MC6845 - CRT CONTROLLER (CRTC) The MCW5 CRT controller performs the nterface between an MPU and a raster-scan CRT dsplay. t s ntended for use n MPU-based controllers for CRT termnals n stand-alone or cluster confguratons. The CRTC s optmzed for the hardware/software balance requred for maxmum flexblty. All keyboard functons, reads, wrtes, cursor movements, and edtng are under processor control. The CRTC provdes vdeo tmng and refresh memory addressng. Useful n Monochrome or Color CRT Applcatons Alphanumerc, Sem-Graphc, and Full-Graphc Capablty Sngle M6803 Compatble Bus nterface.<.,.:$,..+,.<? TTL-Compatble nputs and Outputs.) $:.4.:$?:\ + Start Address Regster Provdes Hardware Scroll (by Page or...~,:,:t, * ~.$+, Character)....\,,,,..,...<3. Programmable Cursor Regster Allows Control of Cursor~~&Q~? and Blnk Rate.J..:.,,\::..+ %.A*%<.$:j Lght Pen Regster.:,. Refresh (Screen) Memory May be Multplexed Bq,ee# the CRTC :J<.t,,, and the MPU Thus Removng the Requrement~~o~j:&ne Buffers or.,,,,, ~ External DMA Devces ~.k$+.>x,!k~~ d,,}.. t.\ : Programmable nterlace or Non-nterlace,$~~.~~odes o 4-Bt Refresh Address Allows Up to $$~\# ~efresh Memory for e Applcatons nclude Glass-Teletype, Smart, Programmable, ntellgent CRT Termnals; Vdeo Games; nformaton Dsplays Fully Programmable Va Processor Data Bus. Tmng May Be Generated for Almost Any Alphanumerc Screen Format, e.g., 80x 24, 72x64, 32 x20 + 5 V Supply Use n Character or Sem-Graphc ~%~]~ 5-Bt Row Address Allows Up to.&z ~$%h-lne Character Blocks By Utlzng Both the Refres$$Et$~3es and the Row Addresses, a 52K Address Space s ~y~~w~,~ for Use n Graphcs Systems Refresh Addresses are Pr~~d~ Durng Retrace, Allowng the CRTC to Provde Row Add(##*~~*&R%efresh Dynamc RAMs Pn Compatble w[~h {$~$$ CM35..,,,,,,.$$;... AGE PN ASSGNMENT ]Vs RESET[ 2 39 ]HS LPSTB~ 3 3 ]RAO MAO[ 4 37 ] RA MA [ 5 36 ]RA2 MA2[ 6 35 ] RA3 MA3[? w ]RA4 MA4[ 8 33 ] DO -.,.~.5 Tem~erature Order Number O c to 70 c MC6845L 40 C to 85 C MC6845CL O c to 70 c M CWA45L 40 C to 85 C McmA45cL O c to 70 c McmB45L Ooc to 700c M CW5S 40 C to 85 C MC6845CS Ooc to 700c M CWA45S 40 C to 85 C M C68A45CS Ooc to 70 C MC845S O c to 700c MC6845P MA5[ 9 MA6[ 0 MA7[ MA8[ 2 MA9[ 3 MAO[ 4 MA[ 5 MA2[ 6 MA3[ 7 DE [ la 32 ]Dl 3 ] D2 30 ] D3 29 ] D4 28 ]D5 27 ] D6 26 ] D7 25 ]m 24 ]RS 23 ]E CURSOR[ 9 22 ] RG Vccq 20 2 ]CLK )MOTOROLA NC., 984 DS98%- F
FGURE WPCAL CRT CONTROLLER APPLCATON Processor *AB *DB Ptmary Bus v Secondary.,,. w MWMUM RATNGS?:,,a[d :?.. **!.,..*:; Ratng Symbol Value $,*;, Supply Voltage Vcc 0.3 to +7.0 % nput Voltage Vn 0.3 lq~+ 7.of v Operatng Temperature Range T~~o %~ M CW5, M CA45, MC68B45 TA +~~q$~o c M C6645C, MC68A45C ~P~&3<o +85 Storage Temperature Range Tstg~{$$?&,$.. to +50 OC s.,.,.,,.<, * \:>:\,,y,,,.:$,,,,. < THERMAL CHARACTERSTCS ~~.. s,..>k.>... Characterstc,,*O Value Ratng?. ~:~ Thermal Resstance,:;:$+,.,,,,*,.,>> Plastc Package.,$4. -+$+... 00,, J ~ c/w Cerdp Package {t, :?. 60,.t$~..:\\:wb.,.,,:,~t.>:)~ Ceramc Package..!<:., >,..,.,. : 50.s,~;..:$$:;-~ The devce contans crcutry to protect the nputs aganst damage due to hgh statc voltages or electrc felds; however, t s advsed that normal precautons be taken to avod applcaton of any voltage hgher than maxmum rated voltages to ths hghmpedance crcut. For proper operaton t s recommended that Vn and Vout be constraned Vout)svcc, to the range VSS=(Vn or MOTOROLA Semconductor Products nc. 2
POWER CONSDERATONS he average chp-juncton temperature, TJ, n C can be obtaned from: TJ =TA+ Where: (PD*OJA) TAS Ambent Temperature, C OJA= Package Thermal Resstance, Juncton-to-Ambent, OC/W.!,. A)t PDz PNT+ PpORT *,..,,, :J!,,.+.t:;$,.\,f~:.,,...*,,. PNT= CCX VCC, Watts Chp nternal Power ~,:.;./:,,,*\>, * ~.\t >$ \<,,:,. PpORT = Port Power Dsspaton, Watts User Determned ::3*., ~.**,,...$}$..,y~. For most applcatons PpORT< PNT and can be neglected. PPORT may become sgnfcant f the devce ~:qured to () DC ELECTRCAL CHARACTERSTCS (Vcc= 5.o Vdc + 5%, VSS=O, TA=O~}OOC unless otherwse noted, see Fgures 2-4) (M] MOTOROLA Semconductor Products nc. 3
BUS TMNG CHARACTERSTCS (See Notes and 2) (Reference Fgures 2 and 3).. 3 Pulse Wdth, E Hgh PWEH 450 280 220 ns 4 Clock Rse and Fall Tme tr, tf 25 25 20 ns 9 Address Hold Tme (RS) tah 0 0 0 ns, 3 RS Setup Tme Before E tas 80 60 40 *.,QS 4 R/~ and ~ Setup Tme Before E tcs 80 60 40 - tksa~a,,.,,t,t 5 R/~and ~ Hold Tme tch 0 0 0,\..$.,~,+,<, ~$hs 8 Read Data Hold Tme tdhr 20 50* 20 50* 20,3 ~t\b*$? ns 2 Wrte Data Hold Tme tdhw 0 0, ;~$p :L ns 30 Perpheral Output Data Delav Tme tddf 280 8Q~ $0+ 50 ns 3 Perpheral nput Data Setup Tme tdsw 65 80,$$ w$:;:p,a ns E RS R/W, CS +0 5 Read Data >? Wrte Data NOTES: FGURE 3 BUS TMNG TEST LOAD C= 30 pf for DO-D7 =30 pf for MAO-MA3, RAO-RA4, DE, HS, VS, and CURSOR R = kq for DO-D7 =24 kq for All Other Outputs m MOTOROLA Semconductor Products nc. 4
