Forums

Things that relate to the kind of stuff we may be doing here.

8088 Domination Post-Mortem, Part 1
Playing full-motion video on a 1981 IBM PC
http://trixter.oldskool.org/2014/06/19/8088-domination-post-mortem-part-1/

GCR decoding on the fly
http://www.linusakesson.net/programming/gcr-decoding/index.php

www.cs.cmu.edu/~tom7/mario/

Entertaining YouTube videos too.

It's a shame that programmers nowadays favour bloated programming languages and don't bother with optimisations at all. Real programmers are becoming rarer and rarer, between a C# and the next useless eye candy. But hey, we have 16-cores, who cares if 15 of them are used for the UI. And hey, we have 64 gigabytes of RAM, who cares if I use a 64-bit variable to store a boolean flag.
</rant>

On topic, I always liked this video: http://www.youtube.com/watch?v=eUv0jSYRBZo

Thanks for linking these wonderful posts.
They also reminded me of the feelings I had when I found out how to do a 25%-75% weighted average between two 15bpp RGB pixels with only 7 ARM 1-cycle ASM instructions, and how then I did two of those in 11 cycles using 'SWAR'... ah, the memories...

http://www.sbnation.com/2014/2/28/5453556/jons-basketball-game-garrys-mod

Maybe a tiny bit not serious, but it shows the importance of flexibility to your target platform and perseverance. Also, giving up if it doesn't pan out.

http://www.sega-16.com/forum/showthread.php?22763-Let-s-consolize-and-old-dirty-...

I want to be this guy. This is inspiring to me. It makes me want to find a trash bag.

He also mentions us!

Also, If you guys have not seen it already, here's a link to a truly impressive consolized Game Gear.
http://www.smspower.org/forums/viewtopic.php?t=13381

This guy has insane skills and pushed it to the extreme, I found this very inspiring.
Im definitely NOT going that far though. My goal is to have it work well and be practical.

Apparently, the guys at Sonic Retro are liking this: http://www.youtube.com/watch?v=mBHB51TS5a0

It's a port of Wolfenstein for the Mega Drive / Genesis. I have to admit, it looks impressive.

The discussion about 8x8 type graphics reminded me of this beautiful little website http://www.puzzlescript.net

It is an integrated web-based environment for creating puzzle games using a custom rule-based language, with graphics & levels described in embedded ASCII. On any game if you click "HACK" you can see how they are done.

Levels can be hand-edited in code. You define the possible items as a list of ASCII characters (the "Legend") and then draw the level as a rectangle using those characters.

I also like what they do with sounds: the software include a simple sound synthesizer with a dozen of hard-coded base settings ("collect item" "explosion") from which you can generate random variation. The output of which is a single 32-bit number which encode the sound type and the random parameters which served to seed that specific sound. So basically you click the "explosion" button until you get an explosion sound you like and then you can use this number in your code.

I liked the Heroes of Sokoban serie, it becomes really interesting from part 2.
http://www.puzzlescript.net/play.html?p=6860122
http://www.puzzlescript.net/play.html?p=6910207
http://www.puzzlescript.net/play.html?p=7072276

Also many of those games would be prime candidate for a nice-looking SMS port.

10 mins of making of

Bock wrote

The discussion about 8x8 type graphics reminded me of this beautiful little website http://www.puzzlescript.net

(..)

Also many of those games would be prime candidate for a nice-looking SMS port.

Yes, I once thought about creating a tool to generate SMS ROMs from puzzlescript games; I've taken a look at their source code (https://github.com/increpare/PuzzleScript), inspected the JS object that it generates from the parsed source, but never went much beyond that, choosing to make Twee2SAM, instead. Maybe I'll come back to that someday, but being the procrastinator that I am, I wouldn't count on that. :P

Under the amusing title there is research to "emulate" a worm down to its cellular and neuronal system. So essentially an emulator of a real living thing based on copying the neuronal map/weights of the original.

http://www.i-programmer.info/news/136-open-source/7347-openworm-building-life-ce...
http://www.i-programmer.info/news/105-artificial-intelligence/7985-a-worms-mind-...

