Fix handler address for FIV exception

core/cpu.c

@@ -495,7 +495,7 @@ static int cpuException(VB *sim) {
         sim->cpu.eipc     = sim->cpu.pc;
         sim->cpu.psw.ep   = 1;
         sim->cpu.nextPC   = 0xFFFF0000 |
-            ((cause & 0xFFF0) == 0xFF60 ? 0xFF60 : cause & 0xFFF0);
+            ((cause & 0xFFF0) == 0xFF70 ? 0xFF60 : cause & 0xFFF0);
     }
 
     /* All exceptions */

core/vb.c

@@ -361,6 +361,7 @@ struct VB {
 
             /* Other state */
             uint32_t clocks;   /* Clocks until modification */
+            uint8_t  freqmask; /* Frequency mask */
             uint8_t  modmask;  /* Modifications masked */
             uint16_t next;     /* Next frequency value */
             int      sample;   /* Current sample index */

core/vip.c

@@ -42,14 +42,15 @@ static const uint8_t BG_TEMPLATES[][64] = {
 
 /* 8-bit color magnitude by brightness level */
 static const uint8_t BRIGHT8[] = {
-      0,  2,  4,  6,  8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30,
-     32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62,
-     64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94,
-     96, 98,100,102,104,106,108,110,112,114,116,118,120,122,124,126,
-    129,131,133,135,137,139,141,143,145,147,149,151,153,155,157,159,
-    161,163,165,167,169,171,173,175,177,179,181,183,185,187,189,191,
-    193,195,197,199,201,203,205,207,209,211,213,215,217,219,221,223,
-    225,227,229,231,233,235,237,239,241,243,245,247,249,251,253,255
+      0,  1,  3,  5,  7,  9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 28,
+     30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 57, 59,
+     61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 86, 88, 90,
+     92, 94, 96, 98,100,102,104,106,108,110,112,113,115,117,119,121,
+    123,125,127,129,131,133,135,137,139,141,142,144,146,148,150,152,
+    154,156,158,160,162,164,166,168,170,171,173,175,177,179,181,183,
+    185,187,189,191,193,195,197,198,200,202,204,206,208,210,212,214,
+    216,218,220,222,224,226,227,229,231,233,235,237,239,241,243,245,
+    247,249,251,253,255
 };
 
 
@@ -435,6 +436,9 @@ static void vipWriteIO(
 
         case 0x5F802>>1: /* INTENB */
             sim->vip.intenb = (sim->vip.intenb & mask) | (value & 0xE01F);
+            if (sim->vip.intenb & sim->vip.intpnd)
+                sim->cpu.irq  |=  0x0010;
+            else sim->cpu.irq &= ~0x0010;
             break;
         case 0x5F804>>1: /* INTCLR */
             sim->vip.intpnd &= ~value;
@@ -546,7 +550,7 @@ static void vipWriteIO(
             break;
 
         case 0x5F870>>1: /* BKCOL */
-            sim->vip.bkcol = (sim->vip.bkcol & mask) | (value & 3 * ~mask);
+            sim->vip.bkcol = (sim->vip.bkcol & mask) | (value & 3 & ~mask);
             break;
     }
 
@@ -586,7 +590,7 @@ static void vipComputeBrightness(VB *sim) {
 
     /* Transform brightness values to 0..255 */
     for (x = 1; x < 4; x++)
-        sim->vip.dp.brt[x] = brt[x] > 127 ? 255 : BRIGHT8[brt[x]];
+        sim->vip.dp.brt[x] = brt[x] > 132 ? 255 : BRIGHT8[brt[x]];
 }
 
 /* Transfer one column of frame buffer pixels to output */
@@ -1060,8 +1064,8 @@ static void vipDrawAffine(VB *sim, World *world) {
 
