For a basic idea on whats inside the iPod, how it works and how it is build, let’s try to design our own iPod. Think of the iPod as a computer that is exclusively used to play music. It can further be equipped to add more features like video playback and games.
- Hard Drive/Flash Memory
- Audio Chip
- Added features like Video Chip(if needed)
- LCD Display device
- Rechargeable Li Battery
- Pixo OS 2.1
- iOS(for iPod Touch)
- LCD/Touch Screen
- Click Wheel
A computer works when its got two things-Hardware & Software. The hardware is the CPU-which we would refer to as a microprocessor. A microprocessor performs all the functions of the CPU on a single IC unit. It has a memory-We need RAM to run the various processes and we also need memory to store the data(music files and stuff).
Consider the RAM already chipped on to the microprocessor as microprocessor memory. We got the microprocessor, now we need memory for data storage. (Note-we can also have RAM and flash memory on our microprocessor) We now got two options for memory-
- A Hard Drive(a highly sensitive one with lots of space)
- Flash Memory(EEPROM using NAND sequential logic)
We can use flash memory if we need about 1-8 GB memory and for all other purposes, we would go for a hard drive. The iPod Classic & Mini use drives while Nano, Shuffle & Touch use Flash Memory.
So, we now got the microprocessor & memory for data storage. We now need an audio chip that can perform the decoding and encoding of the digital stream of data(we are dealing with digital audio here.) This could also be chipped on to the microprocessor like in iPod Shuffle which uses a SigmaTel chip. So, we now have the following-
- A Microprocessor-the heart of the iPod
- An Audio Chip that encodes/decodes audio.
- Either a hard drive or flash memory for data storage
The other hardware we would require is a display device and a controlling device. For display, we use LCD(Liquid Crystal Display) for most of our purposes except when we need a touch screen. For the controls, we use the Click Wheel.
The click wheel is an interesting part of the iPod. It’s plastic when we look at it. But inside it is a metal channel in the form of a grid. The grid hold charge and acts as a capacitance equivalent. Our fingers act as conductors that vary this capacitance. These capacitance variations are interpreted by a control chip that translates the variations into instructions for the microprocessor.
We now add a rechargeable lithium ion battery to supply power to our iPod. Well, we are done with the iPod hardware but to make sense of the hardware, we need a platform or software or host-the Operating System is the host-a bridge between the user and the hardware.
The iPod uses the Pixo OS 2.1(found by Paul Mercer after he left Apple to create his own company-Pixo!). The Pixo OS framework uses C++(if you care). And as everyone would agree, iTunes would be our desired jukebox/media player software. Now, we all know about iTunes, don’t we?