27 Feb
2006
27 Feb
'06
5:12 p.m.
The Mindset is something less then conventional
(depending on who you talk to I guess). I guess this
is a little more complicated then I expected, and it
occurred to me after I sent this that if the 8042
supervises the activation, then, duh, it has to be
getting power as long as the thing is plugged in (I
think the Byte article indicated this). I don't have
schematics, so I have to take another look at the
thing soon. 2 piece modular design - lower half has
mobo and p/s, upper half has big floppy controller
board (NEC 765) and 2 drives. I am SO sorry I didn't
buy one from ACP (Dave Freemen?) back in the late
80's. He blew them out for $300, later $200 sans
floppy drives. It takes cartridges and all sort of
plug ins (ram, serial ports, frame grabber connection,
etc) in the rear of the unit. One of the niftiest
units out there IMHO.
I think the keyboard connector is an extra wide
modular type (like a phone jack/ethernet). Didn't
study it intently. I'm awash in machines here. Thanks
for your time.
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
would it be accurate to say that a unit, such as
my
Mindset II, which has the power switch built into
the
keyboard turns the system on by asserting the
power-good signal (when the switch is activated)?
I
Unlikely, if you're talking about a conventional PC.
The Power-good line
is an output from the PSU, it's used to reset the
CPU until the power
lines have all come up. If you want to be able to turn the machine on/off,
presumably you need a
special PSU with either some kind of relay
(solid-state or
electromechanical) in the mains input circuitm or
some way to shut the
chopper circuit down.
I would also expect at least one 'alwyas on' output.
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know from the Byte article that an 8042
supervises
the
keyboard (same or similar to the IBM PC/AT). I
was
The 8042 is a microcontorller. It can be programmed
to do almost
anything.
It might even be powered all the time, and control
the rest of the PSU
via one of its output port lines. In which case the
power on/off switch
might send a keycode to the main unit, the 8042
would detect this and
control the PSU appropriately.
Do you even know that the keyboard connecotr is the
same as on a PC? Is
it possible there's an extra pin dedicated to the
power on/off control?
Rememebr the PC keyboard connector has 5 pins, but
one of them was almost
never used (if's officially a reset output from the
PC).
thinking I could tie something? to +5 volts in
an
attempt to determine if my pos even works. And how
far
is it from reality to suggest all pc kbs are the
same
except for their 8048/9/8748/9 programming?
If by 'PC' you mean IBM compatible, well all clone
keyboards should lookl
the same to the host computer (byt be warned I've
found bugs here!). Anny
differences in the microcontroller program would be
to handle a
difference electical layout of the keys.
-tony