Browse24

In the age of globalization, no body can think a very single moment without a computer. Once upon a time computer has considered as fashionable equipment or an equipment of entertainment. But with the passage of time now computer is not only an equipment of fashion or entertainment but also it is the main device of today’s world.

In this modern age people are badly depend on computer because by the help of internet technology computer makes the all kind of services much easier and faster than previous. Moreover, it makes the communication system much easier than previous. Nowadays, all kind of businesses and trades require computer. These days, there is no office without computer, even you get computer in any types of little shop. No body can deny the contribution of computer in the modern world but sometimes some people make a debate on which types of computer is very helpful for us – desktop PC or laptop.

Some gives arguments on favor of desktop whereas others give on behalf of laptop. Though both types of computers have some extra advantages alongside some disadvantages such as a desktop PC gives you more storage capacity over a laptop but it is not easily movable. On the other hand, you can move easily anywhere and stay connect all the time with your laptop but with PC it’s quite impossible move here and there easily. So, which types of computer is better, it’s totally depends on your requirement.

If you need more storage capacity and more features then you should prefer a desktop PC. There are many kinds of desktop in several brands from different companies but Dell Inspiron 530 Desktop PC  is now very popular for its incredible features. On the other hand, Acer Desktop PC is also popular for their quality services. You may know more about it from Acer Desktop PC Reviews.

Throughout history, every generation has had to stand up for freedom. Now it’s our turn

Bangladesh Open Source Network (BdOSN) is a not-for-profit, voluntary organization to promote Open Source (OS) Philosophy in Bangladesh. It was initiated as an umbrella organization of different OS groups and organizations in Bangladesh and now evolves as one of the coordinating hubs for OS related activities in Bangladesh.The following types of memberships are available with BdOSN.

1. Individual Membership: Individuals who are eager to support the aims and activities of the Network and aspire to gain knowledge and develop Open Source and Open Content may apply for Individual Membership.
2. Civil Society Membership: Civil society organizations which are eager to support the aims and activities of the Network and need assistance for development and implementation of Open Source and Open Content culture may apply for Civil Society Membership. The individual members of each such organization will have the similar facilities that are entitled to an Individual Member.
3. Academic Membership: Educational institutions eager to support the aims and activities of the Network and aspire to gain knowledge and develop Open Source and Open Content may apply for Academic Membership. The individual members of each such organization will have similar facilities that are entitled to an Individual Member.
4. Community Membership: BdOSN will help local communities to develop their own network. The network will be known as local Open Source Network. Institutional or administrative unit based community network may be formed. All individual members of such OSN will enjoy similar facilities that are entitled to an Individual Member.
5. Corporate Membership: Business organizations/organizations which are eager to support the aims and activities of the Network and need assistance for development and implementation of Open Source and Open Content culture may apply for Corporate Membership. The individual members of each such organization will have the similar facilities that are entitled to an Individual Member.
6. Sponsor Membership: Organizations who are eager to fund on regular basis or sponsor the aims and activities of the Network may apply for Sponsor Membership. Each such Sponsor Member can nominate up to 1 (one) Observer to the GC. The Sponsor Members will have the same status as Corporate Members in all other respect.
7. Patron Membership: Individuals who are eager to fund on regular basis or sponsor the aims and activities of the Network may apply for Patron Membership. The Patron Members will have the same status as Individual Members in all other respect.

Anybody interested in open source may join BdOSN

In order to understand the MIDI keyboard, we should know about the musical keyboard first. A musical keyboard is the set of adjacent depressible levers on a musical instrument which cause the instrument to produce sounds.

Keyboards almost all share the common layout shown. Musical instruments with keyboards of this type include the piano, harpsichord, virginals, clavichord, organ, electric piano, digital piano, synthesizer, “arranger keyboard” or “home keyboard” (also called “electronic keyboard”), celesta, dulcitone, accordion, melodica, glasschord, and carillon. Since the most commonly encountered keyboard instrument is the piano, the keyboard layout is often called the piano keyboard.

The twelve notes of the Western musical scale are laid out with the lowest note on the left; the larger keys (for the seven “natural” notes of the C major scale: C, D, E, F, G, A, B) jut forward. Because these keys are often coloured white on a keyboard, these are often called the white notes or white keys. The keys for the remaining five notes which are not part of the C major scale (namely C#/D#, D#/E#, F#/G#, G#/A#, A#/B#) are set back. Because these keys are often coloured black, these notes are often called the black notes or black keys.

The pattern repeats at the interval of an octave. The arrangement of longer keys for C major with intervening, shorter keys for the intermediate semitones dates to the 15th century. Many keyboard instruments dating from before the nineteenth century have a keyboard with the colours of the keys reversed - darker coloured keys for the white notes and white keys for the black notes.

A few electric and electronic instruments have had this feature. It should be noted that the reverse-colored keys on Hammond organs such as the B3, C3 and A100 are not playable keys; they physically latch when pressed like radio buttons, and serve as selector switches for preset sounds. There are 21 white keys on the keyboard and 15 black.

How to make a MIDI Keyboard
MIDI keyboard connects to computer sound card or synthesizer module to create MIDI code.

This Project is built around the 8031 microcontroller. Once keyboard circuit diagram is drawn out, one can construct scanning circuitry that continuously loops through a test of each key to see if it is open or closed.

Circuit Components
Microcontroller, memory, keyboard/switch interface, MIDI/RS232 interface and power supply

Software Algorithm

• The software loops through a check of each 1st switch for every key.
• If it finds that switch 1 is open it checks to see if it was open the last time it looked. If this is the case it continues scanning.
• If it finds that it is open but was closed the last time it looked then it stores info that it is now open and then sends the “note off value” for that key out the midi port.
• If it finds that switch 1 is closed then it checks to see if switch 2 for that key is open.
• If it is open then it increments the velocity register value and continues the scan. If it finds that switch 2 is closed then it checks a register to see if that note is already on. If so then it continues the scan.
• If not then it sends the “note on value for that key out the midi port and also sends a velocity value from the velocity table that is incremented for each key check loop. Therefore, the more times that the software loops the lower the velocity value sent.