Im actually trying to make my own computer (and an OS for it) with a ZiLOG Z80 cpu, and I had a question that should be easy to answer by someone knoledgable in this kind of electronics.
When I attach a device to the bus (like memory) would the only thing I have to do be to hook up the CPU's address bus to the EPROM's address bus (and the same thing for the data bus and control bus)? No extra chips or circuits to 'interface' the cpu with the EPROM?
(Btw, I'll also hook the power up and stuff)
[glow=red,2,300]Thanks[/glow] ;D
CPU Bus question
Re:CPU Bus question
This should work OK. In fact, you should be able to get EEPROMs which will interface directly with the processor.
However:
-- The processor's address bus will probably be bigger than the EEPROM's. If you connect them straight up, you will need to leave the unused lines disconnected (or tie them to ground via some resistors). This will cause the memory to repeat itself thoughout the address space.
-- In future, you might want to have additional types of memory (e.g. RAM, ROM, video frame buffer, memory-mapped devices, etc.). It's worth leaving room in your design for additional decoding logic which will handle this.
However:
-- The processor's address bus will probably be bigger than the EEPROM's. If you connect them straight up, you will need to leave the unused lines disconnected (or tie them to ground via some resistors). This will cause the memory to repeat itself thoughout the address space.
-- In future, you might want to have additional types of memory (e.g. RAM, ROM, video frame buffer, memory-mapped devices, etc.). It's worth leaving room in your design for additional decoding logic which will handle this.
Re:CPU Bus question
Such as a memory controller? Since I know the GBA maps everything in memory (all the device registers, ram, rom, video ram, etc..) and it needs a special device to do so, and the only things that can be would probably be the memory controller, right?Tim Robinson wrote:...
-- In future, you might want to have additional types of memory (e.g. RAM, ROM, video frame buffer, memory-mapped devices, etc.). It's worth leaving room in your design for additional decoding logic which will handle this.