diff --git a/avr/common/utils_io.asm b/avr/common/utils_io.asm
index 8309a1e..e9f3a1f 100644
--- a/avr/common/utils_io.asm
+++ b/avr/common/utils_io.asm
@@ -7,7 +7,7 @@
 ; * Please see toplevel file COPYING of that project for license details.   *
 ; ***************************************************************************
 
-
+#if 0
 ; M_IO_READ DEST, SRC
 .macro M_IO_READ
 .if @1 < 64
@@ -27,3 +27,26 @@
   sts @0, @1
 .endif
 .endmacro
+
+#endif
+
+
+; inr DEST, SRC
+.macro inr
+.if @1 < 64
+  in @0, @1
+.else
+  lds @0, @1
+.endif
+.endmacro
+
+
+
+; outr DEST, SRC
+.macro outr
+.if @0 < 64
+  out @0, @1
+.else
+  sts @0, @1
+.endif
+.endmacro
diff --git a/avr/devices/all/hw_m8515.asm b/avr/devices/all/hw_m8515.asm
index 040bc8e..f5cc047 100644
--- a/avr/devices/all/hw_m8515.asm
+++ b/avr/devices/all/hw_m8515.asm
@@ -69,25 +69,25 @@ systemSleep:
   ; only modify SE, SM2, SM1 and SM0
   cli
 
-  M_IO_READ r16, MCUCR
+  inr r16, MCUCR
   cbr r16, (1<<SE) | (1<<SM2) | (1<<SM1)
-  M_IO_WRITE MCUCR, r16
+  outr MCUCR, r16
 
-  M_IO_READ r16, EMCUCR
+  inr r16, EMCUCR
   cbr r16, (1<<SM0)
-  M_IO_WRITE EMCUCR, r16
+  outr EMCUCR, r16
 
   sei                        ; make sure interrupts really are enabled
 
-  M_IO_READ r16, MCUCR       ; enable sleep mode
+  inr r16, MCUCR       ; enable sleep mode
   sbr r16, (1<<SE)
-  M_IO_WRITE MCUCR, r16
+  outr MCUCR, r16
 
   sleep                      ; sleep, wait for interrupt
 
-  M_IO_READ r16, MCUCR       ; disable sleep mode
+  inr r16, MCUCR       ; disable sleep mode
   cbr r16, (1<<SE)
-  M_IO_WRITE MCUCR, r16
+  outr MCUCR, r16
 
   ret
 ; @end
@@ -140,13 +140,13 @@ systemSetupTimer0:            ; setup timer for IRQ every 100ms
 .endif
   
 .ifdef TIMSK0
-  M_IO_READ r16, TIMSK0
+  inr r16, TIMSK0
   sbr r16, (1<<OCIE0)        ; Timer/Counter0 Output Compare Match A Interrupt Enable
-  M_IO_WRITE TIMSK0, r16
+  outr TIMSK0, r16
 .else
-  M_IO_READ r16, TIMSK
+  inr r16, TIMSK
   sbr r16, (1<<OCIE0)        ; Timer/Counter0 Output Compare Match A Interrupt Enable
-  M_IO_WRITE TIMSK, r16
+  outr TIMSK, r16
 .endif
 
   sec
diff --git a/avr/modules/spi_hw/main.asm b/avr/modules/spi_hw/main.asm
index ea6fd7b..b8cfab4 100644
--- a/avr/modules/spi_hw/main.asm
+++ b/avr/modules/spi_hw/main.asm
@@ -93,13 +93,13 @@ SPIHW_MasterStart:
   sbrc r16, SPIHW_MODE_SPEED1_BIT
     sbr r17, (1<<SPR1)
   sbr r17, (1<<SPE) | (1<<MSTR)
-  M_IO_WRITE SPCR, r17
+  outr SPCR, r17
   
   ; setup SPSR
   clr r17
   sbrc r16, SPIHW_MODE_DOUBLESPEED_BIT
     sbr r17, (1<<SPI2X)
-  M_IO_WRITE SPSR, r17
+  outr SPSR, r17
   
   ret
 ; @end
@@ -115,9 +115,9 @@ SPIHW_MasterStart:
 
 SPIHW_MasterStop:
 ;  sbi SPIHW_SS_OUTPUT, SPIHW_SS_PIN   ; SS high
-  M_IO_READ r16, SPCR
+  inr r16, SPCR
   cbr r16, (1<<SPE)
-  M_IO_WRITE SPCR, r16
+  outr SPCR, r16
   ret
 ; @end
 