the dots. As x and y get larger a more detaled character The processor communcates wth the CRTC through an may be created. Two common dot matrces are 5 x 7 and 8-bt data bus by readng or wrtng nto the 9 regsters. 7 x 9. Many varatons of these standards wll allow Chnese, The refresh memory address s multplexed between the Japanese, or Arabc letters nstead of Englsh. Snce processor and the CRTC. Data appears on a secondary bus characters requre some space between them, a character separate from the processor s bus. The secondary data bus block larger than the character s typcally used, as shown n concept n no way precludes usng the refresh RAM for other Fgure 8. The fgure also shows the correspondng tmng purposes. t looks lke any other RAM to the processor. A and levels for a vdeo sgnal that would genel-ate the number of approaches are possble for solvng contenf, ns,<,.*:l. characters. for the refresh memory:.!., Y. :*\($,~~~,}}~~. ~ ~t,.. Referrng to Fgure, the CRT controller generates the refresh addresses (MAO-MA3), row addresses (R AO-RA4), and the vdeo tmng (vertcal sync VS, horzontal sync 2, HS, and dsplay enable DE). Other functons nclude an nternal cursor regster whch generates a cursor output when ts contents compare to the current refresh address. A lght pen strobe nput sgnal allows capture of the refresh ad- 3. dress n an nternal lght pen regster. All tmng n the CRTC s derved from the CLK nput. n alphanumerc termnals, ths sgnal s the character rate. The vdeo rate or dot clock s externally dvded by hgh-speed logc (TTL) to generate the CLK nput. The hgh-speed logc must also generate the tmng and control sgnals necessary for the shft regster, latch, and MUX control. 4. One Character Clock / A \ Character Dsplay } Lne Space / Frst Scan Second Scan MO~OROLA Semconductor Products nc. 7
FGURE 9 TRANSPARENT REFRESH MEMORY CONFGURATON TMNG USNG Mm FAMLY MPU T CRTC Accesses Refresh Memory. E M PU Accesses Refresh Memory T ~tcyc= nxtcor tc/m - Where: m, n are ntegers; tc s character perod PROCESSOR NTERFACE The CRTC nterfaces to a processor bus on the bdrectonal data bus (DO-D7) usng ~S, RS, E, and R/~ for control sgnals. Data Bus (DD7) The bdrectonal data lnes (DO-D7) allow data transfers between the nternal CRTC regster fle and the processor. Data bus output drvers are n the hghmpedance state untl the processor performs a CRTC read operaton. Enable (E) The enable sgnal s a hgh-mpedance TTL/MOS compatble nput whch enables the data bus nput/output buffers and clocks data to and from the CRT$, Ths sgnal s usually derved from the processor clock..3%$, hgh-to-low transton s the actve edge. =?:* ~!.~.,,.}>,,.,,,$lj~t,,.,,,.\y>,.,,,, :,{:.~ Chp Selet (~) The = lne s a hg~w~~>nce TTL/ MOS compatble nput whch selects th,~ ~~,~J?& when low, to read or wrte to the nternal regst~~~~~~:~s sgnal should only be actve when there s a vald,. st%~l&address be- *;..\~~}.,, ng decoded from the processor..,.,~.!..,.,:... ~- $,~j. -.),* >,V>,+:,4, l~\,+,/.,}+ Regster Select (RS) The R$ l~~ls a hgh-mpedance TTL/MOS compatble nput ~%t&~cts ether the address regster (RS = O) or one of t~,d~ta regster (RS = ) or the nternal regster fle..,.:,.!., < ve~ca Sync (VS) a~~~q?~ontal Sync (HS) These TTL-compatble out~~~$~~$%ctve hgh sgnals whch drve the montor drectly &~&a* fed to the vdeo processng crcutry to gener~t&~ co:hposte vdeo sgnal. The VS sgnal determnes t~~~%#m&al poston of the dsplayed text whle the HS sg~al~$ ~ermnes the horzontal poston of the d splay $L~~$awL..l:(.:,,~~!,::,:h ~~layenable (DE) Ths TTL-compatble output san,q$v$%gh sgnal whch ndcates the CRTC s provdng ad- ~,~~,~e$lng n the actve dsplay area..,...,,, ~~.,>,, $~ +%~*EFRESH MEMoRY/cHAflAcTEfl GENERATOR,)XJ ADDRESSNG The CRTC provdes memory addresses (M AO-MA3) to scan the refresh RAM. Row addresses (RAO-RA4) are also provded for use wth character generator ROMs. n a graphcs system, both the memory addresses and the row addresses would be used to scan the refresh RAM. Both the memory addresses and the row addresses contnue to run durng vertcal retrace thus allowng the CRTC to provde the refresh addresses requred to refresh dynamc RAMs. Refresh Memory Addresses (MAO-MA3) These 4 outputs are used to refresh the CRT screen wth pages of data located wthn a 6K block of refresh memory. These outputs are capable of drvng one standard TTL load and 30 pf.. Row Addresses (RAO-RA4) These fve outputs from the nternal row address counter are used to address the character generator ROM. These outputs are capable of drvng one standard TTL load and 30 pf. NOTE Care should be exercsed when nterfacng to CRT montors, as many montors clamng to be TTL compatble have transstor nput crcuts whch requre the CRTC or TTL devces bufferng sgnals from the CRTC/vdeo crcuts to exceed the maxmum-rated dtve currents. OTHER PNS Cursor Ths TTL-compatble output ndcates a vald cursor address to external vdeo processng logc. h s an actve hgh sgnal. Clock (CLK) The CLK s a TTL/MOS-compatble nput used to synchronze all CRT functons except for the processor nterface. An external dot counter s used to derve ths sgnal whch s usually the character rate n an alphanumerc CRT. The actve transton s hgh-to-low. -. MOTOROLA Semconductor 8 Producfs nc.
