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(MESS) a7800.c:

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- Brought initial Maria cycle counts inline from measurements taken with logic analyzer/tests. [Mike Saarna/Robert Tuccitto]
 - Added interrupts to DMA cycle eating. Updates to LL, OL, and spin accounting for HALT behavior. [Mike Saarna]
This commit is contained in:
Scott Stone 2014-05-06 21:40:45 +00:00
parent b913a7501c
commit db260f64bb
3 changed files with 26 additions and 10 deletions
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2
src/mame/drivers/taotaido.c
View File

@ -470,6 +470,6 @@ ROM_START( taotaido3 )
ROM_LOAD( "u15.bin", 0x000000, 0x200000, CRC(e95823e9) SHA1(362583944ad4fdde4f9e29928cf34376c7ad931f) )
ROM_END
GAME( 1993, taotaido, 0, taotaido, taotaido, driver_device, 0, ROT0, "Video System Co.", "Tao Taido (2 button verison)", GAME_NO_COCKTAIL )
GAME( 1993, taotaido, 0, taotaido, taotaido, driver_device, 0, ROT0, "Video System Co.", "Tao Taido (2 button version)", GAME_NO_COCKTAIL )
GAME( 1993, taotaidoa,taotaido, taotaido, taotaido6,driver_device, 0, ROT0, "Video System Co.", "Tao Taido (6 button version)", GAME_NO_COCKTAIL ) // maybe a prototype? has various debug features
GAME( 1993, taotaido3,taotaido, taotaido, taotaido3,driver_device, 0, ROT0, "Video System Co.", "Tao Taido (2/3 button version)", GAME_NO_COCKTAIL )

7
src/mess/drivers/a7800.c
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@ -82,6 +82,9 @@
regarding the potentiometer.
2014/03/25 Mike Saarna Fixed Riot Timer
2014/05/06 Mike Saarna/Robert Tuccitto Brought initial Maria cycle counts
+ inline from measurements taken with logic analyzer and tests.
***************************************************************************/
#include "emu.h"
@ -1139,7 +1142,7 @@ static MACHINE_CONFIG_START( a7800_ntsc, a7800_state )
/* video hardware */
MCFG_SCREEN_ADD("screen", RASTER)
MCFG_SCREEN_RAW_PARAMS( 7159090, 456, 0, 320, 263, 27, 27 + 192 + 32 )
MCFG_SCREEN_RAW_PARAMS( 7159090, 454, 0, 320, 263, 27, 27 + 192 + 32 )
MCFG_SCREEN_UPDATE_DRIVER(a7800_state, screen_update_a7800)
MCFG_SCREEN_PALETTE("palette")
@ -1181,7 +1184,7 @@ static MACHINE_CONFIG_DERIVED( a7800_pal, a7800_ntsc )
// MCFG_TIMER_ADD_SCANLINE("scantimer", a7800_interrupt, "screen", 0, 1)
MCFG_SCREEN_MODIFY( "screen" )
MCFG_SCREEN_RAW_PARAMS( 7093788, 456, 0, 320, 313, 35, 35 + 228 + 32 )
MCFG_SCREEN_RAW_PARAMS( 7093788, 454, 0, 320, 313, 35, 35 + 228 + 32 )
MCFG_PALETTE_MODIFY("palette")
MCFG_PALETTE_INIT_OWNER(a7800_state, a7800p )

27
src/mess/video/a7800.c
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@ -4,6 +4,9 @@
Routines to control the Atari 7800 video hardware
2014-05-06 Mike Saarna Added interrupts to DMA cycle eating. Updates to
LL, OL, and spin accounting for HALT behavior.
2014-03-24 Mike Saarna Fixed DMA regarding startup, shutdown and
cycle stealing.
@ -126,10 +129,17 @@ void a7800_state::maria_draw_scanline()
int x, d, c, i, pixel_cell, cells;
int maria_cycles;
if ( m_maria_offset == 0 )
maria_cycles = 5+21; // DMA startup + last line shutdown
else
maria_cycles = 5+16; // DMA startup + other line shutdown
if ( m_maria_offset == 0 )
{
if(READ_MEM(m_maria_dll+3) & 0x80)
maria_cycles=40; // DMA + maria interrupt overhead
else
maria_cycles=19; // DMA
}
else
{
maria_cycles = 16; // DMA
}
cells = 0;
@ -202,9 +212,12 @@ void a7800_state::maria_draw_scanline()
}
}
}
// spin the CPU for Maria DMA, if it's not already spinning for WSYNC
if ( ! m_maria_wsync )
m_maincpu->spin_until_time(m_maincpu->cycles_to_attotime(maria_cycles/4)); // Maria clock rate is 4 times that of the CPU
// Spin the CPU for Maria DMA, if it's not already spinning for WSYNC.
// MARIA generates the 6502 clock by dividing its own clock by 4. It needs to HALT and unHALT
// the 6502 on ths same clock phase, so MARIA will wait until its clock divides evenly by 4.
// To spin until an even divisor, we just round-up any would-be truncations by adding 3.
if ( ! m_maria_wsync )
m_maincpu->spin_until_time(m_maincpu->cycles_to_attotime((maria_cycles+3)/4));
// draw line buffer to screen
m_active_buffer = !m_active_buffer; // switch buffers