             /* Adjust left-edge parameters */
             if ((mp < 0) ^ i) {
-                mx += dx * (wx - mp);
-                my += dy * (wx - mp);
+                mx += dx * (wx + mp);
+                my += dy * (wx + mp);
             } else {
                 mx += dx * wx;
                 my += dy * wx;

core/vsu.c

@@ -50,7 +50,7 @@ static uint8_t vsuCheckFreqMod(VB *sim) {
     return
         sim->vsu.freqmod.enb           &&
         sim->vsu.freqmod.interval != 0 && (
-            !sim->vsu.freqmod.modmask || (
+            sim->vsu.freqmod.modmask != 2 || (
                 sim->vsu.freqmod.func == 1 &&
                 sim->vsu.freqmod.rep
             )
@@ -62,6 +62,12 @@ static uint8_t vsuCheckFreqMod(VB *sim) {
 static void vsuNextFreqMod(VB *sim, Channel *chan) {
     int32_t next;
 
+    /* Modulation mask control */
+    if (sim->vsu.freqmod.modmask == 1 && sim->vsu.freqmod.func == 1) {
+        sim->vsu.freqmod.modmask = 2;
+        chan->freqmod = vsuCheckFreqMod(sim);
+    }
+
     /* Sweep */
     if (sim->vsu.freqmod.func == 0) {
         next = chan->freq.current >> sim->vsu.freqmod.shift;
@@ -76,35 +82,31 @@ static void vsuNextFreqMod(VB *sim, Channel *chan) {
 
     /* Modulation */
     else {
-
-        /* Compute the modulated value */
-        next = (int32_t) chan->freq.written +
-            sim->vsu.modulation[sim->vsu.freqmod.sample];
-        if (next < 0)
-            next = 0;
-        if (next > 2047)
-            next = 2047;
-
-        /* Not the final modulation sample */
-        if (sim->vsu.freqmod.sample != 31)
-            sim->vsu.freqmod.sample++;
-
-        /* Last modulation sample processed */
-        else {
-            sim->vsu.freqmod.modmask = 1;
-            if (sim->vsu.freqmod.rep)
-                sim->vsu.freqmod.sample = 0;
-        }
-
+        next = ((int32_t) chan->freq.written +
+            sim->vsu.modulation[sim->vsu.freqmod.sample]) & 0x7FF;
+        if (sim->vsu.freqmod.freqmask == 1)
+            next = (next & 0x700) | (chan->freq.written & 0x0FF);
+        else if (sim->vsu.freqmod.freqmask == 2)
+            next = (next & 0x0FF) | (chan->freq.written & 0x700);
     }
 
     /* Configure state */
+    if (chan->freqmod)
         sim->vsu.freqmod.next = next;
 }
 
+/* Advance the noise channel's shift register */
+static void vsuNextNoise(VB *sim) {
+    uint32_t bit = ((
+        sim->vsu.noise.register_ >> NOISE_TAPS[sim->vsu.noise.tap] ^
+        sim->vsu.noise.register_ >> 7
+    ) & 1) ^ 1;
+    sim->vsu.noise.register_ = bit |
+        (sim->vsu.noise.register_ << 1 & 0x7FFE);
+}
+
 /* Process one channel */
 static void vsuEmulateChannel(VB *sim, Channel *chan) {
-    uint32_t bit; /* Pseudorandom bit */
 
     /* Automatic shutoff */
     if (chan->int_.auto_ && chan->int_.clocks == 0) {
@@ -124,12 +126,7 @@ static void vsuEmulateChannel(VB *sim, Channel *chan) {
         /* Noise */
         else {
             chan->clocks = 40 * (2048 - (uint32_t) chan->freq.current);
-            bit = ((
-                sim->vsu.noise.register_ >> NOISE_TAPS[sim->vsu.noise.tap]^
-                sim->vsu.noise.register_ >> 7
-            ) & 1) ^ 1;
-            sim->vsu.noise.register_ = bit |
-                (sim->vsu.noise.register_ << 1 & 0x7FFE);
+            vsuNextNoise(sim);
         }
 
     }
@@ -147,15 +144,39 @@ static void vsuEmulateChannel(VB *sim, Channel *chan) {
     }
 
