June 25, 2008

HyperTerminal & Code Page 437

Code Page 437 Link: http://en.wikipedia.org/wiki/Code_page_437

When you are setting up and testing a communication protocol you may need to send and receive some protocol flags such as SYN, ACK, STX, DLE, etc. In Windows (I am not sure if Vista has it) you can make use of the tool called HyperTerminal to do the testing. For more details on HyperTerminal refer to
a) http://technet2.microsoft.com/windowsserver/en/library/02c2459f-5b84-45fb-afab-610374d359941033.mspx?mfr=true
b) http://www.tech-faq.com/hyperterminal.shtml


After you have figured out how to use the HyperTerminal you will be wondering what are the characters that appear on the screen. Obviously they correspond to some ASCII value but what the values are is a big question. To find out that you can refer to the very first link in this post.

That link really helped me and my project mate when we were testing an asynchronous serial RS232 communication. Infact if we hadn't found it using Google we would have been stuck with our project for ages.

From the chart in the link you can interpret the ASCII value. You might also question how on earth can I send a for example DLE flag especially when none of the characters are present on the keyboard.

Here is the formula:
"Ctrl" + alphabet
alphabet = corresponding ASCII value of {64 + ASCII value corresponding to the flag}

- To send DLE (ASCII value = 16), find the sum of 64 and 16 (64 + 16 = 80).
- Now check which character corresponds to the ASCII value 80 in the chart. In this case it is 'P'.
- So press "Ctrl + P" to send a DLE.
Note: Although 80 corresponds to P in CAPS you can just press Ctrl + p (in small) as it works. I have never tested with capital letters.

June 20, 2008

Ad hoc wireless server

Having only one LAN point in your room is sometimes annoying especially since NUS on-campus housing doesnt have Wi-Fi available. To solve this issue you can obviously buy a wireless router and set a wireless server provided you are fine with spending on one. If you dont want to spend, and dont want the LAN point in your room to be barred since you have bridged your network cards trying to setup an ad hoc wireless server (NUS does block your LAN point if it detects that your Network cards are bridged as it considers it to be a Security threat. I have had my LAN point blocked from using the Internet for a fortnight.)... here is the solution.

Step 1: Go to any of these links - http://www.hardwaresecrets.com/article/418 (or) http://www.microsoft.com/windowsxp/using/networking/expert/bowman_02april08.mspx

Step 2: Follow the instructions there carefully. The first link has better screen shots and is much more organised than the Microsoft link.

Step 3: Becareful of your Security. Try to make sure no one breaches your connection.

NOTE: 1) An ad hoc wireless server was successfully created and tested in DTU not NUS network. If any you manage to accomplish it in NUS network, please drop a comment on the results.
2) So far I have managed to get one friend of mine access Internet using the ad hoc wirelss server I set up. Couldnt find more people to test it out as most of them were asleep by the time this was accomplised.

Any comments are welcome.