diff --git a/sdk/include/rst28.mac b/sdk/include/rst28.mac
new file mode 100644
index 0000000..68cd441
--- /dev/null
+++ b/sdk/include/rst28.mac
@@ -0,0 +1,18 @@
+; rst28.mac - macros definition for `rst28.inc'.
+;
+; SPDX-FileCopyrightText: Copyright (C) 2019, 2021 Antonio Villena
+;
+; SPDX-License-Identifier: GPL-3.0-only
+
+; Compatible compilers:
+;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
+
+ ifndef rst28_mac_included
+ define rst28_mac_included
+
+ macro wreg dir, dato
+        call    rst28
+        defb    dir, dato
+ endm
+
+ endif  ; !rst28_mac_included
diff --git a/sdk/include/zxuno.def b/sdk/include/zxuno.def
index f5faa92..3e03e2f 100644
--- a/sdk/include/zxuno.def
+++ b/sdk/include/zxuno.def
@@ -43,9 +43,4 @@
         define  CMD55           $77
         define  CMD58           $7a
 
-              macro wreg  dir, dato
-                call    rst28
-                defb    dir, dato
-              endm
-
  endif  ; !zxuno_def_included
diff --git a/utils/Makefile b/utils/Makefile
index 3c7de30..24c2b0b 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -70,6 +70,7 @@ $(DESTDIR)$(bindir):
 build/BACK16M: $(srcdir)/back16m.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -79,6 +80,7 @@ build/BACK16M: $(srcdir)/back16m.asm\
 build/BACKZX2: $(srcdir)/back32m.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -90,6 +92,7 @@ build/BACKZX2: $(srcdir)/back32m.asm\
 build/BACKZXD: $(srcdir)/back32m.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -101,6 +104,7 @@ build/BACKZXD: $(srcdir)/back32m.asm\
 build/BACKUP: $(srcdir)/backup.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -109,6 +113,7 @@ build/BACKUP: $(srcdir)/backup.asm\
 
 build/CORCLEAN: $(srcdir)/corclean.asm\
  $(INCLUDEDIR)/zxuno.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/wrflsh.inc\
@@ -119,6 +124,7 @@ build/CORCLEAN: $(srcdir)/corclean.asm\
 build/COREBIOS: $(srcdir)/corebios.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/wrflsh.inc\
@@ -129,6 +135,7 @@ build/COREBIOS: $(srcdir)/corebios.asm\
 build/ROMSBACK: $(srcdir)/romsback.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -138,6 +145,7 @@ build/ROMSBACK: $(srcdir)/romsback.asm\
 build/ROMSUPGR: $(srcdir)/romsupgr.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/rdflsh.inc\
  $(INCLUDEDIR)/wrflsh.inc\
@@ -148,6 +156,7 @@ build/ROMSUPGR: $(srcdir)/romsupgr.asm\
 build/UPGR16M: $(srcdir)/upgr16m.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/wrflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -157,6 +166,7 @@ build/UPGR16M: $(srcdir)/upgr16m.asm\
 build/UPGRZX2: $(srcdir)/upgr32m.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/wrflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
@@ -179,6 +189,7 @@ build/UPGRZXD: $(srcdir)/upgr32m.asm\
 build/UPGRADE: $(srcdir)/upgrade.asm\
  $(INCLUDEDIR)/zxuno.def\
  $(INCLUDEDIR)/esxdos.def\
+ $(INCLUDEDIR)/rst28.mac\
  $(INCLUDEDIR)/Print.inc\
  $(INCLUDEDIR)/wrflsh.inc\
  $(INCLUDEDIR)/rst28.inc\
diff --git a/utils/back16m.asm b/utils/back16m.asm
index bb42666..44c1b5a 100644
--- a/utils/back16m.asm
+++ b/utils/back16m.asm
@@ -32,10 +32,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  BACK16M
+;               output  BACK16M
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  FLASH_FILE "FLASH.ZX1"
diff --git a/utils/back32m.asm b/utils/back32m.asm
index 86f14c7..7240c67 100644
--- a/utils/back32m.asm
+++ b/utils/back32m.asm
@@ -36,14 +36,15 @@
                 ; definition of "zxdos" flag
                 include back32m.def
 
