diff --git a/README.md b/README.md
index 6757cd3..f2e63a2 100644
--- a/README.md
+++ b/README.md
@@ -92,6 +92,7 @@ ready-assembled projects:
 * `nibble.tal`: small demo drawing all the nibble dice
 * `audio-prototype0.tal`: first iteration of sequencer / tracker with nibble dice. the dice are used to read/write into memory:
 	- you can manipulate the dice in order to change pulse period (1 byte), pitch (1 byte), adsr values (2 bytes), volume (1 byte), "bang" sequencing (?) (1 byte); to toggle a melody sequencer (1 bit), and/or modify the melody (8 bytes), and even the super low-res wave shape (8 bytes), for two audio devices (3 columns for the first one, 3 columns for the second one)
+* `calculadora.tal`: experiment for an 8-bit rpn calculator, from before there was a console/vector available. for the moment it uses the keyboard input
 
 # media
 
diff --git a/sketches/calculadura.tal b/sketches/calculadura.tal
new file mode 100644
index 0000000..c693de0
--- /dev/null
+++ b/sketches/calculadura.tal
@@ -0,0 +1,162 @@
+( dev/console )
+
+%RTN { JMP2r }
+%print { DUP #18 DEO }
+%printhex { DUP #19 DEO #0a #18 DEO }
+%printnl { #0a #18 DEO }
+%resetnumber { #00 STH }
+%setnumber { #01 STH }
+
+|00 @System     [ &vector $2 &pad     $6 &r      $2 &g     $2 &b      $2 ]
+|80 @Teclado [ &vector $2 &button $1 &key ]
+
+|0000
+
+
+( init )
+
+|0100 ( -> )
+
+( theme ) 
+	#a1f3 .System/r DEO2 
+	#a14d .System/g DEO2 
+	#a16c .System/b DEO2
+	
+	LIT 'h #18 DEO 	
+	LIT 'o #18 DEO
+	LIT 'l #18 DEO 	
+	LIT 'a #18 DEO
+	#0a #18 DEO ( \n )
+
+	( #db ( 219 )
+	( #63 ,printdigits JSR )
+
+	( printhex )
+
+	resetnumber ( estado de número )
+
+
+	;tecla .Teclado/vector DEO2
+
+BRK
+
+
+@tecla
+	( get key )
+	.Teclado/key DEI
+
+ 	( echo )
+	print
+
+	( is digit? )
+	DUP #2f GTH ,numGT JCN
+
+	DUP #20 EQU ,spacebar JCN
+
+	( + )
+	DUP #2b EQU ,add JCN
+
+	( - )
+	DUP #2d EQU ,sub JCN
+
+	( * )
+	DUP #2a EQU ,mul JCN
+
+	( / )
+	DUP #2f EQU ,div JCN
+
+	( enter )
+	DUP #0d EQU ,enter JCN
+
+	POP ( descarta input leido )
+BRK
+
+@spacebar
+	POP
+	( printhex )
+	STHr POP
+	resetnumber
+BRK
+
+@enter
+	POP
+	printnl
+	LIT '> #18 DEO
+	#20 #18 DEO
+	,printdigits JSR
+	( printhex )
+	STHr POP
+	resetnumber
+BRK
+
+@add
+	POP
+	ADD
+BRK
+
+@sub
+	POP
+	SUB
+BRK
+
+@mul
+	POP
+	MUL
+BRK
+
+@div
+	POP
+	DIV
+BRK
+
+@numGT
+	DUP #3a LTH ,numLT JCN
+BRK
+
+@numLT ( is number )
+	#30 SUB ( calculate number )
+	STHr ,decimal JCN ( if not the first digit )
+	setnumber ( estado de número )
+BRK
+
+@decimal
+	SWP #0a MUL
+	ADD
+	( printhex )
+	setnumber ( estado de número )
+BRK
+
+@printdigits ( subroutine to print a byte in decimal )
+	DUP #64 DIV ( divide over 100 )
+	DUP2 #64 MUL SUB SWP DUP ( get the remainder )
+	,&print3digits JCN ( jump if there are 3 digits )
+	POP 
+
+	( print 2 digits )
+	DUP #0a DIV ( divide over 10 )
+	DUP2 #0a MUL SUB SWP DUP ( get the remainder )
+	,&print2nddigit JCN ( jump if there are 2 digits )
+	POP 
+	,&print1stdigit JMP
+
+	&print2nddigit
+		#30 ADD #18 DEO 
+
+	&print1stdigit
+		#30 ADD #18 DEO  
+		POP
+		printnl
+	RTN
+
+	&print3digits
+		#30 ADD #18 DEO
+	
+	( print 2 digits )
+	( same routine as above but without conditionals )
+		DUP #0a DIV DUP2 #0a MUL SUB SWP
+		#30 ADD #18 DEO ( 2nd digit ) 
+		#30 ADD #18 DEO ( 1st digit )
+
+	POP
+	printnl
+RTN