linker: ensured .bss comes after .data, and added map file output

.gitignore

@@ -11,6 +11,6 @@
 *.srec
 *.s19
 *.elf
-
+*.map
 AGENTS.md
 .pre-commit-config.yaml

Makefile

@@ -2,9 +2,10 @@
 # SPDX-FileCopyrightText: (c) 2025 A.M. Rowsell
 ASM=vasm_z80_std
 LINK=vlink
+MAP=zone.map
 
 ASMFLAGS=-Fvobj
-LINKFLAGS=-b ihex -T linker.cmd
+LINKFLAGS=-b ihex -T linker.cmd -M
 
 all: zone.hex
 
@@ -21,9 +22,9 @@ boot.o: boot.asm
 	$(ASM) $(ASMFLAGS) -o $@ $<
 
 zone.hex: float.o vectorTable.o zone.o boot.o linker.cmd
-	$(LINK) $(LINKFLAGS) -o $@ float.o vectorTable.o zone.o boot.o
+	$(LINK) $(LINKFLAGS) -o $@ float.o vectorTable.o zone.o boot.o > $(MAP)
 
 clean:
-	rm -f float.o vectorTable.o zone.o boot.o zone.hex
+	rm -f float.o vectorTable.o zone.o boot.o zone.hex $(MAP)
 
 .PHONY: all clean

boot.asm

@@ -5,6 +5,10 @@
 .global os_warm_boot
 .extern os_main_loop
 
+; ==================================
+; This is the cold boot entry point!
+; It is linked to land at 0xC3C3
+; ==================================
 zone_setup:
     ld sp, 0x6FFF
     jp os_main_loop

linker.cmd

@@ -6,5 +6,6 @@ SECTIONS
   .boot     0xC3C3 : { *(.boot) *(boot) }
   .vectors  0xF000 : { *(.vectors) }
   .data     0x7000 : { *(.data) }
-  .bss            : { *(.bss)  }
+  __data_end = .;
+  .bss      __data_end : { *(.bss)  }
 }