GT40

[isy...@gmail.com]

Dear All,

Here is a virtual GT40 for you to play with!

See Readme.md

link: https://drive.google.com/file/d/19MXiOrtfrCaUHPP-o8VKP85lIh9oeMO0/view?usp=sharing

Have fun

[Oscar Vermeulen]

Ian,

Brilliant, thank you! It all seems to work (still have to try the serial connection).

Except I still can't properly land the Lunar Lander, but that does not have to do with the GT40 simulation. I guess I need to hack Lunar Lander so that it has a higher tolerance for speed upon landing. Popped to the To Do list...

Kind regards,

Oscar.

[isy...@gmail.com]

Dear Oscar,

 Many thanks. This may be a timing problem as the app runs much faster than the real thing. Could try throttling the cpu....

Regards, Ian.

[isy...@gmail.com]

Dear All,

 It occurred to me that for the users of the other OS (Windows) you will need this directory in your projects folder to build the app in Visual Studio.

 Ie in the same place as the GT40 directory.

 In fact, this is my primary DevEnv!

This is kindly provided by Mark Pizzolato and might not be the current version on the simh hub.

 It is possible that if you are building any simh components and you have this directory already, please let me know

 and I will update the Studio build env to match the current simh version.

https://drive.google.com/file/d/1M7hzEASBOyXU8Dd0ee33GG1CcWwBEb2B/view?usp=sharing

Regards, Ian.

[Tom Wilson]

Thanks for that. I also use Visual Studio, and have had mixed luck in the past trying to create project files for programs created on Linux (or even on older versions of Visual Studio.)  

Part of the problem stems from the fact that Microsoft created a whole new slew of "secure" APIs meant to prevent string overflows, and so building POSIX programs on Windows is more challenging than it used to be. 

Here's the one I've been working on:

I was planning on connecting to an Altair emulator on the back end. The plan was to make some changes to David Hansel's Altair 8080 emulator to allow connections via TCP/IP, then use this console to remote control the emulator - blinkenlights and all. 

[Marc Howard]

Speaking of GT40 I have a real PDP-11/40 that I'd someday like to set up as a GT44.  The three UNIBUS cards and backplane could easily be re-implemented as an FPGA and some analog I/O but the User Manual mentions RT-11/GT.  Is that available somewhere on the web?

Thanks,

Marc Howard

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[Lars Brinkhoff]

oscarv wrote:

> Except I still can't properly land the Lunar Lander, but that does not have to do with the GT40 simulation. I guess I need to hack Lunar Lander so that it has a higher tolerance for speed upon landing. Popped to the To Do list...

I'm prepared to teach lunar lander lessons at a reduced rate.

[Rob Pike]

Did anyone here play it on the real device back in the day? Late at night when one had the lab to oneself, it was an addiction.

I can almost remember the octal location to update to add fuel.

-rob

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[Lars Brinkhoff]

Hello GT40 fans,

I got the MIT version of Spacewar running.  It was written by the Mini-Robot group at the AI lab.

Their PDP-11/45 computer running DOS-11 and had a GT40 attached.  I used "iamvirtual"'s DOS-11

disk image to assemble the sources.

[isy...@gmail.com]

Dear All,

Just to add to what I can do with this.

Using the vt07 script you can connect to any telnet server.

NB: The screen may initially be blank. Just start typing you username....

Apart from being a dumb terminal, this app will do emacs on most distros.

If you can kick of BSD 2.11 on our favourite PiDP11 , you can use vi as well with the settings below.

Unfortunately, modern vi versions will not play nicely.

Use:

TERM=datapoint

export TERM

(In tcsh use setenv TERM datapoint)

stty rows 30

And, off you go. 

Obviously, graphics are an option. Watch this space for a c application.

Regards, Ian.

[isy...@gmail.com]

Dear All,

 Looks like Mr Musk might need some lessons from Lars......

Regards, Ian.

[Lars Brinkhoff]

Ian wrote:

 Looks like Mr Musk might need some lessons from Lars......

How  so?

Sure, I'm happy to lecture anyone on some of my favourite topics!

[isy...@gmail.com]

Ah. It was only because he (SpaceX) has failed to land 2 mars ships so far!!!!

[Lars Brinkhoff]

Ian wrote:

Ah. It was only because he (SpaceX) has failed to land 2 mars ships so far!!!!

Maybe it's time for a Mars Lander game.  Although it's a bit tedious to wait a year to travel from Earth.

[Paul Birkel]

Assume a 1 G thrust all-the-way (turnover mid-flight, of course).

 

https://www.quora.com/How-much-thrust-is-1G-and-how-fast-would-it-take-us-to-get-to-Mars

 

21 hours at inferior conjunction.

56 hours at superior conjunction.

 

It took ~2.5 hours to descend to the lunar surface from orbit.  Who knows how long for a manned Mars descent …

 

Interplanetary SF was a lot more fun when we didn’t need to worry about reaction mass (and motors) …

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[jon....@gmail.com]

Or waste heat from your super-rocket engine that can make its fuel last 56 hours while burning at 1g. Just the power that needs to go into the kinetic energy of your exhaust and spacecraft ends up being in the kilotons / minute range for a spacecraft with the mass of the Apollo CSM. If your rocket isn't very energy efficient, you'll get something on the order of that much power in waste heat. And if your spacecraft is bigger than the Apollo CSM, the power requirements are proportionately higher. If it's the size of an A380, you're in the kilotons/second range, which also (being around 10 terawatts) is a good chunk of the current electrical generating capacity of human civilization. If it gets 50% efficiency (letting off as much as heat as goes into the exhaust stream as kinetic energy), when it arrives at Mars, it will be only slightly dimmer, as seen from Earth, than Mars itself. At a third of the way to the moon, it will outshine the moon, and at 250 km it will be as bright as the Sun. And even if it gets 100% efficiency, if it should inadvertently (or advertently) point its exhaust stream at a planet/moon/etc, all that kinetic energy will be deposited in some fairly small area (if we have 100% efficiency, that means that the exhaust stream goes straight back and doesn't spread out, if we have nearly, but not quite 100%, it would spread out a bit, but not much). That area will rapidly heat up until it is radiating the full power that the engine is putting into the exhaust blast.

So if you have engines that can boost at 1G for 56 hours, the local authorities at any given planet will have a (large) NIMBY zone, and any ship with such engines that comes within the NIMBY zone will attract the weapons-hot attention of the local military. So transit time from Earth to Mars is likely to be dominated by the time it takes to transit the NIMBY zone at either end in... errr... less performant spacecraft. Don't be too surprised if the NIMBY zone is a light-second or more, especially for larger spacecraft.

[Lars Brinkhoff]

Lars Brinkhoff wrote:

Hello GT40 fans,

I got the MIT version of Spacewar running.  It was written by the Mini-Robot group at the AI lab.

Their PDP-11/45 computer running DOS-11 and had a GT40 attached.  I used "iamvirtual"'s DOS-11

disk image to assemble the sources.

At long last, this is now available here:

https://github.com/pdp11/mit-gt40-spacewar

Source code, build instructions, binaries, disk image, etc are all included.