diff --git a/.github/workflows/build_zeal8bitos.yml b/.github/workflows/build_zeal8bitos.yml
index 1a2042a..351ebdb 100644
--- a/.github/workflows/build_zeal8bitos.yml
+++ b/.github/workflows/build_zeal8bitos.yml
@@ -36,11 +36,7 @@ jobs:
       - name: Build Zeal 8-bit OS (zeal8bit target)
         shell: bash
         run: |
-          make alldefconfig
-          echo 'CONFIG_ENABLE_EMULATION_HOSTFS=y' >> os.conf
-          make asmconf
-          z88dk-z80asm
-          make
+          make config=configs/zealemu.default
           mv build/os_with_romdisk.img build/$(git describe --tags).img
 
       - name: Update index.json
diff --git a/Makefile b/Makefile
index 1ad39d4..660c75c 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,18 @@ ifndef PYTHON_BIN
 endif
 export PATH := $(realpath packer)/:$(PATH)
 # Kconfig related
-export KCONFIG_CONFIG = os.conf
+export KCONFIG_CONFIG = configs/zeal8bit.default
+ifneq ("$(wildcard os.conf)", "")
+    export KCONFIG_CONFIG = os.conf
+endif
+ifdef config
+    export KCONFIG_CONFIG = $(config)
+else
+	ifdef ZOS_CONFIG
+        export KCONFIG_CONFIG = $(ZOS_CONFIG)
+	endif
+endif
+
 export MENUCONFIG_STYLE = aquatic
 export OSCONFIG_ASM = include/osconfig.asm
 export ZOS_PATH := $(PWD)
@@ -88,7 +99,7 @@ endef
 # If the target is not defined, no os.conf file was created.
 # In that case, do not try to evaluate the build depenendies.
 ifdef CONFIG_TARGET
-$(eval $(call IMPORT_subunitmk,ASMSRCS,INCLUDEDIRS,PRECMD,POSTCMD))
+    $(eval $(call IMPORT_subunitmk,ASMSRCS,INCLUDEDIRS,PRECMD,POSTCMD))
 endif
 
 # Generate the .o files out of the .c files
@@ -103,11 +114,14 @@ LINKERFILE_BUILT=$(BINDIR)/$(LINKERFILE_OBJ)
 
 .PHONY: check menuconfig $(SUBDIRS) version packer asmconf
 
-all:$(KCONFIG_CONFIG) version packer precmd $(LINKERFILE_OBJ) $(OBJS)
+all:$(KCONFIG_CONFIG) asmconf version packer precmd $(LINKERFILE_OBJ) $(OBJS)
 	$(CC) $(ASMFLAGS) -o$(FULLBIN) -b -m -s $(LINKERFILE_BUILT) $(BUILTOBJS)
 	@mv $(BINDIR)/$(BIN_GENERATED) $(FULLBIN)
-	@echo "OS binary: $(FULLBIN)"
 	@echo "Executing post commands..."
+	@echo "Config: $(KCONFIG_CONFIG)"
+	@echo "Kernel Physical Address: $(CONFIG_KERNEL_PHYS_ADDRESS)"
+	@echo "Host FS: $(CONFIG_ENABLE_EMULATION_HOSTFS)"
+	@echo "OS binary: $(FULLBIN)"
 	$(POSTCMD)
 
 # Generate a version file that will be used as a boilerplate when the system starts
@@ -115,7 +129,7 @@ all:$(KCONFIG_CONFIG) version packer precmd $(LINKERFILE_OBJ) $(OBJS)
 version:
 	@echo Zeal 8-bit OS `git describe --tags` > version.txt
 	@[ -z "$(CONFIG_KERNEL_REPRODUCIBLE_BUILD)" ]  && \
-	 echo Build time: `date +"%Y-%m-%d %H:%M"` >> version.txt || true
+		echo Build time: `date +"%Y-%m-%d %H:%M"` >> version.txt || true
 