     /* Frequency modification */
-    if (chan->freqmod && sim->vsu.freqmod.clocks == 0) {
+    if (chan == &sim->vsu.channels[4] && sim->vsu.freqmod.clocks == 0) {
+
+        /* Apply previously computed frequency modification */
+        if (chan->freqmod)
             chan->freq.current = sim->vsu.freqmod.next;
-        vsuNextFreqMod(sim, chan);
+
+        /* Channel itself is disabled */
         if (!chan->int_.enb)
             return;
+
+        /* Frequency modifications are enabled */
+        if (chan->freqmod) {
+
+            /* Not the final modulation sample */
+            if (sim->vsu.freqmod.sample != 31)
+                sim->vsu.freqmod.sample++;
+
+            /* Last modulation sample processed */
+            else {
+                sim->vsu.freqmod.modmask = 1;
+                if (sim->vsu.freqmod.rep)
+                    sim->vsu.freqmod.sample = 0;
+            }
+
+            /* Schedule next modification */
             sim->vsu.freqmod.clocks = (uint32_t) sim->vsu.freqmod.interval *
                 (sim->vsu.freqmod.clk == 0 ? 19200 : 153600);
         }
 
+        /* Always process and validate next frequency value */
+        vsuNextFreqMod(sim, chan);
+    }
+
 }
 
 /* Produce output for a channel */
@@ -194,8 +215,10 @@ static void vsuWriteEV0(VB *sim, int index, uint8_t value) {
     chan->env.interval = value      &  7;
     chan->env.value    = value >> 4 & 15;
     chan->env.reload   = chan->env.value;
-    if (index == 4)
+    if (index == 4) {
+        chan->freqmod = vsuCheckFreqMod(sim);
         vsuNextFreqMod(sim, chan);
+    }
 
     /* Configure state */
     chan->env.clocks = 307220 * ((uint32_t) chan->env.interval + 1);
@@ -223,6 +246,7 @@ static void vsuWriteEV1(VB *sim, int index, uint8_t value) {
         case 5: /* Channel 6 */
             sim->vsu.noise.tap       = value >> 4 & 7;
             sim->vsu.noise.register_ = 0x0000;
+            vsuNextNoise(sim);
     }
 
 }
@@ -233,7 +257,9 @@ static void vsuWriteFQH(VB *sim, int index, uint16_t value) {
     value = value << 8 & 0x0700;
     chan->freq.current = (chan->freq.current & 0x00FF) | value;
     chan->freq.written = (chan->freq.written & 0x00FF) | value;
-    if (index == 4)
+    if (index != 4)
+        return;
+    sim->vsu.freqmod.freqmask = 2;
     vsuNextFreqMod(sim, chan);
 }
 
@@ -242,7 +268,9 @@ static void vsuWriteFQL(VB *sim, int index, uint8_t value) {
     Channel *chan = &sim->vsu.channels[index];
     chan->freq.current = (chan->freq.current & 0x0700) | value;
     chan->freq.written = (chan->freq.written & 0x0700) | value;
-    if (index == 4)
+    if (index != 4)
+        return;
+    sim->vsu.freqmod.freqmask = 1;
     vsuNextFreqMod(sim, chan);
 }
 
@@ -265,6 +293,7 @@ static void vsuWriteINT(VB *sim, int index, uint8_t value) {
         chan->clocks =  4 * (2048 - (uint32_t) chan->freq.current);
     } else {
         sim->vsu.noise.register_ = 0x0000;
+        vsuNextNoise(sim);
         chan->clocks = 40 * (2048 - (uint32_t) chan->freq.current);
     }
     if (index == 4) {
@@ -272,6 +301,8 @@ static void vsuWriteINT(VB *sim, int index, uint8_t value) {
             (sim->vsu.freqmod.clk == 0 ? 19200 : 153600);
         sim->vsu.freqmod.modmask = 0;
         sim->vsu.freqmod.sample  = 0;
+        chan->freqmod = vsuCheckFreqMod(sim);
+        vsuNextFreqMod(sim, chan);
     }
 
