DMD: doc cleanups

vpinball · Oct 7, 2024 · 390274f · 390274f
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Showing 2 changed files with 5 additions and 6 deletions.
diff --git a/docs/dmd.md b/docs/dmd.md
@@ -31,7 +31,7 @@ The table below gives the main information (PWM FPS / Display FPS / PWM pattern)
 
 | Name                                                        | PWM FPS / Disp.FPS     | PWM pattern | Emulation comments                                             |
 |-------------------------------------------------------------|------------------------|-------------|----------------------------------------------------------------|
-|[WPC](#wpc)                                                  | **122.1** / 40.7       | 3 frames    |                                                                |
+|[WPC](#wpc)                                                  | **122.1** / 40.7       | 2/3 frames  |                                                                |
 |[WPC Phantom Haus](#wpc)                                     | 61.05 / 30.1           | 2 frames    |                                                                |
 |[Data East 128x16](#data-east-128x16)                        | 177.5 / **59.2**       | 2u row      |                                                                |
 |[Data East 128x32](#data-east-128x32-segastern-whitestar)    | 234.2 / **78.1**       | 2u row      |                                                                |

diff --git a/src/wpc/wpc.c b/src/wpc/wpc.c
@@ -409,10 +409,9 @@ MACHINE_DRIVER_START(wpc_95S)
   MDRV_IMPORT_FROM(wmssnd_dcs2)
 MACHINE_DRIVER_END
 
-// The FIRQ line is wired to 3 sources:
+// The FIRQ line is wired to 2 sources:
 // - the WPC FIRQ output, which is triggered by its internal high res timer
-// - the sound board FIRQ output
-// - the programmable DMD FIRQ output (raise when a given row is reached, clear when the FIRS row is defined)
+// - the programmable DMD FIRQ output (raised when a choosen row is reached, cleared when the FIRQ row is defined)
 static void update_firq() {
   cpu_set_irq_line(WPC_CPUNO, M6809_FIRQ_LINE, (wpclocals.wpcFIRQ | dmdlocals.firq) ? HOLD_LINE : CLEAR_LINE);
 }
@@ -1572,15 +1571,15 @@ static VIDEO_START(wpc_dmd) {
 // VBlank divider. All of this was deduced from the pre WPC-95 schematics.
 // lucky1 measured on a real machine 122.1Hz which validates it.
 //
-// Most WPC games uses a 3 frame PWM pattern to create 0/33/66/100 shades.
+// WPC games uses either a 2 or 3 frame PWM pattern to create 0/50/100 or 0/33/66/100 shades.
 // For Phantom Haus, the DMD is bigger with 64 rows instead of 32, therefore
 // the rasterizer timings are 2MHz / (128*64*2*2) = 61.04Hz. The PWM pattern 
 // used is therefore limited to 2 frames (30.5Hz) with 0/50/100 shades to avoid 
 // flickering.
 // 
 // CPU may ask the DMD board to raise FIRQ when a given row is reached.
 // The FIRQ is then acked (pulled down) by writing again the requested FIRQ row 
-// to the corresponding register (if >31, it disables DMD FIRQ).
+// to the corresponding register (game code use 0xFF to disables DMD FIRQ).
 static void wpc_dmd_hsync(int param) {
   dmdlocals.row = (dmdlocals.row + 1) % dmdlocals.pwm_state.height; // FIXME Phantom Haus uses the same AV card than other WPC95 but with a 64 row display, therefore the CPU must tell the rasterizer that it is 64 row high somewhere we don't know
   if (dmdlocals.row == 0) { // VSYNC