Editing Apple IIe (section)

===Revision B motherboard===
Shortly after the "Revision A" motherboard's release in 1983, engineers discovered that the bank-switching feature (which used a paralleled 64 KB of RAM on the Extended 80-Column Card or 1 KB to produce 80 columns using bank-switching) could also be used to produce a new graphics mode, Double-High-Resolution, which doubles the horizontal resolution and increases the number of colors from the 6 of standard High-Resolution to 16. In order to support this, some modifications had to be made to the motherboard, which became the Revision B. In addition to supporting Double-High-Resolution and a rarely used Double-Low-Resolution mode (see specifications above) it also added a special video signal accessible in slot 7.

Apple upgraded the motherboard free of charge. In later years Apple labeled newer IIe motherboards with a "-A" suffix once again, although in terms of functionality they were Revision B motherboards.