This section describes the relationship between the T6963C display memory (VRAM) and the display position on the LCD screen. Text Home address (TH); Text Area number (TA); Graphic Home address (GH) and Graphic Area number (GA) are also described in this section. TH, TA, GH and GA are set by the Control Word Set command described in sections 8.2.1 - 8.2.4. TH defines the starting address for Text data in the VRAM, GH defines the starting address for Graphic data in the VRAM for graphics modes and the starting address for Text Attribute data in Attribute mode ( Refer to section 11.3). TA defines the number of columns of text on a LCD screen and GA sets the number of display bytes per line on a LCD screen.
The relationship between display memory addresses and display position on a single drive LCD screen is shown below for both Text and Graphic Areas.
| TH | TH+1 | -------- | TH+CL-1 | TH+CL | |
| TH+TA | TH+TA+1 | : | TH+TA+CL-1 | TH+TA+CL | ½ |
| : | : | : | : | : | m lines |
| : | : | : | : | : | of text |
| TH+(m-2)TA | TH+(m-2)TA+1 | -------- | TH+(m-1)TA+CL-1 | TH+(m1)TA+CL | ½ |
| TH+(m-1)TA | TH+(m-1)TA+1 | -------- | TH+mTA+CL-1 | TH+mTA+CL | ¯ |
<----X characters per line---->
| GH | GH+1 | --------- | GH+CL-1 | GH+CL | |
| GH+GA | GH+GA+1 | : | GH+GA+CL-1 | GH+GA+CL | ½ |
| : | : | : | : | : | n rows |
| : | : | : | : | : | of dots |
| GH+(n-2)GA | GH+(n-2)GA+1 | --------- | GH+(n-1)GA+CL-1 | GH+(n-1)GA+CL | ½ |
| GH+(n-1)GA | GH+(n-1)GA+1 | --------- | GH+nGA+CL-1 | GH+nGA+CL | ¯ |
<----Y dots per line---->
Where:
| Display | Font | Text Display | Graphics Display | CL+1 | ||||
|---|---|---|---|---|---|---|---|---|
| Format | Size | X | m | TA | Y | n | GA | typ. |
| 64x120 | 6x8 | 20 | 8 | 14H | 120 | 64 | 14H | 14H |
| 1/64 duty | 8x8 | 15 | 8 | 0FH | 120 | 64 | 0FH | 0FH |
| 128x128 | 6x8 | 21 | 16 | 16H | 128 | 128 | 16H | 16H |
| 1/128 duty | 8x8 | 16 | 16 | 10H | 128 | 128 | 10H | 10H |
| 64x240 | 6x8 | 40 | 8 | 28H | 240 | 64 | 28H | 28H |
| 1/64 duty | 8x8 | 30 | 8 | 1EH | 240 | 64 | 1EH | 1EH |
| 128x240 | 6x8 | 40 | 16 | 28H | 240 | 128 | 28H | 28H |
| 1/128 duty | 8x8 | 30 | 16 | 1EH | 240 | 128 | 1EH | 1EH |
Note: In the case of the Graphics Area with 6x8 font size selected, the most significant
bits D6 and D7 of graphics data are ignored, and not displayed on the LCD screen.
| 0000H | |
| Graphic Ram Area (0000H-13FFH: 5120 bytes) | |
| 13FFH | |
| 1400H | |
| Attribute RAM Area | |
| 16FFH | |
| 1700H | |
| Text RAM Area (1700H-1BFF: 1280 bytes) | |
| 1BFFH | |
| 1C00H | |
| CG-RAM Area (1C00H-1FFFH: 1024 bytes) | |
| 1FFFH |
Note: This example shows RAM map for "CG-ROM" mode (section 8.3 & 11). If "CG-RAM" mode is required allocat 2048 bytes for CG-RAM area
The Display RAM (VRAM) is usually built onto the LCD module along with T6963C and LCD driver LSI chips. The T6963C automatically reads data from the VRAM, processes it and sendsit out to the LCD LSI driver chips. The Control Word Set commands (section 8.2) are used to set the Text Home, Graphic Home and Text/Graphics Areas. The VRAM map made be changed to suit the users preference. The above RAM map is just an example. If more than one screen can be stored in the RAM, vertical scrolling and paging can be performed, by resetting the Text Home and Graphic Home addresses. Usually LCD modules with on-board T6963C controllers have 4K or 8K byes of RAM, check individual LCD module specifications for RAM size information.
