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HTC G1 Cellphone
Hardware Features

Jim Carter, 2009-03-30

Here is a rundown of my experiences with the G1's hardware features. The communication and networking features are discussed under Networking.


Processor and Memory

I've found that the processor (Qualcomm MSM7201A at 528 MHz, ARM family) is adequately fast for what I use it for, though of course eight-dimensional gravitation simulations are a bit beyond its capabilities. RAM (192Mb) seems to be plenty. Main flash (256Mb) holds all the listed applications, though it's kind of full; a number of hackers report transferring application storage to the memory card. I bought an 8Gb memory card, replacing the provided 1Gb card.


The display's size is 3.2 inches (81mm) diagonal, with an aspect ratio of 4:3. It has 480x320 pixels, or 188 pixel/inch, or 1.35e-4 meter dot pitch. The display is transflective, meaning that it is visible in direct sunlight. Turn the display so the sun reflects almost, but not quite, into your eyes. You get good display performance up to about 20 degress off specular reflection; white areas of the screen are 60% to 70% gray (i.e. closer to white than to black), and color is visible clearly, which is better than other transflective displays that I have seen.

Before getting the phone I was worried that the display has less pixels and less size than the 800x480px display on the Nokia N810. However, I've found that text is perfectly readable. Fine detail in photos can be seen better on the 800x480px display, but I think it's worth it to compromise on this aspect to get the other good features of the G1 phone.

Pointing: Trackball and Touch Screen

The touch screen is capacitive, compared to the older generation of resistive screens. The advantage of the resistive screen is that you can make very small touch areas, e.g. with a fingernail, for drawing or for selecting small objects like links on a web page. The capacitive screen requires a fingerprint. The Android display subroutines generally allow a big enough area that you can select items easily, but on a web page with many closely spaced links you're better off clicking the trackball. Several forum commenters say they prefer the capacitive screen, but I am not so sure.

The trackball has worked out well. In most programs the ratio of ball turns to cursor motion is reasonable, though in some I would prefer quicker action. To select an object you press down on the trackball, and you need to be careful not to turn it when pressing. It needs a good push; I think I would prefer a lighter touch.


I am very happy with the keyboard. While it is of course easier to type long texts on a full-size keyboard, I'm able and willing to write notes and e-mail messages if not too long, and I rarely make a mistake entering my password (23 bytes). All the ASCII code points are there if you use the Alt key, plus a few of the more useful ones from ISO-8859-1. The keys are far enough apart and on the numeric row I can move between them by feel.

On the Nokia N810 I was disappointed in the keyboard, and I found myself reverting to the on-screen keyboard and stylus whenever possible What makes the G1's keyboard superior?



The accelerometer reports to an application the local acceleration of the phone, which in the normal case that the phone is held by a non-walking human, would be the acceleration of gravity, which is vertical. A few applications flip between portrait and landscape orientation of the display according to acceleration, or in some cases responding to shaking the phone. Starting in v1.5 Cupcake the display library handles this behavior intrinsically if so configured. On the iPhone this behavior is much more widespread. When an application uses the magnetometer it needs to also use the accelerometer, so it can project the magnetic field onto the Earth's tangent plane.

On my device the accelerometer reports vertical at 9.2 m/s2 when the phone is tilted about 10 degrees away from flat, whereas on my planet and point of physical presence, 9.8 m/s2 is expected. When the phone is held vertical or sideways, i.e. the acceleration vector is in the plane of the phone, the Z component is much more accurately zero, but Y is 2% high and X is 7% high. In other words, don't put a G1 into a cruise missile and expect it to blow up the target.


The magnetometer provides to applications an approximation of which way the phone is facing, if combined with the local acceleration of gravity obtained from the accelerometer.

+X is phone north, i.e. toward the edge with the camera button; +Y is phone west, i.e. toward the speaker slot; and +Z is toward the front. Toward means that in the geomagnetic field of Terra that part of the phone needs to be turned towards planetary north for the respective axis to read positive. The axes are not precisely aligned with the phone's chassis; informal measurements indicate that they can be as much as 30 degrees away from the expected direction. I do not have any absolute calibration standard, but the magnitude of the field is reported as around 50; the help for the Tricorder app say the units are micro-Tesla, so this value is about right for my location.

Remember that the geomagnetic field is approximately a dipole and will have a substantial vertical component generally proportional to -sin(latitude), i.e. toward the ground in the northern hemisphere. Also the field source is turbulent convection in Terra's liquid core, which is off center (the solid inner core is in the way). So the magnetic field rarely points truly north; in Los Angeles (USA) it is currently about 13 degrees east of north while in Maine it is 17 degrees west of north. These values change year by year. See for updated worldwide values.

I had an unfortunate experience with my magnetometer. The case for my phone has a magnetic closure (bad choice), and the phone came too close to the magnet. After that the magnetometer's Z axis reported over 1000 units, and the X and Y axes were around 300 each, independent of orientation. Repeated power cycling failed to return it to normal. However, after about three days it recovered by itself.

I put some time into hunting for a new cellphone case, but unfortunately, every candidate case has a magnetic closure.


(Need to write; see the camera application.)

Power Management

How much power do various activities take? The ideal is to report power in watts, but that is probably not going to happen. Percent is available easily. I will make two assumptions. First, the denominator of the percentage is the battery's nominal capacity of 1150 mAh. This is normal for a smart battery. Second, the readout is linear. I will do the tests with between 30% and 80% of charge, for which a LiIon battery puts out a nearly constant voltage, so this assumption is probably fairly good. With any luck the reported numbers are accurate to 10% or so.

The standard configuration for testing has the lamp at 33% (when it's on), 3G on, WiFi on, Bluetooth off, GPS off, doing the activity continuously, i.e. not sleeping.

Activity Duration
Percent Rate
Asleep (WiFi off) 8.5 5% 0.6 170
Asleep (WiFi on) 8.0 9% 1.1 89
Doing nothing (no sleep, lamp on)
Music via Bluetooth (lamp off) 2.1 31% 15.0 6.7
Web browser, all local content 0.66 12% 18.0 5.6
Sudoku game 0.85 11% 12.9 7.7
Map display, GPS on 1.0 30% 30.0 3.3
Camera, viewfinder only
Camera, picture every 10 seconds

T-Mobile Accessories

Handling the Memory Card

To remove the SD card, first select Settings - SD Card - Unmount SD Card.

Now, following along in the setup guide, open the display and find the card cover at the southeast corner (under the green Call button). At its west corner which is inaccessible when the display is closed, you can feel a bump, by which you can pull it southward. It is made of flexible plastic, and can be rotated downward out of the way.

If you have long fingernails you can press the card in (north), then let it pop out by spring pressure. If you have short fingernails you will need to use an instrument to do this.

The card turns out to be made by SanDisk. In format, it is a Micro-SD card, 1Gb. Up to 16Gb can be accomodated.

When you are through working with the card externally, re-insert it in the slot -- push it in as far as it goes, and it will spring back slightly. Re-seal the card cover including on the west end with the bump. The operating system will re-mount the card automatically.

If you software-eject the card, then change your mind and want to remount it, this could be done from the command line but there is no way in the GUI to do it. Physically remove the card, then re-insert it. Or power cycle the phone.