Re: Request for Product

["Bill Garber" <willy46pa@comcast.net>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message
JeWdnRnWgPO2eE_fRVn-3w@comcast.com">news:JeWdnRnWgPO2eE_fRVn-3w@comcast.com...
: No, that's not enough, nor should it be done at all.
: Power should be left on on both cards at all times so
: that unpowered bus tranceivers don't load the bus.

I agree. Switching power between the cards could also
add undue strain on the PSU, unless you shut down each
time.

: Instead, the select lines should be switched:  I/O Select,
: Device Select, I/O Strobe.  That will be enough to switch
: almost all cards (execptions would be that do their own
: slot decoding on board--a dubious practice).

I believe only /DEVSEL is needed to be switched in.
/IOSEL and /IOSTROBE are rendered inactive while /DEVSEL
is High. So, therefore, with device select switched out,
the card will not be accessed at all.

: BTW, as long as neither switched card is active, it should
: be possible to switch the select lines with the power on
: without any problem.

So, you're saying the cards can be flipped, and a warm boot init'd.
Interesting. Wonder if the slot itself can be init'd without having
an effect on the other slots, possibly allowing an annunciator line
to select the card in use.

Apple II Forever, Apple II Together
Bill @ GarberStreet Enterprizez
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