 }
@@ -304,6 +335,7 @@ static void vsuWriteSWP(VB *sim, uint8_t value) {
     if (clocks < sim->vsu.freqmod.clocks)
         sim->vsu.freqmod.clocks = clocks;
     sim->vsu.channels[4].freqmod = vsuCheckFreqMod(sim);
+    vsuNextFreqMod(sim, &sim->vsu.channels[4]);
 }
 
 
@@ -479,6 +511,7 @@ static void vsuReset(VB *sim) {
     sim->vsu.freqmod.clocks   = 0;
     sim->vsu.freqmod.dir      = 0;
     sim->vsu.freqmod.enb      = 0;
+    sim->vsu.freqmod.freqmask = 0;
     sim->vsu.freqmod.func     = 0;
     sim->vsu.freqmod.interval = 0;
     sim->vsu.freqmod.modmask  = 0;
@@ -508,11 +541,14 @@ static void vsuWrite(VB*sim,uint32_t address,int type,int32_t value,int debug){
     }
 
     /* Unmapped */
-    if (address & 3)
+    if (address & 1)
         return;
 
     /* Working variables */
-    address &= 0x7FF;
+    address &= 0x7FC;
+
+    /* Clear frequency mask */
+    sim->vsu.freqmod.freqmask = 0;
 
