[Coco] About those EPROMS...

[Salvador Garcia]

Thanks Stephen,


I'll have a look at the data sheets. I appreciate the info and comments :-) Salvador








-----Original Message-----
From: Stephen H. Fischer <SFischer1 at Mindspring.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Wed, Apr 8, 2015 8:17 pm
Subject: Re: [Coco] About those EPROMS...


For ROMs there were some made that you could only execute the program in the
ROM. 

That made even reading the contents by addressing the ROM one address at
a time not possible. 

The intent of the EPROM designers did not include any
method that the EPROM contents could be "dumped" by any other method except by
addressing the (E) (P) ROM one address at a time.

For the speed and size of the
EPROMs we are discussing that does not take too long. The data sheet for the
various EPROMs shows differences in the various versions. 

There was no grand
plan to make them all the same.

So you need to look at the various EPROM's data
sheets.

The web page you linked to is not normal usage.

CoCo programs could
read carts just by taping one PCB finger and other EPROMs on new boards that are
being designed for the CoCo.

I fail to see the use of the method displayed
beyond Gee It Works.

Sort of like the EE professor that brought to class the
first and only IC the EE department had. A two input NAND IC.

SHF
 
-----
Original Message ----- 
From: "Robert Gault" <robert.gault at att.net>
To:
"CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent:
Wednesday, April 08, 2015 5:34 PM
Subject: Re: [Coco] About those EPROMS...


>
Salvador Garcia wrote:
>>
>> Hi all, I’ve been reading the discussions that talk
aboutEPROMs. This got my curiosity going. What reference material is recommended
tolearn more on how to interface an EPROM (family 2732/64/128 etc) ?
>> For
example, if I want a dump of its contents, how would I goabout that? I found
this instructable:
>> http://www.instructables.com/id/EPROM-reader/
>> However, 
I would hopeto find something better as it is not my idea to address the EPROM
one addressat a time! I searched for the pinout and it seems rather simple. Only
threecontrol signals: /PGM, /OE and /CE. For normal use keep /PGM high and to
readget the address on the bus and bring down /CE and /OE. The documentation
doesnot specify what the difference between these two signals is or what happens
ifI tie them together and just bring them down at the same time. It also does
notmention if these inputs are high (or low) if not connected (or HiZ); I
wouldimagine that they would be high.
>> Any pointers on where I can find
reading material to learnmore about these ships is appreciated. In the meantime
I'll continue looking. Thanks! Salvador
>>
> 
> There was a good article in The
Rainbow by Tony DiStefano, March 1988, p158-159. 
> You can also get data sheets
for specific EPROMs.
> 
> Robert


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