diff --git a/mik32_parsers.py b/mik32_parsers.py
index 14ace0a..746b69d 100644
--- a/mik32_parsers.py
+++ b/mik32_parsers.py
@@ -40,11 +40,15 @@ def parse_hex_line(line: str) -> Record:
     rectype = int(line[7:9], base=16)               # Record type field
     data_bytes_line = line[9:datalen*2 + 9]         # Data field
     crc = int(line[datalen*2 + 9:datalen*2 + 11], base=16)
+
     splitted_by_bytes: List[str] = []
     for i in range(datalen):
         splitted_by_bytes.append(data_bytes_line[i*2:i*2+2])
     
     data_bytes = list(map(lambda x: int(x, base=16), splitted_by_bytes))
+    checksum = (datalen + int(line[3:5], base=16) + int(line[5:7], base=16) + rectype + sum(data_bytes)) % 256
+    if (checksum + crc) % 256 != 0:
+        raise Exception("Checksum mismatch in %s" % line)
 
     record = Record(RecordType.UNKNOWN, 0, [])
 
@@ -175,11 +179,11 @@ def parse_hex(file: str) -> Dict:
 
 
 def bytes2words(arr: List[int]) -> List[int]:
-    word = []
+    bytes = []
     words = []
     for byte in arr:
-        word.append(byte)
-        if word.__len__() == 4:
-            words.append(word[0]+2**8*word[1]+2**16*word[2]+2**24*word[3])
-            word = []
+        bytes.append(byte)
+        if bytes.__len__() == 4:
+            words.append(bytes[0]+2**8*bytes[1]+2**16*bytes[2]+2**24*bytes[3])
+            bytes = []
     return words
diff --git a/mik32_upload.py b/mik32_upload.py
index bf8acbf..8e805d1 100644
--- a/mik32_upload.py
+++ b/mik32_upload.py
@@ -37,8 +37,13 @@ def test_connection():
         raise Exception("ERROR: no regs found, check MCU connection")
 
 
-def read_file(filename: str) -> List[Record]:
-    segments: List[Record] = []
+@dataclass
+class Segment:
+    offset: int
+    data: List[int]
+
+def read_file(filename: str) -> List[Segment]:
+    segments: List[Segment] = []
     lines: List[str] = []
 
     file_name, file_extension = os.path.splitext(filename)
@@ -52,13 +57,25 @@ def read_file(filename: str) -> List[Record]:
     else:
         raise Exception("Unsupported file format: %s" % (file_extension))
 
+    lba: int = 0        # Linear Base Address
+    expect_address = 0  # Address of the next byte
+
     for line in lines:
         record: Record = parse_line(line, file_extension)
-        print(record)
         if record.type == RecordType.DATA:
-            pass
+            drlo: int = record.address # Data Record Load Offset
+            if segments.__len__() == 0:
+                expect_address = lba+drlo
+                segments.append(Segment(offset=expect_address, data=[]))
+            if expect_address != lba+drlo:
+                expect_address = lba+drlo
+                segments.append(Segment(offset=expect_address, data=[]))
+            
+            for byte in record.data:
+                segments[-1].data.append(byte)
+                expect_address += 1
         elif record.type == RecordType.EXTADDR:
-            pass
+            lba = record.address
         elif record.type == RecordType.LINEARSTARTADDR:
             print("Start Linear Address:", record.address)