Learn a bit about the other side.

I always thought 'the other side' was NES ;)

It's bigger than that, it's Z80 vs 6502!

Detailed hack
http://www.neocomputer.org/projects/et/

Bock wrote

Detailed hack
http://www.neocomputer.org/projects/et/

I really like this one.

My motivators/inspirators:

I really love the design and gameplay.
I even created my own Z80 game engine for a la-mulana like game:

http://handmadehero.org/
https://www.youtube.com/user/handmadeheroarchive

Casey Muratori on programming a game in C, for PC, from scratch. By "from scratch" it means excluding standard libraries, build systems, not even using OpenGL or DirectX librairies, everything is done at nearly the lowest level it can be done to be able to explain what is going on.

All the programming is recorded along with live commentary. There's lots of interesting topics being discussed, interesting tricks. Casey is a very experimented programmers so he goes in details, implement things that are not often done in your typical C codebase (live code reloading, state reloading/playback) and he like to do things "correctly".

Unfortunately by nature it's really long, 1-2 hours a day and forever ongoing. Bit hard to swallow that much. It is great as a documentation problem and hopefully will be indexed in details someday.

3D Afterburner is out on the 3DS eshop today, and Sega is continuing to translate the series of interviews with M2 about porting these games to the 3DS: http://blogs.sega.com/2015/01/12/sega-3d-classics-3d-afterbunner-ii-%E2%80%93-a-...

Really interesting stuff, they really went all-out on these conversions.

It has been in the news a few weeks ago, The Internet Archive (archive.org) has been steadily growing into hosting software and more recently emulation with a Javascript port of MESS and DosBox.

https://archive.org/details/software
e.g.
https://archive.org/details/sega_sms_library
https://archive.org/stream/gg_Columns_1991_Sega/Columns_1991_Sega.bin?module=gam...

And this article about the Internet Archive works (and how Google effectively dropped a lot of their archiving work)
https://medium.com/message/never-trust-a-corporation-to-do-a-librarys-job-f58db4...

We're going to be able to play Sonic X-treme finally. Even if it is an unfinished mess.

Bob Pape, the coder behind the Spectrum version of R-Type (which was quite impressive for the hardware) has written a book about the creation of the port and the state of computer game development at the time it was created. It can be downloaded for free from his website.

http://bizzley.com/

While it only occasionally touches on technical stuff, it's an entertaining read nonetheless. Highly recommended.

Extract from a recently released book about the Megadrive
http://www.polygon.com/features/2015/2/3/7952705/sega-genesis-masami-ishikawa

A great read - thanks!

I wish mr. Ishikawa could be pursuaded to do a similar interview regarding the SMS.

Also - the 8-bit community should also have/make a nice book on the SMS someday :) the raw material is already here on the site.

Kagesan wrote

Bob Pape, the coder behind the Spectrum version of R-Type (which was quite impressive for the hardware) has written a book about the creation of the port and the state of computer game development at the time it was created. It can be downloaded for free from his website.

http://bizzley.com/

While it only occasionally touches on technical stuff, it's an entertaining read nonetheless. Highly recommended.

I'm reading it at the moment :) It is indeed a very interesting account of coder life in those days! it seems like it was kind of a digital wild west back then. I like the story of how he converted Rampage from arcade to ZX Spectrum - without having the actual arcade machine available!

Yeah, it's a neat read. It's also neat when he describes how one of his coworkers figured out a way to make a game uncopyable. He never reveals the secret, but he drops some clues.

This is a pretty cool thread. I enjoyed the machine learning based approach to playing video games and the atari2600 reworking of et. Pretty thorough.

Lots of the other articles here are pretty nice as well.

