MID Overview

As I've mentioned in previous chapters, there's a huge range of J2ME-compatible devices already available, and new devices, ranging from mobile phones to PDAs, seem to be released on a daily basis.

The most common form of MID is basically a suped-up mobile phone. Memory is generally limited, with the greatest restriction being that the maximum size of an individual J2ME MIDlet is as low as 30 KB. The input device is typically the traditional phone keypad, although direction pads are becoming popular.

There is, however, a very serious end of the market (in gaming terms), which includes high-end devices such as the Nokia Series 60 (including the N-Gage) and the Sony Ericsson P800/P900. Sporting big screens, tons of memory, and fast processors, these devices provide an excellent experience for gamers.

All right, enough talkit's time to check out the gear. In the next few sections you'll see what's offered by the likes of Nokia, Sony Ericsson, and Motorola.

Nokia

As one of the largest manufacturers of MIDs, Nokia represents a significant proportion of your current (and future) user base, so spending a little time understanding their product range is well worth your while. The best place to find out about Nokia phones is at http://forum.nokia.com.

Although they have a great many different phone models, Nokia standardizes all devices into the five series listed in Table 3.1.

Table 3.1. Nokia Series Devices

Series	Screen	Type	Input Use
Series 30	96 x 65	Monochrome/Color	One-handed
Series 40	128 x 128	Color	One-handed
Series 60	176 x 208	Color	One-handed
Series 80	640 x 200	Color	Two-handed
Series 90	640 x 320	Color	Two-handed

Having all models follow a series is great for us developers. You can develop a game for a particular series and be comfortable that it will work on all phones that conform to the specification. Take a closer look at each of the series and some example phones in the following sections.

Series 30

The Series 30 is mass-market range from Nokiathe sort of thing given away when you buy more than three bananas at the fruit shop. The focus, therefore, is price, and that means the devices don't come loaded with features. However, you can still write games for these devices; you just need to work within their constraint.

The original Series 30 phones were all monochrome (2-bit grayscale), with a maximum MID JAR size of 30 KB and heap memory of around 150 KB. Series 30 phones are always 96 x 65 pixels. There are some newer Series 30 models now available that sport a 4096-color screen, an increased JAR size of 64 KB, and a slightly larger heap. All Series 30 phones use the regular phone keypad layout you see in Figure 3.1. A more advanced version, the 3510i, is shown in Figure 3.2.

Series 40

The Nokia Series 40 is what you might call the J2ME gaming heartland. They are cheap, extremely popular, and pack enough power to make for some fun gaming. This combination means they are the most widely supported and targeted phone class for J2ME developers.

All Series 40 devices have a 128 x 128-pixel 4096-color screen. They support a minimum MID JAR size of 64 KB and have 200 KB of heap memory (though some devices exceed these capabilities). The input layouts can vary, as you can see in Figures 3.3 and 3.4.

Series 60

The Nokia Series 60 is where things start to get serious. The standard screen size jumps to the far more respectable 176 x 208, although it's still 12-bit (4096) color. The real news, though, is that the maximum JAR size increases to a whopping 4 MB on average! Heap memory is also up considerably, to 1 MB or more. That's enough space for some serious gaming.

Devices in this series include the 3600, 3650, 6600, 7650, and N-Gage. You can see a picture of a 3650 in Figure 3.5 and an N-Gage in Figure 3.6.

Series 80

The Nokia Series 80 devices are very high-end PDA phones based on the "communicator" range. The form factor is a bi-fold device that opens to present a large screen (640 x 200) and a small QWERTY keyboard. JAR size is a massive 1416 MB.

Unfortunately the price and bulk of these devices severely limits the total market for your games. If you're developing for the Series 60, consider a port to the Series 80 (or 90). I don't recommend developing a game exclusively for the Series 80, though. You can see a typical Series 60 device in Figure 3.7.

Series 90

The Nokia Series 90 devices are also PDA-come-phones with high-end capabilities. However, they differ from the Series 80 devices in that they do not include the keyboard; they rely instead on pen-based input, so they tend to be of a more manageable size. They're also dead sexy!

A Series 90 device sports a 640 x 320 16-bit (65536-color) display and a maximum MIDlet size of 64 MB. (Yep, I didn't get that wrong64 MB!) Now you're talking!

Like the Series 80, however, the 90 has a limited market due to cost. One of the first Series 90 phones is shown in Figure 3.8.

Sony Ericsson

Combining the mobile technology of Ericsson with the style and marketing of Sony seems to have been a successful idea for the partners and consumers. Sony Ericsson has a broad range of capable phones that incorporate strong support for J2ME. To find out more details about developing for Sony Ericsson, visit http://www.sonyericsson.com/developer.

T6xx and Z600 Series

J2ME support starts with the T6xx series of devices, all of which have a 128 x 160 screen and 16-bit color. Maximum MID size is around 60 KB with 256 KB of RAM. The Z600 also falls into this category because it's a fold-out version of the same platform. You can see an image of the T610 in Figure 3.9.

P800 and P900

At the high end of the market, Sony Ericsson weighs in with the popular P-series (currently the P800 and P900). These are extremely capable devices with screens measuring 208 x 20; the P800 has 12-bit color and the P900 (shown in Figure 3.10) has 16-bit color. Both units have very fast processors in J2ME terms and 16 MB of base memory. Probably the only drawback is the use of a touchscreen for primary input. This is great for general PDA use, but for gaming it's quite cumbersome and unresponsive.

Motorola

Motorola has two distinct ranges of phones, each with its own developer Web site and support system. For the regular GSM and GPRS network-based models, you can use Motocoder for support, which is available at http://www.motocoder.com.

Motorola also supports a range of devices for their iDEN network (mostly sold through Nextel in the United States). The support site for this range is http://idenphones.motorola.com/iden/developer/developer_home.jsp.

In the next couple sections, you can take a look at a few examples of both the device ranges.

General Phones

Motorola has a broad range of Java-enabled phones with varying capabilities. The basic A380 shown in Figure 3.11 has a 96 x 45 12-bit color display with a max MIDlet size of 100 KB and a heap memory of 1 MB. It's a great gaming phone but a little limited in terms of screen real estate.

Another example of Motorola's J2ME phones is the higher-end A830 is shown in Figure 3.12. With a very respectable 176 x 220 12-bit color screen, a 100 KB max MIDlet, and 512 KB of RAM, this device is an excellent gaming machine.

iDEN Phones

All Motorola phones that have a model number starting with "i" are within the iDEN range, starting with the i85s, which has a 119 x 64 monochrome screen and a maximum MIDlet size of 50 KB. Like most of the lower-end iDEN phones, memory is limited to 256 KB.

The i730 shown in Figure 3.14 is at the top end of the iDEN offerings. It includes a 130 x 130 16-bit color screen, more than 1 MB of heap, and a maximum MIDlet size of 500 KBmore than enough for some serious gaming.