Any interest in collaborating on a REBOOT for the Apple II?

I don't understand the requirement entirely and know nothing about Apple computers. (if the issue is RAM has contents it shouldn't have, can it not be erased by running a few lines of code after the soft-reset)?

But, it seems to me, if the Apple power supply is fragile then it's going to break at some point anyway, regardless of if it's kids performing a hard reset or not. Maybe better to swap out the power supply (in a non-destructive way so you can put the old one back in if you ever want to).

Looks like the PSU is one big metal box, so there is plenty of room. I don't know what voltages it needs, but it doesn't sound like an insurmountable problem to simply replace that brick with a more modern smaller AC-DC supply, perhaps followed by additional converters if you need unusual voltages too. You could even switch on/off the output voltages, rather than having to perform a mains connection disconnect to reset.

EDIT: Google reveals that there there are replacement supplies sold for about $80 USD.

For a DIY solution, some info is at this site:

From that, one method would be to get a 12V AC-DC supply module, and generate the other three rails from it. Or, there may be supply modules with +12V and +5V rails, and then the negative rails can be generated from there.

Thank you for the PSU info but I have rebuilt many Apple II power supplies and am comfortable doing so.  When an Apple crashes it  drops  into the monitor rom (which is not a kind environment for a 9 year  old). I don't want to teach them about the pokes they need to do (in HEX) to perform a clean reboot from the keyboard.  Because dynamic ram decays so slowly, the reset vectors in RAM cannot be reliably trusted.  Again, asking a kid to wait 10 seconds is also a pain in the rear.  

But above all, I just think it could be fun to create this simple little add-on function for an otherwise clunky feature of the Apple II.  

barryhills said:

I don't want to teach them about the pokes they need to do (in HEX) to perform a clean reboot from the keyboard.

Could your add-on reset button perhaps automate these keystrokes via the keyboard connection ? 

barryhills said:

I don't want to teach them about the pokes they need to do (in HEX) to perform a clean reboot from the keyboard.

Could your add-on reset button perhaps automate these keystrokes via the keyboard connection ? 

This is an interesting idea.  I've done several Arduino projects that talk to a PC/Mac etc over usb.  The keyboard.h library pairs well with the Arduino Leonardo.  Building a macro keyboard from scratch was actually trivial using this approach.  I think the challenge would be integration with the Apple's keyboard interface both electrically and software.   If I recall correctly, the Apple keyboard works from a matrix map; rows vs columns with intersections being a single key that connects one row to one column.  then there is the  keyboard ROM where a signal might be able to be injected.  Electrical timing would become a lesser issue which is nice.  A mezzanine board with an Arduino and the keyboard ROM might just do the trick.  At most it may require an additional serial to parallel converter such as 74LS164.  It would be very clean and portable solution.  The biggest limitation I imagine would be that the Apple could be in several states 1) running a program 2) Apple Basic prompt or 3) Monitor ROM prompt.  To make this work, I would want to force it into a known state before taking over the keyboard.  This is why my gut went to the IO card because it can force a NMI and has access to the 6502 memory space for running a little program.  excellent reply....thank you 

barryhills said:

the Apple keyboard works from a matrix map; rows vs columns with intersections being a single key that connects one row to one column.

Don't all keyboards work that way?

Maybe you can combine two methods. From what you mentioned earlier, your shortcoming of the DC supply power-down was that you may have to wait 10 seconds. In that case, what if the DC supply was disconnected briefly (like for a second or less, since you don't wish to wait 10 seconds), does it then go into a known state then (i.e. either the BASIC, or Monitor prompt), where you can then apply the soft reset in the method that Dave mentions? That is technically not hard to do, the row/column matrix isn't a hurdle. You could also then develop all this quite easily, it wouldn't need any knowledge of the Apple II internals (which let's face it, not many people nowadays will know as well to help out, compared to power supplies and keyboard matrices).

deep inside I suppose.  but when I look at a PS2 or USB keyboard I think more about the communication protocol over the wire.  in the case of PS2 the wire carries clock and data.  In the case of USB is carries a much more complicated differential signal.  In the case of the Apple 2 we have full access to all of the row and column signal lines due to the embedded nature of the keyboard.

You also have full access to the matrix in PS2 or USB keyboards. 

The nature of dynamic ram is very different from the static ram we use today.  Dynamic ram has an uncanny ability to hold its charge for a vey long time.   It is fairly common to power up an Apple II only to see it crash immediately because the reset vector in dram has some decayed content that sends the cpu into never never land.  Crazy but true.  This is why I want to clear memory before jumping to the reboot code in prom

not for this project but for Arduino projects I am curious to learn more about raw access to a modern keyboard without using the ps2 or usb interface

Simple X Y matrix.