What are the different methods in which IO devices can be addressed in 8085 based design?
I never heard of Gaonkar, never read it. I always start with the manufacturers datasheets.
- Program memory must be present at address 0x0000 because that is where the porcessor goes to start fetching instructions after RESET_IN* (pin 36) is released. I believe that if there is no memory at location 0x0000 that the data buss will return an 0xFF which is an RST 7 instruction. This will then go to locatio 0x0038 with predictable results.
- Just put the proper return instruction at the appropriate location, or tie the TRAP (pin 6) high or low as appropriate so that a TRAP condition never occurs.
- The HOLD (pin 39) and HLDA (pin 38) are used to request bus mastership. The hold state will not be released until HOLD goes low.
http://www.engineer.gvsu.edu/students/part_inventory/p8085ah.pdf
Don't know if they are still available on the Intel website. NOT
Instruction set reference
http://ce.sharif.edu/~a_eslamifar/instructionset8085.pdf
Don't know why you need me to do your google searches for you.
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