36 Years and 1800 Issues of TidBITS

@mschmitt Michael Schmitt
Tue, 05 May 2026 18:40:22 +0000

Matt McCaffrey:

Well observed. And let’s recall how vehemently opposed Steve was to making the inner workings of a Mac accessible or expandable to an end user. In the parallel universe “personal computers” were in large cases that opened with the twist of a screwdriver, port covers that could be removed so that accessory cards could poke their sockets out the back, and other strange and scary things that he’d seen Woz doing to circuit boards and boxes in that garage where the whole thing started.

The February 1984 issue of BYTE magazine had An Interview: The Macintosh Design Team which discussed their reasoning. Here’s a link to the text from the interview: BYTE Interview with the Creators of the Macintosh from 1984.

The gist was that…

They felt that they “already built in the hardware that most people want” (Bill Atkinson), so didn’t need hardware expandability like in the Apple ][.

The cost of hardware expandability was that the hardware cards changed the memory map of the computer – “on the Apple II you keep having the rug sort of changed on you”, and “You get into incompatible combinations”. (Burrell Smith and Atkinson).

They didn’t need other ports because they included the new and fantastically fast RS-422A serial ports, which could run up to 230 kbps or even 1 mbps with an external clock. (Compared to RS-232 on PCs that maxed out at 92 kbps.*)

Also, should recognize that giving users access to the Macintosh was dangerous! It had a CRT inside!

[Sorry, I meant a Cathode Ray Tube (CRT), and Recommended Standard 232 (RS-232)]

* That’s straight from the interview: “Rather than putting in serial ports that operate at 9600 or 92,000 bits per second […]”, but I bet that was a transcription error in the original interview. 19.2 kbps would make more sense.