Apple didn't use the IEC power symbol on their keyboards until the iMac-- prior keyboards used a left-pointing triangle on the power button. But most of these

Apple didn't use the IEC power symbol on their keyboards until the iMac-- prior keyboards used a left-pointing triangle on the power button. But most of these machines shipped in an era where there wasn't necessarily any standardization of how to turn the machine on in the PC-compatible world either-- the now-standard momentary electronic switch on the front of the case came with the ATX spec in 1995. Before that, you'd usually have a flip switch or latching power button somewhere on the case. (Macs were unusual for the era in having power on the keyboard from the ADB keyboard on.)