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New game port: Fairlight


mariuszw
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Here is my next C64 to Atari 8-bit port: Fairlight: A Prelude.

 

For now only joystick is implemented, so you can walk around and fight the guards, but you cannot take and use items etc.

 

It should work on real Atari, however I tested it under Altirra only.

 

Enjoy!

fl.obx

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Great start!

 

It's not like Spectrum version but at least it's not slower than C64 version ;)

 

No chance for code to be slower than C64 - 1,79MHz vs. 1MHz makes the difference ;)

 

The code really looks to be converted line-by-line from Z80 to 6502, so I expect it may be quite well optimized later. I also wonder why original programmer didn't use hardware sprites on C64 - they would fit nicely in the game, making less work for the programmer (no need to convert software-sprite routines) and the game speed would be really good.

 

BTW: is there an easy way to estimate real clock of Atari during executing given software, i.e. how much CPU time (expressed in MHx) is stolen by ANTIC? Here in Fairlight narrow screen is used (32 bytes), but in character mode. There are also 24 character lines displayed (192 pixel lines).

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The code really looks to be converted line-by-line from Z80 to 6502, so I expect it may be quite well optimized later. I also wonder why original programmer didn't use hardware sprites on C64 - they would fit nicely in the game, making less work for the programmer (no need to convert software-sprite routines) and the game speed would be really good.

You're right. Looks like fast conversion, similar to how Head over heels was done. Working with hardware sprites would demand too much new code I guess...

 

BTW: is there an easy way to estimate real clock of Atari during executing given software, i.e. how much CPU time (expressed in MHx) is stolen by ANTIC? Here in Fairlight narrow screen is used (32 bytes), but in character mode. There are also 24 character lines displayed (192 pixel lines).

For Pal mode one scanline is 114 cycles. There are 312 lines, 50 frames/second = 1778400 ~ 1,78MHz

 

In character mode Antic takes 74 cycles in 'badline' (first line of character) and 48 cycles in each of remaining 7 character lines.

 

So.... One frame time = 312*114-24*(74+7*48) = 25728.

50*25728 / 1778400 ~ 0.72 - Almost 30% slower :(

Still faster than C64 ;)

 

ps. Here is how antic stealing cycles looks like (cpu timing explained in attached file):

                                0 1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728293031                    
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|-
IPPPPAA                  RC CGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGCGRG                     M  Mode 2,3,4,5 - Narrow
 PPPPAA                  R   GRG GRG GRG GRG GRG GRG GRG GRG G G G G G G G G G G G G G G G G                     M  Mode 2,3,4,5 - Narrow

Antic_Timings.txt

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  • 3 weeks later...

Here is next version of Fairlight port. New features:

- screens are colored

- keyboard is working (although there are issues under Altirra, it seems that not all keypresses are properly recognized, I am not sure if it is my bug - please test on real Atari and let me know, game keys are listed on title screen, please do not shift key, it doesn't work)

- code optimization - game seems to be up to two times faster (or less slow) than C64 version, but still slows down when there is a lots happening on screen. Screen drawing which happens when hero enters the room is also faster.

 

Mariusz.

 

fl.obx

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- keyboard is working (although there are issues under Altirra, it seems that not all keypresses are properly recognized, I am not sure if it is my bug - please test on real Atari and let me know, game keys are listed on title screen, please do not shift key, it doesn't work)

 

Input > Keyboard > Send raw key strokes

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Here is next version of Fairlight port. New features:

- screens are colored

- keyboard is working (although there are issues under Altirra, it seems that not all keypresses are properly recognized, I am not sure if it is my bug - please test on real Atari and let me know, game keys are listed on title screen, please do not shift key, it doesn't work)

- code optimization - game seems to be up to two times faster (or less slow) than C64 version, but still slows down when there is a lots happening on screen. Screen drawing which happens when hero enters the room is also faster.

 

Mariusz.

Great work! Thanks for improved version!
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It's quite ironic that the best games on a computer with the name of "Spectrum" are black and white.

No Sir you're not right! They are in black and one color ;)

 

On serious note, I must admit those hires sprites are some of the best looking graphics ever imho... Head over Heels, Target Renegade, Heartland, Trantor, Laser squad...

Wish Atari would have some better way of adding color to hires mode than dli and pm overlay... Adding just a little bit of color difference here and there makes it look so much better.

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Batman can not be unless he starts studying Z80 assembly, it wasn't available for C64 and only for ZX Spectrum and Amstrad CPC.

 

I already know Z80 assembly from working on MAME project ;)

 

There are still two hires isometric games on C64: Bobby Bearing and Nosferatu. I was actually looking at Bobby Bearing and for now it looks that this one should be also quite easy to port to Atari.

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8086/8 or Z80 it still isn't 6502, even if he's familiar with these processors assembly and that one gives him the code commented he still has to code all 6502 new.

I don't think that's Marius purprose but he is who knows. And after these 2.5D/isometric there are some others 6502 C64 without hardware sprites and he can even go to BBC/Electron 2bpp 4colours games (in this moment I am remembering one that I kindly converted the loading screen but someone didn't do anything more ;) :grin: ).

Unless his name isn't Marius but indeed XXL then maybe a quicky Z80 port is sure possible to in a few days :).

:thumbsup:

Edited by José Pereira
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Jose, you're right about it being hard to code 6502 from start.

 

I would just like to see new 3d iso game on Atari. And more important - better than any existing C64, Spectrum, Amstrad version :)

 

Imho, having graphics and gamemap done is a good start. Chimera for example took a lot of effort but we learned a lot while fixing it. New 3d iso game is not so far away on A8 ;)

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I would just like to see new 3d iso game on Atari. And more important - better than any existing C64, Spectrum, Amstrad version :)

 

Imho, having graphics and gamemap done is a good start. Chimera for example took a lot of effort but we learned a lot while fixing it. New 3d iso game is not so far away on A8 ;)

 

Can you please reveal some more details on this?

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And after these 2.5D/isometric there are some others 6502 C64 without hardware sprites

 

Can you please list these C64 without hardware sprites games you have found? Also, they should run in bitmap mode, due to 128 characters limit on tilemaps (vs. 256 on C64) to make porting easy.

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Can you please list these C64 without hardware sprites games you have found? Also, they should run in bitmap mode, due to 128 characters limit on tilemaps (vs. 256 on C64) to make porting easy.

I started a new here to not 'polute' this one:

http://atariage.com/forums/topic/241868-c64-games-without-software-sprites/

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