<div dir="ltr"><div>I have a working vt240 under MAME. <br></div><div><br></div><div>¿When you press F3 the emulation is restarted?</div><div>¿Do you like to test with another ROM image? <br></div><div>Gus<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">El vie., 3 de jul. de 2020 a la(s) 11:44, Gustavo Del Dago (<a href="mailto:gdeldago@gmail.com">gdeldago@gmail.com</a>) escribió:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Peter, <br></div><div>¿Can you access the configuration screen after pressing F3?</div><div><br></div><div><div>"More power to whoever wants to do this. Let's help them instead of explaining why it is useless."</div><div>+1</div></div><div><br></div><div>Gus<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">El vie., 3 de jul. de 2020 a la(s) 10:24, Johnny Billquist (<a href="mailto:bqt@softjar.se" target="_blank">bqt@softjar.se</a>) escribió:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 2020-07-03 14:54, Lars Brinkhoff wrote:<br>
> Johnny Billquist wrote:<br>
>>> Oh, and just for the people who don't want to read a lot of<br>
>>> documentation, the smooth scrolling is essentially done by the<br>
>>> terminal by changing where the source of the video signal generation<br>
>>> picks up font information [...]<br>
>>> I hope that made sense... :-)<br>
> <br>
> Thanks, I think it does.<br>
> <br>
> Emulation at this level of detail really isn't that uncommon now.<br>
<br>
I can't say that I've seen much of it anywhere. The VT100 also have a <br>
lookup table for each line, so that scrolling can be done fast, but <br>
which also means that the video generation needs to also go through that <br>
table. While obviously you can always emulate anything, the emulating of <br>
detail down to analog signals is not something you do that often, unless <br>
there is additional reasons to. One reason being that this starts <br>
becoming a performance problem. Many analog simlulations/emulations are <br>
not done in realtime because of that.<br>
<br>
But if we want to emulate a terminal, I would say that realtime <br>
emulation of the hardware is a must.<br>
<br>
And it's easy to just do it partially. You do have the video memory, and <br>
for most purposes that would be good enough for the emulation to work <br>
satisfactory, a thing like the smooth scrolling means you no longer can <br>
stop at the abstraction of the video memory...<br>
<br>
>> And to take this one step further. Emulation of this then means you<br>
>> need to start emulation the video signal generation. And that in turn<br>
>> means you are going to do emulation of the CRT phosphor.<br>
> <br>
> I have no idea how MAME works, but SIMH does that for vector displays.<br>
<br>
Well, MAME also do vector displays. Asteroids being the classical example.<br>
<br>
> The current implemenation may not be suitable for raster displays, but<br>
> it wouldn't be a huge step to add this.<br>
<br>
At some level this is obviously rather trivial. We are after all simply <br>
talking about generation of a signal based on the scanning of memory, <br>
and a bit of logic to do the sweeps and sync. An interesting question <br>
becomes at what speed it can be done. Vector displays have a limit on <br>
the number of vectors that can be displayed without flicker, and for the <br>
old machines, that was not too great to start with, so simulations can <br>
certainly deal with it, and can even get away with some cheating to make <br>
it work even when pressed. After all, since you're also faking the <br>
phosphor decay, it can be varied as needed. With a raster display <br>
though, you need to be doing all the lines all the time, at an <br>
acceptable rate, and deal with the additional hardware logic of the CRT.<br>
<br>
Again, definitely not impossible. But I'm curious what the speed would <br>
look like, and I cannot remember seeing anyone who have already done it.<br>
<br>
Johnny<br>
<br>
-- <br>
Johnny Billquist || "I'm on a bus<br>
|| on a psychedelic trip<br>
email: <a href="mailto:bqt@softjar.se" target="_blank">bqt@softjar.se</a> || Reading murder books<br>
pdp is alive! || tryin' to stay hip" - B. Idol<br>
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