New RISC OS Port - The Great Escape test build (soon)

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spanners
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New RISC OS Port - The Great Escape test build (soon)

Post by spanners » Tue Mar 03, 2020 1:27 pm

How do folks,

For some years I've been reverse engineering and documenting the classic ZX Spectrum game The Great Escape. I've also translated it into portable C code, and from that built macOS and Windows versions of the game. I've written much about it here: http://www.davespace.co.uk/the.great.escape/.

Now next up on my list is a port to RISC OS. There's a tweet with a video of an early version of it running here: https://twitter.com/bagospanners/status ... 3330217984

Assuming everything goes to plan (it won't) at some point I'll have an build of desktop The Great Escape ready for some testing. It'll likely be missing support for sound, but the game will be playable, with multitasking and a zoomable display based on the code I wrote for my PrivateEye image viewer.

Who's up for a bit of alpha testing? It'll likely need RISC OS 3.7+ initially but I plan to lower that requirement in the future to support Arcs.

D.

tgespr.gif
tgespr.gif (6.63 KiB) Viewed 2017 times

hubersn
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Re: The Great Escape test build (soon)

Post by hubersn » Thu Mar 05, 2020 10:21 am

spanners wrote:
Tue Mar 03, 2020 1:27 pm

Who's up for a bit of alpha testing? It'll likely need RISC OS 3.7+ initially but I plan to lower that requirement in the future to support Arcs.
I always hated that game on the Amstrad CPC - was the Spectrum version any better?

Despite knowing the movie inside out, that game never worked for me...

Have fun
hubersn

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lurkio
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Re: The Great Escape test build (soon)

Post by lurkio » Thu Mar 05, 2020 11:52 am

spanners wrote:
Tue Mar 03, 2020 1:27 pm
For some years I've been reverse engineering and documenting the classic ZX Spectrum game The Great Escape ...
I don't know the game, but I've had a quick look through your webpages about reverse-engineering it, and I found them very interesting. I'm a little envious of the profiling and disassembly tools that seem to be available in the Spectrum world!

The RISC OS port looks promising. I'm afraid I can't help with testing as my feet are firmly planted in the 8-bit camp, but I wish you good luck!

=D> =D>

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Re: The Great Escape test build (soon)

Post by Kazzie » Thu Mar 05, 2020 12:00 pm

I'd throw my hat into the testing ring, but I don't have hardware running anything more recent than RISC OS 3.11.
BBC Model B 32k issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
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Re: The Great Escape test build (soon)

Post by spanners » Thu Mar 05, 2020 6:45 pm

lurkio wrote:
Thu Mar 05, 2020 11:52 am
I don't know the game, but I've had a quick look through your webpages about reverse-engineering it, and I found them very interesting. I'm a little envious of the profiling and disassembly tools that seem to be available in the Spectrum world!
No need for envy: SkoolKit https://skoolkit.ca/ has been made pluggable so you can use it to pull 6502-based games apart using this plugin: https://github.com/skoolkid/sk6502
e.g. here's the C64 ROM https://skoolkid.github.io/sk6502/c64rom/

Disclaimer: I've not tried it out on 6502 code, yet.

D.
Last edited by spanners on Fri Mar 06, 2020 10:44 am, edited 1 time in total.

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Re: The Great Escape test build (soon)

Post by spanners » Thu Mar 05, 2020 6:45 pm

hubersn wrote:
Thu Mar 05, 2020 10:21 am
I always hated that game on the Amstrad CPC - was the Spectrum version any better?
Exactly the same, but a bit quicker. Sorry!

D.

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Re: The Great Escape test build (soon)

Post by spanners » Thu Mar 05, 2020 6:46 pm

Kazzie wrote:
Thu Mar 05, 2020 12:00 pm
I'd throw my hat into the testing ring, but I don't have hardware running anything more recent than RISC OS 3.11.
Ace. I'll see how far back I can make it run.

TGE-for-Arthur here we come!

D.

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Re: The Great Escape test build (soon)

Post by marcusjambler » Fri Mar 06, 2020 11:42 am

Wow... great work!!

Would be awesome to see this on the Master :shock:

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Re: The Great Escape test build (soon)

Post by spanners » Fri Mar 06, 2020 1:28 pm

marcusjambler wrote:
Fri Mar 06, 2020 11:42 am
Wow... great work!!
Thanks!
marcusjambler wrote:
Fri Mar 06, 2020 11:42 am
Would be awesome to see this on the Master :shock:
There is a C64 version of The Great Escape which could work as a starting point. It does suffer performance-wise though so it might need some Beeb optimisation wizardry to be playable, like Elysium did on the C64 when they sped it up: https://csdb.dk/release/?id=178037

D.

