Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Grant Beattie
12/08/17 19:39
Read: 83 times
San Juan Capistrano, Ca
USA


 
#190825 - Old School SRAM Memory Expansion
Responding to: Grant Beattie's previous message
I'm thinking now that in the rest of the circuit, the SRAM address lines are all tied to TTL 74LSxx chips powered by +5v (rather than Vmem). So perhaps the switch upper position should be tied to +5v too. That way Axx (the highes addr line, that I am using for bank switching) will be at 0v when power is off, regardless of the switch position. For instance,



                  .------U-------
 +5v---.   Vmem---| Vcc
       |          |  
       |          |  
       <          |  
       < 1k       |   SRAM
       <          |  
       |   SPDT   |  
         /--------| Axx (highest addr line)
       |          |  
       |          |  
       <          |  
       < 10k      |  
       <
       |
       |
      ===  GND
       =

 

 


This means that in standby, Axx is always at 0v. Also, there is this knowledge base item:
https://community.cypress.com/docs/DOC-10268

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      

Back to Subject List