A pretty phenomenal Castlevania fan-game for the ZX Spectrum:

http://spectralinterlude.com/

Kroc wrote

A pretty phenomenal Castlevania fan-game for the ZX Spectrum:

http://spectralinterlude.com/

Good lord that's amazing.

This one is simply awesome:

a deep convolutional neural network that's capable of learning how to play Atari 2600 games by itself

I have been enjoying following this.
http://forums.nesdev.com/viewtopic.php?f=12&t=10696

Ni****do coder base working on snes version of Bad Apple. Interesting from a technical and community perspective.

edit: also makes you chuckle at the difficulty of getting it to happen in comparison to the genesis version.

We need to get a competitive SMS version of Bad Apple done some day...

https://youtube.com/watch?v=5zeV-yi-iY4

I love demakes!

F-Zero clone for the MSX Turbo-R:

You might have seen or been passed some of those videos. Using bugs in Super Mario World people were able to inject custom code by crafting careful object placement. Initially this was used to teleport to the ending but in some video you can see people injecting mini-games and even a port of the original Super Mario Bros within Super Mario World.

This video explains the technicalities and is pretty impressive

Yeah, the "Executes Arbitrary Code" thing is a relatively recent fad on tasvideos, here is a list of games in which something like that was done.

Bock wrote

Using bugs in Super Mario World people were able to inject custom code by crafting careful object placement.

Wow - amazing hacking going on! It is really inspiring, and yet somehow it also affirms my concerns about the state of the world, where nukes, money and identities are being controlled by software.

More original IBM PC awesomeness with novel hacky hardware effects (e.g. 1024 colour mode)

http://trixter.oldskool.org/2015/04/07/8088-mph-we-break-all-your-emulators/

Details on the 1024 colors mode on CGA
http://www.reenigne.org/blog/1k-colours-on-cga-how-its-done/

And the MOD player
http://www.reenigne.org/blog/8088-pc-speaker-mod-player-how-its-done/
This is an easier read than the one above. Basically highly self-modifying routine. Similar technique would work on Z80 to stream data?

It doesn't work as well on Z80 because the instruction set is more limited. For example, there's no add hl, #imm. My guess is people who make music/sound engines for Mega Drive have figured things out.

Calling it a MOD player can be misleading, because it can't play back arbitrary MOD files, and the code for actual (ProTracker) MODs is in the converter.

This is some great demo using the TMS modes present on the SMS VDP.

@Martin and @Bock

For what it's worth, there are some games for the Mega Drive / Genesis which use existing file formats (such as MOD and MIDI) "as is".

Some follow-up done by myself:

Discussion about the MOD player in Toy Story (co-credit to Oerg)
Discussion about the MIDI player in that tennis game

I'm sure they use the 68K to mix. There are special trackers on Amiga which do 8 channel music, or TFMX based games with 7 channels, but only on title screens/credits scrollers. So the 68K is capable to do mixing in software.

The MSX IO demo confirms my impression that the legacy modes are often better for demo effects ;)

Bock wrote

Similar technique would work on Z80 to stream data?

The problem I see is that the PSG can't be programmed to generate a 'pulse', which is something like having a variable duty cycle... so PWM should be replaced with PCM.

I don't know about the MIDI player, but I can confirm that the MOD player uses the 68K, yes.

64k demo documentary

Nice dump of lots of Streets of Rage II (Bare Knuckle II) development docs.
http://ancgames.blog28.fc2.com/blog-entry-55.html

ZIP
http://www.ancient.co.jp/~game/download/bk2_docs.zip

Just thought I'd share an interesting Z80 technique I came across looking for a fast way to fill memory in Windows (via
http://stackoverflow.com/questions/387654/why-is-there-no-z80-like-ldir-functionality-in-c-c-rtl/388442#388442)

You temporarily set the stack pointer to the area you want to clear and then just push the stack down repeatedly to fill the memory! This is supposedly 4x as fast as a typical write look.

