diff --git a/utils/BACKZXD b/utils/BACKZXD
deleted file mode 100644
index 4f63efa..0000000
Binary files a/utils/BACKZXD and /dev/null differ
diff --git a/utils/Makefile b/utils/Makefile
index 1cd1841..c26cc5e 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -20,6 +20,7 @@ AFLAGS		= --nobanner
 TARGETS=\
  BACK16M\
  BACKZX2\
+ BACKZXD\
  BACKUP\
  CORCLEAN\
  COREBIOS\
@@ -27,6 +28,7 @@ TARGETS=\
  ROMSUPGR\
  UPGR16M\
  UPGRZX2\
+ UPGRZXD\
  UPGRADE
 
 .PHONY: all
@@ -43,7 +45,16 @@ $(BUILD_DIR)/BACK16M: back16m.asm\
 $(BUILD_DIR)/BACKZX2: back32m.asm\
  zxuno.inc\
  | $(BUILD_DIR)
+	echo ' define zxdos 1' >back32m.def
 	$(AS) $(AFLAGS) --raw=$@ $<
+	rm -f back32m.def
+
+$(BUILD_DIR)/BACKZXD: back32m.asm\
+ zxuno.inc\
+ | $(BUILD_DIR)
+	echo ' define zxdos 0' >back32m.def
+	$(AS) $(AFLAGS) --raw=$@ $<
+	rm -f back32m.def
 
 $(BUILD_DIR)/BACKUP: backup.asm\
  zxuno.inc\
@@ -78,7 +89,16 @@ $(BUILD_DIR)/UPGR16M: upgr16m.asm\
 $(BUILD_DIR)/UPGRZX2: upgr32m.asm\
  zxuno.inc\
  | $(BUILD_DIR)
+	echo ' define zxdos 1' >upgr32m.def
 	$(AS) $(AFLAGS) --raw=$@ $<
+	rm -f upgr32m.def
+
+$(BUILD_DIR)/UPGRZXD: upgr32m.asm\
+ zxuno.inc\
+ | $(BUILD_DIR)
+	echo ' define zxdos 0' >upgr32m.def
+	$(AS) $(AFLAGS) --raw=$@ $<
+	rm -f upgr32m.def
 
 $(BUILD_DIR)/UPGRADE: upgrade.asm\
  zxuno.inc\
@@ -87,4 +107,5 @@ $(BUILD_DIR)/UPGRADE: upgrade.asm\
 
 .PHONY: clean
 clean:
+	rm -f back32m.def upgr32m.def
 	rm -f $(foreach t,$(TARGETS),$(BUILD_DIR)/$(t))
diff --git a/utils/UPGRZXD b/utils/UPGRZXD
deleted file mode 100644
index 226010f..0000000
Binary files a/utils/UPGRZXD and /dev/null differ
diff --git a/utils/back32m.asm b/utils/back32m.asm
index cb5ad67..e288054 100644
--- a/utils/back32m.asm
+++ b/utils/back32m.asm
@@ -7,6 +7,7 @@
 ; wrongly set to 0.
 ;
 ; Copyright (C) 2019, 2021 Antonio Villena
+; Contributor: 2021 Ivan Tatarinov <ivan-tat@ya.ru>
 ;
 ; This program is free software: you can redistribute it and/or modify
 ; it under the terms of the GNU General Public License as published by
@@ -22,12 +23,15 @@
 ;
 ; SPDX-FileCopyrightText: Copyright (C) 2019, 2021 Antonio Villena
 ;
+; SPDX-FileContributor: 2021 Ivan Tatarinov <ivan-tat@ya.ru>
+;
 ; SPDX-License-Identifier: GPL-3.0-only
 
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                define  zxdos 1
+                ; definition of "zxdos" flag
+		include back32m.def
 
               IF zxdos=1
                 output  BACKZX2
diff --git a/utils/upgr32m.asm b/utils/upgr32m.asm
index e277cd4..c11f59e 100644
--- a/utils/upgr32m.asm
+++ b/utils/upgr32m.asm
@@ -4,6 +4,7 @@
 ; It must be run while using a "root" mode ROM.
 ;
 ; Copyright (C) 2019, 2021 Antonio Villena
+; Contributor: 2021 Ivan Tatarinov <ivan-tat@ya.ru>
 ;
 ; This program is free software: you can redistribute it and/or modify
 ; it under the terms of the GNU General Public License as published by
@@ -19,12 +20,15 @@
 ;
 ; SPDX-FileCopyrightText: Copyright (C) 2019, 2021 Antonio Villena
 ;
+; SPDX-FileContributor: 2021 Ivan Tatarinov <ivan-tat@ya.ru>
+;
 ; SPDX-License-Identifier: GPL-3.0-only
 
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                define  zxdos 1
+                ; definition of "zxdos" flag
+                include upgr32m.def
 
               IF zxdos=1
                 output  UPGRZX2