diff options
author | Vas Crabb <vas@vastheman.com> | 2019-05-26 15:43:33 +1000 |
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committer | Vas Crabb <vas@vastheman.com> | 2019-05-26 15:43:33 +1000 |
commit | 987365c5c5573ddfa70ce043d0502ff25602e9df (patch) | |
tree | 21a52a7982d4165d10a27e72bf2cc4a9ecd81ae6 | |
parent | 626b566feeea0863644a45232b92568417542af9 (diff) |
starrider: few more notes (nw)
-rw-r--r-- | src/mame/drivers/starrider.cpp | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/mame/drivers/starrider.cpp b/src/mame/drivers/starrider.cpp index 261371963c5..a76e7c57e29 100644 --- a/src/mame/drivers/starrider.cpp +++ b/src/mame/drivers/starrider.cpp @@ -138,6 +138,9 @@ Q ______------------____________------------____________------------______ LATCH ______________--------________________--------________________--------__ __----__----__----__----__----__----__----__----__----__----__----__---- + /SRL --------____--------------------____--------------------____------------ + 4MHz ___---___---___---___---___---___---___---___---___---___---___---___--- + 2MHz ______------______------______------______------______------______------ Video RAM consists of 6 4416 16k*4 DRAMs at U25, U26, U41, U42, U55 and U56. The CPU and DMA chips have their addressing mangled by the 6349 @@ -170,10 +173,13 @@ U14.6 (active low) 1111x xxxx xxxxxxxx xxxxxxxx + U15.13 (active high) xxxxx xx11 xxxxxxxx xxxxxxxx (W) + U18.8 (active low) xxxxx xx10 xxxxxxxx xxxxxxxx (CPU access) U46.3 /1E 11110 xxxx xxxxxxxx xxxxxxxx U46.8 /1F 11111 xxxx xxxxxxxx xxxxxxxx + U46.11 (active low) 11110 xx01 xxxxxxxx xxxxxxxx U33.8 (active low) 11001011 xxxxxxxx 0xcb00-0xcbff @@ -613,6 +619,8 @@ u16 sr_state::vgg_drams_map(u16 a) const void sr_state::vgg_drams_w(offs_t offset, u8 data) { + if (((m_main_page & 0x03) == 0x03) || (((m_main_page & 0x03) == 0x01) && ((m_vgg_image_page & 0x1f) == 0x1e))) + offset ^= 0x8000; u16 const addr(vgg_drams_map(offset)); if ((offset & 0xc000) != 0xc000) m_vgg_drams[addr] = data; @@ -621,7 +629,7 @@ void sr_state::vgg_drams_w(offs_t offset, u8 data) void sr_state::vgg_impg_w(u8 data) { // 6 bits latched by U13 (74LS173) but only 5 bits used - m_vgg_image_page = data & 0x1f; + m_vgg_image_page = data & 0x3f; } void sr_state::vgg_xlate_w(u8 data) @@ -640,7 +648,7 @@ void sr_state::vgg_disable_w(u8 data) void sr_state::vgg_color_palet_w(u8 data) { // all 8 bits latched by U94 (74LS374) but only 6 bits used - m_vgg_color_palet = data & 0x3f; + m_vgg_color_palet = data; } |