diff --git a/day10.lisp b/day10.lisp
index 41062d3..f8d3218 100644
--- a/day10.lisp
+++ b/day10.lisp
@@ -211,3 +211,106 @@
       while line
       do (parse-command-line line my-machine))
     (accumulated-signal my-machine)))
+
+;;; Cleaning up:
+;;; part 1
+
+;; state of the CPU
+(defclass machine ()
+  ((clock :reader clock :initform 0)
+   (register :reader register :initform 1)
+   (accumulated-signal :reader accumulated-signal :initform 0)
+   (next-special-clock :reader next-special-clock :initform 20)))
+
+(defmethod print-object ((obj machine) stream)
+      (print-unreadable-object (obj stream :type t)
+        (with-accessors ((clock clock )
+                         (register register )
+                         (accumulated-signal accumulated-signal)
+                         (next-special-clock next-special-clock))
+            obj
+          (format stream "clock: ~a, register: ~a, accum: ~a; next-special: ~a" clock register accumulated-signal next-special-clock))))
+
+;; passing of sinlge step
+(defgeneric tick (obj)
+  (:method ((obj machine))
+    (incf (slot-value obj 'clock))
+    (when (= (next-special-clock obj) (clock obj))
+      (incf (slot-value obj 'accumulated-signal) (* (clock obj) (register obj)))
+      (update-special-clock obj))))
+
+(defgeneric update-special-clock (obj)
+  (:method ((obj machine))
+    (incf (slot-value obj 'next-special-clock) 40)))
+
+;; actual cpu commands in terms of ticks and register changes:
+(defgeneric noop (mach)
+  (:method ((mach machine))
+    (tick mach)))
+
+(defgeneric addx (mach num)
+  (:method ((mach machine) num)
+    (tick mach)
+    (tick mach)
+    (incf (slot-value mach 'register) num )))
+
+(require 'cl-ppcre)
+(defun parse-command-line (line machine)
+  (let* ((the-split (cl-ppcre:split " " line))
+         (command (intern (string-upcase (first the-split)))))
+    (case command
+      ('addx (addx machine (parse-integer (second the-split))))
+      ('noop (noop machine))
+      (t "hello"))))
+
+;; now it's time to simiulate the file evaluation
+(let ((my-machine (make-instance 'machine)))
+  (with-open-file (in "day10-test.txt")
+    (loop
+      for line = (read-line in nil nil)
+      while line
+      do (parse-command-line line my-machine))
+    (accumulated-signal my-machine)))
+
+(let ((my-machine (make-instance 'machine)))
+  (with-open-file (in "day10-input.txt")
+    (loop
+      for line = (read-line in nil nil)
+      while line
+      do (parse-command-line line my-machine))
+    (accumulated-signal my-machine)))
+
+;;; PART 2
+
+(defclass crt (machine)
+  ((next-special-clock :reader next-special-clock :initform 40)))
+
+(defun cur-pixel-in-sprite (pixel-index sprite-center)
+  (and (>= pixel-index (1- sprite-center))
+       (<= pixel-index (1+ sprite-center))))
+
+(defmethod tick :before ((obj crt))
+  (let ((pixel (if (cur-pixel-in-sprite (clock obj) (register obj))
+                   "#"
+                   ".")))
+  (format t pixel))
+  (when (= (clock obj) (1- (next-special-clock obj)))
+    (incf (slot-value obj 'register) 40)
+    (terpri)))
+
+;; and same code reading in commands, but with CRT results in printing
+(let ((my-machine (make-instance 'crt)))
+  (with-open-file (in "day10-test.txt")
+    (loop
+      for line = (read-line in nil nil)
+      while line
+      do (parse-command-line line my-machine))
+    (accumulated-signal my-machine)))
+
+(let ((my-machine (make-instance 'crt)))
+  (with-open-file (in "day10-input.txt")
+    (loop
+      for line = (read-line in nil nil)
+      while line
+      do (parse-command-line line my-machine))
+    (accumulated-signal my-machine)))