summaryrefslogtreecommitdiffstatshomepage
diff options
context:
space:
mode:
author cam900 <dbtlrchl@naver.com>2021-02-20 14:35:50 +0900
committer GitHub <noreply@github.com>2021-02-20 06:35:50 +0100
commit6dfcaef06fdfe47e74ca14ba8cbd044a2523aaeb (patch)
treed81848d1eda5e017c6e484d8abdbd2101da0a72c
parentd913d6ed606ee002e82e2e46f4e6c541efbc6652 (diff)
315_5313.cpp: Fix/Add hardware related notes (#7567)
-rw-r--r--src/devices/video/315_5313.cpp15
1 files changed, 12 insertions, 3 deletions
diff --git a/src/devices/video/315_5313.cpp b/src/devices/video/315_5313.cpp
index 69f86f67ccc..d1cc757f7ba 100644
--- a/src/devices/video/315_5313.cpp
+++ b/src/devices/video/315_5313.cpp
@@ -1,6 +1,15 @@
// license:BSD-3-Clause
// copyright-holders:David Haywood
-/* Sega 315-5313 - Megadrive VDP */
+/*
+ Sega 315-5313 VDP emulation, used by Mega Drive/Genesis
+
+ TODO:
+ - Video, DMA timing and HV counter is seems to incorrect,
+ Needs verifications from real hardware.
+ - Support 128KB VRAM configuration, Any hardware used it?
+ - Border area is displayable?
+ - 32X overlay with H32 mode, all known software used this?
+*/
#include "emu.h"
#include "video/315_5313.h"
@@ -159,7 +168,7 @@ static const unsigned hres_mul[4] = { 5, 5, 4, 4 };
inline u8 sega315_5313_device::get_hres() { return (MEGADRIVE_REG0C_RS0 | (MEGADRIVE_REG0C_RS1 << 1)) & 3; }
int sega315_5313_device::screen_hpos() { return screen().hpos() / (m_lcm_scaling ? hres_mul[get_hres()] : 1); }
-#define MAX_HPOSITION 480
+#define MAX_HPOSITION 480 // TODO: 342(H32) or 427.5(H40), each scanline used 3420 cycle
DEFINE_DEVICE_TYPE(SEGA315_5313, sega315_5313_device, "sega315_5313", "Sega 315-5313 Megadrive VDP")
@@ -2321,7 +2330,7 @@ void sega315_5313_device::vdp_handle_eof()
if (MEGADRIVE_REG01_240_LINE)
{
- /* this is invalid in PAL! */
+ /* this is invalid in NTSC! */
m_total_scanlines = m_base_total_scanlines;
m_visible_scanlines = 240;
m_irq6_scanline = 240;