LD DE, SP
LD HL, 0
LD BC, 0x1800 ; Size of screen
LD SP, 0x4000 ; Start of screen
LOOP:
PUSH HL
DEC BC
JNZ LOOP
LD SP, DE

You'd probably unroll the loop a bit for speed. Using ldir for memory blanking is a bit lazy because it involves a read and write for every byte, but it's short and easy to write. Writing zeroes is faster but still slower than the stack abuse method, but I'd be slightly worried about NMIs happening while you do it - which is why I avoid stack changes.

Author	Message
Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Off-topic inspiring technical stuff Posted: Fri Jun 20, 2014 1:26 pm
	Things that relate to the kind of stuff we may be doing here.

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	8088 Domination Post-Mortem Posted: Fri Jun 20, 2014 1:26 pm
	8088 Domination Post-Mortem, Part 1 Playing full-motion video on a 1981 IBM PC http://trixter.oldskool.org/2014/06/19/8088-domination-post-mortem-part-1/

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Realtime fastloading on C64+1541 drive solved after 30 years Posted: Fri Jun 20, 2014 1:27 pm
	GCR decoding on the fly http://www.linusakesson.net/programming/gcr-decoding/index.php

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	learnfun & playfun: A general technique for automating NES games Posted: Fri Jun 20, 2014 6:19 pm
	www.cs.cmu.edu/~tom7/mario/ Entertaining YouTube videos too.

Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Posted: Fri Jun 20, 2014 7:16 pm
Tom Joined: 16 May 2002 Posts: 1378 Location: italy	It's a shame that programmers nowadays favour bloated programming languages and don't bother with optimisations at all. Real programmers are becoming rarer and rarer, between a C# and the next useless eye candy. But hey, we have 16-cores, who cares if 15 of them are used for the UI. And hey, we have 64 gigabytes of RAM, who cares if I use a 64-bit variable to store a boolean flag. </rant> On topic, I always liked this video: http://www.youtube.com/watch?v=eUv0jSYRBZo

sverx Joined: 05 Sep 2013 Posts: 3936 Location: Stockholm, Sweden	Posted: Fri Jun 20, 2014 8:11 pm
	Thanks for linking these wonderful posts. They also reminded me of the feelings I had when I found out how to do a 25%-75% weighted average between two 15bpp RGB pixels with only 7 ARM 1-cycle ASM instructions, and how then I did two of those in 11 cycles using 'SWAR'... ah, the memories...

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	Jon's Basketball Game: Creating a sports video game has proven to be rather difficult Posted: Mon Jun 30, 2014 2:26 pm
	http://www.sbnation.com/2014/2/28/5453556/jons-basketball-game-garrys-mod Maybe a tiny bit not serious, but it shows the importance of flexibility to your target platform and perseverance. Also, giving up if it doesn't pan out.

Capt. 2110 Joined: 27 Apr 2014 Posts: 281 Location: Texas	Posted: Wed Jul 09, 2014 8:57 pm
	http://www.sega-16.com/forum/showthread.php?22763-Let-s-consolize-and-old-dirty-... I want to be this guy. This is inspiring to me. It makes me want to find a trash bag. He also mentions us! Also, If you guys have not seen it already, here's a link to a truly impressive consolized Game Gear. http://www.smspower.org/forums/viewtopic.php?t=13381 This guy has insane skills and pushed it to the extreme, I found this very inspiring. Im definitely NOT going that far though. My goal is to have it work well and be practical.

Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Posted: Thu Jul 10, 2014 6:08 am
Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Apparently, the guys at Sonic Retro are liking this: http://www.youtube.com/watch?v=mBHB51TS5a0 It's a port of Wolfenstein for the Mega Drive / Genesis. I have to admit, it looks impressive.

