<24/86> VDP2 User's Manual / 4.6 Pattern Name Table (Page) -1

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■ 4.6 Pattern name table (page)

The pattern name table (or page) stores the pattern name data in a table shape in VRAM, showing how to arrange the character patterns in a square with a size of 64 cells horizontally and 64 cells vertically. The pattern name data specifies the start address of the character pattern stored in VRAM and other control information for each character pattern.
The pattern name data on the pattern name table is 1 word or 2 words. In the case of 1 word, the auxiliary data of the lower 10 bits of the pattern name control register is added to make up for the missing bits.

● Data structure of pattern name table

The VRAM capacity required for the pattern name table of 64 cells horizontally x 64 cells vertically (1 page) and the boundary stored in VRAM vary depending on the pattern name data size (number of words) and character size. The capacity of the pattern name table and the data structure of the table are shown in Table 4.4 and "Details".

Table 4.4 Pattern name table capacity and page boundary for one page

Pattern name data size	Character size	Capacity per page	Powder when storing VRAM	detail
1 word	1 horizontal cell x 1 vertical cell	8192 bytes	2000H	→
1 word	2 horizontal cells x 2 vertical cells	2048 bytes	800H	→
2 words	1 horizontal cell x 1 vertical cell	16384 bytes	4000H	→
2 words	2 horizontal cells x 2 vertical cells	4096 bytes	1000H	→

Reference: Click the details column of "Table 4.8" for the data structure of the pattern name table.

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★ HARDWARE Manual VDP2 User's Manual ★ Chapter 4 Scroll screen