Which year did ATX first come to the shops...

Anyone know?

I bought a Pentium 60 when first launched from Gateway back in 1993. Had a big expensive 17" monitor and 256mb's RAM, if I remember correctly. Paid right at $4,000 cash, for CAD geometry adjustments and drafting so I could progress my surveying internship.

Pentium 60 came in an AT case. I was doing refurbishments in the mid to late 90's and vaguely remember every model of Gateway available back then.

I'm fairly certain Gateway introduced ATX chassis in 1994. Those ones that converted from a tower to a desktop, though most people didn't realise conversion was posible.

AT and ATX crossover for Gateway was Pentium 90-120 as far as I can remember, I don't remember an AT 133 from them, nor a 75MHz ATX. I upgraded most of the AT style Pentium boards to a Pentium Overdrive 166MMX.

AST stood out because they had an ATX case before ATX became "a standard" The one I had was a 486SX, so probably 1992 rather than 93, plastic, using the old port layout that was flat across the bottom.

Cases used to come with that backplate, forgot the name. There were actually three standard port configurations back then, and the most common of them became "the" later standard.

Full tower or convertable mid-tower?

I'm not sure when Gateway shrunk their full tower. The original AT full-tower was around two inches taller than the ATX one that replaced it. The ATX version had a removable back panel and was available with either AT or ATX filler panels, so even if you got an AT version of the later case you could mount an ATX board.