The relationship between display memory addresses and display position on a dual drive LCD screen is shown below for both Text and Graphic Areas.
| TH | TH+1 | ----- | TH+CL-1 | TH+CL | |
| TH+TA | TH+TA+1 | : | TH+TA+CL-1 | TH+TA+CL | |
| : | : | : | : | : | m lines |
| : | : | : | : | : | of text |
| TH+(m-1)TA | TH+(m-1)TA+1 | ------ | TH+mTA+CL-1 | TH+mTA+CL | |
| TH+8000H | TH+8000H+1 | ----- | TH+8000H+TA+CL-1 | TH+8000H+TA+CL | |
| : | : | : | : | : | |
| : | : | : | : | : | m lines |
| TH+8000H+(m-2)TA | TH+8000H+(m-2)TA+1 | ----- | TH+8000H+(m-1)TA+CL-1 | TH+8000H+(m-1)TA+CL | of text |
| TH+8000H+(m-1)TA | TH+8000H+(m-1)TA+1 | ----- | TH+8000H+mTA+CL-1 | TH+8000H+mTA+CL |
| GH | GH+1 | ---- | GH+CL-1 | GH+CL | |
| GH+GA | GH+GA+1 | : | GH+GA+CL-1 | GH+GA+CL | |
| : | : | : | : | : | n rows |
| : | : | : | : | of dots | |
| GH+(m-1)GA | GH+(m-1)GA+1 | ---- | GH+mGA+CL-1 | GH+mGA+CL | |
| GH+8000H | GH+8000H+1 | ------- | GH+8000H+GA+CL-1 | GH+8000H+GA+CL | |
| : | : | : | : | : | |
| : | : | : | : | : | n rows |
| GH+8000H+(m-2)GA | GH+8000H+(m-2)GA+1 | ---- | GH+8000H+(m-1)GA+CL-1 | GH+8000H+(m-1)GA+CL | of dots |
| GH+8000H+(m-1)GA | GH+8000H+(m-1)GA+1 | ---- | GH+8000H+mGA+CL-1 | GH+8000H+mGA+CL |
Where:
| Display | Font | Text Display | Graphics Display | CL+1 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Format | Size | X | m | TA | Y | n | GA | typ. | ||
| 64x120 | 6x8 | 20 | 4 | 14H | 120 | 32 | 14H | 14H | ||
| 1/32 duty | 8x8 | 15 | 4 | 0FH | 120 | 32 | 0FH | 0FH | ||
| 128x160 | 6x8 | 21 | 8 | 16H | 128 | 64 | 16H | 16H | ||
| 1/64 duty | 8x8 | 16 | 8 | 10H | 128 | 64 | 10H | 10H | ||
| 64x240 | 6x8 | 40 | 4 | 28H | 240 | 32 | 28H | 28H | ||
| 1/32 duty | 8x8 | 30 | 4 | 1EH | 240 | 32 | 1EH | 1EH | ||
| 128x256 | 6x8 | 40 | 8 | 2BH | 256 | 64 | 2BH | 2BH | ||
| 1/64 duty | 8x8 | 30 | 8 | 20H | 256 | 64 | 20H | 20H | ||
Note: In the case of the Graphics Area with 6x8 font size selected, the most significant
bits D6 and D7 of graphics data are ignored, and not displayed on the LCD screen.
| 0000H | Upper half scrren |
| Graphic Ram Area (0000H-07FFH: 2048 bytes) | |
| 07FFH | |
| 0800H | |
| Attribute RAM Area (0800H-09FFH: 512 bytes | |
| 09FFH | |
| 0A00H | |
| Text RAM Area (0A00H-0BFF: 512 bytes) | |
| 0BFFH | |
| 0C00H | |
| CG-RAM Area (0C00HH-0FFFH: 1024 bytes) | |
| 0FFFH |
| 8000H | Lower half screen |
| Graphic Ram Area (8000H-87FFH: 2048 bytes) | |
| 87FFH | |
| 8800H | |
| Attribute RAM Area (8800H-89FFH: 512 bytes | |
| 8BFFH | |
| 8A00H | |
| Text RAM Area (8A00H-8BFF: 512 bytes) | |
| 8BFFH | |
| 8C00H | |
| CG-RAM Area (8C00H-8FFFH: 1024 bytes) | |
| 8FFFH |
Note: This example shows RAM map for "CG-ROM" mode (section 8.3 & 11). If
"CG-RAM" mode is required allocat 2048 bytes for CG-RAM area
The above is just an example of a suitable RAM map for a dual drive LCD screen. The Control Word Set commands (section 8.2) are used to set the Text Home, Graphic Home and Text/Graphics Areas. The VRAM map made be changed to suit the users preferences.
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