[Simh] MAME and simh

[Gustavo Del Dago]

I have a working vt240 under MAME.

¿When you press F3 the emulation is restarted?
¿Do you like to test with another ROM image?
Gus

El vie., 3 de jul. de 2020 a la(s) 11:44, Gustavo Del Dago (
gdeldago at gmail.com) escribió:

> Peter,
> ¿Can you access the configuration screen after pressing F3?
>
> "More power to whoever wants to do this. Let's help them instead of
> explaining why it is useless."
> +1
>
> Gus
>
> El vie., 3 de jul. de 2020 a la(s) 10:24, Johnny Billquist (bqt at softjar.se)
> escribió:
>
>> On 2020-07-03 14:54, Lars Brinkhoff wrote:
>> > Johnny Billquist wrote:
>> >>> Oh, and just for the people who don't want to read a lot of
>> >>> documentation, the smooth scrolling is essentially done by the
>> >>> terminal by changing where the source of the video signal generation
>> >>> picks up font information [...]
>> >>> I hope that made sense... :-)
>> >
>> > Thanks, I think it does.
>> >
>> > Emulation at this level of detail really isn't that uncommon now.
>>
>> I can't say that I've seen much of it anywhere. The VT100 also have a
>> lookup table for each line, so that scrolling can be done fast, but
>> which also means that the video generation needs to also go through that
>> table. While obviously you can always emulate anything, the emulating of
>> detail down to analog signals is not something you do that often, unless
>> there is additional reasons to. One reason being that this starts
>> becoming a performance problem. Many analog simlulations/emulations are
>> not done in realtime because of that.
>>
>> But if we want to emulate a terminal, I would say that realtime
>> emulation of the hardware is a must.
>>
>> And it's easy to just do it partially. You do have the video memory, and
>> for most purposes that would be good enough for the emulation to work
>> satisfactory, a thing like the smooth scrolling means you no longer can
>> stop at the abstraction of the video memory...
>>
>> >> And to take this one step further. Emulation of this then means you
>> >> need to start emulation the video signal generation. And that in turn
>> >> means you are going to do emulation of the CRT phosphor.
>> >
>> > I have no idea how MAME works, but SIMH does that for vector displays.
>>
>> Well, MAME also do vector displays. Asteroids being the classical example.
>>
>> > The current implemenation may not be suitable for raster displays, but
>> > it wouldn't be a huge step to add this.
>>
>> At some level this is obviously rather trivial. We are after all simply
>> talking about generation of a signal based on the scanning of memory,
>> and a bit of logic to do the sweeps and sync. An interesting question
>> becomes at what speed it can be done. Vector displays have a limit on
>> the number of vectors that can be displayed without flicker, and for the
>> old machines, that was not too great to start with, so simulations can
>> certainly deal with it, and can even get away with some cheating to make
>> it work even when pressed. After all, since you're also faking the
>> phosphor decay, it can be varied as needed. With a raster display
>> though, you need to be doing all the lines all the time, at an
>> acceptable rate, and deal with the additional hardware logic of the CRT.
>>
>> Again, definitely not impossible. But I'm curious what the speed would
>> look like, and I cannot remember seeing anyone who have already done it.
>>
>>    Johnny
>>
>> --
>> Johnny Billquist                  || "I'm on a bus
>>                                    ||  on a psychedelic trip
>> email: bqt at softjar.se             ||  Reading murder books
>> pdp is alive!                     ||  tryin' to stay hip" - B. Idol
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>
>
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