[Simh] MAME and simh

[Johnny Billquist]

On 2020-07-03 06:51, Peter Svensson wrote:
> Hi all,
> 
> This is getting a bit silly. Compared to some of the other things MAME 
> emulates the vt100 and other terminals should be downright easy.

I am not at all sure I agree with that... I think you too should look at 
the VT100 technical manual and see how soft scrolling is done, as an 
example of a place where the hardware emulation can actually become 
rather tricky...

> As to why, well there is not much reason to run simh either, except that 
> it pleases us. I guess the same applies here. More power to whoever 
> wants to do this. Let's help them instead of explaining why it is useless.

If you actually bothered reading through my answer, you would have seen 
that I didn't argue against running MAME as a terminal emulator, or 
claimed that it was useless.
Instead I was trying to point out that he should only run the correct 
firmware on the emulated hardware, and he needed to get it running by 
itself before he started figuring out how to connect to simh.

> For the connection to simh the quickest way may be to start with the tcp 
> connection to the console / serial line cards.

And before he actually have a working terminal in MAME, I would say he 
should fix that instead of trying to get something non-working connected 
to simh.

   Johnny

> 
> Peter
> 
> On July 3, 2020 12:05:39 AM GMT+02:00, Johnny Billquist <bqt at softjar.se> 
> wrote:
> 
>     Just a couple of comments...
> 
>     On 2020-07-02 13:16, Peter Allan wrote:
> 
>         Well my request for help getting MAME to talk to simh has
>         generated a
>         lot of replies, so let me deal with them in groups.
> 
>             Why not use PuTTY for the VT emulator?
>             What is the point of trying to use MAME for VT emulation?
> 
> 
>         My reason for being interested in using MAME is that it is NOT a
>         terminal emulator program All terminal emulator programs such as
>         PuTTY,
>         xterm, SecureCRT, etc, are pieces of software that aim to
>         emulate the
>         functions of a particular type of terminal. While all of them
>         are useful
>         (I use putty and xterm quite a lot myself), all of them fail to
>         implement some features of the physical terminal. Usually this
>         is not a
>         problem, but occasionally I find it really annoying. The point
>         about
>         MAME is that, rather like simh itself, it simulates the hardware
>         and
>         runs the real firmware from real VTxxx ROMs. In the case of the VT
>         terminal configuration, MAME simulates an 8085 microprocessor and
>         executes the code from the original ROMs. Hence all the features
>         of a
>         physical terminal should be present automatically.
> 
> 
>     I can understand the need/interest/fun of running the actual firmware
>     instead of some emulation. But of course you then have the question of
>     how accurately that hardware emulation is. It's more than just a
>     question of emulating the CPU that is inside the terminal. DEC was doing
>     some pretty nifty things in hardware to allow some features to work.
>     You really should check out of smooth scrolling on the VT100 is
>     accomplished...
>     (http://www.bitsavers.org/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf,  
>     page 4-97, section 4.7.9 - "Split Screen Smooth Scrolling". Emulating
>     those hardware tricks are not going to be easy...
> 
>     Anyway, to also point out something else, the VT100 have an 8080. The
>     VT220 have an 8051, while the VT240 have a T11 as the main processor,
>     and an 8085 for the video logic.
> 
>     This should tell you a little bit about the futility of trying to run
>     the wrong ROMs on the emulator...
> 
>     As for getting MAME to talk to simh, I think you need to start with just
>     MAME playing a terminal at all. Once you accomplish that, then you can
>     start looking at how to hook them up. If the VT simulation in MAME was
>     fully accurate, you would have a serial connector on the back, which the
>     terminal uses. So then you need to run a cable to a serial port used by
>     simh. But of course, you probably do not want an emulation down to that
>     level, but are expecting to simulate the serial ports...
> 
>         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