Month: May 2015

RIP Joseph Lechleider, who came up with the idea behind ADSL

If you have one of these — often called a “DSL modem”, but it’s more likely to be a DSL router — in your home or office…

…then you have this engineer to thank:

This is Joseph Lechleider, who used to be an engineer at Bellcore, Bell Telephone’s research wing formed after it was broken up into the “Baby Bells”. In the late 1980s, he came up with a clever solution to a problem that came with trying to send high-speed electronic signals over ordinary copper wire and into this familiar connection:

Electricity and magnetism are bound together in interesting ways, and this connection turns up when you send a current through a wire. The current induces a magnetic field around the wire:

The tight connection between electricity and magnetism means that the reverse is true as well: put a wire into a magnetic field, and you’ll induce a current in it.

This behavior made it difficult to send high-speed signals through copper wires, which to this day often make up the “last mile” between your wireline carrier and you. The magnetic fields induced by sending signals at very high speeds create a lot of interference, which mangles the data being carried, which slows down the rate at which you receive actual usable data.

Lechleider’s solution to this problem was both simple and clever: why not make it so that downloading (getting information from the network to you) was faster than uploading (sending information from you to the network)? This arrangement reduced the interference between the upload and download channels and offered more than twice the bandwidth that transmitting and receiving at the same rate did. His idea got incorporated into what we now know as ADSL (the “A” is for asymmetric), a key part of DSL service

The “receive data much faster than you transmit it” solution is an engineer’s dream: it’s clever, and it’s cheap, because it doesn’t require much change to existing infrastructure. It meant that phone companies didn’t have to spend a lot of money to provide broadband service, and it’s how DSL became popular. As recently as the end of 2012, it was the primary means of access for almost 60% of the world’s wireline broadband subscribers.

Lechleider died at home in Philadelphia on April 18th from cancer of the esophagus. We didn’t want his contribution to telecommunications to go unnoticed.

For your work in changing wireline broadband — as well as the way we live, work, and play — we thank you, Mr. Lechleider.

HP’s history of telecom in just three minutes

It’s been over two years since I published my visual catalog of iOS’ virtual keyboards on the iPhone, which covered iOS 6. At the time, it was the only place you could get a listing of the names of the iOS keyboards and see what they looked like. Even now, I think it’s still the only information source of its kind.

We’re now well into iOS 8’s run, and it’s likely that iOS 9 will be released sometime this year. Since there still isn’t a visual catalog of iOS 8’s built-in keyboards on the iPhone, and since I’m still of the “see a need, fill a need” ethos, I put one together. It starts with a table listing all the built-in keyboard types; you can click on the name to jump to pictures of all the views for the corresponding keyboard.

I hope you find it useful!

iOS 8’s built-in virtual keyboards

iOS 8 features a total of 11 built-in virtual keyboards, all of which are variations on two basic types: the typewriter keyboard and the phone keypad, both pictured below:

Typically, the keyboard isn’t shown until the user taps on a text field or text view. You can specify the type of keyboard for a text field or text view visually in Interface Builder…

…or you can do so in code using the text field or text view’s keyboardType property and values from the UIKeyboardType enum:

vowelsOnlyTextField.keyboardType = UIKeyboardType.ASCIICapable
noVowelsTextField.keyboardType = UIKeyboardType.Default
digitsOnlyTextField.keyboardType = UIKeyboardType.NumberPad
numericOnlyTextField.keyboardType = UIKeyboardType.NumbersAndPunctuation
positiveIntegersOnlyTextField.keyboardType = UIKeyboardType.DecimalPad

If you don’t specify a keyboard type for a text field or text view, the typewriter-based Default keyboard is used.

Thanks to their growing popularity (first in Japan, and then the rest of the world), many of these keyboards feature a way to enter emoji, which have been available on iOS since version 5, which was released in mid-2011:

All of iOS’ virtual keyboards come in both a light and dark appearance, with the light version being the default:

As with the keyboard type, you can choose this appearance either visually in Interface Builder (via the Appearance menu) and in code using the text field or text view’s keyboardAppearance property and values from the UIKeyboardAppearance enum.

I haven’t been able to find anything in the Human Interface Guidelines on when the light and dark keyboards should or shouldn’t be used, so let your common sense be your guide, keeping in mind this fact about common sense:

Click the image to enjoy Deadpool’s wisdom at full size.

UIKeyboardType.ASCIICapable

This used to be the default keyboard; now it’s the “no-nonsense alphanumeric keyboard”. It lets you enter letters, numbers, punctuation, and symbols, and nothing else. Use this keyboard if you need the user to enter something that’s completely or primarily letters and don’t want them to enter emoji and especially for data entry in business, productivity, scientific, health, and other “serious” apps.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the #+= key):

UIKeyboardType.DecimalPad

Use this keyboard if you want the user to enter either whole or fractional numbers. This keyboard provides the decimal separator appropriate for the user’s locale; the screenshots below show my locale settings, English/US. Note that there’s no return key of any sort on this keyboard.

UIKeyboardType.Default

If you don’t specify the keyboard type, you get this one, which lets the user enter letters, numbers, punctuation and symbol characters, and emoji. This is the most general-purpose keyboard in iOS.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the #+= key):

Alternate view 3 (accessed via the the 😀 key):

UIKeyboardType.EmailAddress

If you want the user to provide an email address, this is the preferred keyboard.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the #+= key):

Alternate view 3 (accessed via the the 😀 key):

UIKeyboardType.NamePhonePad

For fields where you want the user to enter data without punctuation — typically names or integers — use the NamePhonePad keyboard. It features typewriter-style input for entering letters, and phone-style input for entering numbers.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the the 😀 key):

UIKeyboardType.NumberPad

This is amother numeric entry keyboard. It lets the user enter digits, but not the decimal separator.

Note that there’s no return key of any sort on this keyboard.

Primary view:

UIKeyboardType.NumbersAndPunctuation

Think of this as the ASCIICapable keyboard, but with an emphasis on numeric entry. Like the ASCIICapable keyboard, it lets you enter letters, numbers, punctuation, and symbols, and nothing else.

Use this keyboard if you need the user to enter something that’s primarily numeric but may also include letters, symbols and punctuation, but not emoji. You’ll find it especially useful for numeric data entry in business, productivity, scientific, health, and other “serious” apps. You should also use this keyboard when you want the user to enter numbers in scientific notation.

Primary view (accessed via the 123 key):

Alternate view 1 (accessed via the ABC key):

Alternate view 2 (accessed via the #+= key):

UIKeyboardType.PhonePad

If you want the user to enter a phone number or a touch-tone sequence, this is the preferred keyboard.

Primary view (accessed via the 123 key):

Alternate view 2 (accessed via the +*# key):

UIKeyboardType.Twitter

If you want the user to enter a tweet, this is the preferred keyboard.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the #+= key):

Alternate view 3 (accessed via the the 😀 key):

UIKeyboardType.URL

If you want the user to enter a URL, this is the preferred keyboard.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the #+= key):

Alternate view 3 (accessed via the the 😀 key):

UIKeyboardType.WebSearch

This keyboard is very similar to the Default keyboard, with two notable differences:

• There’s a . key in the bottom row
• The return key is blue, and by default is labelled Go.

It’s meant for entering both URLs and web search terms, but it’s equally useful for any kind search or even typed commands.

Primary view (accessed via the ABC key):

Alternate view 1 (accessed via the 123 key):

Alternate view 2 (accessed via the #+= key):

Alternate view 3 (accessed via the the 😀 key):