Fixed the "minor bug fix" in the AT / PS/2 keyboard controller, reworked PS/2 keyboard controller IRQ latches, and correctly disabled memory top remaps if there's more than (16 MB - remap size) RAM (fixes segmentation faults on some machines with 16+ MB of RAM).

src/chipset/intel_sio.c

@@ -27,6 +27,7 @@
 #include <86box/dma.h>
 #include <86box/mem.h>
 #include <86box/pci.h>
+#include <86box/pic.h>
 #include <86box/timer.h>
 #include <86box/pit.h>
 #include <86box/port_92.h>
@@ -201,6 +202,7 @@ sio_write(int func, int addr, uint8_t val, void *priv)
         case 0x4c:
         case 0x4d:
             dev->regs[addr] = (val & 0x7f);
+            pic_mouse_latch(!!(val & 0x10));
             break;
         case 0x4f:
             dev->regs[addr] = val;
@@ -392,6 +394,7 @@ sio_reset_hard(void *priv)
     dev->regs[0x4b] = 0x0f;
     dev->regs[0x4c] = 0x56;
     dev->regs[0x4d] = 0x40;
+    pic_mouse_latch(0x00);
     dev->regs[0x4e] = 0x07;
     dev->regs[0x4f] = 0x4f;
     dev->regs[0x57] = 0x04;
@@ -444,6 +447,9 @@ sio_reset(void *p)
 {
     sio_t *dev = (sio_t *) p;
 
+    /* Disable the PIC mouse latch. */
+    sio_write(0, 0x4d, 0x40, p);
+
     sio_write(0, 0x57, 0x04, p);
 
     dma_set_params(1, 0xffffffff);
@@ -538,6 +544,8 @@ sio_init(const device_t *info)
 
     // device_add(&i8254_sec_device);
 
+    pic_kbd_latch(0x01);
+
     return dev;
 }