Uh, no. I’ve got a 540c right here and it does not have a PCMCIA slot.

There was an optional PCMCIA card module that could go in the 500-series left battery bay, but it was never popular and few were sold. Most likely this was due to the fact that the main initial reason for PCMCIA cards in laptops were for Ethernet and modem cards (WiFi PCMCIA cards came much later), and the 500-series came with Ethernet built in, and could be configured with an optional internal modem (19.2 Kbps max).

The twin battery bays in the 500-series were an innovation you left out, however. You could supposedly get up to 2.5 hours of life out of each battery, adding up to a whopping possible 5 hours of use with two batteries. In practice, though, we all know how inflated official battery life claims are.

The 500-series also came with video-out ports that supported an expanded desktop on an external display.

There was some thought within Apple of shipping a 500-series model with the 100 MHz PowerPC 603 CPU card pre-installed. It’s unfortunate that it never happened and Apple’s resources were entirely put behind the PowerBook 5300 and 190 (same design as the 5300 but with a 68040 CPU) and Duo 2300.

The PowerBook 5300 and 190 were the actual first Mac laptops to include PCMCIA slots. They also used IDE internal drives instead of SCSI (2.5″ SCSI drives were *expensive* at higher capacities, and I don’t think anyone made them larger than 1 GB before discontinuing SCSI drives in that form factor completely).

As a bit of an oddity now, but as a pre-cursor to WiFi wireless networking, the PowerBook 5300 and 190 were the first PowerBooks to include IR ports that let you point two of them at each other and create a network over “IRtalk” (AppleTalk over infrared). There were even some 3rd party IR pods you could hook up to desktop computers to provide a “wireless network” for these PowerBooks much like a WiFi base station. Unfortunately IRtalk was extremely slow, line-of-sight only, short range, and generally flakey, so you might as well have used a cable.

Except… The 5300 and 190 did NOT include built-in Ethernet or modems. So you had to buy and carry around PCMCIA cards for these functions, which had previously been built-in or available as an internal option.

The other reason Apple decided to focus on the 5300 and 190 PowerBooks was because they designed its expansion bay (where its 3.5″ floppy drive normally lived) to accept a 3.5″ CD-ROM drive. Apple figured that there was no way anyone was going to cram a full 5.25″ CD-ROM drive into a laptop, so most likely 3.5″ CD-ROMs were going to become the rule for portable computing. Then, while the 5300/190 was under development, a few other manufacturers announced laptops with full-sized 5.25″ CD-ROM drives at an industry trade show. Oops.

In hindsight Apple would have been much better off selling a PowerBook 500-series machine with a PowerPC CPU card pre-installed. It could have been based it on the (Japan-only) 550c, which had a full 640×480 active matrix display (the 520 and 540 models had 640×400 displays). The top of the line 5300 had an 800×600 display, but with the size of the display bezel on the 500-series Apple probably could have fit one of those into it. They then could have used the development resources they spent on the 5300/190 on a more revolutionary laptop with a 5.25″ CD-ROM drive and full built-in features that could have been a true successor to the 500-series.

“Motorola’s early 90s 68040 CPU was becoming too hot for use in a portable, making it difficult for Apple to compete against 486-based PC laptops.”

It wasn’t so much a heat problem. The 33 MHz 68LC040 in the PowerBook 540 ran cool enough, and it was the fastest ‘040 they made then. It was more about speed. Apple had already decided to transition to the PowerPC architecture and their laptops naturally had to go along.

“A new Newton Message Pad 2000 series also shipped in 1997, but the entire PDA line, including the eMate, was canceled early the next year after sales failed to take off.”

Newton, Inc. was being spun out as a separate company. Steve Jobs really liked the eMate and wanted to keep its designers. The Newton, Inc. spin out was canceled and then Apple decided the Newton was too much of a distraction to be kept going in-house. Notice how much of the design of the iMac and the original iBook followed from the eMate. (Even the curvy Wallstreet and Lombard/Pismo gave nods to the eMate, especially with the later translucent “chocolate” keyboards.)