diff options
| -rw-r--r-- | blastem.c | 4 | ||||
| -rw-r--r-- | z80_to_x86.c | 3 |
2 files changed, 7 insertions, 0 deletions
@@ -473,6 +473,8 @@ m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value { genesis_context * gen = context->system; if (location < 0x10000) { + //Access to Z80 memory incurs a one 68K cycle wait state + context->current_cycle += MCLKS_PER_68K; if (!z80_enabled || z80_get_busack(gen->z80, context->current_cycle)) { location &= 0x7FFF; if (location < 0x4000) { @@ -591,6 +593,8 @@ uint8_t io_read(uint32_t location, m68k_context * context) uint8_t value; genesis_context *gen = context->system; if (location < 0x10000) { + //Access to Z80 memory incurs a one 68K cycle wait state + context->current_cycle += MCLKS_PER_68K; if (!z80_enabled || z80_get_busack(gen->z80, context->current_cycle)) { location &= 0x7FFF; if (location < 0x4000) { diff --git a/z80_to_x86.c b/z80_to_x86.c index 215a7cb..54f4c6e 100644 --- a/z80_to_x86.c +++ b/z80_to_x86.c @@ -2630,6 +2630,9 @@ void z80_clear_busreq(z80_context * context, uint32_t cycle) z80_run(context, cycle); context->busreq = 0; context->busack = 0; + //there appears to be at least a 1 Z80 cycle delay between busreq + //being released and resumption of execution + context->current_cycle += context->options->gen.clock_divider; } uint8_t z80_get_busack(z80_context * context, uint32_t cycle) |