Lght Pen Strobe (LPSTB) A low-to-hgh transton on (a) ths hgh-mpedance TTL/ MO S-compatble nput latches the current Refresh Address n the lght pen regster. The latchng of the refresh address s nternally synchronzed to the character clock (CLK). the VCC and VSS These nputs supply + 5 Vdc ~ 5% to CRTC. The RESET n~ut and the LPSTB n~ut are encoded as shown n Table. TABLE CRTC OPERATNG MODE RESET The RESET nput s used to reset the CRTC. A low level on the RESET nput forces the CRTC nto the followng state: (a) All counters n the CRTC are cleared and the devce stops the dsplay operaton, (b) All the outputs are drven low. mthe test node confgures the memory a( dresses as two ndependent 7-bt counters # mnmze test tme. -t.:,> {. :. NOTE The horzontal sync output s not defned untl after (b) R2 s programmed, (c) The control regsters of the CRTC are not affected and reman unchanged. (c) Functonalty of RESET dffers from that of other M6BO0 After RESET has gone low and+~~~~~~= O), MAO- MA3 and RAO-RA4 wll be ~+~~$~<w on the fallng edge of CLK, RESET mus~.re~~~~$fow for at least one cycle of the character cl~~~}j,clk). The CRTC resumes, ~&~$~~~~y operaton mmedately after the release opw, DE and the CURSOR are parts n the followng functons: not actve untl ~~t~~~~~rst frame has been dsplayed. ~~,x,,,.,,.>t:. $Jl:.. CRTC DESCRPTON,$s...:. s.,,, ~ <:,,,.j,:..>,)j....,,,,,.,. The CRTC conssts of programmable horzontal and ver- regster, Th~*&~~~~ts of the lght pen regster are subsetcal tmng generators, programmable lnear address quently r$~:,&e processor. regster, programmable cursor logc, lght pen capture lntern#~,~~t~ regsters are programmed by the processor regster, and control crcutry for nterface to a processor thro~h tt% data bus, DO-D7, and the control sgnals bus. A block dagram of the CRTC s shown n Fgure 0, R~~Y~~, RS, and E, ~~. +xj., All CRTC tmng s derved from the CLK, usually the out-.$t, $: put of an external dot rate counter, Concdence (CO) cr- :$~.t;.?~} :*$; :,.?.,t,l$, cuts contnuously compare counter contents to the con-?..:.$;. REGSTER FLE DESCRPTONS tents of the ~roarammable regster fle, RO-R7. For horzon- tal tmng gene~aton, comp~rsons result n: ) horzontst sync pulse (HS) of a frequency, poston, and wdth d$<~$~:$$ mned by the regsters; 2) horzontal dsplay sgnal of$&,$~ quency, poston, and duraton determned by the.f~~j$$~rs. The horzontal counter produces H clock wh~~~#v,& the scan lne counter and vertcal control. The,qs~~~$l of the raster counter are contnuously compared *$w,,~~maxmum scan lne address regster. A concde~c &~~~~ts the raster counter and clocks the vertcal count~~.,, $ Comparsons of vertcal coun~~*.:~&~~nts and vertcal regsters result n: ) vertcal synct$:ul$ (VS) of a frequency and poston determned by ~ ~$f~~ers; 2) vertcal dsplay of a frequency and post~u d~$~~ned by the regsters..,,,$ The vertcal control l~$~y h~s other functons,. Generate row&$l~~t&~{~ao-ra4, from the raster count for the c~~f~s~~kdng nterlace or non-nterlace,,*,. modes. A,,,N.,. ~~~ :f~ 2, Exten~~h&&mber of scan lnes n the vertcal total by th$,~ ~:~~t programmed n the vertcal total adjust r~~sa~. T&*&~~r address generator s drven by the CLK and locat&~yt~e relatve postons of characters n memory wth ther postons on the screen. Fourteen lnes, MAO-MA3, are avalable for addressng up to four pages of 4K characters, eght pages of 2K characters, etc. Usng the start address regster, hardware scrollng through 6K characters s possble. The lnear address generator repeats the same sequence of addresses for each scan lne of a character row. The cursor logc determnes the cursor locaton, sze, and blnk rate on the screen. All are programmable. The lght pen strobe gong hgh causes the current contents of the address counter to be latched n the lght pen The nneteen regsters of the CRTC may be accessed through the data bus. Only two memory locatons are requred as one locaton s used as a ponter to address one of the remanng eghteen regsters. These eghteen regsters control horzontal tmng, vertcal tmng, nterlace operaton, row address operaton, and defne the cursor, cursor address, start address, and lght pen regster. The regster addresses and szes are shown n Table 2. ADDRESS REGSTER The address regster s a 5-bt wrte-only regster used as an ndrect or ponter regster. t contans the address of one of the other eghteen regsters. When both RS and ~ are low, the address regster s selected, When ~S s low and RS s hgh, the regster ponted to by the address regster s selected. TMNG REGSTERS ROR9 Fgure shows the vsble dsplay area of a typcal CRT montor gvng the pont of reference for horzontal regsters as the left-most dsplayed character poston. Horzontal regsters are programmed n character clock tme unts wth respect to the reference as shown n Fgure 2, The pont of reference for the vertcal regsters s the top character poston dsplayed. Vertcal regsters are programmed n scan lne tmes wth respect to the reference as shown n Fgure 3, Horzontal Total Regster (RO) Ths 8-bt wrte-only regster determnes the horzontal sync (HS) frequency by defnng the HS perod n character tmes, t s the total of the dsplayed characters plus the non-dsplayed character tmes (retrace) mnus one..,, MOTOROLA Semconductor Products nc. 9
