diff --git a/src/pic.c b/src/pic.c
index f4e1a0a60..c01053268 100644
--- a/src/pic.c
+++ b/src/pic.c
@@ -51,23 +51,20 @@ pic_t pic2;
 
 static pc_timer_t pic_timer;
 
-static uint16_t smi_irq_mask       = 0x0000;
-static uint16_t smi_irq_status     = 0x0000;
-
-static uint16_t enabled_latches    = 0x0000;
-static uint16_t latched_irqs       = 0x0000;
-
 static int shadow = 0;
 static int elcr_enabled = 0;
 static int tmr_inited = 0;
+static int latched = 0;
 static int pic_pci = 0;
+static int kbd_latch = 0;
+static int mouse_latch = 0;
 
-static void    (*update_pending)(void);
+static uint16_t smi_irq_mask   = 0x0000;
+static uint16_t smi_irq_status = 0x0000;
 
-static void    pic_update_request(pic_t *dev, int irq);
-static void    pic_update_irr(pic_t *dev, uint16_t num);
+static uint16_t latched_irqs   = 0x0000;
 
-static void    pic_cascade(int set);
+static void (*update_pending)(void);
 
 #ifdef ENABLE_PIC_LOG
 int pic_do_log = ENABLE_PIC_LOG;
@@ -226,29 +223,37 @@ find_best_interrupt(pic_t *dev)
 static __inline void
 pic_update_pending_xt(void)
 {
-    if (!(pic.flags & PIC_FREEZE))
-        pic.int_pending = (find_best_interrupt(&pic) != -1);
+    if (find_best_interrupt(&pic) != -1) {
+        latched++;
+        if (latched == 1)
+            timer_on_auto(&pic_timer, 0.35);
+    } else if (latched == 0)
+        pic.int_pending = 0;
 }
 
 static __inline void
 pic_update_pending_at(void)
 {
-    if (!(pic2.flags & PIC_FREEZE)) {
-        pic2.int_pending = (find_best_interrupt(&pic2) != -1);
+    pic2.int_pending = (find_best_interrupt(&pic2) != -1);
 
-        pic_cascade(pic2.int_pending);
-    }
+    if (pic2.int_pending)
+        pic.irr |= (1 << pic2.icw3);
+    else
+        pic.irr &= ~(1 << pic2.icw3);
 
-    if (!(pic.flags & PIC_FREEZE))
-        pic.int_pending = (find_best_interrupt(&pic) != -1);
-
-    pic_log("pic_update_pending_at(): dev->int_pending = %i (%i)\n", pic.int_pending, !!(pic.flags & PIC_FREEZE));
+    pic.int_pending = (find_best_interrupt(&pic) != -1);
 }
 
 static void
-pic_callback(UNUSED(void *priv))
+pic_callback(void *priv)
 {
-    update_pending();
+    pic_t *dev = (pic_t *) priv;
+
+    dev->int_pending = 1;
+
+    latched--;
+    if (latched > 0)
+        timer_on_auto(&pic_timer, 0.35);
 }
 
 void
@@ -263,13 +268,8 @@ pic_reset(void)
     pic.is_master = 1;
     pic.interrupt = pic2.interrupt = 0x17;
 
-    pic.has_slaves = 0;
-    pic2.has_slaves = 0;
-
-    if (is_at) {
+    if (is_at)
         pic.slaves[2] = &pic2;
-        pic.has_slaves = 1;
-    }
 
     if (tmr_inited)
         timer_on_auto(&pic_timer, 0.0);
@@ -320,25 +320,14 @@ picint_is_level(int irq)
 }
 
 static void
-pic_acknowledge(pic_t *dev, int poll)
+pic_acknowledge(pic_t *dev)
 {
     int pic_int     = dev->interrupt & 7;
     int pic_int_num = 1 << pic_int;
 
     dev->isr |= pic_int_num;
-
-    /* Simulate the clearing of the edge pulse. */
-    dev->edge_lines &= ~pic_int_num;
-    /* Clear the edge sense latch. */
-    dev->irq_latch &= ~pic_int_num;
-
-    if (!poll) {
-        dev->flags |= PIC_FREEZE;    /* Freeze it so it still takes interrupts but they do not
-                                        override the one currently being processed. */
-
-        /* Clear the reset latch. */
-        pic_update_request(dev, pic_int);
-    }
+    if (!pic_level_triggered(dev, pic_int) || (dev->lines[pic_int] == 0))
+        dev->irr &= ~pic_int_num;
 }
 