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	PuzzleScript Posted: Sun Jul 13, 2014 3:14 pm
	The discussion about 8x8 type graphics reminded me of this beautiful little website http://www.puzzlescript.net It is an integrated web-based environment for creating puzzle games using a custom rule-based language, with graphics & levels described in embedded ASCII. On any game if you click "HACK" you can see how they are done. Levels can be hand-edited in code. You define the possible items as a list of ASCII characters (the "Legend") and then draw the level as a rectangle using those characters. I also like what they do with sounds: the software include a simple sound synthesizer with a dozen of hard-coded base settings ("collect item" "explosion") from which you can generate random variation. The output of which is a single 32-bit number which encode the sound type and the random parameters which served to seed that specific sound. So basically you click the "explosion" button until you get an explosion sound you like and then you can use this number in your code. I liked the Heroes of Sokoban serie, it becomes really interesting from part 2. http://www.puzzlescript.net/play.html?p=6860122 http://www.puzzlescript.net/play.html?p=6910207 http://www.puzzlescript.net/play.html?p=7072276 Also many of those games would be prime candidate for a nice-looking SMS port.

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Retro City Rampage ported to NES Posted: Mon Jul 14, 2014 1:25 pm
	10 mins of making of

haroldoop Joined: 25 Feb 2006 Posts: 903 Location: Belo Horizonte, MG, Brazil	Posted: Mon Jul 14, 2014 3:46 pm
	Bock wrote The discussion about 8x8 type graphics reminded me of this beautiful little website http://www.puzzlescript.net (..) Also many of those games would be prime candidate for a nice-looking SMS port. Yes, I once thought about creating a tool to generate SMS ROMs from puzzlescript games; I've taken a look at their source code (https://github.com/increpare/PuzzleScript), inspected the JS object that it generates from the parsed source, but never went much beyond that, choosing to make Twee2SAM, instead. Maybe I'll come back to that someday, but being the procrastinator that I am, I wouldn't count on that. :P

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	OpenWorm Posted: Tue Nov 18, 2014 10:22 am
	Under the amusing title there is research to "emulate" a worm down to its cellular and neuronal system. So essentially an emulator of a real living thing based on copying the neuronal map/weights of the original. http://www.i-programmer.info/news/136-open-source/7347-openworm-building-life-ce... http://www.i-programmer.info/news/105-artificial-intelligence/7985-a-worms-mind-...

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	25c3: The Ultimate Commodore 64 Talk Posted: Tue Nov 18, 2014 12:18 pm
	Learn a bit about the other side.

sverx Joined: 05 Sep 2013 Posts: 3936 Location: Stockholm, Sweden	Posted: Tue Nov 18, 2014 2:05 pm
	I always thought 'the other side' was NES ;)

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	Posted: Tue Nov 18, 2014 2:29 pm
	It's bigger than that, it's Z80 vs 6502!

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Fixing E.T. The Extra-Terrestrial for the Atari 2600 Posted: Thu Dec 11, 2014 2:16 pm
	Detailed hack http://www.neocomputer.org/projects/et/

Zipper Joined: 06 Apr 2011 Posts: 250 Location: Netherlands	Posted: Fri Dec 12, 2014 8:47 am
	Bock wrote Detailed hack http://www.neocomputer.org/projects/et/ I really like this one. My motivators/inspirators: I really love the design and gameplay. I even created my own Z80 game engine for a la-mulana like game:

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Handmade Hero Posted: Fri Jan 02, 2015 6:36 pm
	http://handmadehero.org/ https://www.youtube.com/user/handmadeheroarchive Casey Muratori on programming a game in C, for PC, from scratch. By "from scratch" it means excluding standard libraries, build systems, not even using OpenGL or DirectX librairies, everything is done at nearly the lowest level it can be done to be able to explain what is going on. All the programming is recorded along with live commentary. There's lots of interesting topics being discussed, interesting tricks. Casey is a very experimented programmers so he goes in details, implement things that are not often done in your typical C codebase (live code reloading, state reloading/playback) and he like to do things "correctly". Unfortunately by nature it's really long, 1-2 hours a day and forever ongoing. Bit hard to swallow that much. It is great as a documentation problem and hopefully will be indexed in details someday.

