~t data lines D0 (L$B~
through D7 (MSB). The five input lines 36 are connected to address lines A2-A6. Lines ~J-A8 are mode-control lines not relevant to the present in~ention. Originating in I/O adapters 17, ~IG. 1, the "converge mode" line inhibits lines 51-58 while the CRT is being adjusted for color conver~ence, while the "2-color mode" line passes the monochrome attrlbutes substantially unchanged to the output monochrome attributes, using the colors only to the extent that, for example, normal intensity characters are green (G), while high-intensity (INT
attribute on) characters are in white (R+G+B). Low~
order address lines A0-Al are used to identify the last scan of the odd scan field, i.e., scan Sll, for producing underscores and column separators at the proper times, since these shapes are not contained in character ~enerator 22.

Table II shows the complete contents of ROM 50 addressed by lines ~Q~~8. It should be noted that the data lines DQ(LSB) throu~h D7(MS~) occasionally deYiate from the values they would be expected to ha~e. This occurs because ROM SQ does more than merely tr~nslate ~ttributes; it also aids lo~ics 60 and 70 in the direct production of some attributes. ~or example, the UNSC
output line 54 not always be activated when the UNSC
attribute is active, but rather only when both UNSC and COLS attributes are active, in order to simplify logic ~''3~436 60. Likewise, the UNSC attri~ute is actuall~ produced by actiyating REV line 51 and B line 58 during scan Sll, i.e., when ~0 and A1 both are high; thi.s simpli~ies color lo~ic 7Q~

Table II ~hows the contents of ~OM 50 for the seven-color mode, located in addresses 128 throu~h 255.
The leftmost "~TTR" column of Table II contains hex attribute codes. The 'IADDR'' column contains the ~irst address of a four-byte group of data repxesenting that attribute. The "Data @ A" column is the hex data contained ~n each of the four bytes. In some cases, the last byte of the four differs from the other three;
the "Data ~ ~+3" column lists those bytes for the appropriate rows of the table.

1~94~6 TABLE I I
DATA DATA
ATTR ~ - ADDR . @ ~ - @ A~3 __ _ __ 2~ 128 80 23 140 El 148 ~1 25 2~ 164 41 2~ 168 48 31 196 Al Bl 33 204 Cl Dl 34 208 A0 3,5 212 Al 35 3C 240 6~ 25 g~3~;

Monochrome logic 60 basically modifies the displayed character ~mage in accordance with the output set of ~onochrome attributes COLS, BLNK, UNSC, RE~, and "non-display" (NOND). This may be done not only by direct action upon ~onochrome video si~nals, but also in concert with translator 50 and/or color logic 70, as will appear. REV output line 51 enters a true/co~plement input of serializer 27. This acts as an exclusive-or gate on serial video 28; that is, REV=0 for normal video allows the signal on line 28 to pass unchanged, while REV=l for reverse video inverts line 28, making bright dots dark and vice versa. NOND output line 52 is transmit~ed through OR gate 61 to force a reset in register 25, so as to blank out the parallel video signals from lines 24. L~g 32 of OR 61 effectively causes all attribute codes themselves to have an implied NOND attribute, and thus to appear as blanks on the CRT. A thlrd leg implements the sLNK attribute by ANDing output line 53 with any convenient clock signal 62 of several pulses per second in gate 63. COLS line 55 is combined in AND 64 with a signal 65 which is active during dot times T0 and TB of each character of eyery scan. Translater 50~ however, inhibits COLS
except during scan Sll of those characters having the underscore attribute, so that line 66 is active only at the proper dot and scan times of the proper characters.
UNSC line 54, as mentioned above, need be active only during those characters for which both the underscore and the column-separator attributes are to be in effect.
AND 67 combines lines 54 and 66 to place a signal on line 68 to indicate this situation. Lines 66 ~nd 68 work their will on the video si~nal by way of logic 70.

Color-control logic 7Q receives the color-attribute lines 56-58 to specify one of seven colors in which the appropriate characters are to be displayed. Serial 1~.'39g36 yideo signal 28 controls AND gates 71 73 for selective enabling of the color si~nals. $ignals 56-58 are thereby passed unaltered when ~ideo signal 28 is high, and are turned of~ when video si~nal 28 is low. The effect of this is to paint the video dots belonging to the character i~age in one of the seven colors specified by translator 50, and to paint background dots in ~lack, i.e., the absence of all color. In the reverse-~ideo mode, the background color is specified b~ lines 10 56-58, while character ima~es are black. Gates 7~-77 are required to control column-separator color, because the col~nn-separator dots are always displayed in blue, regardless o~ the color o~ the character at that position on the CRT. The inverting inputs of ANDs 74 and 75 turn off the G and R color signals whenever the previously described line 66 becomes active. This line also forces the ~ color on, by means of OR 76. AND 77 cuts off the B color during dot times T0 and T8 when line 68 indicates both UNSC and COLS, so that T0 and T8 are 2~ always black when both UNSC and COLS are active.

