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Richard Erlacher
12/11/17 12:26
Read: 62 times
Denver, Co
USA


 
#190826 - maybe this isn't the easiest way ...
Responding to: Grant Beattie's previous message
If I understand you correctly, I've done a lot of this though it was in the distant past, since there are several 805x chips that have plenty of on-board xRAM. Additionally, there are battery-backed RAM's that help manage the voltages and RST and nWE signal for you. However, if you want to use the original 805x sort of device together with the 6116 and 6264 devices, or their CMOS equivalents, I'd recommend using the high-order address bus and then handling the entire 16-bit address bus in the "classic" manner. Nowadays, there are MOSFETs with low enough gate voltages that you can control relevant voltages with the power turned off with little burden on the Vbat. Further, those batteries are recharged every time they're powered on. Since you didn't say what your goal is, I'm not sure what will best suit your needs. IIRC, there is at least one manufacturer offering an 8052-equivalent with on-board 8kx8 "external" RAM on-chip. I've never used 'em, but I have used the ones with 1kx8 on-chip RAM. That's a LOT more convenient than what you're suggesting, and you can probably get samples so you can try it.

There are also bus-switches from manufacturers like Pericom that can completely isolate your memory from the MCU when power is off, eliminating the risk that your Vbat will power the MCU through the address lines. That's something you have to consider with CMOS parts.

RE

List of 4 messages in thread
TopicAuthorDate
Old School SRAM Memory Expansion      Grant Beattie      12/08/17 12:51      
   Old School SRAM Memory Expansion      Grant Beattie      12/08/17 19:39      
   maybe this isn't the easiest way ...       Richard Erlacher      12/11/17 12:26      
      Banked SRAM      Grant Beattie      12/11/17 19:40      

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