Sharp MZ-3500 service manual #07FFA, Structure of character Vram When read/write from GDC, #0000

2) Read/write from Z 80 to VRAM

(1)Timing period for display and V-RAM Read/write.

M 7 3500

//><-' Range wh°r? GDC can draw.

H • SYNC-

BLNK-

(2)Timing that the Z-80 can read/write VRAM The Z-80 can read/write VRAM when buffer is either empty or Full, and can be

3)Structure of character VRAM

(1)When read/write from GDC

#07FF(A)

2KX8

ASC I I

J

GDC FIFO accessed by

Fly back period

refreshing during the display period. Number of characters that can be read/write within one raster in any mode.

(A)(B)

ASCI I ( 8 b i t )

#0000

8bi t		4 b i t		( 12bit )
DO	"D7	V&	« - Dll	D2 D3 D4 D5 1)6 D7DO Dl D2 D3
			DO Dl

• Blink

Reverse (G)

Vertical line (R)

. Horizontal line (B)

(2)During display #07FF

(A)( B )

2KX8 2KX4

#0000

12bi t