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with the assistance of the technical literature listed below. Inter Press Tokyo, Japan 1990 Kyoritsu Publishing Co., LTD. Tokyo, Japan 1978 McGraw-Hill, Inc. New York, New York |
· Minor corrections · Total 155 pages · Added even/odd coordinate selection bit (EOS) to the command table. · Explained functions for version 0 of the VDP1 device. · The following functions added to version 1 are not >The frame buffer change mode register (FBCR) does not have an even/odd coordinate selection bit (EOS) function. >The draw (paint) mode word (+04H) in the command table does not high speed shrink (HSS) and pre-clip- ping disable (Pclp) functions. |
High Speed Shrink (HSS) .................................................................... 1 Pre-Clipping Disable (Pclp) ................................................................. 1 High Speed Shrink (HSS) .................................................................... 2 Pre-Clipping Disable (Pclp) ................................................................. 3 Even/Odd Coordinate Selection Bit (EOS) .......................................... 5 High Speed Shrink (HSS) .................................................................... 5 Pre-Clipping Disable (Pclp) ................................................................. 5 |
explains the functions of version 0 while noting the differences between the func- tions of version 1 and the functions of version 0 of the VDP1 device. Refer to VDP1 User's Manual, 1st edition, regarding version 1. priate manual regarding VDP1 devices other than version 0. version number. register (MODR, 100016H), thus the version number of the VDP1 device is indicated by four bits. Bits 15 to 12 indicate the version number when the mode register is read out. When the value is 0 (0000B), the version number of the VDP1 device is 0. |
plained below. These functions are not included in the version 0 VDP1 device. Refer to the VDP1 User's Manual, 1st edition (version 1). frame buffer change mode register (FBCR, 100002H). However, in version 0, this bit does not have that function. set bit 4 to "0". Version 0 does not have the bit for high speed shrink (HSS) in the draw (paint) mode word (CMDPMOD) or that function. word (CMDPMOD, +04H). However, version 0 does not have this function at this bit. the draw (paint) mode word (CMDPMOD) in the command table to "0". word (CMDPMOD, +04H). However, version 0 does not have this function at this bit. mode word (CMDPMOD) in the command table to "0". |
plained below. These functions are not included in version 0 VDP1 devices. The newly added functions are as follows. For more information, refer to each item. change mode register (FBCR, 100002H). (painting) a scaled sprite or a distorted sprite. When HSS = 1 is specified, lines with respect to which the drawing is scaled down are drawn by sampling only pixels at even or odd coordinates in the original picture data. The sampling of pixels at even or odd coordinates is specified by this bit. odd coordinates are sampled. +04H). to select whether precedence is given to speed or to accuracy. This is valid only for the drawing (painting) commands of scaled sprites and distorted sprites. Leave it fixed at "0" for all other drawing commands. down are drawn by sampling only the even or odd pixels of the original picture data. The selection of even coordinates or odd coordinates is done with the even/ odd coordinate selection bit (EOS) of the frame buffer change mode register (FBCR). odd coordinates at any magnification ratio. Use "0" to give precedence to accuracy over speed, and use "1" to give precedence to speed. |
(CMDPMOD, 04H). This bit specifies whether pre-clipping is performed or dis- abled. When "0" is specified, pre-clipping is performed. When "1" is specified, pre- clipping is not performed. spective lines comprise a number of dots. Each dot is drawn (painted) based on clipping area (drawing [painting] area) information specified by the CPU. line drawing (painting) is not required--can be detected in advance, and drawing (painting) efficiency can be increased by not allowing the drawing (painting) to be started. Also, when one end of 1 line is outside the drawing (painting) area, effi- ciency can be improved by starting drawing (painting) from inside the drawing (painting) area (that line is limited to vertical and horizontal directions). points are in the (A)--(B) or (D)--(C) direction, the overhead required for that detec- tion (up to five CPU clock cycles for one line) becomes conspicuous and can lower the drawing (painting) efficiency. is more efficient to perform pre-clipping. This bit is only valid for drawing (paint- ing) commands. Fix it to "0" for other commands. |
is possible to specify high speed shrink in order to give precedence to speed. scaled sprites and distorted sprites are scaled down and drawn (painted), a method other than one that scales down and draws (paints) scaled sprites and distorted sprites is required. reduced scaled sprites or distorted sprites and draws (paints) them without reduc- tion must be used. If the drawing (painting) speed is slow in version 0, confirm whether or not a scaled sprite or distorted sprite is being scaled down and drawn. raised by specifying pre-clipping disable. vertical lines, it is necessary to employ a method that reduces the overhead required to detect whether drawing (painting) with pre-clipping is necessary. drawing (painting) them or exchanging left and right for up and down and increas- ing the size when drawing (painting) them. If the drawing (painting) speed is slow in version 0, confirm whether or not many small elements are being drawn (painted). |
the following changes. The manual can be used for version 0 by deleting the explanations of these func- tions. 100016H) is "0" (0000B). frame buffer change mode register (FBCR, 100002H) is deleted. Bit 4 of FBCR is set to "0". Information regarding the even/odd coordinate selection bit (EOS, bit 7) of the mode register (MODR, 100016H) is also deleted. Bit 7 of MODR becomes unde- fined. word (CMDPMOD, +04) is deleted. Bit 12 of CMDPMOD is set to "0" for scaled sprites and distorted sprites. Information regarding HSS = 1 in the explanation of end code disable is deleted. The information regarding HSS = 0 remains valid. word (CMDPMOD, +04) is deleted. Bit 11 of FBCR is set to "0" in the draw (paint) command table. |
V0 in the table refers to version 0 of the VDP1 device. This bit is not defined in version 0. register Set bit 4 to "0". This bit is not defined in V0. Set bit to "0". This bit is not defined in V0. This bit is not defined in V0. (CMDPMOD, +04H). Set both bits 11 and 12 to "0". These bits are not defined in V0. Set both bits 12 and 11 to "0". These bits are not defined in V0. 82 -- (HSS). Set bit 12 to "0". This bit is not defined in V0. Set bit 11 to "0". This bit is not defined in V0. HSS is not defined in V0. Set HSS to "0". |
command Delete Pclp definition. Set bit 11 of CMDPMOD to "0". 121 command (Specification of two coordinate points) Delete definition of HSS and Pclp. Set bits 12 and 11 of CMDPMOD to "0". command (Specification of zoom point) command Set bit 11 of CMDPMOD to "0". Set bit 4 of MODR to "0". Set both bits 12 and 11 to "0". Set bit 12 of CMDPMOD to "0". HSS is not defined in V0. Set HSS to "0". command Set bit 11 of CMDPMOD to "0". command right 33 right 42 Delete "high speed shrink." Delete "pre-clipping". |