A couple of novice questions

[R+C Webb]

Stop me if you are talking about potato chips or something ;-}

In the context of microcontroller interfacing, CE is usually
"Chip Enable" and it is a
line used to enable a particular device.

If you have wired up the address decoder to pull a line active
(usually low) when the address 8000h (as an example) is accessed,
this line would be tied to the chip's CE line. That way, whenever
the processor accesses address 8000h, this gets translated as
"hey, I'm talking to you" to the device.

As for OE, that's "output enable". Used when a whole bunch of
devices are hanging off the same buss. All of the devices would
load down the output of the one who was trying to talk, except
that the electronics is included on chip to tri-state them. They
are not high, they are not low, they are effectively disconnected
(the third state). The OE line is used to say to a particular
device "OK it's your turn" by turning on it's output drivers.


TBK wrote:

> This is what CE and OE are for.
>
> TK
> -----Original Message-----
> From: Wayne Blair <wayneb at foxln.com.au>
> To: diy_efi at efi332.eng.ohio-state.edu
> <diy_efi at efi332.eng.ohio-state.edu>
> Date: Sunday, February 15, 1998 3:38 PM
> Subject: Re: A couple of novice questions
>
> >At 08:46 13/02/98 -0500, you wrote:
> >>
> >>
> >>I've got a couple of "newbie" questions that came to mind...
> >>
> >>1) Is a modified ECM EPROM a violation of copyright? I know
> changing
> >>the maps (data) might not be a violation, but I'd also have
> to carry a
> copy
> >>of the original microprocessor code too. Is this in the
> public domain or
> >>is it just something no OEM bothers to enforce?
> >
> >
> >I 'd like to know too !!
> >>
> >>2) Would it be possible to use a larger size EPROM and wire
> up some kind
> >>of switch so I could hold the original maps and code, and a
> copy of the
> >>modified maps in the upper area. Switching from one bank to
> the other
> (with
> >>the ECM unplugged of course). This way I could do semi-live
> comparisons or
> >>revert back to the original maps if needed.
> >
> >It is down down here, eg stick a 256 in where a 128 was and
> pull up or down
> >the top addr line. Getsmart us a PAL/GAL  and some logic a 10
> way switch
> >and only remap the data area and have 10 maps on line.
> >
> >>Might it make more sense to disassemble the code and have the
> firmware
> point
> >>to the original maps or the modified maps based on some
> toggle/flag/signal
> >>(stomping on the gas peddle 3 times or flipping a switch or
> something...
> >>whatever, you get the idea).
> >
> >The hardware is easier.
> >
> >wayne
> >
> >
> >
> >