This prototype build, in May 2007, was the first to use an updated electrical design for the laptop. It was the first build providing the processor and memory capabilities of the production version. A very small number (around a hundred) were built, all were used for hardware and low level software development.
Noticeable improvements over BTest-2 included:
- A faster, lower power processor: the Geode LX-700
- 64 KB I/64 KB D of L1 Cache, 128 KB of L2 Cache (vs. 32 KB of L1 cache)
- Faster processor and memory clock (433/333 vs. 366/266)
- 1.5 W typ. vs. 3 W typ.
- Much better graphics processor, including support for rotated blits and depth conversion
- More memory: 256 MB of SDRAM (vs. 128 MB)
- 11-19V DC input voltage usable, -40-40V tolerated
- A colored XO on the back cover --- 400 different color combinations so kids can distinguish their laptops from each other
- Insert molded rubber ears for better robustness
- A smaller battery cavity to improve robustness, make the bumper lines clearer
- An improved case design (addressing strength)
- new bumper tooling to allow the bumpers to be made of polycarbonate (as opposed to PC/ABS) with 3mm thickness and ribbing to 1.8mm (was 2mm and 1.2mm respectively)
- A steel plate inside the entire keyboard base to reduce the feeling of flimsiness
- A new hinge design allows greater tilt of the screen
- A keyboard that is much better to type on
- A newer touchpad from ALPS that is much easier to use and much more responsive
- A flipped USB connector so each side has the same way up for a USB key or device
- Extra screws
- No texturing of any exterior plastic
- A smooth "XO" in color on the back of the laptop
- A grey bezel around the display
- No keyboard illumination LEDs as present on B2 prototypes.
- Beta Test 3 Systems have a label under the battery that says B3-*, where * is a number from 1 to 8
 Software Support
BTest-3 Systems work with current software releases.
As they may experience hardware problems with extensive suspend/resume or low battery current software releases prevents suspend/resumes on B3s.
The polarity of the audio amplifier enable is inverted relative to later versions (and what the software expects), but may be corrected manually.
- There may be occasional crashes (possibly made worse by suspend/resume) when the battery is running low. Above 25% of capacity, or plugged into a power adapter, you should be OK (Trac #1835)
- There may be times when the WLAN (USB) hangs (possibly made worse by suspend/resume) (Trac #1752, #4476)
- Power cycling the DCON is liable to crash the laptop. This power cycling will occasionally happen in response to a DCON bug triggered by suspend/resume (#4479);
- Rare crashes may be caused by other sources during suspend/resume (Camera, SD card, clock settling time), some units may be more sensitive than others (#1835)