Computer History 2 : MacAir

As we known, laptop design has always been a big competition. Though a lot of big companies come a long way in the past few years, but laptops have never been able to have features as same as desktop, and not at comparable prices. In order to design a computer with a portable shell and a power-efficient enough to run for couple hours at a time, computer designer have to make new computer much smaller and lighter than desktop, and the more compromise their needs to be.

On January 15, 2008, Steven introduced the first MacBook Air, Apple’s latest Intel-based laptop, is the thinnest, lightest laptop Apple has ever constructed and it’s the thinnest laptop in the world at that time. The first-generation MacBook Air was a 13.3"-only model, Entire MacBook Air only has three-pound package and three-quarters of an inch thick at its thickest point. “It featured a custom Intel MeromCPU and Intel GEM graphics. In late 2008, the CPU was updated to a faster, non-custom Penryn CPU and integrated NVidia GeForce graphics while the hard drive capacity was increased and the micro-DVI video port was replaced by the Mini-display ports.”

The MacBook Air is available in two sizes, with the length of the diagonal display determining the model size: 13.3-inch and 11.6-inch. All models of MacBook Air use solid-state drive storage and Intel Core i5 or i7 CPU. 

On October 20, 2010, Apple released a redesigned 13.3" model, with improved enclosure, screen resolution, battery, and flash storage instead of a hard drive.

On July 20, 2011, Apple released an updated model in the same form factor as the prior model.

On June 10, 2013, Apple released another update in the same form factor as the 2012 model during the company's Worldwide Developer Conference (WWDC).

http://en.wikipedia.org/wiki/MacBook_Air

http://www.macworld.com/article/1131864/macbookair.html

Computer History 1 : IBM 1401

The first time I heart IBM 1401 was in CS 149 class. I know the IBM 1401 is the first member of the IBM 1400 series. IBM announced it on October 5, 1959 and withdrawn on February 8, 1971.

The IBM 1401 Data Processing System, a stored-program transistor-logic computer announced October 1959. At $2500 per month minimally configured, this was IBM's first affordable general-purpose computer, and it was intended to take the place of all the accounting machines and calculator that still provided a cheaper alternative to IBM's650 and 70x computers. Thousands of 1401s were sold or rented; in fact, it was the first computer to deploy 10000 units. The 1401was a decimal computer, with variable-length words composed of 8-bit bytes containing 6-bit BCD binary coded decimal characters and was intended primarily for business applications. The 1401 were the first in IBM's 1400 series of computers, which later included the 1440, and 1460. Originally programmed only in machine or assembly language or Auto coder, which proved difficult for many people, the 1401 were soon host to one of the earliest high-level business-oriented programming languages, RPG which increased its usability and popularity. Later FORTRAN was added for scientific programming. The 1401 were so popular that 1401 applications were still running in 2000 on 1401 simulators, and this presented a special challenge in the Year-2000 conversion. You can bet that 1960-era programmers with an only few thousand bytes of memory at their disposal didn't "waste core" on 4-digit years.

http://www.columbia.edu/cu/computinghistory/1401.html  http://ibm-1401.info

http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP1401.html

http://ausersmanual.org

http://spectrum.ieee.org/computing/hardware/rebuilding-the-ibm-1401

File Share : AirDrop

AirDrop is a method of transferring files wirelessly from one device to another device, it is an Ad-hoc service in the IOS operating systems, introduced in IOS 7 and Mac OS Lion using AirDrop, users can transfer photos, videos and other supported documents to other Apple computers and Apple mobile devices without the need of wireless and mass storage devices. 

“IOS and OS X use different AirDrop protocols and are currently not interoperable.” AirDrop makes file sharing a lot much easier, especially for family’s Apple users. It is easy to transfer files from your Mac via AirDrop to any others’ Apple devices. That means you can easily copy over those pictures, files and Docs to any Apple device without use storage space on a shared photostream, but AirDrop does more than just share files. You can share just anything; from a nice game you found in the App Store to any web page like Facebook, Twitter, RenRen just go through AirDrop. AirDrop transfers information using Wi-Fi and Bluetooth. You need an iCloud account to share with Contacts. You can turn AirDrop on or off and control with which you can share content using Airdrop.

To share files with AirDrop, both users need one of the following devices using iOS 7:

• iPhone 5 

• iPad 

• iPod touch 

AirDrop settings

1. Swipe up from the bottom of any screen to reveal Control Center.

2. Tap AirDrop.

3. Choose from one of the following:

• Off: Turns off AirDrop.

• Contacts Only: Your iOS device is visible only to your contacts.

• Everyone: Your iOS device is visible to all nearby iOS devices that use AirDrop.

Sharing with AirDrop

When AirDrop is enabled, you can share content from apps such as Photos, Safari, Contacts, and more:

1. Tap Share or the icon.

2. If necessary, tap the content or additional items you want to share.

3. Tap the name of a nearby AirDrop user or the iOS device.

4. The other user receives an alert with a preview of the content you want to share, and can either accept or decline.

5. If the other user accepts, the content will open in the application from which it was sent.

http://support.apple.com/kb/HT5887?viewlocale=en_US&locale=en_US

Data Structure

In my option, a data structure is a particular way of storing and organizing data in a computer so that it can be used efficiently.

Data structures are the best ways to reorganize data. There are many different types of data structures, for example, primitive types; simple variables, collection of data items of various types; objects, collection of data items of the same type, stored contiguously; array, and also the sequence of data items, each on points to the next one; linked list. My favorite data structure is Array. The reason is array has method for storing information on multiple devices and an array is a number of objects arranged in some specified way, for example, a list. Normally, there are always have algorithms to with the array to manipulate the data, for example, the methods of sort an array. 

There also have another data type; it is called abstract data type (ADT), which are a state of operations that act on the object, for example, evaluate arithmetic expressions; a stack, simulate complex systems; a queue, simple and fast sorting; a tree, and database applications, with quick look-up; a table.

All the computer science students should know that the data structures are widespread, so it is significant to implement them efficiently. There have couple ways to measure their efficiency. They are to check their worst case, running time, average case, usage of the space, big-oh notation, and the speed of one operation.

Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks, so I think being a programmer, it is very important to nicely choose a data structures for the entire code. How well a programmer to choose a suitable type of data structure, it is depend on the experience of programmer’s coding.  

http://www.cs.sunysb.edu/~skiena/214/lectures/