Sprinter/mame
2
0
Fork 0
mirror of https://github.com/holub/mame synced 2025-04-20 23:42:22 +03:00
Code Issues Actions 7 Packages Projects Releases Wiki Activity

sega/segaai.cpp: Improve upd7759 banking. (#11991)

Browse Source
This commit is contained in:
wilbertpol 2024-01-31 23:53:48 +00:00 committed by GitHub
parent 90d840b635
commit 0afa2b7765
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
1 changed files with 17 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
src/mame/sega/segaai.cpp
View File

@ -216,6 +216,7 @@ private:
u8 m_i8255_portb;
u8 m_upd7759_ctrl;
u8 m_upd7759_bank_ff;
u8 m_port_1c;
u8 m_port_1d;
u8 m_port_1e;
@ -544,13 +545,25 @@ void segaai_state::upd7759_ctrl_w(u8 data)
{
LOG("I/O Port $0b write: $%02x\n", data);
u8 prev_upd7759_ctrl = m_upd7759_ctrl;
m_upd7759_ctrl = data;
// bit0 is connected to /md line of the uPD7759
m_upd7759->md_w((m_upd7759_ctrl & UPD7759_MODE) ? 0 : 1);
// bit1 selects which ROM should be used?
m_upd7759->set_rom_bank((m_upd7759_ctrl & UPD7759_BANK) >> 1);
if (BIT(prev_upd7759_ctrl, 0))
{
if (!BIT(m_upd7759_ctrl, 0))
{
m_upd7759_bank_ff = 0;
m_upd7759->set_rom_bank(m_upd7759_bank_ff);
}
}
else
{
m_upd7759_bank_ff ^= 0x01;
m_upd7759->set_rom_bank(m_upd7759_bank_ff);
}
}
@ -632,6 +645,7 @@ void segaai_state::machine_start()
{
m_i8255_portb = 0x7f;
m_upd7759_ctrl = 0;
m_upd7759_bank_ff = 0;
m_port_1c = 0;
m_port_1d = 0;
m_port_1e = 0;
@ -645,6 +659,7 @@ void segaai_state::machine_start()
save_item(NAME(m_i8255_portb));
save_item(NAME(m_upd7759_ctrl));
save_item(NAME(m_upd7759_bank_ff));
save_item(NAME(m_port_1c));
save_item(NAME(m_port_1d));
save_item(NAME(m_port_1e));