diff --git a/system/buffer.s65 b/system/buffer.s65
new file mode 100644
index 0000000..208cc53
--- /dev/null
+++ b/system/buffer.s65
@@ -0,0 +1,97 @@
+;********************************************************************************
+; @module ringbuffer
+; @type utility
+; @details
+;   Size of the ringbuffer is RBUF_MEM_END - RBUF_MEM_START - 2, since two bytes
+;   are used by the read and write pointer
+;   The RBUF_NAME variable must be defined, the functions will then be exported
+;   as rb_<RBUF_NAME>_<function> where <function> = init, read or write
+; @requires
+;   RBUF_MEM_START: Start address of ringbuffer memory space
+;   RBUF_MEM_END: End address of ringbuffer memory space
+;   RBUF_NAME: Name of the ringbuffer
+;********************************************************************************
+
+.ifndef RBUF_MEM_START
+    .fatal "RBUF_MEM_START not defined"
+.endif
+.ifndef RBUF_MEM_END
+    .fatal "RBUF_MEM_END not defined"
+.endif
+
+; can not detect if RBUF_NAME is defined, if it is not you will get 
+; "String constant expected" Error on the line below
+.define _RBUF_NAME .concat("rb_", RBUF_NAME)
+RB_WRITE    = RBUF_MEM_START        ; write pointer, relative to RB_WRITE
+RB_READ     = RBUF_MEM_START + 1    ; read ponter, relative to RB_START
+RB_START    = RBUF_MEM_START + 2
+RB_LENGTH   = RBUF_MEM_END - RBUF_MEM_START - 2
+
+.if RB_LENGTH < 1
+    .fatal "buffer size too small, must be at least 1"
+.endif
+.if RB_LENGTH > $ff
+    .fatal "buffer size too large, must be <= $ff"
+.endif
+
+
+;********************************************************************************
+; @function Initialize the buffer
+;********************************************************************************
+.ident(.concat(_RBUF_NAME, "_init")):
+.scope
+    stz RB_WRITE
+    stz RB_READ
+    rts
+.endscope
+
+;********************************************************************************
+; @function Read a value from the buffer
+; @details
+;   If there is no value to be read, the Pz will be set
+; @returns A: value
+; @modifies: A, X
+;********************************************************************************
+.ident(.concat(_RBUF_NAME, "_read")):
+.scope
+    ldx RB_READ
+    cpx RB_WRITE
+    beq @rb_read_rts  ; if buffer empty
+    lda RB_START,x
+    inx ; increment RB_READ pointer
+    cpx #RB_LENGTH
+    beq @rb_read_jump
+    stx RB_READ 
+@rb_read_rts:
+    rts
+@rb_read_jump:
+    stz RB_READ
+    ; make sure Pz is not set
+    ldx #$01
+    rts
+.endscope
+
+;********************************************************************************
+; @function Write a value to the buffer
+; @param A: value to store
+; @modifies: X
+;********************************************************************************
+.ident(.concat(_RBUF_NAME, "_write")):
+.scope
+    ; lda kp_VALUES, x  ; load the char in a
+    ldx RB_WRITE
+    sta RB_START,x
+    inx  ; increment write pointer
+    cpx #RB_LENGTH
+    beq @rb_jump_write
+    stx RB_WRITE
+    rts
+@rb_jump_write:  ; when the end of the buffer is reached, the next keys go to the start again
+    stz RB_WRITE
+    rts
+.endscope
+
+.undefine _RBUF_NAME
+.undefine RBUF_NAME
+
+
diff --git a/system/keypad.s65 b/system/keypad.s65
index 240e0b8..d6400d0 100644
--- a/system/keypad.s65
+++ b/system/keypad.s65
@@ -6,112 +6,95 @@
 ;   The LCD must be connected to a W65C22N Interface Chip:
 ;     - IO.RB0-7  -> 
 ; @requires KP_IO: Base Address of IO Chip
-; @depends IO-W65C22N
+; @depends IO-W65C22N 
 ;********************************************************************************
 
+
 .ifndef INCLUDE_KEYPAD
 INCLUDE_KEYPAD = 1
 .ifndef KP_IO
     .fatal "KP_IO is not defined: set it to the base address of the IO chip of the Keypad"
 .endif
 
-;********************************************************************************
-; Keypad Buffer from $202 to $2ff
-;********************************************************************************
-KB_VAR      = $00
-KB_WRITE    = $200  ; write pointer, relative to KB_WRITE
-KB_READ     = $201  ; read ponter, relative to KB_START
-KB_START    = $202
-KB_LENGTH   = $fd
 