 packer:
 	@echo "Building packer"
@@ -147,13 +161,13 @@ check:
 #    DEFM "test", 0
 # ENDM
 define CONVERT_config_asm =
-    echo -e "IFNDEF OSCONFIG_H\nDEFINE OSCONFIG_H\n" > $2 && \
-    cat $1 | \
-    grep "^CONFIG_" | \
-    sed 's/=y/=1/g' | sed 's/=n/=0/g' | \
-    sed 's/\(.*\)=\(".*"\)/MACRO \1\n    DEFM \2\nENDM/g' | \
-    sed 's/^CONFIG/DEFC CONFIG/g' >> $2 && \
-    echo -e "\nENDIF" >> $2
+	echo -e "IFNDEF OSCONFIG_H\nDEFINE OSCONFIG_H\n" > $2 && \
+	cat $1 | \
+	grep "^CONFIG_" | \
+	sed 's/=y/=1/g' | sed 's/=n/=0/g' | \
+	sed 's/\(.*\)=\(".*"\)/MACRO \1\n    DEFM \2\nENDM/g' | \
+	sed 's/^CONFIG/DEFC CONFIG/g' >> $2 && \
+	echo -e "\nENDIF" >> $2
 endef
 
 asmconf: $(KCONFIG_CONFIG)
@@ -161,14 +175,12 @@ asmconf: $(KCONFIG_CONFIG)
 	@$(call CONVERT_config_asm,$(KCONFIG_CONFIG), $(OSCONFIG_ASM))
 
 menuconfig:
+	@test -e os.conf || cp $(KCONFIG_CONFIG) os.conf
+	$(eval export KCONFIG_CONFIG = os.conf)
 	$(MENUCONFIG)
-	@echo "Converting $(KCONFIG_CONFIG) to $(OSCONFIG_ASM) ..."
-	@$(call CONVERT_config_asm,$(KCONFIG_CONFIG), $(OSCONFIG_ASM))
 
 alldefconfig:
 	$(ALLDEFCONFIG)
-	@echo "Converting $(KCONFIG_CONFIG) to $(OSCONFIG_ASM) ..."
-	@$(call CONVERT_config_asm,$(KCONFIG_CONFIG), $(OSCONFIG_ASM))
 
 prepare_dirs:
 	@mkdir -p $(BINDIR)
@@ -180,4 +192,4 @@ fdump:
 	$(DISASSEMBLER) -o 0x0000 -x $(BINDIR)/$(MAPFILE) $(BINDIR)/$(BIN) > $(BINDIR)/os.dump
 
