neo6502: Output .neo file format (#344) (#345)

mos-platform/neo6502/link.ld

@@ -7,7 +7,7 @@ ASSERT(__rc31 == 0x001f, "Inconsistent zero page map.")
 
 MEMORY {
     zp : ORIGIN = __rc31 + 1, LENGTH = 0x100 - (__rc31 + 1)
-    ram (rw) : ORIGIN = 0x0800, LENGTH = 0xf600 - 0x0800
+    ram (rw) : ORIGIN = 0x0200, LENGTH = 0xf600 - 0x0200
 }
 
 REGION_ALIAS("c_readonly", ram)
@@ -26,6 +26,21 @@ SECTIONS {
 /* Set initial soft stack address to just above last memory address. (It grows down.) */
 __stack = 0xf600;
 
+/*
+ * .neo file format
+ * http://neo6502.com/reference/formats/#neo-load-file-format
+ */
 OUTPUT_FORMAT {
+    BYTE(0x03)          /* magic cookie (not a valid 65c02 opcode) */
+    BYTE(0x4E)          /* 'N' */
+    BYTE(0x45)          /* 'E' */
+    BYTE(0x4F)          /* 'O' */
+    BYTE(0x00)          /* min version - major */
+    BYTE(0x00)          /* min version - minor */
+    SHORT(_start)       /* execute address */
+    BYTE(0x00)          /* ctrl bits. bit 7=another block follows */
+    SHORT(ORIGIN(ram))  /* load address */
+    SHORT(__data_end - ORIGIN(ram))  /* size in bytes */
+    BYTE(0x00)          /* string - comment, filename, whatever */
     TRIM(ram)
 }