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 Forum index » DIY Hardware and Software » Microcontrollers and Programmable Logic
Write Protect and battery backup Qs
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richardc64



Joined: Jun 01, 2006
Posts: 666
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PostPosted: Sat Jan 13, 2018 9:52 am    Post subject: Write Protect and battery backup Qs
Subject description: General, not electro music specific
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Which is the better way to Write Protect memory? To prevent the RAMs' /WE (and /OE of course,) from going low when the RAMs' /CS and R/W =0, or by preventing /CS from going low altogether?

Is either way more vulnerable to glitches I might have overlooked?

Two-part 2nd Q: In the past I have battery-backed SRAM with a 74HC__ gate powered by +5v and the battery voltage in the /CS path, and that has worked well. I am wondering, though, if it makes any difference whether any unused other gates in the package are terminated high or low? Does it make any difference if other gates in the package ARE used elsewhere in the circuitry? Past experience tells me "No", so consider this question me double-checking with people who know more than I do.

Thanks.

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PostPosted: Mon Jan 15, 2018 4:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Heh, has been 25 years or so since I looked into stuff like that .. all I remember is that static 2k and 8k RAMs were very forgiving for whatever timing I threw at them.
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