-              IF zxdos=1
-                output  BACKZX2
-              ELSE
-                output  BACKZXD
-              ENDIF
+;             IF zxdos=1
+;               output  BACKZX2
+;             ELSE
+;               output  BACKZXD
+;             ENDIF
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1.1"
               IF zxdos=1
diff --git a/utils/backup.asm b/utils/backup.asm
index 2bcf18b..f71ca38 100644
--- a/utils/backup.asm
+++ b/utils/backup.asm
@@ -27,10 +27,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  BACKUP
+;               output  BACKUP
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  FLASH_FILE "FLASH.ZX1"
diff --git a/utils/corclean.asm b/utils/corclean.asm
index 48effb6..4b907ca 100644
--- a/utils/corclean.asm
+++ b/utils/corclean.asm
@@ -25,9 +25,10 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  CORCLEAN
+;               output  CORCLEAN
 
                 include zxuno.def
+                include rst28.mac
 
         define  VERSION "0.1"
 ;        define  ROMS_FILE "ROMS.ZX1"
diff --git a/utils/corebios.asm b/utils/corebios.asm
index b43af43..c2dca69 100644
--- a/utils/corebios.asm
+++ b/utils/corebios.asm
@@ -25,10 +25,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  COREBIOS
+;               output  COREBIOS
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  CORE_FILE "SPECTRUM.ZX1"
diff --git a/utils/romsback.asm b/utils/romsback.asm
index bdf1c6d..f52eb23 100644
--- a/utils/romsback.asm
+++ b/utils/romsback.asm
@@ -32,10 +32,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  ROMSBACK
+;               output  ROMSBACK
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  ROMS_FILE "ROMS.ZX1"
diff --git a/utils/romsupgr.asm b/utils/romsupgr.asm
index b07802e..0e3d3ee 100644
--- a/utils/romsupgr.asm
+++ b/utils/romsupgr.asm
@@ -29,10 +29,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  ROMSUPGR
+;               output  ROMSUPGR
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  ROMS_FILE "ROMS.ZX1"
diff --git a/utils/upgr16m.asm b/utils/upgr16m.asm
index b08bfa8..212f65b 100644
--- a/utils/upgr16m.asm
+++ b/utils/upgr16m.asm
@@ -28,10 +28,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  UPGR16M
+;               output  UPGR16M
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  FLASH_FILE "FLASH.ZX1"
diff --git a/utils/upgr32m.asm b/utils/upgr32m.asm
index b198477..363da9f 100644
--- a/utils/upgr32m.asm
+++ b/utils/upgr32m.asm
@@ -33,14 +33,15 @@
                 ; definition of "zxdos" flag
                 include upgr32m.def
 
-              IF zxdos=1
-                output  UPGRZX2
-              ELSE
-                output  UPGRZXD
-              ENDIF
+;             IF zxdos=1
+;               output  UPGRZX2
+;             ELSE
+;               output  UPGRZXD
+;             ENDIF
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1.1"
               IF zxdos=1
diff --git a/utils/upgrade.asm b/utils/upgrade.asm
index 69f2a3e..d784f4a 100644
--- a/utils/upgrade.asm
+++ b/utils/upgrade.asm
@@ -25,10 +25,11 @@
 ; Compatible compilers:
 ;   SJAsmPlus, <https://github.com/sjasmplus/sjasmplus/>
 
-                output  UPGRADE
+;               output  UPGRADE
 
                 include zxuno.def
                 include esxdos.def
+                include rst28.mac
 
         define  VERSION "0.1"
         define  FLASH_FILE "FLASH.ZX1"