     /* Wave memory */
     if (address < 0x280) {

util/isx.c

@@ -0,0 +1,297 @@
+/* This file is included into vbu.c and cannot be compiled on its own. */
+#ifdef VBUAPI
+
+
+
+/********************************* Constants *********************************/
+
+/* Range types */
+/*
+0x41 ('A')   8-bit integer (.db), string
+0x42 ('B')   8-bit integer (.db), numeric
+0x43 ('C')   Compiled C code
+0x44 ('D')   16-bit integer (.dd, high byte first)
+0x45 ('E')   65C816 code (8-bit accumulator, 8-bit index)
+0x46 ('F')   65C816 code (8-bit accumulator, 16-bit index)
+0x47 ('G')   65C816 code (16-bit accumulator, 8-bit index)
+0x48 ('H')   65C816 code (16-bit accumulator, 16-bit index)
+0x4C ('L')   32-bit integer (.dl SNES, .dw Virtual Boy, low byte first)
+0x53 ('S')   Size reservation, as in .bss allocation (.ds)
+0x57 ('W')   16-bit integer (.dw SNES, .dh Virtual Boy, low byte first)
+*/
+
+
+
+/***************************** Module Functions ******************************/
+
+/* Skip ISX record type 0x01 */
+static size_t isx01(uint8_t *bytes, size_t length, size_t src) {
+    /*
+      u8   Type         =0x01
+      u8   Bank         Cartridge bank number
+      u8   BankHigh     Only if Bank >= 0x80
+      u16  Address      CPU bus address
+      u16  DataLength   Number of bytes in Data
+      u8[] Data         Code bytes
+    */
+
+    /* Bank field is not present */
+    if (src + 2 > length)
+        return (size_t) -1;
+
+    /* Advance to DataLength field */
+    src += bytes[src + 1] >= 0x80 ? 5 : 4;
+
+    /* DataLength field is not present */
+    if (src + 2 > length)
+        return (size_t) -1;
+
+    /* Advance past Data field */
+    return src + 2 + ((uint16_t) bytes[src + 1] << 8 | bytes[src]);
+}
+
+/* Decode ISX record type 0x11 */
+static size_t isx11(uint8_t *bytes, size_t length, size_t src,
+    uint32_t *address, uint32_t *size) {
+    /*
+      u8   Type         =0x11
+      u32  Address      CPU bus address
+      u32  DataLength   Number of bytes in Data
+      u8[] Data         Code bytes
+    */
+
+    /* DataLength field is not present */
+    if (src + 9 > length)
+        return (size_t) -1;
+
+    /* Parse Address and DataLength fields */
+    *address = (uint32_t) bytes[src+4] << 24 | (uint32_t) bytes[src+3] << 16 |
+               (uint32_t) bytes[src+2] <<  8 |            bytes[src+1];
+    *size    = (uint32_t) bytes[src+8] << 24 | (uint32_t) bytes[src+7] << 16 |
+               (uint32_t) bytes[src+6] <<  8 |            bytes[src+5];
+
+    /* Advance past Data field */
+    return src + 9 + *size;
+}
+
+/* Skip ISX range records */
+static size_t isxRange(uint8_t *bytes,size_t length,size_t src,size_t size) {
+    /*
+      u8      Type            =0x03 (SNES) or 0x13 (Virtual Boy)
+      u16     Count           Number of ranges
+      Range[] Ranges
+       === SNES fields ===
+       u8      Bank           Cartridge bank number
+       u16     StartAddress   Lowest CPU bus address
+       u16     EndAddress     Highest CPU bus address
+       u8      RangeType      See range types
+       === Virtual Boy fields ===
+       u32     StartAddress   Lowest CPU bus address
+       u32     EndAddress     Highest CPU bus address
+       u8      RangeType      See range types
+    */
+
+    /* Count field is not present */
+    if (src + 3 > length)
+        return (size_t) -1;
+
+    /* Advance past Ranges field */
+    return src + 3 + size * ((uint16_t) bytes[src + 2] << 8 | bytes[src + 1]);
+}
+
+/* Skip ISX symbol record */
+static size_t isxSymbol(uint8_t *bytes,size_t length,size_t src,size_t size) {
+    size_t count; /* Number of symbols */
+    size_t x;     /* Iterator */
+
+    /*
+      u8       Type          =0x04 (SNES) or 0x14 (Virtual Boy)
+      u16      Count         Number of symbols
+      Symbol[] Symbols
+       u8       NameLength   Number of bytes in Name
+       u8[]     Name         Symbol name
+       === SNES fields ===
+       u8       Flags        Undocumented
+       u8       Bank         Cartridge bank number
+       u16      Address      CPU bus address
+       === Virtual Boy fields ===
+       u16      Flags        Undocumented
+       u32      Address      CPU bus address
+    */
+
+    /* Count field is not present */
+    if (src + 3 > length)
+        return (size_t) -1;
+
+    /* Working variables */
+    count = (uint16_t) bytes[src + 2] << 8 | bytes[src + 1];
+    src  += 3;
+
+    /* Process all symbols */
+    for (x = 0; x < count; x++) {
+
+        /* NameLength field is not present */
+        if (src > length)
+            return (size_t) -1;
+
+        /* Advance past remainder of symbol */
+        src += size + bytes[src];
+
+        /* Remainder of symbol is not present */
+        if (src > length)
+            return (size_t) -1;
+    }
+
+    return src;
+}
+
+/* Skip ISX system record */
+static size_t isxSystem(uint8_t *bytes, size_t length, size_t src) {
+    /*
+      u8   Type         =0x20, 0x21 or 0x22
