Rear power button

[boitoy1996]

So, I noticed some of these 68k Macs with the ability to power on using the keyboard also have a power button in the back, which I was told was the same thing as using the reset button on the keyboard to power on.  I also notice the power button is slotted and that you can push in on it with a flathead screwdriver and turn it and keep it locked in.  Whats going on here.  Is there more than meets the eye?

 

[Bolle]

Locking the power switch into the pushed in position was yesterdays ‘turn on again automatically after power loss‘-setting.

 

[boitoy1996]

I thought the Mac quadra had soft power.

 

[TheWhiteFalcon]

So do modern PCs, you can still set auto reboot.

 

[Bolle]

The switch on the back does trigger the soft power circuit on the logicboard just like the keyboard power switch does.

 

[Scott Baret]

Which Quadra? The 700 has the same basic soft switch as the IIcx/IIci. Others had hard switches.

In regard to turning that switch with the screwdriver: this keeps the power locked to the on position. This was designed for people using these computers as servers. If there's a power outage and the server isn't constantly manned, it could turn on automatically in the event of a power failure.

 

[boitoy1996]

So why the switch. If it's software controlled power?  Why not an option in the settings like restart after ac power failure?

 

[Scott Baret]

Remember, we are dealing with a computer from 1987. Power supply managers were not built into mainstream computers for a few more years.

 

[Bolle]

"Soft power" does not actually mean it is software controlled - which it really is not in case of the 68k Macs that had soft power.

It is more meant to be the opposite of "hard" power which turns the machine on as soon as mains power is applied.

The advantage of soft power was that you could use the power switch on the keyboard to turn it on. Also the RTC and PRAM was powered by the 5V supply that was always present as soon as you plugged a Mac with soft power into mains.

Having software controlled power states would need some kind of microcontroller as a power manager which was first featured in later PPC machines.

While a lot of 68k Macs already had a CUDA which was a really basic power manager already it was far away from being up to tasks like restoring power states after loosing main power.

 

[techknight]

Its hardware controlled, but the latch reset was connected to a VIA so the OS could kill the power when it was shut down. 

 

[boitoy1996]

Its hardware controlled, but the latch reset was connected to a VIA so the OS could kill the power when it was shut down. 

That's quite an ingenuity way of doing things.  Someone had to specifically want the computer to turn off when you hit shutdown, that didn't come about by accident.  I wish I could meet the engineer who thought of this.  During a time when PCs couldn't be powered on or off via the keyboard, I bet this was a deciding feature to buy a mac.

 

[xboxown]

That's quite an ingenuity way of doing things.  Someone had to specifically want the computer to turn off when you hit shutdown, that didn't come about by accident.  I wish I could meet the engineer who thought of this.  During a time when PCs couldn't be powered on or off via the keyboard, I bet this was a deciding feature to buy a mac.

To be honest I saw this feature when macs where used in high school to store students grades and enter attendance...every class had that mac computer. Saw the teacher sit down in front of the computer press a button on keyboard and chime. When I saw that at school I found it to be...elegant..cool...elite....wow....the list of that of type of reaction continued. I found windows 95 safe to turn off computer archaic and barbaric and useless and pointless.