Explanation of Dwight diagnostic board

The goal of the board is to prevent the KIM-1 to boot from the builtin ROM. Or using any other KIM-1 component except the CPU.
 
So the KIM-1 will respond to the diagnsotic baordeven if the KIM-1 ROM in the 6530--2 is bad or not present.
Therefore an EPROM is used that is mapped into the KIM-1 memory at boot.

A 27128 128Kb, which gives 16K ROM. Every 1K can hold a test program.

The 1K ROM  partis selected (with a DIP switch with four switches) when:
- A15 is high (which is during RESET) and the vectors are mapped in. 
- when K3 is high, address range 0C00 - 0FFF
The vectors in the upper part of the EPROM  are therefore in the FFFA-FFFF range.
Also, when A15 is high, DECODE ENABLE is used to prevent the KIM ROM to be mapped in. 

Status and Access lEDs

K4 is used to toggle the green status LED via a flipflop 74LS74. 
The Data input is high, any address written to K4 (1000-13FF) will clock this high in and light the LED.
K3 is used to light or turn off the Red access LED via the other flipflop in the 74ls74, the Data input is connected to D0. 
The flipflops are reset with the RST signal at boot.

In the EPROM various test programs can be stored. Activated by storing the start address in the RESET vector.
The DIP switch 1, 2, 3 ,4 select with the high address A10-A13 another part of the 16 in total. When selected the ROM appears at K3, 0C00 -0DFF
And the upper six addresses are the RESET/IRQ/NMI vectors.

DIP swith 6 allows the EPROM to be disabled by blocking access to Decode enable of the card.  

