Home > Technology > New Dash 3G ROMs Being Cooked

New Dash 3G ROMs Being Cooked

August 28th, 2009 Leave a comment Go to comments

[Update: I’ve flashed my phone to ookba’s 3volution ROM. See this post for the flashing procedure and this post for my initial review.]

Closely watching XDA-Developers member ‘ookba’ who has been cooking some new ROMs for the Dash 3G based on the Windows Mobile 6.5 core and his “3volution” design. (The Dash 3G ships with a Windows Mobile 6.1 core.)

ookba is on his second release as of today (Build 3VO.1.00.082609). I usually wait for the early adopters to find the most critical bugs (like a white text on a white background problem in the first release on the caller ID pages so you couldn’t see who was calling.) But I think I’ll be flashing my phone soon.

ookba’s released ROMs for the HTC Maple (T-Mobile Dash 3G) found here and for the HTC Cedar (Sprint Snap & Verizon Ozone) found here.

For those not familiar with cell phone software, here is a very basic primer, at least for Windows Mobile / HTC phones.

Operating Systems

Like any computing device, a cell phone has an operating system or OS. For the Dash 3G, that OS is Windows Mobile 6.1 Standard.

Unlike regular Windows XP or Vista, when a cell phone manufacturer and carrier decide to release a Windows Mobile phone, they have the ability to customize the OS to a great extent. Think of T-Mobile’s “My Faves” application as an example — this is something T-Mobile builds into the phone’s OS.

The OS for a cell phone resides in a memory chip on the phone that the phone itself can not change or write information to. So it is called Read Only Memory or ROM. The copy of the computer code that resides in this memory is called a ROM Image, or also simply a ROM. So, in the lingo of cell phone hackers, the terms ROM and OS are interchangeable.

Almost anyone can use a  Software Development Kit (SDK) (called a Kitchen) to build their own ROM (called “cooking” a ROM). Getting it installed on the phone is the hard part.

Protection

Cell phone carriers and manufacturers are notoriously protective of their OSes. So every cellphone is locked in multiple ways to prevent people from changing the software. The two most common locks for GSM phones (like the Dash 3G) are CID locks and SIM locks. The SIM lock prevents a SIM card from another carrier from working in your phone, so you can’t move to another carrier easily. More important to the OS is the CID (Carrier ID) lock, which prevents software ROMs not “signed” by the carrier from installing on your phone. This is why you can’t normally change the OS on your phone.

Luckily, there are some very talented people out there who are able to break this lock for most phones.

Bootloader

Every cell phone is equipped with something called a bootloader, which is a program that is designed to take the ROM Image from its memory and load it into the working memory of the phone (normally, this resets the phone to its factory settings, and can be invoked on the Dash 3G by powering the phone off, then turning it on while holding the volume up button).

This bootloader also verifies that the image its loading is a “signed” or authorized image. It does this with an SPL program (no idea what SPL stands for).

In order to replace the ROM on a phone you need to defeat this security check. One way is to defeat it permanently (a Hard SPL break). Another way is to change the routine so it can be bypassed as needed (Soft SPL break).

Updating Sequence

So, this means that the basic sequence to changing your phone’s ROM is this:

  1. Change the SPL security.
  2. Load or ‘flash’ a new ROM image to the Phone’s ROM.
  3. Engage the bootloader to load the new ROM to the phone.

Of course the devil is in the details. A very good primer on flashing ookba’s ROMs is: http://forum.xda-developers.com/showthread.php?t=551959

This content is published under the Attribution-Share Alike 3.0 Unported license. Please click link for information.

Post Revisions:

  1. No comments yet.
  1. No trackbacks yet.