-kb_init:
-    stz KB_WRITE
-    stz KB_READ
-    ; write null to entire buffer
-    ldx #$00
-@kb_init_loop:
-    stz KB_START,x
-    inx
-    cpx #KB_LENGTH
-    bne @kb_init_loop
-    rts
+RBUF_MEM_START = $200
+RBUF_MEM_END = $2ff
+.define RBUF_NAME "keypad"
+.include "buffer.s65"
 
-; read from keybuffer, if empty null will be read
-kb_read:
-    ldx KB_READ
-    lda KB_START,x
-    beq @kb_read_rts  ; if a buffer is null, dont increment KB_READ
-    stz KB_START,x  ; set buffer location to null
-    inx  ; increment KB_READ pointer
-    cpx #KB_LENGTH
-    beq @kb_read_jump
-    stx KB_READ 
-@kb_read_rts:
-    rts
-@kb_read_jump:
-    stz KB_READ
-    rts
+KB_VAR      = $05
+KB_LAST     = $06
 
-; write to keybuffer
-_kb_write:
-    lda kp_VALUES, x  ; load the char in a
-    ldx KB_WRITE
-    sta KB_START,x
-    inx  ; increment KB_WRITE pointer
-    cpx #KB_LENGTH
-    beq @kb_jump_write
-    stx KB_WRITE
-    rts
-@kb_jump_write:  ; when the end of the buffer is reached, the next keys go to the start again
-    stz KB_WRITE
-    rts
+.proc kp_init
+    ; todo remove
+    stz KB_LAST
+    ; todo remove later
+    lda #$ff
+    sta KP_IO+IO_DDRB
+    stz KP_IO+IO_RB
 
-kp_init:
     ; INIT KEYPAD 
     lda #%00001111; KP_IO+IO_RB 0-3 output
     sta KP_IO+IO_DDRB
     stz KP_IO+IO_RB        ; KP_IO+IO_RB 4-7 1 so keypad press can be detected
     stz KP_IO+IO_ACR
 
-    lda #%10010000  ; enable interrupt for CB1 on KP_IO+IO_IO
-    sta KP_IO+IO_IER
-    lda #%00010000  ; set CB1 to interrupt on pos. edge
+    ; lda #%00010000  ; set CB1 to interrupt on pos. edge
+    lda #IO_PCR_CB1_IP_AE
     sta KP_IO+IO_PCR
-    jsr kb_init  ; init keybuffer
+    jsr rb_keypad_init  ; init keybuffer
+    lda #%10010000  ; enable interrupt for CB1 on KP_IO
+    sta KP_IO+IO_IER
     rts
+.endproc
 
 ;********************************************************************************
-; Reading the Keypad 
+; @function Read which key is pressed on the keypad
+; @details
+;   Checks which key is pressed and stores it in the keybuffer
+;   The value stored in the keybuffer is the offset which must be added to 
+;   kp_VALUES to retrieve the key that was pressed
 ;********************************************************************************
-kp_read:  ; test each "row" and check which column is 1
+.proc kp_read_on_irq
+    ; test each "row" and check which column is 1
     lda #%00001110
     ldx #$00
-    jsr @kp_read_branch
+    jsr @kp_read_column
     lda #%00001101
     ldx #$04
-    jsr @kp_read_branch
+    jsr @kp_read_column
     lda #%00001011
     ldx #$08
-    jsr @kp_read_branch
+    jsr @kp_read_column
     lda #%00000111
     ldx #$0c
-    jsr @kp_read_branch
-@kp_read_rts:
-    stz KP_IO+IO_RB
-    lda KP_IO+IO_RB  ; read to definetly clear the interrupt flag
-    rts
-@kp_read_branch:
+    jsr @kp_read_column
+    bra @kp_read_rts
+@kp_read_column:
     sta KP_IO+IO_RB
     lda KP_IO+IO_RB
     sta KB_VAR  ; store result in zeropage so that bbr can be used
-    bbr4 KB_VAR,_kb_write
+    bbr4 KB_VAR,@kp_write
     inx
-    bbr5 KB_VAR,_kb_write
+    bbr5 KB_VAR,@kp_write
     inx
-    bbr6 KB_VAR,_kb_write
+    bbr6 KB_VAR,@kp_write
     inx
-    bbr7 KB_VAR,_kb_write
+    bbr7 KB_VAR,@kp_write
     rts
+@kp_write:
+    ; temporary: store last keypress in KB_LAST, TODO: remove
+    lda kp_VALUES,x
+    sta KB_LAST
+    txa
+    jsr rb_keypad_write
+@kp_read_rts:
+    stz KP_IO+IO_RB
+    ; lda KP_IO+IO_RB  ; read to definetly clear the interrupt flag
+    rts
+.endproc
+
+.segment "RODATA"
 kp_VALUES:
     ; TODO change to literal
     .byte "123A", "456B", "789C", "*0#D"