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CHAPTER 3Display Memory BusKANJI ROM PINOUTSAddressDataKANJI ROM ORGANIZATION• ="1"o ="0"one scan linenext scan lineUnused Area(ArAo : 11000to11111Figure 3.3·2 Kanji ROM Pinouts and OrganizationPID 09682A 3.3-23-41
CHAPTEH3Display Memory BusThe String InstructionThe String instruction is used to move characters fromthe font area to a (normally) visible area of the displaymemory. The String instruction specifies the beginninglocation where the text is to appear. The String instructionis followed by a variable-length list of charactercodes. Each entry in this list is processed as onecharacter.The QPDM processes list entries as follows: The entryis used as an index into the font. Since characters in thefont are ordered vertically, the index is a Y -offset from thebase of the font. The attribute word is fetched first so thatthe QPOM knows the size of the character.Then, for each scan line ofthe character, as many 16-bitpattern words as necessary are fetched and placed intothe display memory. Since we are processing 24-bitwidecharacters, two pattern words per scan line are required(the right-most eight bits are discarded).The QPOM processes all the scan lines of a character (inthis case there are 24) and moves the Current PenPosition to the beginning of the next character space.The high-order bit of the current list entry is tested todetermine if it is the last in the list. If not, the processcontinues with the next entry.3.3.3 Memory Requirements for VeryLarge FontsThis method of storing fonts in the display memorypresents a problem when the fonts become very large.Consider a 24 x 24 font containing 8192 entries. Eachscan line of each character is stored in 32 bits (eight ofwhich are unused). There are 768 bits for pattern storageplus 16 bits for the attribute word. Each characterrequires 784 bits; the complete font requires over 6 Mbits.At least in the short run (until 1 M x 4 VHAMs becomeavailable), this is sufficiently expensive that we would liketo find a better way.3.3.4 The Solution for KANJIKanjifonts are available in 300 ns HOMs. There are twosets of three HOMs each; 1st level Kanjicontains 2965characters and 2nd level Kanjicontains 3388 characters.Each ROM in the three-chip set contains an 8-bit slice ofeach scan line of each character. The ROMs are addressedin parallel; there are 12 address bits to select acharacter and 5 address bits to select a scan line. Not allofthe character codes are used, and only the first 24 scanlines are used. The arrangement of the three ROMs isshown in Figure 3.3-2. The development of the addressesis shown in Table 3.3-1These ROMs have an access time (both address andChip Select) of 300 ns, but the QPOM provides theaddress only 60 ns before the data are required. So thereis insufficient memory access time. This problem issolved by pipelining the accesses.Figures 3.3-3 and 3.3-4 show how this works. When theQPOM executes the display memory read to fetch theattribute word, this is detected in the PAL device since X"is a one and Xg through X 4 are all zeroes. This is definedas an attribute word. EN_ATTRIB_WORO" enables U6and U7 onto the OM lines during CAS. This is a "hardwired"attribute word which specifies a 24 x 24 character.The bits in the attribute word are described in Section3.3.5.Ouring this same memory cycle, the character address isclocked into U2 and U3 with ClK_CHAR at the beginningof CAS. Further, the scan line number (which alwaysbegins at zero) is clocked with ClK_SCAN_L1NE, also atthe beginning of CAS. X,o is also clocked withClK SCAN LINE. This is used to enable one or theothertriplet of ROMs based on the level selected.The ROMs begin to access the data for the first scan line,i.e., scan-line number zero, as the QPOM completesfetching the attribute word. Even assuming back-to-backcycles, the ROMs have somewhat over 300 ns before thedata are required.When the QPOM executes a memory-read cycle to fetchthe first word of the first scan line, the address will haveboth X and X 4 as ones. The PAL device U5 will makeEN_lEh_WORO" active while ICAS is active, gatingthe upper 16 bits onto the OM lines via U8 and U9. At thefalling edge of ICAS, ClK_RIGHT _ WORO will clock thelower eight bits into U,o.When the QPOM executes a memory-read cycle to fetchthe second word of the first scan line, the address willhave X and Xs ones, and X 4 will be a zero. The PALdevice ~iII then make term EN_RIGHT_WORO" activewhich will enable the lower eight bits of the font ontoOM'5-8 via U10 and zeroes onto OM 7 _ 0 via U11. Thepurpose of the zeroes is to guarantee blanks betweencharacters. At the falling edge of ICAS, Xg through XJ? areclocked into U4 with ClK_SCAN_L1NE and the ROMswill begin to access the second scan line (scan line one).Referring to Table 3.3-1, one can observe that X 4 from3-42