 /* Find IRQ for non-specific EOI (either by command or automatic) by finding the highest IRQ
@@ -375,7 +364,6 @@ pic_action(pic_t *dev, uint8_t irq, uint8_t eoi, uint8_t rotate)
         if (rotate)
             dev->priority = (irq + 1) & 7;
 
-        pic_update_request(dev, irq);
         update_pending();
     }
 }
@@ -415,10 +403,13 @@ pic_latch_read(UNUSED(uint16_t addr), UNUSED(void *priv))
 {
     uint8_t ret = 0xff;
 
-    pic_log("pic_latch_read(%04X): %04X\n", enabled_latches, latched_irqs & 0x1002);
+    pic_log("pic_latch_read(%i, %i)\n", kbd_latch, mouse_latch);
 
-    if (latched_irqs & 0x1002)
-        picintc(latched_irqs & 0x1002);
+    if (kbd_latch && (latched_irqs & 0x0002))
+        picintc(0x0002);
+
+    if (mouse_latch && (latched_irqs & 0x1000))
+        picintc(0x1000);
 
     /* Return FF - we just lower IRQ 1 and IRQ 12. */
     return ret;
@@ -447,23 +438,24 @@ pic_read(uint16_t addr, void *priv)
         dev->data_bus = dev->irr;
 #endif
         if (dev->ocw3 & 0x04) {
+            dev->interrupt &= ~0x20; /* Freeze the interrupt until the poll is over. */
             if (dev->int_pending) {
                 dev->data_bus = 0x80 | (dev->interrupt & 7);
-                pic_acknowledge(dev, 1);
+                pic_acknowledge(dev);
                 dev->int_pending = 0;
+                update_pending();
             } else
                 dev->data_bus = 0x00;
             dev->ocw3 &= ~0x04;
-            dev->flags &= ~PIC_FREEZE; /* Freeze the interrupt until the poll is over. */
-            pic_update_irr(dev, 0x00ff); /* Update IRR, just in case anything came while frozen. */
-            update_pending();
         } else if (addr & 0x0001)
             dev->data_bus = dev->imr;
         else if (dev->ocw3 & 0x02) {
             if (dev->ocw3 & 0x01)
                 dev->data_bus = dev->isr;
+#ifdef UNDEFINED_READ
             else
-                dev->data_bus = dev->irr;
+                dev->data_bus = 0x00;
+#endif
         }
         /* If A0 = 0, VIA shadow is disabled, and poll mode is disabled,
            simply read whatever is currently on the data bus. */
@@ -502,10 +494,7 @@ pic_write(uint16_t addr, uint8_t val, void *priv)
                 break;
             case STATE_NONE:
                 dev->imr = val;
-                if (is286)
-                    update_pending();
-                else
-                    timer_on_auto(&pic_timer, 1.0 * ((10000000.0 * (double) xt_cpu_multi) / (double) cpu_s->rspeed));
+                update_pending();
                 break;
 
