1.1.b Memory in Mobile Phones
The cell phone memory is one of the primary features of a cell phone. It is basically assures multiple services and possibilities of the device.
Different types of memories in mobile phone are:
1.SIM memory: It is basically used with GSM phones. The weak spot is that it contains a tiny amount of memory to store data. Using a SIM card you can choose either to store data in your cell phone or to store it only on the memory card. A SIM card memory mainly stores an account identification data, as well as additional information such as phone book entries. However, a SIM card memory has a relatively small capacity, so in the modern mobile phones this memory is used only to store the service account data. Because a SIM card memory contains almost no user data, in most cases you just don't need to recover it. Anyway, you can't extract any data from a SIM card at home, because both special equipment and software available only in service centers are required.
2.ROM (read-only memory): This type of memory contains the basic operating system of the cell phone. It is non-writ able, which means you can't add applications or any other software to it. This is especially important in case you need to reset your hard disk and boot the memory of the cell phone to the factory settings. The data set as default will stay on the ROM eliminating any possible malware or virus. The amount of ROM can't be changed since you can't add to it.
3.RAM (random access memory): RAM is a temporary memory used to run applications and programs. The stored data can be accessed in any order. Its random character refers to the idea that any piece of data can be quickly restored, no matter where it is located.
4.Flash/internal memory: The internal memory is actually the one to store your programs, messages, contacts, appointments, etc. The amount of internal memory, or flash memory, is usually indicated in the cell phone description. It is measured in MBs. If you want to download some games or applications then you'd need to take care about the memory issues, which can be not enough.
5.External memory: This type of memory is easy to use and can be added to the cell phone in any amount available. It's about external flash memory cards, which are inserted in specially provided slots. The most used among the memory cards are MMC, RS MMC, MiniSD cards. The maximum size they support ranges from 28 MBs to 2GB. The flash memory cards for cell phones differ by their physical size and power consumption. Some recent models of flash memories have DRM capacity (copy protection).
"Memory Effect":Suppose you recharge your phone battery every time when your battery is 60% discharged. Eventually, it will so occur that as soon as the phone gets discharged by 60%, it will "forget" that the battery has the 40% charge remaining. It will hence show the "Battery Low" indication. The rest of the 40% charge is wasted (You cannot recover it). This simply leads to a huge reduction in talk-time and standby time.
1.1.c Battery Life in Mobile Phones
Battery life of a mobile phone can be measured in terms given below:
1. Stand-by time: Stand-by time is the officially quoted longest time that a single battery charge will last when the phone is constantly connected to the GSM network but is not in active use. The stand-by time is highly dependent on the cellular network environment, such as the distance to the closest GSM cell tower (base station). Moving the phone (as in a vehicle) also negatively affects battery life.
2. Talk time: Talk time is the officially quoted longest time that a single battery charge will last when you are constantly talking on the phone. The talk time is highly dependent on the cellular network environment such as the distance to the closest GSM cell tower. Moving fast while talking (as in a vehicle) also negatively affects battery life.
3. Music playback time: Music playback time is the officially quoted longest time that a single battery charge will last when you use the phone as a music player only. Usually those numbers are only achievable when the phone is set to Flight mode (i.e. all transceivers are off) and the headphones are used (as opposed to the loudspeaker). These numbers are best used as reference when comparing phones from the same manufacturer because battery life measurement methodology will probably vary from manufacturer to manufacturer.
There are four types of batteries available for mobile phones:
1.Nickel Cadmium (NiCd): These are least expensive of rechargeable batteries, but suffer from inherent shortcomings like memory effect. Here, if the battery is not fully drained before recharging, the unused portion crystallizes hence the complete capacity of the battery is not fully used.
- Cheapest variety of batteries.
- Highly affordable.
- Brings down the overall cost of the mobile phone.
- Extremely prone to the "Memory Effect".
- Must be discharged and recharged fully on every recharge cycle.
2.Nickel Metal Hydride (NiMH): This technology offers 30 to 40 percent longer operation as compared to NiCd batteries but it is susceptible to loss of performance at higher temperatures.
- Cheaper than Li-Ion Batteries.
- More affordable.
- Brings down the overall cost of the mobile phone.
- Prone to the "Memory Effect" to a small extent.
- Must be discharged fully on every 20th recharge cycle.
3.Lithium Ion (Li-ion): The prime advantage of these batteries over NiMH is that they hold more energy for same weight and volume. Therefore, Li-ion batteries are much smaller and thinner in comparison. Also, they don't have any inherent memory effect. The only disadvantage is that they cost more than others.
- Lighter and slimmer than the NiMH and NiCad batteries.
- Usually, offer a longer standby time and talk time.
- Are not subject to the "Memory Effect".
4.Lithium Ion Polymer (Li-Po): Li-Po batteries are rechargeable batteries that have evolved technologically from Li-ion batteries. A significant advantage of these batteries is that manufacturers can shape the battery almost however they please, which is very important to mobile phone manufacturers constantly working on smaller, thinner, and lighter phones. Many latest phones, PDAs use these types of batteries.