FGURE 0 CRTC BLOCK DAGRAM CLK - +HS A V Dsplay v~llcdl + COrlrOl H -. Vertcal Dlsplaved + <H -- +Vs m H..,!V N Cursor ~ w Control $ Cursor End -.. d Reg ml +CURSOR Hend CLK L LPST8 ~RAO.RA4 ~ MAO-MA3 (M) MOTOROLA Semconductor Products nc. 0
TABLE 2 CRTC NTERNAL REGSTER ASSGNMENT u u u n[ v. 3VTG rusluur) Lllal. nuvv l-u Yes \ o 0 0 0 0 R8 nterlace Mode and Skew Note No Yes o 0 0 0 R9 Max Scan Lne Address Scan Lne No Yes o 0 0 0 RO Cursor Start Scan Lne No Yes ~ ;:p+ p (Note 2) o 0 0 Rll Cursor End Scan Lne Nc! o 0 0 0 R2 Start Address (H) N(,.mw o 0 0 R3 Start Address (L) 0 0 0 R4 Cursor (H) o 0 R5 Cursor (L) o 0 0 0 0 R6 Lght Pen (H) o 0 0 0 R7 Lqht Pen (L).J>.~t;: FGURE lllust~~~qn OF THE CRT SCREEN FORMAT,,/+ ~. ~~~wsr of Horzontal Total Char. (Nht+ ) Lne (NSL) Dsplay Perod Total Scan Lne Adjust (Nadj)- L NOTE : Tmng values are descrbed n Table 5. MOTOROLA Semconductor Products nc.
Horzontal Dsplayed Regster (R ) Ths 8-bt wrte-only regster determnes the number of dsplayed characters per lne. Any 8-bt number may be programmed as long as the contents of RO are greater than the contents of R. Horzontal Sync Poston Regster (R2) Ths 8-bt wrteonly regster controls the HS poston. The horzontal sync poston defnes the horzontal sync delay (front porch) and the horzontal scan delay (back porch). When the programmed value of ths regster s ncreased, the dsplay on the CRT screen s shfted to the left. When the programmed value s decreased the dsplay s shfted to the rght. Any 8-bt number may be programmed as long as the sum of the contents of R2 and R3 are less than the contents of RO. R2 must be greater than R. nterlace Mode and Skew Regster ( R8) The M CW5 only allows control of the nterlace modes as programmed by the low order two bts of ths wrt~only regster. Table 3 shows the nterlace modes avalable to the user. These modes are selected usng the two low order bts of ths 6-bt wrte-only regster. TABLE 3 NTERLACE MODE REGSTER. Sync Wdth Regster ( R3) Ths 8-bt wrte-only regster determnes the wdth of the horzontal sync (HS) pulse. The vertcal sync pulse wdth s fxed at 6 scan-lne tmes. The HS pulse wdth may be programmed from l-to-5 character clock perods thus allowng compatblty wth the HS pulse wdth specfcatons of many dfferent montors. f zero s wrtten nto ths regster then no HS s provded. Horzontal Tmng Summary (Fgure 2) The dfference between RO and R s the horzontal blankng nterval, Ths nterval n the horzontal scan perod allows the beam to return (retrace) to the left sde of the screen. The retrace tme s determned by the montor s horzontal scan components. Retrace tme s less than the horzontal blankng nterval. A good rule of thumb s to make the horzontal blankng about the CRT screen: w~,programmed n character row tmes. Any number sf~~~;than the contents of R4 may be programmed n~sr#~$ ~t,~ $~+;F,..,,;~ Vert&&~&~c Poston (R7) Ths 7-bt wrte-only regster Contwy${% poston of vertcal sync wth respect to the 4. refere $~e. t s programmed n character row tmes, When the programmed value of ths regster s ncreased, the dsplay poston of the CRT screen s shfted up. When the programmed value s decreased the dsplay poston s shfted down. Any number equal to or less than the vertcal total (R4) and greater than or equal to the vertcal dsplayed (R6) may be used. *:$,:. ::)., > :44;:.!::,Q n the normal sync mo~ ~~~nterlace) only one feld s avalable as shown n ~J ~&$6 and 4a. Each scan lne s refreshed at the VS f&w~& W (e. g., 50 or 60 Hz). TWO nterlace ~~de$~re avalable as shown n Fgures 7, 4b, and 4c. T.$$~~{q,rne tme s dvded between even and odd alternat.~:,~}l~~s. The horzontal and vertcal tmng relatonshp (V.S:;~,el~yed by one half scan lne tme) results n the dsplaced~pt ~~scan lnes n the odd feld wth respect to the? s ~ event&eld.6,,l$s~} nterlace sync mode the same nformaton s panted,~ ~;h ~elds as shown n Fgure 4b. Ths s a useful mode 20% of the total horzontal scannng perod for a CRT, n nexpensve TV recevers, the beam overscans the dsplay ~tl+?a~,$p?llngn a character to enhance readablty. screen so that agng of parts does not result n underscannng. ~~~ n the nterlace sync and vdeo mode, shown n Fgure 4c, Because of ths, the retrace tme should be about one *~j, alternatng lnes of the character are dsplayed n the even ~:t:. thrd the horzontal scannng perod. The horzontal syn~ feld and the odd feld. Ths effectvely doubles the gven delay, HS pulse wdth, and horzontal scan delay are ty~ca~%% bandwdth of the CRT montor..+,$,..~$,~r programmed wth a :2:2 rato, Care must be taken when usng ether nterlace mode to. %~y). ~.. ~/*?