Instruction manual

• Assert CS_ROM if Configuration is 0, Mem_Req is asserted, and the address is 0x0000 to 0x07FF – that is, if A11 to A15 are all
zero.
• Assert CS_RAM0 if Configuration is 0, Mem_Req is asserted, and the address is 0x0800 to 0x7FFF – that is, A15 is zero, and any of
A11 to A15 is 1.
• Assert CS_RAM0 if Configuration is 1, Mem_Req is asserted, and the address is 0x0000 to 0x7FFF – that is, if A15 is zero
• Assert CS_RAM1 if Configuration is 0 or 1 (a “don't care”) and the address is 0x8000 to 0xFFFF – that is, A15 is one.
The formal logic equations are here:
CS_ROM = ~Mem_Req + Config + A11 + A12 + A13 + A14 + A15
CS_RAM0 = ~A14 ~A13 ~A12 ~A11 ~Config + ~Mem_Req + A15
CS_RAM1 = ~A15 + ~Mem_Req
I used the Logisim program to help design this part of the circuit.
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