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Re: The Great Escape test build (soon)

Post by jms2 » Fri Mar 06, 2020 10:32 pm

What a great website, and an interesting write-up on the game. I'd not seen it before (not having owned a Spectrum) but it looks excellent.

I do have a Pi with Risc OS on it, so I could do some playtesting - or perhaps more accurately I could persuade my kids to do it! They quite like old 8 bit games.

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Re: The Great Escape test build (soon)

Post by spanners » Mon Mar 23, 2020 10:38 am

Here's The Great Escape coming to life on RISC OS 3.11 (via ArcEm running on my Iyonix). It's presently suffering from some problems including poor speed. It might be alright on real hardware, we'll see.
tge.png
D.

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Re: The Great Escape test build (soon)

Post by AndyMc1280 » Tue Apr 14, 2020 12:01 am

spanners wrote:
Mon Mar 23, 2020 10:38 am
Here's The Great Escape coming to life on RISC OS 3.11 (via ArcEm running on my Iyonix). It's presently suffering from some problems including poor speed. It might be alright on real hardware, we'll see.

tge.png

D.
Once we are out of this social isolation gash, bring it round to mine, A5000 and R260 are willing to test. A3010 still borked.

Would be good to see on real hardware.
:mrgreen: That Redbush mint tea you like will be provided. :lol:

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Re: The Great Escape test build (soon)

Post by spanners » Tue Apr 14, 2020 10:32 am

Cheers! I've fixed most of the redraw issues now, so I should have a test build downloadable once I've worked out why the input is choppy...

D.

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Re: The Great Escape test build (available now)

Post by spanners » Tue Apr 21, 2020 8:10 pm

Beta test build attached!
  • It'll run on RISC OS 3.1, I've not tested earlier than that.
  • It'll also need an ARM250 machine, which shows the amazing performance hit of converting it into C and desktop-ising it.
  • There's separate help file and instructions for the game both available from the icon bar icon.
  • There are various ways to twiddle the window sizing (fixed/stretchy) and various exciting keyboard shortcuts.
  • There's no sound yet, nor a full screen mode, nor any way to save your game. All are planned.
  • Unfinished features are present on the menus, but greyed out until they arrive.
GtEscape-090.zip
The Great Escape for RISC OS, version 0.90
(82.77 KiB) Downloaded 22 times
[ OBSOLETED BY 0.91 -- SEE BELOW ]


If you spot any issues, let me know.

If you want to compare with the original Spectrum version on an emulator you can grab tape images from WoS: http://www.worldofspectrum.org/infoseek ... id=0002125.

D.
Last edited by spanners on Wed May 06, 2020 11:01 am, edited 1 time in total.

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Re: The Great Escape test build (soon)

Post by spanners » Sat Apr 25, 2020 12:47 pm

There's definitely something fishy going on in this build. I've seen the red cross parcel mispositioned, fellow prisoners disappearing at points only to be resurrected the next day and some characters walking out of bounds. I suspect it's an unsigned chars thing.

D.

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Re: The Great Escape test build (soon)

Post by spanners » Tue Apr 28, 2020 10:44 am

It turned out to be some wonky structure alignment assumptions which stopped some items and characters spawning properly #-o. I'll get a new build up soon.

D.

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Re: The Great Escape test build (available now)

Post by spanners » Wed Apr 29, 2020 12:48 pm

Here's 0.91. The following bugs have been squashed:
  • Red cross parcel appearing in the wrong place
  • Characters disappearing on room transitions
GtEscape-091.zip
The Great Escape for RISC OS, version 0.91
(82.71 KiB) Downloaded 24 times
[ OBSOLETED BY 0.92 -- SEE BELOW ]

As ever, if you see anything wonky just let me know.

D.
Last edited by spanners on Sun May 24, 2020 12:10 am, edited 1 time in total.

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Re: The Great Escape test build (available now)

Post by spanners » Sat May 02, 2020 11:04 pm

A current screenshot...
tge-riscos3.png
D.
Last edited by spanners on Wed May 06, 2020 5:12 pm, edited 1 time in total.

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Re: New RISC OS Port - The Great Escape test build (soon)

Post by SteveF » Tue May 05, 2020 1:41 am

I'd never heard of this game before, but I really enjoyed reading your writeup about the disassembly process. Thanks a lot for that! Screenshot of the port is looking good too...

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Re: New RISC OS Port - The Great Escape test build (available now)

Post by spanners » Sat May 23, 2020 10:24 pm

Here's 0.92. It can now play the menu screen music and in-game sound effects if your RISC OS machine has a 16-bit sound system. I've also added the ability to save screenshots.

GtEscape-092.zip
(98.54 KiB) Downloaded 9 times
I assume no news is good news, but if you see anything askew in this build then let me know.

D.

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