★ HARDWARE Manual ★ VDP1 User's Manual
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VDP1 User's Manual / Chapter 4 System Registers
■ 4.9 Mode status register
- The mode status register (MODR, Mode register) represents the setting value of the write-only register. It is a read-only 16-bit register located at address 100016H.
MODR
100016H
(R) | bit15 | bit14 | bit13 | bit12 | bit11 | bit10 | bit9 | bit8 | bit7 | bit6 | bit5 | bit4 | bit3 | bit2 | bit1 | bit0 |
|---|
| VER | --- | --- | --- | PTM1 | EOS | DIS | DIL | FCM | VBE | TVM |
- Since the registers at addresses 100000H to 10000CH are write-only, the set values cannot be checked by reading them. You can check the setting value of the write-only register in this register. It can be used mainly as help information during program development. However, this value is the system register setting value itself, and may differ from the value captured as an internal signal depending on the timing of frame switching, etc.
- Version number: version number (VER), bits 15-12
- Indicates the version number of VDP1. The value is 1 (0001B).
- Plot trigger mode upper: PTM1, bit 8
- Bit 1 setting value of PTMR (plot trigger register: 100004H).
- Even / odd coordinate selection bits: EOS, bit 7
- Bit 4 setting value of FBCR (frame buffer switching mode register: 100002H).
- Dense interlaced enable bit: DIE, bit 6
- Bit 3 setting value of FBCR (frame buffer switching mode register: 100002H).
- Dense interlaced drawing line: DIL, bit 5
- Bit 2 setting value of FBCR (frame buffer switching mode register: 100002H).
- Framebuffer switching mode bits: FCM, bit 4
- Bit 1 setting value of FBCR (frame buffer switching mode register: 100002H).
- V Blank Erase Light Allow Bits: VBE, Bit 3
- This is the bit 3 setting value of TVHR (TV mode selection register: 100000H).
- TV mode selection bits: TVM, bits 2-0
- This is the setting value of bits 2 to 0 of TVHR (TV mode selection register: 100000H).
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★ HARDWARE Manual ★ VDP1 User's Manual
Copyright SEGA ENTERPRISES, LTD., 1997