Conventional color display head 80 includes a color CRT, video signal amplifiers, scan-generation circuits, power supplies and so forth to display alphanumeric character images in the colors specified by color-25 signal inputs 81-83. Control si~nals 81-83 at this point represent both the color and the outpu-t monochrome attributes speci~ied by the original set of input attributes receiYed on data lines 21. Control signals 81-83 ~re binary-valued, but could ha~e more than two le~els i~ desired to present a broader range of hues and intensities on the CRT. Also, some conventional color displays are an intensity or luminance control signal separate from the color control signals.

As mentioned earlier, the overall attribute-conversion process could be divided differently among the elements 50, 6Q and 70. Also, ROM 50 c~n be loaded with more than one mapping of input attributes into output monochrome and color attributes. Moreo~er, ROM
50 could be totally or partially replaced with read/write (RAM) memory, so as to allow the loading of custom mappings, either from the host CPU via communications adapter 15, Fig. 1, or from keyboard 18.

FIG. 3 shows an example of a conventional video serializer 27 useful in connection with the in~ention.

Ring counter 91 outputs a repetitive sequence of dot signals TQ-~8 in response to dot clock 29. Each dot si~nal represents one dot interval of the nine horizontal dots in each character position on the CXT
display. TG and T8 are ORed in gate 92 to produce the previously described column-separator signal T08 on line 65. Each dot-time signal T0-T8 conditions both of a pair of ANDs 93, 94. ~ach pair of gates also receives a corresponding one of the parallel video signals ~o-V8 from register 25, Fig. 1. Selection between the gates of each pair is ~ased on the state of true/complement input 51: if T/C is high, AND 93 transfers its data to OR 95 unchanged at the appropriate time; if T/C is low, inverting AND (NAND) 94 inverts the value of its data line. OR 95 merely collects the outputs o~ all the ANDs 93, 94 and transfers them to serial video line 28.
~any other implementations are possi~le ~or serializer 27; this one happens to be particularly economical as a pa~t of a custom-logic chip for the present implementation.

Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of operating a color display terminal for alphanumeric data in accordance with a defined input set of monochrome display attributes, said display attributes representing visually perceptible distinctions among character images of said alpha-numeric data, said method comprising:

receiving input codes representing various combinations of said input set of monochrome display attributes;

translating said input set of monochrome display attributes into both a set of color display attributes and an output set of monochrome display attributes;

controlling the display of said character images of said alphanumeric data in accordance with said set of color display attributes and said output set of monochrome display attributes simul-taneously.

2. The method of Claim 1, wherein a plurality of the monochrome display attributes of said input set are the same as those of said output set.

3. The method of Claim 2, wherein said input set of monochrome display attributes includes a reverse-image attribute, an intensify attribute, an underscore attribute, and a blink attribute.

4. The method of Claim 3, wherein said set of color display attributes includes individual attributes representing at least three primary colors.

5. The method of claim 4, wherein said output set of monochrome display attributes includes said reverse-image attribute, said underscore attribute, said blink attribute, and a non-display attribute.

6. The method of Claim 2, wherein both said input set and said output set of monochrome display attributes include a reverse-image attribute, an underscore attribute, a blink attribute, and a column-separator attribute.

7. The method of Claim 1, wherein said input codes further represent said alphanumeric data, said input set of monochrome display attributes and said alphanumeric data occupying distinct ranges of values of said input codes.

8. In a color terminal for displaying character images of alphanumeric data, said terminal including:

input means for receiving character signals representing a set of alphanumeric characters, and for receiving input attribute signals representing a predefined first set of monochrome display attributes, said monochrome display attributes providing visually perceptibly different images of the same one of said alphanumeric characters, independently of the color in which said characters are displayed,

Claim 8 Continued character-generator means for converting said character signals into video signals representing said character images, and display means responsive to a plurality of control signals for displaying said character images in different colors, the improvement comprising:

attribute translator means responsive to said attribute signals for translating said first set of monochrome display attributes into both a set of color display attributes and a second set of monochrome display attributes;

monochrome logic means coupled to said attribute translator means for modifying said video signals in accordance with said second set of monochrome display attributes; and color logic means coupled to said attribute translator means for producing said control signals in accordance with said video signals and said set of color attributes.

9. The color terminal of Claim 8, wherein said display means produces said character images as a plurality of video dots in each of a plurality of scans.

10. The color terminal of Claim 9, wherein said attribute translator comprises a memory addressed by said input attribute signals.

11. The color terminal of Claim 10, further comprising decoding means for producing location signals for certain of said scans in said plurality of scans, said location signals being effective to address said attribute-translator memory.

12. The color terminal of Claim 11, wherein said attribute-translator memory is responsive to said location signals for modifying said color display attributes transmitted to said color logic means.

13. The color terminal of Claim 11, wherein said attribute-translator memory is responsive to said location signals for modifying at least one of said second set of monochrome display attributes.