+      u32  DataLength   Number of bytes in Data
+      u8[] Data         Record data
+    */
+
+    /* DataLength field is not present */
+    if (src + 5 > length)
+        return (size_t) -1;
+
+    /* Advance past Data field */
+    return src + 5 + (
+        (uint32_t) bytes[src + 4] << 24 | (uint32_t) bytes[src + 3] << 16 |
+        (uint32_t) bytes[src + 2] <<  8 |            bytes[src + 1]
+    );
+}
+
+
+
+/***************************** Library Functions *****************************/
+
+/* Decode an ISX debugger file to a Virtual Boy ROM */
+static void* isxFrom(uint8_t *bytes, size_t length, size_t *romLength) {
+    uint32_t addr;    /* Code record base address */
+    uint32_t highMin; /* Lowest address in upper half of ROM */
+    uint32_t lowMax;  /* Highest address in lower half of ROM */
+    uint8_t *rom;     /* Output ROM */
+    uint32_t size;    /* Code record size in bytes */
+    size_t   src;     /* Input position */
+    size_t   start;   /* Offset of first record */
+
+    /* Error checking */
+    if (length < 3)
+        return NULL;
+
+    /* Working variables */
+    highMin = 0xFFFFFF;
+    lowMax  = 0x000000;
+    size    = 0;
+    start   = strncmp((char *) bytes, "ISX", 3) ? 0 : 32;
+
+    /* First pass: determine the size of the ROM */
+    for (src = start; src < length;) {
+        switch (bytes[src]) {
+
+            case 0x11: /* Code (Virtual Boy) */
+
+                /* Decode record fields */
+                src = isx11(bytes, length, src, &addr, &size);
+                if (src > length)
+                    return NULL;
+
+                /* Validate address and data size */
+                addr &= 0x07FFFFFF;
+                if (
+                    addr < 0x07000000 ||
+                    0x08000000 - addr < size
+                ) return NULL;
+                addr &= 0x00FFFFFF;
+
+                /* Requires 16 MiB */
+                if (addr < 0x800000 && addr + size > 0x800000) {
+                    highMin = 0x800000;
+                    lowMax  = 0x7FFFFF;
+                }
+
+                /* Map from top of ROM space */
+                else if (addr & 0x800000) {
+                    if (addr < highMin)
+                        highMin = addr;
+                }
+
+                /* Map from bottom of ROM space */
+                else {
+                    addr += size - 1;
+                    if (addr > lowMax)
+                        lowMax = addr;
+                }
+ 
+                break;
+
+            case 0x01: /* Code (SNES) */
+                src = isx01    (bytes, length, src   ); break;
+            case 0x03: /* Range (SNES) */
+                src = isxRange (bytes, length, src, 6); break;
+            case 0x04: /* Symbol (SNES) */
+                src = isxSymbol(bytes, length, src, 5); break;
+            case 0x13: /* Range (Virtual Boy) */
+                src = isxRange (bytes, length, src, 9); break;
+            case 0x14: /* Symbol (Virtual Boy) */
+                src = isxSymbol(bytes, length, src, 7); break;
+            case 0x20: /* System (undocumented) */
+            case 0x21: /* System (undocumented) */
+            case 0x22: /* System (undocumented) */
+                src = isxSystem(bytes, length, src    ); break;
+            default: /* Invalid record type */
+                return NULL;
+        }
+
+        /* Record contains invalid data */
+        if (src > length)
+            return NULL;
+    }
+
+    /* Produce a ROM buffer of minimal size to fit all the code records */
+    for (
+        src = 1;
+        src < lowMax + 0x1000001 - highMin;
+        src <<= 1
+    );
+    rom = VBU_REALLOC(NULL, src);
+    if (rom == NULL)
+        return NULL;
+    *romLength = src;
+    memset(rom, 0x00, src);
+
+    /* Second pass: fill the ROM buffer with the code records */
+    for (src = start; src < length;) {
+        switch (bytes[src]) {
+
+            case 0x11: /* Code (Virtual Boy) */
+                src = isx11(bytes, length, src, &addr, &size);
+                memcpy(&rom[addr & (*romLength-1)], &bytes[src - size], size);
+                break;
+
+            case 0x01: /* Code (SNES) */
+                src = isx01    (bytes, length, src    ); break;
+            case 0x03: /* Range (SNES) */
+                src = isxRange (bytes, length, src,  9); break;
+            case 0x04: /* Symbol (SNES) */
+                src = isxSymbol(bytes, length, src,  5); break;
+            case 0x13: /* Range (Virtual Boy) */
+                src = isxRange (bytes, length, src, 12); break;
+            case 0x14: /* Symbol (Virtual Boy) */
+                src = isxSymbol(bytes, length, src,  7); break;
+            case 0x20: /* System (undocumented) */
+            case 0x21: /* System (undocumented) */
+            case 0x22: /* System (undocumented) */
+                src = isxSystem(bytes, length, src    ); break;
+        }
+    }
+
+    return rom;
+}
+
+
+
+#endif /* VBUAPI */

