In previous articles we covered both the nearly identical LC and the LC II, both of which were early attempts to bring an affordable color Macintosh to the market. Both machines more or less accomplish what they set out to do but also both were heavily compromised in functionality to achieve this end. The main compromises of the original LC and following LC II were
1 – A 32-bit CPU on a 16-bit motherboard severely hampering the performance of the LCs 16mhz 68020 CPU.
2 – An imposed limit of 10MB of RAM regardless of the size of the RAM stick(s) installed.
3 – complete lack of a MMU or FPU socket on the motherboard.
4 – Difficulty getting the LC to run with monitors outside of the fixed resolution 512×386 monitor it was intended to be paired with or period Apple or early VGA monitors.
The LC II added the ability to use virtual memory via the CPU’s built in MMU and tweaked the video a bit but was otherwise identical. Thankfully the LC III finally addressed all the above issues while maintaining the same small form case. Finally we have a full 32-bit data bus so as not to strangle the 32-bit CPU. There is now a MMU as there was built into the LC II but also much more expandability for RAM as well as a socket for a FPU chip and the video memory supports 640 x 480 resolution without any kind of fiddling or upgrade.
Other then the LC III badge the case is identical to the LC I and II. bear in mind there are two versions of the LC III case and one features a manual eject floppy drive that looks a little different with an indentation to grasp the disk. These cases also have the case badge as more of a label then etched onto the case. Otherwise these machines are identical.
The rear of the case though is identical to the LC I & II. from left to right you have the power connector and switch, Mac video port, modem and printer ports, external SCSI port, ADB port and finally an audio jack for speakers and mic. The Ethernet card installed on the right is the same one that used to be installed in my LC II.
The LC III like the LC I & II does not support power on via the keyboard and use of the rear switch is required. Opening the LC II is exactly the same as the other LC’s with just two fairly sturdy tabs securing the top.
Now with the top removed.
The general layout is basically the same as it was in the LC II with a single floppy drive and space for a SCSI hard drive. Mine came with a standard 80mb SCSI hard drive but I upgraded mine to a 500mb model by transferring the upgraded hard drive from my LC II.
Now lets take a look at the motherboard.
1) Enhanced LC PDS slot – The PDS slot on the LC has a slight extension to it compared to the PDS slot in the LC and LC II. The “enhanced LC PDS slot” in the LC III supports both 16-bit PDS cards of the type that would be used in the older LC machines but also 25mhz 32-bit PDS cards. Unfortunately these 32-bit cards are quite uncommon.
2) CPU – The LC III unlike the LC I & II now uses a full 32-bit data bus as opposed to a 16-bit but so the CPU can be taken full advantage of. The CPU in the LC III is a Motorola 68030 running at 25mhz, also a bump up from the 16mhz of the previous LC’s. Some benchmarks of the time placed the LC III twice as fast as the LC II in overall performance. There is also a version of the LC III known as the LC III+ which is identical save for the CPU which got a speed bump up to 33mhz. There is no way to tell the two models apart as there was no indication given on the outer case. Only opening the case and checking the CPU or powering the machine up and checking in software would reveal the difference. There are guides available on modding the LC III into an LC III+ but perform at your own risk. Also Later LC III’s with the manual floppy drive eject are more likely to be the plus models though be aware this isn’t a sure thing.
3) FPU – Finally we have a socket to add an optional 68882 math coprocessor to assist in complicated math calculations. This doesn’t seem to of been a popular upgrade though as I’ve never come across an LC III with this upgrade though the chips are fairly cheap (as of 2018). Like on the x86 PC though I don’t think the FPU was heavily utilized in any number of games on the Mac so the FPU upgrade was not seen as a priority.
Empty FPU socket to the right of the CPU
68882 coprocessor installed
4) RAM – The LC III has 4mb of RAM on the motherboard but also unlike the previous LC’s the LC III has a single 72 pin SIMM socket with the ability to add up to 32 additional MB or RAM for a potential max of 36mb. This is the configuration of my LC III featured here. The LC III was also the first Macintosh to use 72 pin SIMMs. This was a welcome feature as the previous 10mb was serviceable for the time but the ability to add up to 36MB total went a long way to extending the usefulness of the LC III in the future.
5) Video – The LC III features built in video and 512kb of VRAM standard. This allows 640 x 480 resolution on a 640 x 480 capable monitor out of the box and I had a much easier time hooking this LC up to my various monitors via a Mac to PC VGA adapter and getting a image without any hassle or “out of range” errors. The VRAM is upgradeable to 768kb via a VRAM slot and 256 KB 100ns VRAM SIMM. This will allow a maximum resolution of 832 x 624 at 16-bit
6) PRAM – this is the ever present PRAM battery for saving settings. It is always recommended to swap this battery out when you get a new Mac or if you start encountering strange instabilities.
The Mac LC III was a great evolution of the LC line finally fixing all of the shortcomings of the line while maintaining a lower price point. For all intents and purposes the LC III was a Macintosh IIci in a smaller form factor case with slightly lower performance and much less expansion capabilities. If all you wanted to do was some light work and gaming and didn’t need the expansion slots of the Macintosh II line the LC III was an excellent option that saved money and took up a little space in the house.
For the retro Mac gamer I would easily recommend this machine over the LC I and II. They don’t take up much space, are light and relatively cheap and easy to fine. They also offer enough power to run early color Macintosh games or black and white titles well and can work with most monitors hassle free.
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