             default:
@@ -522,13 +511,11 @@ pic_write(uint16_t addr, uint8_t val, void *priv)
             if (!(dev->icw1 & 1))
                 dev->icw4 = 0x00;
             dev->ocw2 = dev->ocw3 = 0x00;
-            dev->flags = PIC_MASTER_CLEAR;
-            dev->irr  = 0x00;
-            dev->edge_lines  = 0x00;
-            dev->irq_latch  = 0x00;
-            for (uint8_t i = 0; i <= 7; i++)
-                pic_update_request(dev, i);
-            dev->flags &= ~PIC_MASTER_CLEAR;
+            dev->irr              = 0x00;
+            for (uint8_t i = 0; i <= 7; i++) {
+                if (dev->lines[i] > 0)
+                    dev->irr              |= (1 << i);
+            }
             dev->imr = dev->isr = 0x00;
             dev->ack_bytes = dev->priority = 0x00;
             dev->auto_eoi_rotate = dev->special_mask_mode = 0x00;
@@ -539,7 +526,7 @@ pic_write(uint16_t addr, uint8_t val, void *priv)
         } else if (val & 0x08) {
             dev->ocw3 = val;
             if (dev->ocw3 & 0x04)
-                dev->flags |= PIC_FREEZE; /* Freeze the interrupt until the poll is over. */
+                dev->interrupt |= 0x20; /* Freeze the interrupt until the poll is over. */
             if (dev->ocw3 & 0x40)
                 dev->special_mask_mode = !!(dev->ocw3 & 0x20);
         } else {
@@ -566,15 +553,12 @@ pic_set_pci(void)
 void
 pic_kbd_latch(int enable)
 {
-    uint16_t old_latches = enabled_latches;
-
     pic_log("PIC keyboard latch now %sabled\n", enable ? "en" : "dis");
 
-    enable = (!!enable) << 1;
-    enabled_latches = (enabled_latches & 0x1000) | enable;
+    if (!!(enable | mouse_latch) != !!(kbd_latch | mouse_latch))
+        io_handler(!!(enable | mouse_latch), 0x0060, 0x0001, pic_latch_read, NULL, NULL, NULL, NULL, NULL, NULL);
 
-    if (!!(enabled_latches & 0x1002) != !!(old_latches & 0x1002))
-        io_handler(!!(enabled_latches & 0x1002), 0x0060, 0x0001, pic_latch_read, NULL, NULL, NULL, NULL, NULL, NULL);
+    kbd_latch = !!enable;
 
     if (!enable)
         picintc(0x0002);
@@ -583,15 +567,12 @@ pic_kbd_latch(int enable)
 void
 pic_mouse_latch(int enable)
 {
-    uint16_t old_latches = enabled_latches;
-
     pic_log("PIC mouse latch now %sabled\n", enable ? "en" : "dis");
 
-    enable = (!!enable) << 12;
-    enabled_latches = (enabled_latches & 0x0002) | enable;
+    if (!!(kbd_latch | enable) != !!(kbd_latch | mouse_latch))
+        io_handler(!!(kbd_latch | enable), 0x0060, 0x0001, pic_latch_read, NULL, NULL, NULL, NULL, NULL, NULL);
 
-    if (!!(enabled_latches & 0x1002) != !!(old_latches & 0x1002))
-        io_handler(!!(enabled_latches & 0x1002), 0x0060, 0x0001, pic_latch_read, NULL, NULL, NULL, NULL, NULL, NULL);
+    mouse_latch = !!enable;
 
     if (!enable)
         picintc(0x1000);
@@ -603,11 +584,11 @@ pic_reset_hard(void)
     pic_reset();
 
     /* Explicitly reset the latches. */
-    enabled_latches = 0x0000;
+    kbd_latch = mouse_latch = 0;
     latched_irqs = 0x0000;
 
     /* The situation is as follows: There is a giant mess when it comes to these latches on real hardware,
-       to the point that there's even boards with board-level latches that get used in place of the latches
+       to the point that there's even boards with board-level latched that get used in place of the latches
        on the chipset, therefore, I'm just doing this here for the sake of simplicity. */
     if (machine_has_bus(machine, MACHINE_BUS_PS2_LATCH)) {
         pic_kbd_latch(0x01);
@@ -643,125 +624,31 @@ pic2_init(void)
     pic.slaves[2] = &pic2;
 }
 
