A couple of novice questions

[TBK]

Yep.

-----Original Message-----
From: R+C Webb <cwebb at polarnet.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, February 15, 1998 8:52 PM
Subject: Re: A couple of novice questions


>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
>> >
>> >
>> >
>> >
>
>
>
>