The PowerBook Duo is a line of subnotebooks manufactured and sold by Apple Computer from 1992 until 1997 as a more compact companion to the PowerBook line. Improving upon the PowerBook 100's portability (its immediate predecessor and Apple's third-smallest laptop), the Duo came in seven different models. They were the Duo 210, 230, 250, 270c, 280, 280c, and 2300c, with the 210 and 230 being the earliest, and the 2300c being the final incarnation before the entire line was dropped in early 1997.
Weighing and slightly smaller than a sheet of paper at , and only thick, it was the lightest and smallest of all of Apple's PowerBooks at the time, and remains one of Apple's smallest notebooks ever produced. Only the MacBook Air, the Retina MacBook Pro and the Retina MacBook weigh less, though they are wider and deeper (but considerably thinner). The Duo had the most in common with the original MacBook Air which only included one USB 2.0 port, one video port (requiring an adapter) and one speaker port, but no ability for expansion.
The PowerBook Duo line was replaced by the PowerBook 2400, which was slightly larger in size than the Duos, but still only the fifth-smallest behind the 12-inch PowerBook G4 which succeeded it as fourth-smallest. Although both featured much more onboard functionality, they lacked docking ability.
Features
The Duo line offered an ultraportable design that was light and functional for travel and expandable via its unique docking connector. However certain compromises were made to achieve this level of portability. The Duo series used an 88% of standard desktop-sized keyboard which was criticized for being difficult to type on. Likewise, the trackball was reduced in size from even that used on the PowerBook 100. The only usable port which came standard on the Duo was a dual printer/modem EIA-422 serial port.
There was a slot for an expensive, optional, internal 14.4 Express Modem and no provision for built-in Ethernet. This somewhat limited configuration meant the only way to move data in or out of the laptop in a stock configuration, without purchasing additional accessories, was via a relatively slow AppleTalk connection, which was not practical in the event of hard drive problems. Compensating for these limitations, the initial Duo offering provided for a considerably higher RAM limit of 24 MB (as compared to the 100 series' 14 MB), and a standard 80 MB hard drive (versus the 100's 40 MB drive). The debut year for the Duo only offered a passive matrix display on both the mid-level and high-end models, in contrast to the high-end of the PowerBook 100 series - the PowerBook 170 and 180 (in which the Duos shared the same processors). With their crisp active matrix displays, both were already in great demand over the lower-powered models with passive matrix displays. The following year, Apple replaced the Duo models with both an active matrix display and a color active matrix display, the latter becoming the de facto standard of the PowerBook line. The respective Duo models are easily differentiated by their display method and processor. All other features are identical.
Specifications
The 200–series Duos were powered by either Motorola 68030 or 68LC040 processors, ranging from 25–33 MHz. When Apple debuted its next-generation PowerPC processors in 1994, it took over a year for the first PowerPC Duo (the 2300c) to debut. The original PowerPC 601, like the original 68040 before it, produced too much heat and consumed too much power for Apple to use in any laptop but, by the end of 1995, the more efficient PowerPC 603e had been developed, which was featured in the Duo 2300c and its full-size companion, the PowerBook 5300 series. The PowerPC 603e was designed for a 64–bit bus, but was engineered by Apple to run on an older 32–bit bus to maintain compatibility with the Duo Docks. This led to poor system and video performance.
Docking stations
PowerBook Duos lacked most common ports (featuring only one internal printer/modem serial port and an optional fax/modem card port). In their place was docking ability, accomplished via a unique 156-pin Processor Direct Slot (PDS) giving the docks full access to the Duo's central processing unit (CPU) and data buses. Several dock options were offered by Apple and third parties.
Duo Dock (M7779) (1992), Duo Dock II (1994), Duo Dock Plus (1995)