-void
-pic_update_lines(pic_t *dev, uint16_t num, int level, int set, uint8_t *irq_state)
-{
-    uint8_t old_edge_lines;
-    uint8_t bit;
-
-    switch (level) {
-        case PIC_IRQ_EDGE:
-            old_edge_lines = dev->edge_lines;
-
-            dev->edge_lines &= ~num;
-            if (set)
-                dev->edge_lines |= num;
-
-            if ((dev->isr & num) || (dev->flags & PIC_MASTER_CLEAR))
-                dev->irq_latch = (dev->irq_latch & ~num) | (dev->edge_lines & num);
-            else if ((dev->edge_lines & num) && !(old_edge_lines & num))
-                dev->irq_latch |= num;
-            break;
-        case PIC_IRQ_LEVEL:
-            for (uint8_t i = 0; i < 8; i++) {
-                bit = (1 << i);
-                if ((num & bit) && ((!!*irq_state) != !!set))
-                    dev->lines[i] += (set ? 1 : -1);
-            }
-
-            if ((!!*irq_state) != !!set)
-                *irq_state = set;
-            break;
-
-        default:
-            break;
-    }
-}
-
-static uint8_t
-pic_irq_get_request(pic_t *dev, int irq)
-{
-    uint8_t ret;
-
-    ret = ((dev->edge_lines & (1 << irq)) || (dev->lines[irq] > 0));
-
-    return ret;
-}
-
-static uint8_t
-pic_es_latch_clear(pic_t *dev, int irq)
-{
-    uint8_t ret;
-
-    ret = (dev->isr & (1 << irq)) || (dev->flags & PIC_MASTER_CLEAR);
-
-    return ret;
-}
-
-static uint8_t
-pic_es_latch_out(pic_t *dev, int irq)
-{
-    uint8_t ret;
-
-    ret = !((pic_es_latch_clear(dev, irq) && (dev->irq_latch & (1 << irq))) || !pic_irq_get_request(dev, irq));
-
-    return ret;
-}
-
-static uint8_t
-pic_es_latch_nor(pic_t *dev, int irq)
-{
-    uint8_t ret;
-
-    ret = !(pic_es_latch_out(dev, irq) || picint_is_level(irq));
-
-    return ret;
-}
-
-static uint8_t
-pic_irq_request_nor(pic_t *dev, int irq)
-{
-    uint8_t ret;
-
-    ret = !(pic_es_latch_nor(dev, irq) || !pic_irq_get_request(dev, irq));
-
-    return ret;
-}
-
-static void
-pic_update_request(pic_t *dev, int irq)
-{
-    dev->irr &= ~(1 << irq);
-
-    if (!(dev->flags & PIC_FREEZE))
-        dev->irr |= (pic_irq_request_nor(dev, irq) << irq);
-}
-
-static void
-pic_update_irr(pic_t *dev, uint16_t num)
-{
-    for (uint8_t i = 0; i < 8; i++) {
-        if (num & (1 << i))
-            pic_update_request(dev, i);
-    }
-}
-
 void
 picint_common(uint16_t num, int level, int set, uint8_t *irq_state)
 {
-    pic_log("picint_common(%04X, %i, %i, %08X)\n", num, level, set, (uint32_t) (uintptr_t) irq_state);
-
-    set = !!set;
+    int     raise;
+    uint8_t b;
+    uint8_t slaves = 0;
 
     /* Make sure to ignore all slave IRQ's, and in case of AT+,
        translate IRQ 2 to IRQ 9. */
-    if (num & pic.icw3) {
-        num &= ~pic.icw3;
-        if (pic.at)
-            num |= (1 << 9);
+    for (uint8_t i = 0; i < 8; i++) {
+        b     = (uint8_t) (1 << i);
+        raise = num & b;
+
+        if (pic.icw3 & b) {
+            slaves++;
+
+            if (raise) {
+                num &= ~b;
+                if (pic.at && (i == 2))
+                    num |= (1 << 9);
+            }
+        }
     }
 