}:\::,. ~>,.,>,?,~.\, avod an a~uarent,, flcker effect. Ths flcker effect s due to $F s, ~.~., Vetcal Total Regster ( R4) and Vertcal ~~~~$ &just the doublng of the refresh tme for all scan lnes snce each Regster (R5) The frequency of VS s dete($~~~+bv both feld s dsplayed alternately and may be mnmzed wth pro- R4 and R5. The calculated number of chara~%em~~w tmes s per montor desgn (e. g., longer persstence phosphors). usually an nteger plus a fracton to get,e,*fl~ 50 or 60 Hz n addton, there are restrctons on the programmng of vertcal refresh rate. The nteaer number.~~character row the CRTC regsters for nterlace operaton: +$. tmes mnus one s programmed &:$a~qbt wrte-only vertcal total regster (R4). The fract~ o~~haracter lne tmes s. The horzontal total regster value, RO, must be odd programmed n the 5-bt we~&*$~fw vertcal total adjust (. e., an even number of character tmes), regster (R5) as the numb~r o?.~& lnes requred. 2. For nterlace sync and vdeo mode only, the maxmum.v,. ~.: j<k ~+),>... scan-lne address, R9, must be odd (. e., an even Vertcal Dsplayed R~ (R6) Ths 7-bt wrte-only number of scan lnes). regster specfes t~~~~ber of dsplayed character rows on 3. For nterlace sync and vdeo mode only, the number (Nvd) programmed nto the vertcal dsplay regster ( R6) must be one half the actual number requred. The even numbered scan lnes are dsplayed n the even feld and the odd numbered scan lnes are dsplayed n the odd feld. For nterlace sync and vdeo mode only, the cursor start regster (RO) and cursor end regster (R ) must both be even or both odd dependng on whch feld the cursor s to be dsplayed n. A full block cursor wll be dsplayed n both the even and the odd feld when the cursor end regster (R ) s programmed to a value greater than the value n the maxmum scan lne address regster ( R9)..- MOTOROLA Semconductor Products nc. 2
Non-nterlace Mode Lne Number s VSYNC.. Lne Number s VSYNC *J.,$ r o. Nvsp N o Nvsp 0 Ytsl _l - t.! 6*t~l+ ~! P 0 Nvsp jo Non-nterlace Mode, DE RAO- RA4- VSYNC 0 x x ---- ~-~--~----~ Nr 0 O ~ ~-------~ O X ~----x N, ~ O ~---- nterlace Svnc _ and tdeo Mode? VSYNC x 2 x RAO-RA4 VSYNC 2 X----=----j o x 2 X----=----% o x z X ----xx(nz* o x----m, ---e----+ x 3 x (, \ NOTES:. n nterlace sync and vdeo mode, maxmum raster address (Nr) shall be odd. 2. n nterlace mode, Nht shall be odd, ) x----& d
FGURE 4 NTERLACE CONTROL Scan Lne Address o Scan Lne Address o _ l~ - 0 2 e s 3~ 2 Scan (a) Normal Sync :-d-; 6 e5 5 u ~ 6 7 w v ee Even Feld (b) nterlace Sync Maxmum Scan Une Address Regster (R9) Ths 5-bt wrte-only regster determnes the number of scan lnes per character row ncludng the spacng; thus, controllng operaton of the row address counter. The programmed value s a maxmum address and s one less than the number of scan lnes. CURSOR CONTROL Cursor Start Regster (RO) and Cursor End Regster. (Rll) These regsters allow a cursor of UP to 32 scan lq*$ n heght to be placed on any scan lne of the character b$~k $ as shown n Fgure 5. RO s a 7-bt wrte-only regske)?#& to defne the start scan lne and the cursor bln\,,:~$pbj?s 5 and 6 of the cursor start address regster con{r$h&j &rsor ~.*& operaton as shown n Table4. Non-dsplay, j~xw+z bnd two blnk modes (6 tmes or 32 tmes tha. fl%~,rt~erod) are w~( avalable. R s a 5-bt wrte-only reg~,wr W&h defnes the last scan lne of the cursor. $.!s\ ~:j l,;l>.$:.-j#, f..,:..~>. *;,..:S+, TABLE4 CURSO&~~#~%%EGSTER : ;:... CRTC fols ~Ytg cursor and externally nve~tng the~deo sgnal Nw~%l*an \:t:* exclusve-or gate.,,,:j *$ :,:}!,,~~~~~~ Regster (R4-H, R5-L) Ths 4-bt read/wtte ~eg~$er par s programmed to poston the cursor anywhere *\ $$). ~&X,J~~therefresh RAM area; thus, allowng hardware pagng and?~;~~~rollng throughmemory wthout loss of the orgnal cursor,$~ -poston. t conssts of an 8-bt low order (MAO-MA7) regster and a 6-bt hgh order (M A8-MA3) regster. OTHER REGSTERS Start Address Regster (R2-H, R3-L) Ths 4-bt wrte-only regster par controls the frst address output by the CRTC after vertcal blankng. t conssts of an 8-bt low order (MAO-MA7) regster and a 6-bt hgh order (MA8- MA3) regster. The start address regster determnes whch porton of the refresh RAM s dsplayed on the CRT screen. Hardware scrollng by character or page may be accomplshed by modfyng the contents of ths regster. tght Pen Regster (R6-H, R7-L) Ths 4-bt read-only regster par captures the refresh address output by the CRTC on the postve edge of a pulse nput to the LPSTB pn. t conssts of an 8-bt low order (MAO-MA7) regster and a 6-bt hgh order (M A8-MA3) regster. Snce the lght pen pulse s asynchronous wth respect to refresh address tmng an nternal synchronzer s desgned nto the CRTC. Due to delays (Fgure 5) n ths crcut, the value of R6 and R7 wll need to be corrected n software. Fgure 6 shows an nterrupt drven approach although a pollng routne could be used. MOTOROLA Semconductor 5 Products nc.