@@ -176,7 +176,7 @@ SPIHW_MasterTransfer:
 ; @clobbers none
 
 SPIHW_MasterSendByte:
-  M_IO_WRITE SPDR, r16
+  outr SPDR, r16
   ret
 ; @end
 
@@ -191,10 +191,10 @@ SPIHW_MasterSendByte:
 ; @clobbers none
 
 SPIHW_WaitForTransferComplete:
-    M_IO_READ r16, SPSR
+    inr r16, SPSR
     sbrs r16, SPIF
   rjmp SPIHW_WaitForTransferComplete
-  M_IO_READ r16, SPDR
+  inr r16, SPDR
   ret
 ; @end
 
diff --git a/avr/modules/uart_hw/attn.asm b/avr/modules/uart_hw/attn.asm
index 6217f57..faf404c 100644
--- a/avr/modules/uart_hw/attn.asm
+++ b/avr/modules/uart_hw/attn.asm
@@ -23,10 +23,13 @@
 ATTN_Init:
 .ifdef INT0
   .if COM_IRQ_BIT_ATTN == INT0
-    M_IO_READ r16, MCUCR
+    inr r16, MCUCR
     cbr r16, (1<<ISC01) | (1<<ISC00)
     sbr r16, (1<<ISC01) | (0<<ISC00)        ; falling edge of ATTN
+    outr MCUCR, r16
   ;  sbr r16, (0<<ISC01) | (0<<ISC00)         ; low level triggers
+  .endif
+.endif
   
   rcall ATTN_SetHighEnableIrq
   
@@ -44,9 +47,9 @@ ATTN_Init:
 ATTN_SetLowDisableIrq:
 .ifdef INT0
   .if COM_IRQ_BIT_ATTN == INT0
-    M_IO_READ r16, COM_IRQ_ADDR_ATTN        ; disable irq for ATTN line
+    inr r16, COM_IRQ_ADDR_ATTN        ; disable irq for ATTN line
     cbr r16, (1<<COM_IRQ_BIT_ATTN)
-    M_IO_WRITE COM_IRQ_ADDR_ATTN, r16
+    outr COM_IRQ_ADDR_ATTN, r16
   .endif
 .endif
 
@@ -73,9 +76,9 @@ ATTN_SetHighEnableIrq:
 
 .ifdef INT0
   .if COM_IRQ_BIT_ATTN == INT0
-    M_IO_READ r16, COM_IRQ_ADDR_ATTN        ; enable irq for ATTN line
+    inr r16, COM_IRQ_ADDR_ATTN             ; enable irq for ATTN line
     sbr r16, (1<<COM_IRQ_BIT_ATTN)
-    M_IO_WRITE COM_IRQ_ADDR_ATTN, r16
+    outr COM_IRQ_ADDR_ATTN, r16
   .endif
 .endif
 
diff --git a/avr/modules/uart_hw/uart.asm b/avr/modules/uart_hw/uart.asm
index 6dff0d9..ac77876 100644
--- a/avr/modules/uart_hw/uart.asm
+++ b/avr/modules/uart_hw/uart.asm
@@ -38,16 +38,17 @@ UART_Init:
   ldi r17, 0  
 .endif
 
-  M_IO_WRITE UBRRH, r17
-  M_IO_WRITE UBRRL, r16
+  outr UBRRH, r17
+  outr UBRRL, r16
 
   ; set character format 
 .ifdef URSEL
-  ldi r16, (1<<URSEL) | (1<<USBS) | (1<<UCSZ1) | (1<<UCSZ0)
+;  ldi r16, (1<<URSEL) | (1<<USBS) | (1<<UCSZ1) | (1<<UCSZ0)
+  ldi r16, (1<<URSEL) | (1<<USBS) | (3<<UCSZ0)
 .else
   ldi r16, (1<<USBS) | (1<<UCSZ1) | (1<<UCSZ0)
 .endif
-  M_IO_WRITE UCSRC, r16
+  outr UCSRC, r16
 
   ret
 ; @end
@@ -69,16 +70,16 @@ UART_SendBytes:
   