-    if (!pic.has_slaves)
+    if (!slaves)
         num &= 0x00ff;
 
     if (!num) {
@@ -772,40 +659,93 @@ picint_common(uint16_t num, int level, int set, uint8_t *irq_state)
     if (num & 0x0100)
         acpi_rtc_status = !!set;
 
-    smi_irq_status &= ~num;
-    if (set && (smi_irq_mask & num)) {
-        smi_raise();
-        smi_irq_status |= num;
+    if (set) {
+        if (smi_irq_mask & num) {
+            smi_raise();
+            smi_irq_status |= num;
+        }
+
+        if (num & 0xff00) {
+            if (level) {
+                for (uint8_t i = 0; i < 8; i++) {
+                    b     = (uint8_t) (1 << i);
+                    if (((num >> 8) & b) && ((!!*irq_state) != !!set))
+                        pic2.lines[i]++;
+                }
+
+                if ((!!*irq_state) != !!set)
+                    *irq_state = set;
+            }
+
+            /* Latch IRQ 12 if the mouse latch is enabled. */
+            if ((num & 0x1000) && mouse_latch)
+                latched_irqs |= 0x1000;
+
+            pic2.irr |= (num >> 8);
+        }
+
+        if (num & 0x00ff) {
+            if (level) {
+                for (uint8_t i = 0; i < 8; i++) {
+                    b     = (uint8_t) (1 << i);
+                    if ((num & b) && ((!!*irq_state) != !!set))
+                        pic.lines[i]++;
+                }
+
+                if ((!!*irq_state) != !!set)
+                    *irq_state = set;
+            }
+
+            /* Latch IRQ 1 if the keyboard latch is enabled. */
+            if (kbd_latch && (num & 0x0002))
+                latched_irqs |= 0x0002;
+
+            pic.irr |= (num & 0x00ff);
+        }
+    } else {
+        smi_irq_status &= ~num;
+
+        if (num & 0xff00) {
+            if (level) {
+                for (uint8_t i = 0; i < 8; i++) {
+                    b     = (uint8_t) (1 << i);
+                    if (((num >> 8) & b) && ((!!*irq_state) != !!set))
+                        pic2.lines[i]--;
+                }
+
+                if ((!!*irq_state) != !!set)
+                    *irq_state = set;
+            }
+
+            /* Unlatch IRQ 12 if the mouse latch is enabled. */
+            if ((num & 0x1000) && mouse_latch)
+                latched_irqs &= 0xefff;
+
+            pic2.irr &= ~(num >> 8);
+        }
+
+        if (num & 0x00ff) {
+            if (level) {
+                for (uint8_t i = 0; i < 8; i++) {
+                    b     = (uint8_t) (1 << i);
+                    if ((num & b) && ((!!*irq_state) != !!set))
+                        pic.lines[i]--;
+                }
+
+                if ((!!*irq_state) != !!set)
+                    *irq_state = set;
+            }
+
+            /* Unlatch IRQ 1 if the keyboard latch is enabled. */
+            if (kbd_latch && (num & 0x0002))
+                latched_irqs &= 0xfffd;
+
+            pic.irr &= ~(num & 0x00ff);
+        }
     }
 
-    if (num & 0xff00) {
-        pic_update_lines(&pic2, num >> 8, level, set, irq_state);
-
-        /* Latch IRQ 12 if the mouse latch is enabled. */
-        if ((num & enabled_latches) & 0x1000)
-            latched_irqs = (latched_irqs & 0xefff) | (set << 12);
-
-        pic_update_irr(&pic2, num >> 8);
-    }
-
-    if (num & 0x00ff) {
-        pic_update_lines(&pic, num & 0x00ff, level, set, irq_state);
-
-        /* Latch IRQ 1 if the keyboard latch is enabled. */
-        if ((num & enabled_latches) & 0x0002)
-            latched_irqs = (latched_irqs & 0xfffd) | (set << 1);
-
-        pic_update_irr(&pic, num & 0x00ff);
-    }
-
-    update_pending();
-}
-
-static void
-pic_cascade(int set)
-{
-    pic_update_lines(&pic, (1 << pic2.icw3), PIC_IRQ_EDGE, set, NULL);
-    pic_update_irr(&pic, (1 << pic2.icw3));
+    if (!(pic.interrupt & 0x20) && !(pic2.interrupt & 0x20))
+        update_pending();
 }
 
