Re: FLASH ROM replacement

Re: FLASH ROM replacement

From: Jim Brain <>
Date: Tue, 05 May 2009 22:09:54 -0500
Message-ID: <>
Jim Brain wrote:
> M H Stein wrote:
>> Any chance you could also put the two rows of pins for a 6540 
>> replacement
>> on there while you're at it, to use either a 2732 or 1/2 of a 2764?
Would this work:

I made some assumptions:

CS3,4,5 are active low
CS1,2 are active high
CLK is active high

I'd appreciate knowing if those are valid or invalid assumptions.

* As the schematic shows, the design uses a 74'138 to decode all of the 
CS lines and CLK into a single CS line for a 2764-27512
* I can add a jumper to allow 24 pin EPROM operation (hook pin 26 to pin 28)
* Extra address lines are pulled up to 5V and available on pads on top 
of adapter (to allow switchable ROMs)
* logic and resistors are hidden inside 28 pin header.

Let me know if there is any interest.


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Received on 2009-05-06 05:17:26

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