[Simh] Photorealistic panel for PDP-11/20

[Jörg Hoppe]

Olaf,

>> The header line says it all: another panel for BlinkenBone is there, the
>> classic PDP-11/20.
>> In function and style it fills the gap between the PDP-8 and the later
>> PDP-11's.
>
> Looks great! How does it hook into the simh code?
> With the frontpanel API? (of which a very simple VAX example is shown in
> frontpanel/FrontPanelTest.c )
The adapter to SimH is implemented as a "REALCONS" device, which is 
coupled to the CPU type. Internal logic is designed to support multiple 
devices, such as "frontpanel" API does.
"BlinkenBone" is years older (it began in SimH 3.8) than "frontpanel".
Both systems are neither trivial, nor compatible.

Writing a panel adapter does not just mean to access some internal SimH 
variables. Older panels (like PDP-8) expose lot of signals on circuit 
level which SimH does not emulate by default.

To get a feeling, see the sources at
     https://github.com/j-hoppe/BlinkenBone.git
and check out
.../projects/02.3_simh.4.x.jh/src/PDP8/pdp8_cpu.c
.../projects/02.3_simh.4.x.jh/src/PDP8/pdp11_cpu.c
.../projects/02.3_simh.4.x.jh/src/REALCONS/*

Clearly "BlinkenBone" and "frontpanel" should be merged and get part of 
mainstream SimH sources. But whenever there's spare time to work on 
"BlinkenBone", it seems sexier to add another panel than to dive down 
into that system programming hell.

Joerg


>
> -Olaf.
>