[Simh] KL8-JA (Bob Supnik)

[Bob Supnik]

More limitations: the PDP8 interrupts are laid out in a single 32b word. 
There isn't room to have an additional 12*2 = 24 interrupts; the word is 
almost full.

If anyone wants to try this, I suggest looking at the PDP15 
implementation, which supports 16 (or more) lines. It already has the 
mechanisms needed, including use of a subroutine to map the IOT to a 
line number, multiplexing all of the separate interrupts onto a master 
input and a master output interrupt, and the code for varying the number 
of lines. The PDP8 core will still need an extension to the DIB 
mechanism, perhaps an optional "callout" to a configuration routine that 
would fill in IO dispatches as it saw fit, rather than algorithmically 
based on the DIB itself; and the PDP8 would need a more flexible, table 
lookup based mapping algorithm from device number to line number.

/Bob