web/Core.js

@@ -293,6 +293,12 @@ new class Core {
         }, [ output.buffer ]);
     }
 
+    // Reset simulation state
+    reset(message) {
+        this.vbReset(message.sim);
+        this.dom.postMessage({ promised: true });
+    }
+
     // Specify anaglyph colors
     setAnaglyph(message) {
         this.SetAnaglyph(message.sim, message.left, message.right);

web/VB.js

@@ -436,8 +436,17 @@ class Sim extends HTMLElement {
             response.lines.map(l=>new DasmLine(GUARD, l));
     }
 
+    // Reset simulation state
+    reset() {
+        return this.#core.toCore({
+            command : "reset",
+            promised: true,
+            sim     : this.#pointer
+        });
+    }
+
     // Specify anaglyph colors
-    async setAnaglyph(left, right) {
+    setAnaglyph(left, right) {
 
         // Error checking
         if (!Number.isSafeInteger(left ) || left  < 0 || left  > 0xFFFFFF)
@@ -455,7 +464,7 @@ class Sim extends HTMLElement {
         this.#anaglyph[1] = right;
 
         // Send the colors to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setAnaglyph",
             promised: true,
             sim     : this.#pointer,
@@ -475,7 +484,7 @@ class Sim extends HTMLElement {
     }
 
     // Specify new game pad keys
-    async setKeys(keys) {
+    setKeys(keys) {
 
         // Error checking
         if (!Number.isSafeInteger(keys) || keys < 0 || keys > 0xFFFF)
@@ -487,7 +496,7 @@ class Sim extends HTMLElement {
         this.#keys = keys;
 
         // Send the keys to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setKeys",
             promised: true,
             sim     : this.#pointer,
@@ -496,7 +505,7 @@ class Sim extends HTMLElement {
     }
 
     // Specify audio panning
-    async setPanning(panning) {
+    setPanning(panning) {
 
         // Error checking
         if (!Number.isFinite(panning) ||panning < -1 || panning > +1) {
@@ -508,7 +517,7 @@ class Sim extends HTMLElement {
         this.#panning = panning;
 
         // Send the panning to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setPanning",
             promised: true,
             sim     : this.#pointer,
@@ -529,7 +538,7 @@ class Sim extends HTMLElement {
     }
 
     // Specify audio volume
-    async setVolume(volume) {
+    setVolume(volume) {
 
         // Error checking
         if (!Number.isFinite(volume) ||volume < 0 || volume > 10) {
@@ -541,7 +550,7 @@ class Sim extends HTMLElement {
         this.#volume = volume;
 
         // Send the volume to the core
-        await this.#core.toCore({
+        return this.#core.toCore({
             command : "setVolume",
             promised: true,
             sim     : this.#pointer,
@@ -596,7 +605,7 @@ class VB {
     #commands;  // Computed method table
     #core;      // Core worker
     #proxy;     // Self proxy for sim access
-    #sims;      // All sims
+    #sims;      // Mapping of Sim|pointer -> proxy
     #state;     // Operations state
 
 
@@ -683,8 +692,8 @@ class VB {
     ///////////////////////////// Static Methods //////////////////////////////
 
     // Create a core instance
-    static async create(options) {
-        return await new VB(GUARD).#construct(options);
+    static create(options) {
+        return new VB(GUARD).#construct(options);
     }
 
 
@@ -769,6 +778,16 @@ class VB {
 
 
 
+    /////////////////////////////// Properties ////////////////////////////////
+
+    // Number of managed simulations
+    get size() { return this.#sims.size / 2; }
+
+    // Managed simulations
+    get sims() { return [... this.#sims.keys()].filter(s=>s instanceof Sim); }
+
+
+
     ///////////////////////////// Public Methods //////////////////////////////
 
     // Create one or more sims
@@ -809,7 +828,7 @@ class VB {
         if (
             !Array.isArray(sims) ||
             sims.length == 0     ||
-            sims.find(s=>!this.#sims.has(s))
+            sims.some(s=>!this.#sims.has(s))
         ) {
             throw new TypeError("Must specify a Sim or array of Sims " +
                 "that belong to this core.");