Hi, please check my pic below and comment on any potential issues that you find (assuming no I/O at this point). Some connections not shown for clarity:



Thanks, Kei

 

That is not how one would normally do it.
The upper address lines go to the 74138 which determine which /CE is selected.
/RD goes to /OE.

I have not done this in a long time and will have to review how to interface with 8085 chips.

 

It has been many decades since I used the 8085. I liked the part very much. My memory is not good, so I looked for an example of an 8085 memory mapping.

You do not need the area in red. I think the red is the same as your inverter.

I think you are good.

 

That is not how one would normally do it.
The upper address lines go to the 74138 which determine which /CE is selected.
/RD goes to /OE.

I have not done this in a long time and will have to review how to interface with 8085 chips.

I have seen that way too, Mr. Chips. In my case it is simpler since my only upper address line is a15, hence the inverter for 0000H-7FFFH and 8000H-FFFFH, add the memory signals to 74138 give those outputs. Although I admit I got inconsistent results, As long as I don't have to retrieve a value from ram/rom the programs always work, but sometimes if I have to retrieve a value from rom/ram my program does not work (retrieves wrong value).

I will try it the way you suggested.

Thanks, Kei

 

It has been many decades since I used the 8085. I liked the part very much. My memory is not good, so I looked for an example of an 8085 memory mapping.
View attachment 366104
You do not need the area in red. I think the red is the same as your inverter.
View attachment 366105
I think you are good.

Thanks, Ron, I match the way you describe, I am not sure why I am having issues lately (I rebuilt my 8085 computer after the previous one died on me). I will try it on a solderless breadboard first, before I solder another one up...

-Kei