eproms

[Marteney, Steven J.]

If the address range is only 12K, why would a 27C128 be used?  The HC11's
I've worked with have a multiplexed 8-bit data bus with a 16-bit address
bus.  Maximum address space then is 64KB.  I also know the largest register
in the HC11 (ones I've worked with) is 16-bit (PC, Index X and Y, others) so
it's internal address capabilities should be limited to 64kB.  However, I
don't know how other variants work.  There are some glue chips available
from Motorola that do certain things (HC24 comes to mind) but don't of any
that expand the address space.  Now I'm wondering where the 27c128 came
from?

As for Mike's timing questions, I can not address ABSOLUTE timing 'cause I
don't know.  What I would do is try to get datasheets on both parts and
compare the timing parameters (setup and hold times, clock to output delays,
read cycle timing, write cycle timing) and just get a warm fuzzy that the
two are similar enough to work.

Is this helpful?
Steve

-----Original Message-----
From: Akselrud, Boris [mailto:AkselruB at moodys.com]
Sent: Wednesday, November 10, 1999 1:40 PM
To: 'gmecm at efi332.eng.ohio-state.edu'
Cc: 'mrolica at meridian-mag.com'
Subject: RE: eproms


1. I don't think you can use 27c512 in ECM designed to rad 27c128, because
address buss will only address 12K
2. Blank eeproms can be ordered from www.digikey.com
3. If you use eeprom, make sure that it's timing is as fast or faster then
EPROM's

-----Original Message-----
From: Mike Rolica [mailto:mrolica at meridian-mag.com]
Sent: Wednesday, November 10, 1999 1:02 PM
To: Gmecm (E-mail)
Subject: eproms


OK, so I have a 87 165 ecm with a 27c128 eprom.  Now a couple of questions.
Can I huse a 27c512 eprom cause it has extra room?  What would I have to do
to use this one and/ or why can't I?  Second I have asked this question
before... but can I use a eeprom instead (so I don't have to erase it uv all
the time) ?
Lastly  where would I find some blank eproms ?
Mike Rolica
EXT. 260
 :-)