diff --git a/src/ChecksumConverter.cc b/src/ChecksumConverter.cc
old mode 100644
new mode 100755
index 731a607..0e30e07
--- a/src/ChecksumConverter.cc
+++ b/src/ChecksumConverter.cc
@@ -504,6 +504,18 @@ static uint32_t leybold(const uint8_t* data, size_t len, uint32_t sum)
     return sum;
 }
 
+// Checksum used by Brooks Cryopumps
+static uint32_t brksCryo(const uint8_t* data, size_t len, uint32_t sum)
+{
+    uint32_t xsum;
+    while (len--)  {
+        sum += (*data++) & 0x7F;
+    }
+    xsum = (((sum >> 6) ^ sum) & 0x3F) + 0x30;
+    return xsum;
+}
+
+
 struct checksum
 {
     const char* name;
@@ -521,8 +533,13 @@ static checksum checksumMap[] =
     {"sum8",    sum,              0x00,       0x00,       1}, // 0xDD
     {"sum16",   sum,              0x0000,     0x0000,     2}, // 0x01DD
     {"sum32",   sum,              0x00000000, 0x00000000, 4}, // 0x000001DD
+    {"nsum8",   sum,              0xFF,       0xFF,       1}, // 0x23
+    {"nsum16",  sum,              0xFFFF,     0xFFFF,     2}, // 0xFE23
+    {"nsum32",  sum,              0xFFFFFFFF, 0xFFFFFFFF, 4}, // 0xFFFFFE23
+    {"notsum",  sum,              0x00,       0xFF,       1}, // 0x22
     {"xor",     xor8,             0x00,       0x00,       1}, // 0x31
     {"xor8",    xor8,             0x00,       0x00,       1}, // 0x31
+    {"xor8ff",  xor8,             0x00,       0xFF,       1}, // 0xCE
     {"xor7",    xor7,             0x00,       0x00,       1}, // 0x31
     {"crc8",    crc_0x07,         0x00,       0x00,       1}, // 0xF4
     {"ccitt8",  crc_0x31,         0x00,       0x00,       1}, // 0xA1
@@ -541,6 +558,7 @@ static checksum checksumMap[] =
     {"hexsum8", hexsum,           0x00,       0x00,       1}, // 0x2D
     {"cpi",     CPI,              0x00,       0x00,       1}, // 0x7E
     {"leybold", leybold,          0x00,       0x00,       1}, // 0x22
+    {"brksCryo",brksCryo,         0x00,       0x00,       1}  // 0x4A
 };
 
 static uint32_t mask[5] = {0, 0xFF, 0xFFFF, 0xFFFFFF, 0xFFFFFFFF};