What is it?  
This is a PCB for an expansion of 8k Static Ram  
Why did you make it?  
I wanted to be able to use expansion RAM in some programs.  
In the photo below left the red link selects which 32k block this 8k will reside in.
The blue link selects which 8k block this 8k will reside in.
The top 4 links are active.From the top they select:-
This PCB allows me to place an 8K RAM block in one of 8 different locations in the SBC memory Map.  
What makes it special?  

It is a very simple and useable design.

Bill of Materials:-
1 x 74LS245
1 x 74LS139
1 x 74LS00
1 x Toshiba TC5565 or equivalent 8K x 8 Sram.
1 x 36 way right angled header strip
1 x 2 x 8 header strip.( only use 2 x 4 on this board).
1 x 3 header strip.
2 x Links.
I sell on Tindie  
(c) 2021,2022,2023 Paul Bartlett