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From: rstevew@armory.com (Richard Steven Walz)
Subject: Re: Best microprocessor
Organization: The Armory
Date: Thu, 16 Feb 1995 14:59:29 GMT
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References: <nlc111.179.2F42615E@psu.edu>
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In article <nlc111.179.2F42615E@psu.edu>, nate <nlc111@psu.edu> wrote:
>I am wondering if anyone has any suggestions on which microprocessor is the 
>easyest to use in a robot project.  It would have to interface with standard 
>27*** EPROM easily and be simple to program.  I was considering the intel 8085 
>but lately I have grown pissed with its difficulty interfacing with EPROM.  
>Speed is not a concern as the robot will not be that bogged down with 
>computations.  It should also interface with standard I/O with little external 
>logic.  Thanks in advance!!
>  Keith Soldavin
>  KAS219@psu.edu
---------------------------------
You should definitely seek help re: the 8085A interfacing to an EPROM! That
is so simple that I'm stunned that you claim difficulty with it!! You
simply use the ALE line (pin 30) to the pin 11 enable of a 74LS373
transparent latch to time-demultiplex the multiple lower 8 bits that are
shared data and address lines and if you REALLY want to be simple, decode
your IO/M line, and /RD and /WR lines to a 74LS42 to completely separate
the controls into /IOW, /IOR, /MWR, and /MRD by hooking IO/M (pin34) to pin
15 of the 'LS42, and /RD (pin 32) to pin 14, and /WR (pin31) to pin 13,
where /IOW is pin 4, /IOR is pin 6, /MWR is pin 3, and /MRD is pin 5 on the
'LS42 chip. Parenthesized (pin numbers) are on the 8085A. If you're using a
5MHz xtal then you won't need to worry about the EPROM being too slow! Any
other questions and either ask me or somebody who knows, alternatively, use
a Z-80, same size, separate address and data bus and it uses simpler
control signals and also runs on 5 VDC. Also all code will run on it unless
you are using the SI and SO for interface. But that is what the 8085A is
good for!
-Steve Walz   rstevew@armory.com