FGURE5 CURSOR CONTROL [ On off On 4 & Blnk Perod= 6 or 32 Tmes Feld Perod + o ; 3 4 5 6 7 8 9 0 Cursor Start Adr. = 9 Cursor End Adr. =9 Cursor Start Adr. = 9 Cursor End Adr. = 0.,. ** \*.*:$(,.$,* OPERATON OF THE CRTC. :$}a<,t,,r~?} ~ TMNG CHART>,~~& CRT NTERFACE SGNALS TABLE 5 VALUES PROGRAMMED NTO CRTC REGSTERS Tmng char~?:$$%;~~t nterface sgnals are llustrated n ths secton,~wh~ values lsted n Table 5 are programmed nto CRT,G. x~~b regsters, the devce provdes the outputs as sho~~~~k:.~e tmng dagrams (Fgures 2, 3, 7, and 8). The~&~~.format s shown n Fgure whch llustrates the rela~~~%etween refresh memory address (MAO-MA 3), raster bddress (RAO-RA4), and the poston on the screen. n ths example, the start address s assumed to be zero. Reg. # Ro R R2 R3 R4 Regster Name H. Total H, Dsplayed H. Sync Poston H. Sync Wdth V. Total Value Nh\+ Nhd Nhsp Nhsw N t+ Programmed Value Nh~ Nhd Nhsp Nhsw Nvt R5 R6 V. Scan Lne Adjust V, Dsplayed Nadj N d Nad] Nvd R7 R8 V. Sync Poston nterlace Mode Nvsp Nvsp R9 Max. Scan Lne Address NS Nsl (M) MOTOROLA Semconductor Products nc. 6
s FGURE 7 CURSOR TMNG Q\.,\\:r $+\\:~.!?,, +t~. +,..... 0 RAO-RA4* ~ o MAO-MA3* * a o! Character Row # -.~.$. >?:, ~ =g Character # 3 -. s 3 $ Cursor o..: ;: ~ * Tmng s shown for non-nterlace ~~~~?~erlace sync modes. Example shown has cursor prq~~m,f~t as: 3 Cursor Regster = }Jhdf,~$;&:&~ 3 Cursor Start= $(. %,.$ Cursor End = 3.,$<~~tq~$ $ * *The ntal MA s det$~rt~ by the contents of start address regster, R2/R3. Tmng s shown for R2/R3=0..**,)$,,jt:~?.. s NOTE : Tmnqf~~kare desctbed n Table 5,,.$?? F,.,\ -+t:+ g.. l~,tc>.,*.:,,...:.,., ~~..~!:,,..!;/!?,
Horzontal Dsplay Character 0 { N { N 2 { N o Nhd 2xhhd Nhd Nh:- 2xNhd 3xhd Nht Nht Nhd+ Nht Nhd Nht 2Nhd+ Nht 2Nhd +Nht (N d l)xnhd (N d f)x Nhd N d XNhd NvdX Nhd N dx Nhd+ N dx Nhd N d+ ),xnhd N d+l)xnhd ~N d+)x Nhd (N t+l)xnhd dud l)xnhd+n~ N d+ Nhd+ Nht N t+ { N? N t XNhd N t+l)xnhd N t+ ).x Nhd N t+2)xnhd N t+2)xnhd (Nvt+l)XNhd (Nvt+l)xNhd (Nvt+2) (Nvt+2) XNhd X Nhd -.,. >,,,.;,.:,.,, ~~.:) S$.,, \*$-, ~E : The ntal MA s determned by the contents of start address regster, R2/R3, Tmng s shown for R2/R3=0. Only nonnterlace and nterlace sync modes are shown. Nvt XNhd+ Nht Nvt XN~d+Nht ;N +l)~hd+nh Nvt+l)Nhd+Nh.