 clean:
-	rm -rf $(OSCONFIG_ASM) $(BINDIR) $(KCONFIG_CONFIG) version.txt
+	rm -rf $(OSCONFIG_ASM) $(BINDIR) version.txt
diff --git a/configs/zeal8bit.default b/configs/zeal8bit.default
new file mode 100644
index 0000000..7cf1d6f
--- /dev/null
+++ b/configs/zeal8bit.default
@@ -0,0 +1,52 @@
+CONFIG_CPU_FREQ=10000000
+CONFIG_TARGET="zeal8bit"
+CONFIG_TARGET_ZEAL_8_BIT=y
+# CONFIG_TARGET_TRS_80 is not set
+# CONFIG_TARGET_AGON_LIGHT is not set
+
+#
+# Zeal 8-bit Computer configuration
+#
+CONFIG_TARGET_NUMBER=1
+CONFIG_TARGET_HAS_MMU=y
+CONFIG_TARGET_HAS_DRIVERS_HOOK=y
+CONFIG_KERNEL_RAM_PHYS_ADDRESS=0x88000
+CONFIG_ROMDISK_ADDRESS=0x8000
+CONFIG_KERNEL_PHYS_ADDRESS=0x4000
+CONFIG_KERNEL_TARGET_HAS_MMU=y
+CONFIG_TARGET_ENABLE_COMPACTFLASH=y
+
+#
+# CompactFlash driver configuration
+#
+CONFIG_TARGET_COMPACTFLASH_ADDRESS=0x70
+CONFIG_TARGET_COMPACTFLASH_TIMEOUT=30
+# end of CompactFlash driver configuration
+
+# CONFIG_ENABLE_EMULATION_HOSTFS is not set
+CONFIG_TARGET_ENABLE_VIDEO=y
+CONFIG_TARGET_STDOUT_VIDEO=y
+# CONFIG_TARGET_STDOUT_UART is not set
+CONFIG_TARGET_KEYBOARD_QWERTY=y
+# CONFIG_TARGET_KEYBOARD_DVORAK is not set
+# end of Zeal 8-bit Computer configuration
+
+#
+# Kernel configuration
+#
+# CONFIG_KERNEL_REPRODUCIBLE_BUILD is not set
+CONFIG_KERNEL_STACK_ADDR=0xFFFF
+CONFIG_KERNEL_RAM_START=0xC000
+# CONFIG_KERNEL_COLDBOOT_HOOK is not set
+# CONFIG_KERNEL_EXIT_HOOK is not set
+CONFIG_KERNEL_DRIVERS_HOOK=y
+CONFIG_KERNEL_MAX_NESTED_PROGRAMS=3
+CONFIG_KERNEL_MAX_LOADED_DRIVERS=16
+CONFIG_KERNEL_MAX_OPENED_DEVICES=16
+CONFIG_KERNEL_MAX_OPENED_FILES=16
+CONFIG_KERNEL_PATH_MAX=128
+CONFIG_KERNEL_INIT_EXECUTABLE="A:/init.bin"
+CONFIG_KERNEL_INIT_EXECUTABLE_ADDR=0x4000
+CONFIG_KERNEL_LOG_BOOT_MOUNTED_DISKS=y
+CONFIG_KERNEL_ENABLE_ZEALFS_SUPPORT=y
+# end of Kernel configuration
diff --git a/configs/zealemu.default b/configs/zealemu.default
new file mode 100644
index 0000000..0ffca1f
--- /dev/null
+++ b/configs/zealemu.default
@@ -0,0 +1,52 @@
+CONFIG_CPU_FREQ=10000000
+CONFIG_TARGET="zeal8bit"
+CONFIG_TARGET_ZEAL_8_BIT=y
+# CONFIG_TARGET_TRS_80 is not set
+# CONFIG_TARGET_AGON_LIGHT is not set
+
+#
+# Zeal 8-bit Computer configuration
+#
+CONFIG_TARGET_NUMBER=1
+CONFIG_TARGET_HAS_MMU=y
+CONFIG_TARGET_HAS_DRIVERS_HOOK=y
+CONFIG_KERNEL_RAM_PHYS_ADDRESS=0x88000
+CONFIG_ROMDISK_ADDRESS=0x8000
+CONFIG_KERNEL_PHYS_ADDRESS=0x0000
+CONFIG_KERNEL_TARGET_HAS_MMU=y
+CONFIG_TARGET_ENABLE_COMPACTFLASH=y
+
+#
+# CompactFlash driver configuration
+#
+CONFIG_TARGET_COMPACTFLASH_ADDRESS=0x70
+CONFIG_TARGET_COMPACTFLASH_TIMEOUT=30
+# end of CompactFlash driver configuration
+
+CONFIG_ENABLE_EMULATION_HOSTFS=y
+CONFIG_TARGET_ENABLE_VIDEO=y
+CONFIG_TARGET_STDOUT_VIDEO=y
+# CONFIG_TARGET_STDOUT_UART is not set
+CONFIG_TARGET_KEYBOARD_QWERTY=y
+# CONFIG_TARGET_KEYBOARD_DVORAK is not set
+# end of Zeal 8-bit Computer configuration
+
+#
+# Kernel configuration
+#
+# CONFIG_KERNEL_REPRODUCIBLE_BUILD is not set
+CONFIG_KERNEL_STACK_ADDR=0xFFFF
+CONFIG_KERNEL_RAM_START=0xC000
+# CONFIG_KERNEL_COLDBOOT_HOOK is not set
+# CONFIG_KERNEL_EXIT_HOOK is not set
+CONFIG_KERNEL_DRIVERS_HOOK=y
+CONFIG_KERNEL_MAX_NESTED_PROGRAMS=3
+CONFIG_KERNEL_MAX_LOADED_DRIVERS=16
+CONFIG_KERNEL_MAX_OPENED_DEVICES=16
+CONFIG_KERNEL_MAX_OPENED_FILES=16
+CONFIG_KERNEL_PATH_MAX=128
+CONFIG_KERNEL_INIT_EXECUTABLE="A:/init.bin"
+CONFIG_KERNEL_INIT_EXECUTABLE_ADDR=0x4000
+CONFIG_KERNEL_LOG_BOOT_MOUNTED_DISKS=y
+CONFIG_KERNEL_ENABLE_ZEALFS_SUPPORT=y
+# end of Kernel configuration