trykaar Joined: 04 Sep 2014 Posts: 37	Posted: Mon Jan 12, 2015 8:10 pm
trykaar Joined: 04 Sep 2014 Posts: 37	3D Afterburner is out on the 3DS eshop today, and Sega is continuing to translate the series of interviews with M2 about porting these games to the 3DS: http://blogs.sega.com/2015/01/12/sega-3d-classics-3d-afterbunner-ii-%E2%80%93-a-... Really interesting stuff, they really went all-out on these conversions.

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Internet Archive Posted: Fri Jan 30, 2015 11:16 pm
	It has been in the news a few weeks ago, The Internet Archive (archive.org) has been steadily growing into hosting software and more recently emulation with a Javascript port of MESS and DosBox. https://archive.org/details/software e.g. https://archive.org/details/sega_sms_library https://archive.org/stream/gg_Columns_1991_Sega/Columns_1991_Sega.bin?module=gam... And this article about the Internet Archive works (and how Google effectively dropped a lot of their archiving work) https://medium.com/message/never-trust-a-corporation-to-do-a-librarys-job-f58db4...

olaf Joined: 14 Oct 2006 Posts: 256 Location: NYC	Posted: Sat Jan 31, 2015 3:28 am
olaf Joined: 14 Oct 2006 Posts: 256 Location: NYC	We're going to be able to play Sonic X-treme finally. Even if it is an unfinished mess.

Kagesan Joined: 01 Feb 2014 Posts: 895	Posted: Sun Feb 01, 2015 9:22 am
Kagesan Joined: 01 Feb 2014 Posts: 895	Bob Pape, the coder behind the Spectrum version of R-Type (which was quite impressive for the hardware) has written a book about the creation of the port and the state of computer game development at the time it was created. It can be downloaded for free from his website. http://bizzley.com/ While it only occasionally touches on technical stuff, it's an entertaining read nonetheless. Highly recommended.

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	How Sega built the Genesis Posted: Mon Feb 09, 2015 2:05 pm
	Extract from a recently released book about the Megadrive http://www.polygon.com/features/2015/2/3/7952705/sega-genesis-masami-ishikawa

hang-on Joined: 23 Mar 2013 Posts: 611 Location: Copenhagen, Denmark	Posted: Mon Feb 09, 2015 4:38 pm
	A great read - thanks! I wish mr. Ishikawa could be pursuaded to do a similar interview regarding the SMS. Also - the 8-bit community should also have/make a nice book on the SMS someday :) the raw material is already here on the site.

hang-on Joined: 23 Mar 2013 Posts: 611 Location: Copenhagen, Denmark	Posted: Sat Feb 14, 2015 7:05 am
	Kagesan wrote Bob Pape, the coder behind the Spectrum version of R-Type (which was quite impressive for the hardware) has written a book about the creation of the port and the state of computer game development at the time it was created. It can be downloaded for free from his website. http://bizzley.com/ While it only occasionally touches on technical stuff, it's an entertaining read nonetheless. Highly recommended. I'm reading it at the moment :) It is indeed a very interesting account of coder life in those days! it seems like it was kind of a digital wild west back then. I like the story of how he converted Rampage from arcade to ZX Spectrum - without having the actual arcade machine available!

sherpa Joined: 28 Nov 2014 Posts: 365	Posted: Sun Feb 15, 2015 9:11 am
sherpa Joined: 28 Nov 2014 Posts: 365	Yeah, it's a neat read. It's also neat when he describes how one of his coworkers figured out a way to make a game uncopyable. He never reveals the secret, but he drops some clues. This is a pretty cool thread. I enjoyed the machine learning based approach to playing video games and the atari2600 reworking of et. Pretty thorough. Lots of the other articles here are pretty nice as well.