   ; send bytes
 UART_SendBytes_loop1:
-      M_IO_READ r16, UCSRA
+      inr r16, UCSRA
       sbrs r16, UDRE
     rjmp UART_SendBytes_loop1
     ld r16, X+
-    M_IO_WRITE UDR, r16
+    outr UDR, r16
     dec r17
   brne UART_SendBytes_loop1
   ; wait until all data sent
 UART_SendBytes_loop2:
-    M_IO_READ r16, UCSRA
+    inr r16, UCSRA
     sbrs r16, TXC
   rjmp UART_SendBytes_loop2
   rcall UART_StopTx
@@ -100,7 +101,7 @@ UART_SendBytes_secRet:
 UART_RecvPacket:
   cpi r17, 3
   brcs UART_RecvPacket_invalid
-  rcall uartRecvByteWithin10ms   ; recv destination address
+  rcall uartRecvByteWithin10ms   ; recv destination address (R16)
   brcc UART_RecvPacket_ioError
   cp r16, r18
   breq UART_RecvPacket_forMe
@@ -158,10 +159,10 @@ uartRecvByteWithin10ms:
     pop r22
   pop r20
   brcc uartRecvByteWithin10ms_end
-  M_IO_READ r16, UCSRA                              ; check for errors
+  inr r16, UCSRA                              ; check for errors
   andi r16, (1<<FE) | (1<<DOR)
   brne uartRecvByteWithin10ms_error
-  M_IO_READ r16, UDR                               ; read data byte
+  inr r16, UDR                                ; read data byte
   sec
   ret
 uartRecvByteWithin10ms_error:
@@ -213,7 +214,7 @@ uartWaitForData10ms_gotit:
 uartWaitForData1000Cycles:
   ldi r20, 140                         ; 1
 uartWaitForData_loop:
-    M_IO_READ r22, UCSRA               ; 2
+    inr r22, UCSRA               ; 2
     sbrc r22, RXC                      ; 2/3
       rjmp uartWaitForData_gotit       ; 2
     dec r20                            ; 1
@@ -235,14 +236,14 @@ uartWaitForData_gotit:
 ; @clobbers R16
 
 UART_StartRx:
-  M_IO_READ r16, UCSRA                      ; clear errors
+  inr r16, UCSRA                      ; clear errors
   cbr r16, (1<<FE) | (1<<DOR) | (1<<UPE)
   sbr r16, (1<<RXC)
-  M_IO_WRITE UCSRA, r16
+  outr UCSRA, r16
 
-  M_IO_READ r16, UCSRB
+  inr r16, UCSRB
   sbr r16, (1<<RXEN)  ; enable receive
-  M_IO_WRITE UCSRB, r16
+  outr UCSRB, r16
 
   ret
 ; @end
@@ -255,9 +256,9 @@ UART_StartRx:
 ; @clobbers R16
 
 UART_StopRx:
-  M_IO_READ r16, UCSRB
+  inr r16, UCSRB
   cbr r16, (1<<RXCIE | (1<<RXEN))   ; disable RX complete interrupt, disable receive
-  M_IO_WRITE UCSRB, r16
+  outr UCSRB, r16
   ret
 ; @end
 
@@ -270,13 +271,13 @@ UART_StopRx:
 ; @clobbers R16
 
 UART_StartTx:
-  M_IO_READ r16, UCSRA
+  inr r16, UCSRA
   sbr r16, (1<<TXC)      ; clear TXC interrupt
-  M_IO_WRITE UCSRA, r16
+  outr UCSRA, r16
 
-  M_IO_READ r16, UCSRB
+  inr r16, UCSRB
   sbr r16, (1<<TXEN)     ; enable transceive
-  M_IO_WRITE UCSRB, r16
+  outr UCSRB, r16
 
   ret
 ; @end
@@ -290,9 +291,9 @@ UART_StartTx:
 ; @clobbers R16
 
 UART_StopTx:
-  M_IO_READ r16, UCSRB
+  inr r16, UCSRB
   cbr r16, (1<<UDRIE) | (1<<TXC) | (1<<TXEN)  ; disable TX UDRE and TXC1 interrupt, enable transceive
-  M_IO_WRITE UCSRB, r16
+  outr UCSRB, r16
 
   ret
 ; @end
diff --git a/avr/modules/xram/main.asm b/avr/modules/xram/main.asm
index 44cd65e..db999fb 100644
--- a/avr/modules/xram/main.asm
+++ b/avr/modules/xram/main.asm
@@ -40,9 +40,9 @@ XRAM_Init:
   sts xramLastAddress, r16
   sts xramLastAddress+1, r16
 
-  M_IO_READ r16, MCUCR
+  inr r16, MCUCR
   sbr r16, (1<<SRE)
-  M_IO_WRITE MCUCR, r16
+  outr MCUCR, r16
 
   rcall xramWritePattern
   rcall xramVerifyPattern