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Introduction

This manual explains the functions and usage of VDP1. VDP1 mainly defines and draws drawing data.

■ Explanation of words

The words used in this manual are explained below.

VDP1
VDP1 is an IC that controls drawing. VRAM and Frame buffer (both DRAMs) are connected to VDP1. The drawing command is written to VRAM from CPU via VDP1. VDP1 reads the drawing command from VRAM, writes (draws) the drawing data to the frame buffer, and then transfers the drawing data from the frame buffer to the display device for display.
The frame buffer is a so-called bitmap type memory. The data written in the frame buffer and the contents of the display screen have a one-to-one correspondence. The frame buffer is a map of the display screen.
∙ There is a system register inside VDP1, and the display of the screen is controlled by setting a value in this register.

Display
Display uses a general display device TV . The standard for domestic and American TV is the NTSC system. European TV is in the PAL format.
High Resolution is a higher resolution and doubles the horizontal resolution. 31KC is a method that doubles the normal frequency 15KC to increase the vertical resolution. High-definition (HDTV) is a so-called high-definition TV that has twice the vertical and horizontal resolutions of ordinary TV.
* There are Field and Frame in the TV display. The field is the time that the scanning line scans one screen. The NTSC method is 1/60 second, and the PAL method is 1/50 second. A frame is a period during which one image is displayed. One frame is from frame buffer switching to the next switching. When the frame buffer switching mode is 1 cycle mode, one frame is one field. If the frame buffer is switched every 2 fields due to single interlace, etc., 1 frame becomes 2 fields. If you switch only once per second in manual mode, the NTSC system will have 60 fields per frame and the PAL system will have 50 fields per frame.

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