Kroc Joined: 08 Dec 2013 Posts: 200	Castlevania: Spectral Interlude Posted: Sun Feb 15, 2015 2:03 pm
Kroc Joined: 08 Dec 2013 Posts: 200	A pretty phenomenal Castlevania fan-game for the ZX Spectrum: http://spectralinterlude.com/

olaf Joined: 14 Oct 2006 Posts: 256 Location: NYC	Posted: Sun Feb 15, 2015 7:21 pm
olaf Joined: 14 Oct 2006 Posts: 256 Location: NYC	Kroc wrote A pretty phenomenal Castlevania fan-game for the ZX Spectrum: http://spectralinterlude.com/ Good lord that's amazing.

haroldoop Joined: 25 Feb 2006 Posts: 903 Location: Belo Horizonte, MG, Brazil	Posted: Thu Feb 26, 2015 10:46 pm
	This one is simply awesome: a deep convolutional neural network that's capable of learning how to play Atari 2600 games by itself

psidum Joined: 01 Jan 2014 Posts: 331	Posted: Sun Mar 01, 2015 8:29 am
psidum Joined: 01 Jan 2014 Posts: 331	I have been enjoying following this. http://forums.nesdev.com/viewtopic.php?f=12&t=10696 Ni****do coder base working on snes version of Bad Apple. Interesting from a technical and community perspective. edit: also makes you chuckle at the difficulty of getting it to happen in comparison to the genesis version.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	Posted: Sun Mar 01, 2015 10:01 am
	We need to get a competitive SMS version of Bad Apple done some day...

hang-on Joined: 23 Mar 2013 Posts: 611 Location: Copenhagen, Denmark	Sonic for the Atari 2600 Posted: Wed Mar 11, 2015 8:19 pm
	https://youtube.com/watch?v=5zeV-yi-iY4 I love demakes!

haroldoop Joined: 25 Feb 2006 Posts: 903 Location: Belo Horizonte, MG, Brazil	Posted: Sat Mar 14, 2015 8:20 pm
	F-Zero clone for the MSX Turbo-R:

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Super Mario World code injection explained Posted: Tue Apr 07, 2015 2:03 pm
	You might have seen or been passed some of those videos. Using bugs in Super Mario World people were able to inject custom code by crafting careful object placement. Initially this was used to teleport to the ending but in some video you can see people injecting mini-games and even a port of the original Super Mario Bros within Super Mario World. This video explains the technicalities and is pretty impressive

Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Posted: Tue Apr 07, 2015 2:36 pm
Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Yeah, the "Executes Arbitrary Code" thing is a relatively recent fad on tasvideos, here is a list of games in which something like that was done.

hang-on Joined: 23 Mar 2013 Posts: 611 Location: Copenhagen, Denmark	Posted: Wed Apr 08, 2015 8:01 am
	Bock wrote Using bugs in Super Mario World people were able to inject custom code by crafting careful object placement. Wow - amazing hacking going on! It is really inspiring, and yet somehow it also affirms my concerns about the state of the world, where nukes, money and identities are being controlled by software.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	8088 MPH Posted: Fri Apr 10, 2015 8:59 pm
	More original IBM PC awesomeness with novel hacky hardware effects (e.g. 1024 colour mode) http://trixter.oldskool.org/2015/04/07/8088-mph-we-break-all-your-emulators/

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Posted: Fri Apr 10, 2015 10:22 pm
	Details on the 1024 colors mode on CGA http://www.reenigne.org/blog/1k-colours-on-cga-how-its-done/

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Posted: Sun Apr 12, 2015 7:14 pm
	And the MOD player http://www.reenigne.org/blog/8088-pc-speaker-mod-player-how-its-done/ This is an easier read than the one above. Basically highly self-modifying routine. Similar technique would work on Z80 to stream data?

