Overview

The mere fact that a CompactFlash card can be inserted into a PCMCIA adapter sleeve and used as if it were a PCMCIA card implies that the CompactFlash and PCMCIA specifications are almost identical. In fact, the official CompactFlash specification states that CompactFlash cards provide complete PCMCIA-ATA functionality and compatibility including PCMCIA True IDE capability. While we're discussing CompactFlash card specifications, I'll clear up a much-asked question about what voltages CompactFlash cards can tolerate. The CompactFlash specification states that CompactFlash cards can operate with either a +5VDC or +3.3 VDC power supply. The AirDrop modules use the +3.3 VDC power rail. Hmmm The CompactFlash card dual-voltage statement makes me believe that one or all of those unidentified 5-pin SOT-23-5 devices on the 802.11b CompactFlash NICs I "opened up" is a low-dropout voltage regulator. With the exception of the DCF-660W, all of the other 802.11b CompactFlash NIC's have three such devices on their printed circuit board. The DCF-660W has two SOT-23-5 packages and one unpopulated SOT-23-5 site. If we take a look at the PRISM chipset data sheets that we can get our hands on and make the assumption that the newer parts operate in a similar manner, my theory is proven as the ISL3873A's operating voltage range is +2.7 VDC to +3.6 VDC.

We won't be discussing PCMCIA or PCMCIA 802.11b NICs to any great detail within the pages of this book. However, I don't like to talk about things and not show them to you. After all,...