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Fix Wizardry 1 boot failure (#35) #55

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Merged
bubio merged 1 commit into from
Mar 14, 2026
Merged

Fix Wizardry 1 boot failure (#35) #55

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26 changes: 18 additions & 8 deletions Source/ePC-8801MA/vm/event.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,12 @@
#ifdef SDL
#define SINGLE_EXEC_TIMEOUT 10000
// exit single exec mode (us)
#define SINGLE_EXEC_TIMEOUT_8MHZ 20000
// 8MHz mode needs wider window for stable FDC timing
#define SINGLE_EXEC_SLICE 4
// max clocks per single-exec step
#define SINGLE_EXEC_SLICE_8MHZ 20
// 8MHz mode needs larger slice for CPU to keep up
#endif // SDL

void EVENT::initialize()
Expand Down Expand Up @@ -145,8 +151,9 @@ void EVENT::drive()
{
#ifdef SDL
if (single_exec == true) {
// if passed 10ms, disable single_exec
if (passed_usec(single_exec_clock) > SINGLE_EXEC_TIMEOUT) {
// if passed timeout, disable single_exec
int timeout = (config.cpu_type == 0) ? SINGLE_EXEC_TIMEOUT_8MHZ : SINGLE_EXEC_TIMEOUT;
if (passed_usec(single_exec_clock) > timeout) {
single_exec = false;
}
}
Expand Down Expand Up @@ -244,8 +251,9 @@ void EVENT::drive()
if (main_cpu_exec > 0) {
// single execution ?
if (single_exec == true) {
if (main_cpu_exec > 4) {
main_cpu_exec = 4;
int slice = (config.cpu_type == 0) ? SINGLE_EXEC_SLICE_8MHZ : SINGLE_EXEC_SLICE;
if (main_cpu_exec > slice) {
main_cpu_exec = slice;
}
}
cpu_done = d_cpu[0].device->run(main_cpu_exec);
Expand All @@ -263,8 +271,9 @@ void EVENT::drive()
if (cpu_remain > 0) {
sub_cpu_exec = cpu_remain;
if (single_exec == true) {
if (sub_cpu_exec > 4) {
sub_cpu_exec = 4;
int slice = (config.cpu_type == 0) ? SINGLE_EXEC_SLICE_8MHZ : SINGLE_EXEC_SLICE;
if (sub_cpu_exec > slice) {
sub_cpu_exec = slice;
}
}

Expand All @@ -277,8 +286,9 @@ void EVENT::drive()
if (cpu_remain > 2) {
sub_cpu_exec = cpu_remain / 2;
if (single_exec == true) {
if (sub_cpu_exec > 4) {
sub_cpu_exec = 4;
int slice = (config.cpu_type == 0) ? SINGLE_EXEC_SLICE_8MHZ : SINGLE_EXEC_SLICE;
if (sub_cpu_exec > slice) {
sub_cpu_exec = slice;
}
}

Expand Down
20 changes: 15 additions & 5 deletions Source/ePC-8801MA/vm/upd765a.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -400,7 +400,9 @@ void UPD765A::write_signal(int id, uint32 data, uint32 mask)
} else if(id == SIG_UPD765A_TC) {
#ifdef SDL
// phase==PHASE_EXEC support (for Xanadu Scenario II)
if(phase == PHASE_READ || phase == PHASE_WRITE || phase == PHASE_SCAN || (phase == PHASE_RESULT && count == 7) || (phase == PHASE_EXEC)) {
// but disable for 8MHz mode where it destabilizes Wizardry boot
bool tc_accept_exec = (config.cpu_type != 0);
if(phase == PHASE_READ || phase == PHASE_WRITE || phase == PHASE_SCAN || (phase == PHASE_RESULT && count == 7) || (tc_accept_exec && phase == PHASE_EXEC)) {
#else
if(phase == PHASE_READ || phase == PHASE_WRITE || phase == PHASE_SCAN || (phase == PHASE_RESULT && count == 7)) {
#endif // SDL
Expand Down Expand Up @@ -518,7 +520,7 @@ void UPD765A::set_drq(bool val)
if((command & 0x1f) != 0x0d) {
#ifdef SDL
// for customized event manager + 2HD disk
register_event(this, EVENT_LOST, 30000, false, &lost_id);
register_event(this, EVENT_LOST, 15000, false, &lost_id);
#else
register_event(this, EVENT_LOST, disk[hdu & DRIVE_MASK]->get_usec_per_bytes(1), false, &lost_id);
#endif // SDL
Expand Down Expand Up @@ -684,8 +686,8 @@ void UPD765A::cmd_recalib()

void UPD765A::seek(int drv, int trk)
{
// get distance
int seektime = 32 - 2 * step_rate_time;
// get distance (step rate is in msec units, convert to usec)
int seektime = (32 - 2 * step_rate_time) * 1000; // msec -> usec
if(disk[drv]->drive_type == DRIVE_TYPE_2HD) {
seektime /= 2;
}
Expand Down Expand Up @@ -1466,7 +1468,15 @@ double UPD765A::get_usec_to_exec_phase()
int drv = hdu & DRIVE_MASK;
int trk = fdc[drv].track;
int side = (hdu >> 2) & 1;


#ifdef SDL
// Use constant exec-phase delay for SDL mode.
// The SDL event system's position tracking is not precise enough
// for rotational-position-based timing, which causes timing-sensitive
// titles (e.g. Wizardry) to fail during boot.
return 100;
#endif

// XXX: this is a standard image and skew may be incorrect
if(disk[drv]->is_standard_image) {
return 100;
Expand Down
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