> I didn't mind it that much because the higher the number was the more powerful the computer tended to be. The 9500 was super good. The 8500 not bad. The 7500 was the best of the mediocre, and the 7200 was similar but not as great.

The general rule was that the first digit represented the form factor, the second digit represented the base model (logic board), the last two digits represented the value-add configuration (amount of RAM, size of HDD, and included software package), then CPU speed was given after a forward-slash, and there might be a CD somewhere in there for configurations which included an internal AppleCD drive.

The PowerPC-era form factor numbering scheme was actually established in the 68k era with the all-in-one LC 500-series, the pizza-box Centris 600-series (descendant of the original LC form factor), the desktop Quadra 700 (descendant of the Macintosh Ⅱᴄx/ᴄɪ [compact] form factor), the mid-tower Quadra 800/840AV, and the full tower Quadra 900/950. Computers were called Macintosh when sold by Apple (like to schools) or sold through Apple's dealer network, called Workgroup Server (WGS) when sold in server configurations (like with AppleShare/IP) and called Performa when sold direct to consumers (like through CompUSA, etc).

It started well with the initial models of NuBus Power Mac: the pizza-box 6100/60, desktop 7100/66 (I had this one!!!), mid-tower 8100/80, and full-tower WGS 9150 — different form factors but obviously denoted as the first PowerPC model (x1xx) of each series.

The 6100 makes a good example of this era because it got an especially large number of consumer-focused SKUs where it was known as the Performa 611{0..8}CD, a server version known as the WGS 6150/60, and an eventual speed-bump when it became the Power Macintosh 6100/66 and WGS 6150/66: https://en.wikipedia.org/wiki/Power_Macintosh_6100#Models

Then the exceptions to the numbering scheme started with the second generation of PowerPC machines, the first to switch from NuBus to PCI. They reintroduced all-in-ones as the Power Mac 5200 series (famously horrible machines) and stuck the same board in a Quadra 630 style case as the 6200, both with a PowerPC 603. They introduced a desktop 7200 and mid-tower 8200 with PCI but still using a PowerPC 601, so the x2xx still seemed to represent release order and not CPU. But then they simultaneously released the 7500 and 8500 with a PowerPC 604. Were these supposed to be fifth-gen models? What happened to 3 and 4? They introduced a six-slot PPC604 machine at the same time, the Power Mac 9500, but there was no PPC601 9200.

Next year, the 6400 appeared in a curvy and quite nice-looking consumer mid-tower case, but 6xxx has now represented three different form factors. The 7600, 8600, and 9600 replace their respective x500 counterparts, so now we're back to release order? It doesn't mean CPU generation, because there are higher-end 9500s with PPC604e instead of just 604, and lower-end 7600s with just 604 and not 604e.

The year after that, the Power Macintosh 7300 (I had this one!!!) replaces the 7200 and the 7600, so now we're going backwards even though it's a better computer? It doesn't mean release year, because the 5300 and 6300 are a year older and are just speed bumps of the 5200 and 6200. Except the 5260 which is newer than the 5300 and a much better machine, which was replaced by the 5400 which is a 6400 board in a 5xxx-style case. Except the 6360 which is a 6400 board in a 6200/6300-style case because they had already used 6400 for the tower form-factor the board came from. The 6500 and 5500 were speed bumps of the 6400 and 5400, but at the time of their release were two years newer than the 7500/8500/9500.

The 4400 falls outside of all of this, so at the time it felt like Apple trying to build a cheap Wintel-style business machine. There had been 68030 machines numbered 4xx, but they were consumer-only Performa variants of the LC Ⅲ. Except the LC 475 which was a Quadra 605 in a LC Ⅲ style case.

Except, except, except. What a fucking mess lol