DETERMNNG REGSTER CONTENTS The remanng regster contents must be determned from Some of the regster contents are determned rather easly. some basc data related to the CRT montor and from the They are: user-desred dsplay format. The CRTC reference sheet (see Fgure 9) gves a set of formulas for calculatng the regster Regster Name Contents contents as well as other useful characterstcs of the R8 nterlace Mode Regster See Table 3 dsplay. Ths type of data s summarzed under basc parameters n Fgures 20 and 2; most or all of ths data must RO Cursor Start See Fgure 5 and be suppled by the user before he can determne the co~~ents Table 4 for regsters RO-R7 and R9. All varables B-Bo are k~$&*to Rll Cursor End See Fgure 5,.~,~kf,...,,~,:k, basc parameters through 0. :.., ~ R2 Start Address (H) User programs frst.}:),~~::..j l ~>~,, \,lp R3 Start Address (L) memory ocatlon,,.+* 5* ~,,, $.:.~?s. ~:.+,..-..s/.. to be dsplayed,. $./: $ h R4 R5 R6 R7 Cursor (H) Cursor (L) Lght Pen (H) Lght Pen (L) lght-pen strobe only Regster Functon RO Horzontal Total Symbol R Horzontal Dsplayed Y Dot frequency (st approx. ) RO r _l Bo(B7+ Bg) R2 Horzontal Sync Poston R3 Horzontal Sync Wdth tc Character Tme R B5 R4 Vertcal Total f B7 + Bg tc R5 Vertcal Total Adjust R2 (Rl)+ ~ 2 R6 Vertcal Dsplayed [( RO)+ll*tc R3 (RO) (R) 3 R7 Vertcal Svnc Poston scan lnes B2*tsl R8 nterlace Mode R4 N R9 nteger and n =N+ R B8+B0 68+ Bo R5 R RO nteger remander Rll R6 B6 Character row tme (68+ BO)*tsl R7 [(R4)+- 6 (R5) >(R7)>(R6) B8+ Bo R3 Start Address (L) thr Horzontal retrace tme s [( RO)+l B5*(B7+Bg) f R4 Cursor (H) R9 (B8+BO)- R5 Cursor (L) t r Vertcal retrace tme s B B6(B8+ Blo)otsl = R6 R7 Lght Pen (H) Lght Pen (L) m MOTOROLA Semconductor Products nc. 9
n Fgures 20 and 2, worksheet example calculatons are Calculate n. Ths s the total umber of scan lnes shown for 32x 6 and 80x 24 dsplay formats respectvely. for each frame. Dscard any fracton. The followng tems are keyed to the fgures. Basc parathrough 8 8 0 Calculate N and R meters through have been provded; tems Calculate R4. 4 are data about the CRT montor and tems 5 2 Fll n R5. through are data about the user s desred dsplay. 83 Fll n R6, Calculate the approxmate dot frequency. The user Calculate R7, f there s no possble value for R7, should verfy that the bandwdth of hs CRT then the dsplay demands for the CRT montor ex- 3 84 5 8 6 montor wll accommodate ths frequency. Calculate RO, The resultant answer wll usually be an nteger plus a fracton. Assume the next hgh nteger. Fll n value for R, Calculate R3. Use the next hghest nteger. n these examples the sync wdth was chosen to be one thrd of the horzontal blankng nterval. Calculate R2. Agan, use the next hghest nteger. Calculate tc, character te. Ths s the tme requred for one scan lne of one character block to be wrtten. Calculate the exact dot frequency. Calculate tsl, scan lne tme. Ths s the tme re qured for one scan lne of one character row to be wrtten ncludng retrace tme. Basc Parameters (B-BO) ceed ts capablty. A compromse adjustment must be made n basc parameter 6, 8, or 0.!$,?<< 8P. ~>. Calculate R9. t,..~: $.:$.s.,.:l, Calculate tcr. Ths the tme requred $&+~&character row to be wrtten..~, x:, $:,?,~$,,>3;:,,.~,&*,, ~,. Calculate thr. lhr>b3.,,,,~3$>p t\\ \l ~ Calculate tvr. tvr>b~...+~ $.,.,. f FGURE 20 CRTC WORKSHEET EXAM& CALdULATON (32 X 6) J~:;:.,.,,,..: ::,<?, \.[., ntermedate Ca&ula&ns Symbol Value Regster.>, s:$.. \,,,,,,*. -\~<>.,, Another check s c~tw~dn of horzontal sync pulse wdth R3. tc= PW~.~ ( &pcally approxmately equals 4 m crosecon ds~~,a%,,,$ For con&~~e, a blank worksheet s provded n Fgure 22.,,;:$.~:+,. f..\);h.,/:e~.~~::.,f.x? ~: <:$\ Regster Calculatons Decmal Hex Horzontal frequency 4.27 X 06 RO 4.27x 06 38 26 5,750x(5+2) = 2 Vertcal frequency.63x0-6r B5 = 32 32 20 3 4. Mnmum Horzontal retrace tme Mnmum vertcal retrace tme 5. # of dsplayed 5+2.63x 0 6 3gxl,63xlo 6 60x63.6x0 6 4.2gx 06 63.6x 0 6 R2 R3 32+3 2 38 32 = 3 7 = R=7 33 2 2 2 6 0 7 7 6. 7 R6 B6=6 _ 6 0 7. 262 G, R7 R8 6 0 g~x0 6 R9 7+8 = 4 OE 9. Number of dots between = 2 thr (%+ 32)*(5+2) horzontal adjacents 4,2gx 06 =.42 x0 6 RO Rll 0. Number of scan lnes = 8 between vertcal adjacents tvr [~ -6(7 +8)]x63,6x 0 60 6=,43X0 3 R2 R3 6+l-~z(R7)z6 954x0-6x7 =6.28 xlo-3 7.6>(R7)~l6 + 63.6x 0 6x7=,wx0 3 = 6.~3 ms f f=60 Hz R4 R5 MOTOROLA Semconductor Products nc. 20
FGURE 2 CRTC WORKSHEET EXAMPLE CALCULATON (80X 24) Basc Parameters (B -BO) ntermedate Calculatons Regster Calculatons Value Regster Decmal Hex. Horzontal frequency 8,600 r 80S(7 + 2) XO 6 8600 60836xO6 RO 6.836 x06 00 (8,600)(9) M 2. Vertcal frequency 60 tc (OO+)*WOO 3. Mnmum Horzontal retrace tme X O-6 f 7+2 532.3 X 0 9 4. Mnmum vertcal retrace tme X O-3 tsl (00+)(532.3 X 0 9) 5. # of dsplayed characters per row 80 n (60)(53.76 x0 6) 6. # of dsplayed character rows = 24 N 7. # of dots n character dot matrx row = 7 R 8. # of scan lnes n character matrx column RO 00 00 _ 9. Number of dots between = 2 thr horzontal adjacents R OB R2 00 R3 28 80 R4 28 00 R5 80 M070ROLA Semconductor Products nc. 2