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Am95C60Quad Pixel Dataflow ManagerA
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Authors:Tom CrawfordStuart TindallE
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Table of ContentsCHAPTER 1 Overview
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CHAPTER 1OverviewDESIGN APPLICATION
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and the information is read in on t
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CHAPTER 1Overviewservice. As with t
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CHAPTER 2System Bus Interface2.1 Am
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CHAPTER 2System Bus InterfaceT4 1W
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CHAPTER 2System Bus InterfaceALE ~t
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CHAPTER 2System Bus InterfaceDMAQPD
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CHAPTER 2System Bus Interfacevee20
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CHAPTER 2System Bus InterfaceMATOUT
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CHAPTER 2System Bus InterfaceQPDM i
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CHAPTER 2System Bus InterfaceJ01501
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CHAPTER 2System Bus Interfacedresse
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CHAPTER 2System Bus InterfaceCUPL v
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CHAPTER 2System Bus InterfaceCUPL V
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CHAPTER 2System Bus Interface2.2 VM
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CHAPTER 2System Bus InterfaceAs ano
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CHAPTER 2System Bus InterfaceADDRBu
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CHAPTER 2System Bus Interface2.3 68
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CHAPTER 2System Bus InterfaceFCVA+3
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CHAPTER 2System Bus InterfacesEaUEN
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CHAPTER 2System Bus Interfacethat c
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CHAPTER 2System Bus InterfaceAs the
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CHAPTER 2System Bus InterfaceDecode
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CHAPTER 2System Bus InterfaceAppend
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Page 73 and 74: CHAPTER 2System Bus InterfaceData i
Page 76 and 77: CHAPTER 3Display Memory BusIn this
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Page 82 and 83: CHAPTER 3Display Memory BusFurtherm
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Page 118 and 119: CHAPTER 3Display Memory BusTable 3.
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Page 122: CHAPTER 4Video Bus4.1 VIDEO BUS4.2
Page 125 and 126: CHAPTER 4Video Bus4.2.2 High-speed
Page 127 and 128: CHAPTER 4Video BusScan Line End Con
Page 129 and 130: CHAPTER 4Video BusFIFO (VDAF). The
Page 131 and 132: CHAPTER 4Video BusParameter min typ
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Page 159 and 160: C{I~P2-01 T22 T 22 TO. 1 41-44. 48-
Page 161 and 162: (JIN0>2D2PROM_(SA16: :~~~202
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Page 165 and 166: c.nWo607, Be2 DClK2 » ============
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CHAPTER 6Articles/Application Notes
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CHAPTER 6Software10 'This programs
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CHAPTER 6Software950 RETURN960 '970
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CHAPTER 6Software6.2 COPY BLOCK OPE
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CHAPTER 6Software6.2.4 Transparency
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CHAPTER 6Softwarecpy 11 a [temp2] [
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CHAPTER 6Softwarecpy 11 a [temp2] [
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CHAPTER 6SoftwareADDTEMPblk [blksiz
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CHAPTER 6SoftWareSUBSTEMPblk [blksi
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NOTES
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NOTES
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NOTES
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ADVANCED MICRO DEVICES' NORTH AMERI
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