 static uint8_t
@@ -817,13 +757,16 @@ pic_i86_mode(pic_t *dev)
 static uint8_t
 pic_irq_ack_read(pic_t *dev, int phase)
 {
-    uint8_t intr  = dev->interrupt & 0x07;
-    uint8_t slave = dev->flags & PIC_SLAVE_PENDING;
+    uint8_t intr  = dev->interrupt & 0x47;
+    uint8_t slave = intr & 0x40;
+    intr &= 0x07;
     pic_log("    pic_irq_ack_read(%08X, %i)\n", dev, phase);
 
     if (dev != NULL) {
         if (phase == 0) {
-            pic_acknowledge(dev, 0);
+            dev->interrupt |= 0x20; /* Freeze it so it still takes interrupts but they do not
+                                       override the one currently being processed. */
+            pic_acknowledge(dev);
             if (slave)
                 dev->data_bus = pic_irq_ack_read(dev->slaves[intr], phase);
             else
@@ -855,9 +798,6 @@ pic_irq_ack_read(pic_t *dev, int phase)
     return dev->data_bus;
 }
 
-/* 808x: Update the requests for all interrupts since any of them
-         could have arrived during the freeze. */
-        
 uint8_t
 pic_irq_ack(void)
 {
@@ -871,7 +811,7 @@ pic_irq_ack(void)
             exit(-1);
         }
 
-        pic.flags |= PIC_SLAVE_PENDING;
+        pic.interrupt |= 0x40; /* Mark slave pending. */
     }
 
     ret           = pic_irq_ack_read(&pic, pic.ack_bytes);
@@ -879,13 +819,8 @@ pic_irq_ack(void)
 
     if (pic.ack_bytes == 0) {
         /* Needed for Xi8088. */
-        if (pic.flags & PIC_SLAVE_PENDING) {
-            pic2.flags &= ~PIC_FREEZE;
-            pic_update_irr(&pic2, 0x00ff);
+        if (pic.interrupt & 0x40)
             pic2.interrupt = 0x17;
-        }
-        pic.flags &= ~(PIC_SLAVE_PENDING | PIC_FREEZE);
-        pic_update_irr(&pic, 0x00ff);
         pic.interrupt = 0x17;
         update_pending();
     }
@@ -893,9 +828,6 @@ pic_irq_ack(void)
     return ret;
 }
 
-/* 286+: Only update the request for the pending interrupt as it is
-         impossible that any other interrupt has arrived during the
-         freeze. */
 int
 picinterrupt(void)
 {
@@ -909,7 +841,7 @@ picinterrupt(void)
                 exit(-1);
             }
 
-            pic.flags |= PIC_SLAVE_PENDING;
+            pic.interrupt |= 0x40; /* Mark slave pending. */
         }
 
         if ((pic.interrupt == 0) && (pit_devs[1].data != NULL))
@@ -921,13 +853,8 @@ picinterrupt(void)
             pic.ack_bytes = (pic.ack_bytes + 1) % (pic_i86_mode(&pic) ? 2 : 3);
 
             if (pic.ack_bytes == 0) {
-                if (pic.flags & PIC_SLAVE_PENDING) {
-                    pic2.flags &= ~PIC_FREEZE;
-                    pic_update_request(&pic2, pic2.interrupt & 0x07);
+                if (pic.interrupt & 0x40)
                     pic2.interrupt = 0x17;
-                }
-                pic.flags &= ~(PIC_SLAVE_PENDING | PIC_FREEZE);
-                pic_update_request(&pic, pic.interrupt & 0x07);
                 pic.interrupt = 0x17;
                 update_pending();
             }