Martin Joined: 04 Nov 2004 Posts: 273	Posted: Mon Apr 13, 2015 12:08 pm
Martin Joined: 04 Nov 2004 Posts: 273	It doesn't work as well on Z80 because the instruction set is more limited. For example, there's no add hl, #imm. My guess is people who make music/sound engines for Mega Drive have figured things out. Calling it a MOD player can be misleading, because it can't play back arbitrary MOD files, and the code for actual (ProTracker) MODs is in the converter.

Zipper Joined: 06 Apr 2011 Posts: 250 Location: Netherlands	Posted: Mon Apr 13, 2015 12:54 pm
	This is some great demo using the TMS modes present on the SMS VDP.

Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Posted: Mon Apr 13, 2015 1:47 pm
Tom Joined: 16 May 2002 Posts: 1378 Location: italy	@Martin and @Bock For what it's worth, there are some games for the Mega Drive / Genesis which use existing file formats (such as MOD and MIDI) "as is". Some follow-up done by myself: Discussion about the MOD player in Toy Story (co-credit to Oerg) Discussion about the MIDI player in that tennis game

Martin Joined: 04 Nov 2004 Posts: 273	Posted: Mon Apr 13, 2015 2:02 pm
Martin Joined: 04 Nov 2004 Posts: 273	I'm sure they use the 68K to mix. There are special trackers on Amiga which do 8 channel music, or TFMX based games with 7 channels, but only on title screens/credits scrollers. So the 68K is capable to do mixing in software. The MSX IO demo confirms my impression that the legacy modes are often better for demo effects ;)

sverx Joined: 05 Sep 2013 Posts: 3936 Location: Stockholm, Sweden	Posted: Mon Apr 13, 2015 3:13 pm
	Bock wrote Similar technique would work on Z80 to stream data? The problem I see is that the PSG can't be programmed to generate a 'pulse', which is something like having a variable duty cycle... so PWM should be replaced with PCM.

Tom Joined: 16 May 2002 Posts: 1378 Location: italy	Posted: Mon Apr 13, 2015 6:08 pm
Tom Joined: 16 May 2002 Posts: 1378 Location: italy	I don't know about the MIDI player, but I can confirm that the MOD player uses the 68K, yes.

kamillebidan Joined: 25 Feb 2013 Posts: 387 Location: Osaka	Posted: Wed Apr 15, 2015 3:51 pm
	64k demo documentary

Bock Site Admin Joined: 08 Jul 2001 Posts: 8702 Location: Paris, France	Streets of Rage 2 development documentation Posted: Wed Apr 22, 2015 6:17 pm
	Nice dump of lots of Streets of Rage II (Bare Knuckle II) development docs. http://ancgames.blog28.fc2.com/blog-entry-55.html ZIP http://www.ancient.co.jp/~game/download/bk2_docs.zip

Kroc Joined: 08 Dec 2013 Posts: 200	Posted: Wed Jul 15, 2015 6:57 pm
Kroc Joined: 08 Dec 2013 Posts: 200	Just thought I'd share an interesting Z80 technique I came across looking for a fast way to fill memory in Windows (via http://stackoverflow.com/questions/387654/why-is-there-no-z80-like-ldir-functionality-in-c-c-rtl/388442#388442) You temporarily set the stack pointer to the area you want to clear and then just push the stack down repeatedly to fill the memory! This is supposedly 4x as fast as a typical write look. LD DE, SP LD HL, 0 LD BC, 0x1800 ; Size of screen LD SP, 0x4000 ; Start of screen LOOP: PUSH HL DEC BC JNZ LOOP LD SP, DE

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	Posted: Wed Jul 15, 2015 7:07 pm
	You'd probably unroll the loop a bit for speed. Using ldir for memory blanking is a bit lazy because it involves a read and write for every byte, but it's short and easy to write. Writing zeroes is faster but still slower than the stack abuse method, but I'd be slightly worried about NMIs happening while you do it - which is why I avoid stack changes.

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