Added Zenith Data SupersPort. Based on patch from Tux.

src/zenith.c

@@ -0,0 +1,50 @@
+#include <stdlib.h>
+#include "ibm.h"
+#include "device.h"
+#include "mem.h"
+#include "zenith.h"
+
+static uint8_t *zenith_scratchpad_ram;
+static mem_mapping_t zenith_scratchpad_mapping;
+
+static uint8_t zenith_scratchpad_read(uint32_t addr, void *p)
+{
+        return zenith_scratchpad_ram[addr & 0x3fff];
+}
+static void zenith_scratchpad_write(uint32_t addr, uint8_t val, void *p)
+{
+        zenith_scratchpad_ram[addr & 0x3fff] = val;
+}
+
+static void *zenith_scratchpad_init()
+{
+        zenith_scratchpad_ram = malloc(0x4000);
+
+        mem_mapping_disable(&bios_mapping[4]);
+        mem_mapping_disable(&bios_mapping[5]);
+        
+        mem_mapping_add(&zenith_scratchpad_mapping, 0xf0000, 0x4000,
+                        zenith_scratchpad_read, NULL, NULL,
+                        zenith_scratchpad_write, NULL, NULL,
+                        zenith_scratchpad_ram,  MEM_MAPPING_EXTERNAL, NULL);
+
+        return zenith_scratchpad_ram;
+}
+
+static void zenith_scratchpad_close(void *p)
+{
+        free(p);
+}
+
+device_t zenith_scratchpad_device =
+{
+        "Zenith scratchpad RAM",
+        0,
+        zenith_scratchpad_init,
+        zenith_scratchpad_close,
+        NULL,
+        NULL,
+        NULL,
+        NULL,
+        NULL
+};