Basc Parameters FGURE 2 CRTC WORKSHEET ntermedate Calculatons Regster Calculatons Value Regster Decmal Hex...Horzontal frequency RO 2. Vertcal frequency 3. Mnmum Horzontal retrace tme 4. Mnmum vertcal retrace tme 5. # of dsplayed characters per row tc f tsl n R R2 R3 R4 R5 R6 R7 6. # of dsplayed character rows N 7. # of dots n character dot matrx row R 8. # of scan lnes n character matrx column cr 9. Number of dots between = thr horzontal adjacents 0. Number of scan lnes = vr between adjacents vertcal,..; + -. ADDTONAL,CA~&$~PPLCATONS :*2:* S*> The forepb~~stem functon whch maybe performed by the CRTQ~nt:$~ller s the refreshng of dynamc RAM. Ths,)]**yj ~...~: s qute smple as the refresh addresses contnually run. Note that the LPSTB nput may be used to support addtonal system functons other than a lght pen. A dgtal-toanalog converter (DAC) and comparator could be confgured to use the refresh addresses as a reference to a DAC composed of a resstve adder network connected to a comparator. The output of the comparator would generate the LPSTB nput sgnfyng a match between the refresh address analog level and the unknown voltage. The lght-pen strobe nput could also be used as a character strobe to allow the CRTC refresh addresses to decode a keyboard matrx. Denouncng would need to be done n software, Both the VS and HS outputs may be used as a real-tme clock. Once programmed, the CRTC wll provde a stable reference frequency. -. MOTOROLA Semconductor Products nc. 22
FGURE 23 MCW PROGRAM FOR CRTC NTALWTON PAGE 00 CRTCNT. SA:O MC6845 CRTC ntalzaton Program 0000 NAM MC6845 00002 TTL / MC6845- CRTC ntalzaton program 00003 OPT G,S,LLE=85 prnt FCB S, FDB s & XREF tabl~h, 00004 *******************************************************3*~$ >,,.,.. ~ ~.,~ \LK\\:*\ ~.$*,,/> 00005 * Assgn CRTC addresses ::\h../. ~~:~ 00006 *.,.4:\*$.s.,,)?$,>, ~:r!,. 00007 9000 A CRTCAD EQU $9000 Address Regster.~~s:a ) ~?~ ~;,$:.Y..J. 00008 900 A CRTCRG EQU CRTCAD+l Data Regster.~>,~$.3s.. 00009 *******************************************$*.#******** St}> ~, 0000 * ntalzaton program ~..,! \,..<},::l:. \ 000 * $$$;}:.,,.},$, -k:$:& 0002A 0000 ORG O a place to s~,~~~ l~$, 0003A 0000 5F CLRB clear count~~~;;+~ OO04A 000 CB 020 A LDX #CRTTAB table pon%~~~ 0005A 0004 F7 9000 A CRTC STAB CRTCAD load ad,,~~s~regster 0006A 0007 A6 00 LDAA O,X 9et YQ~~\$~rvalue from table 0007A 0009 B7 900 ; STAA CRTCRG pro,g~a~regster 0008A 000C 08 NX ~nt counters 0009A 000D 5C ~gb NCB ~,o. 00020A 000E Cl 0 $ $~$nlshed? 0002A 000 26 F2 000; CRTC (;? no: take branch 00022A 002 3F SM )::t?t.>,t ~W J* yes: +*. call montor 00023 *******************5~*%********************************** 00024 * CRTC regster ntalzaton table 00025 * 80 x 24 n~.d;~lnterlacedfomat 00026A 020 OR~:~:?:, $020 start of table 00027A 020 65 A CRTTAB,~~4 <;. $64,$50 RO, R - H total & H dsplayed A02 50 A ~,~x ~ ~,!:$?+,,$,.,.,. ~,,,,,,,,~~ 00028A 022 56 A $Q%,. $54,$07 R2, R3 - HS pos. 8 HS wdth A 023 09 A,?~g~~ 00029A 024 8 A Y;7%c$ FCB $ B,$02 R4, R5 - V total & V total adj. A 025 OA &$;,> 00030A 026 8 (A+ FCB $8,$9 R6, R7 - V dsplayed $ VS pos.,~gy$p A 027,,,~o ~,~~A 0003A 028 FCB $00,$OA R8, R9 - nterlace & Max scan lne A 029 ;~,f~, A 00032A 02~~~$, ~ A FCB A o~~~+ :;ob $00, $OB RO,R- Cursor start & end 00033A,,,$~~~a :0080 ~ FDB $0080 R2,R3- Start Address 000344: Q2E 0080 A FDB $0080 R4,R5- Cursor Address oooa~(y~ END T~~~W~RRORS.;?., ~,~?.t:, 00000--00000 x$,,. CR~Cl 0004 CRTCAD 9000 CRTCRG 900 CRTTAB 020 Motorola reserves the rght to make changes to any prducts heren to mprove relablty, functon or desgn. Motorola does not assume any ablltyarsng out of the applcaton or use of anv product or crcut descrbed heren; nether does t convev any lcense under ts patent rghts nor the rghts of others. MOTOROLA Semconductor Products nc. 23
PACKAGE DMENSONS L SUFFX CERAMC PACKAGE CASE 75-05 Q ~ a J L NOTES:. lmenson~ls DATUM. 2, POSTONAL TOLERANCE FOR LEAOS: ~. [~ 0.25 (0.00) t T] Ad 3. ~lsseatng PLANE. l-f 4 OMENSON L TO CENTER OF LEADS rl b,dhen FORMED PARALLEL. ~ 3_p\ 0 GJ. M+ f 5 OMENSONNG ANO TO LERANCNG PER ANS Y4.5, 973 *..~.s \,::* :, ~,,~..,:$!L,.,:C%*,)$!!5.,?. *..,: :+% < ~?$.,~>x,a+;~,. (.\,. S SUFFX CERDP PACKAGE CASE 7WW NOTES. POST O NAL TOLERANCE OF LEADS(D) SHALL BE WTHl N0,25mm (O OO)AT MAxMUM MATERAL CO NO TON, N RELATON TO SEATNG PLANE AND EACH OTHER 2 DMENSON LTO CENTER OF LEADS WHEN FORMEO PARALLEL. 3 OMENSONBOOESNOTNCLUOE MOLO FLASH MOTOROLA Semconductor Products nc. 350 ED BLUESTEN BLVD., AUSTN, TEXAS 7872 A SUBSDARY OF MOTOROLA NC.,,,,,-,,,.,,,, s.,-8 LM,h.,m,,, 0 c,,,,,,,,000,,9838 -,