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| Converting Spectrum Games http://www.retrosoftware.co.uk/forum/viewtopic.php?f=20&t=914 |
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| Author: | JonathanC [ Sun Oct 05, 2014 7:08 pm ] |
| Post subject: | Converting Spectrum Games |
Hi guys, If inspiration is proving hard to come by and you fancy the technical challenge of a Sinclair-to-Acorn conversion, I have a back catalogue of Spectrum games that would work rather well on the Beeb and Electron and would be more than happy to share fully commented source code where I have it. Here are a few that might be relatively straightforward to convert: http://www.youtube.com/watch?v=Byz_CISpcao http://www.youtube.com/watch?v=Zj4VyGtYxDs http://www.youtube.com/watch?v=EMpvlPRoST4 http://www.youtube.com/watch?v=7koDi0MeOzY http://www.youtube.com/watch?v=VC7i1Qnt1DI http://www.youtube.com/watch?v=Vq8H8v2ICw8 http://www.youtube.com/watch?v=TeIxWnxFX3k |
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| Author: | tricky [ Sun Oct 05, 2014 9:33 pm ] |
| Post subject: | Re: Converting Spectrum Games |
I like the golf one and the graveyard in Egghead. Don't you fancy having a go yourself? Richard |
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| Author: | DavidB [ Sun Oct 05, 2014 11:00 pm ] |
| Post subject: | Re: Converting Spectrum Games |
I've been keeping an eye on the releases for non-Acorn platforms and I'm tempted to port something, but the only thing I'm needing inspiration for is the ending to my current game.  If you put the source code somewhere, I'm sure Kees will start cranking out Atom conversions fairly rapidly. 
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| Author: | JonathanC [ Mon Oct 13, 2014 2:04 am ] |
| Post subject: | Re: Converting Spectrum Games |
It's hard enough finding time to work on the CPC version of AGD, let alone learn to program a non-Z80 machine! I think this is something that's best left to Acorn programmers. I don't think I'd do the BBC, Electron, Atom etc justice as a newbie. Yes, Kees is a machine! Regarding source code, I have uploaded some files here and there over the years. World of Spectrum has a few examples if anyone wants to take a look: Turbomania is a simple maze game for the 16K Spectrum with a few little minigames. Pressing fire redraws the maze as you're driving through it, handy for shaking off your pursuers: http://www.worldofspectrum.org/infoseekid.cgi?id=0015418 Banger Management was the game I wrote at Byte Back and sees the player changing platforms to direct cups of tea, sausages, sandwiches etc through various serving hatches to fulfill customer orders. It has been compared to Lemmings but it's probably a bit more manic than that: http://www.worldofspectrum.org/infoseekid.cgi?id=0023309 Rallybug is a scrolling platformer. Think Giana Sisters on wheels with Hangman thrown in for good measure. I'm not sure how well this would convert, it uses a screen buffer with PUSH and POP to dump each frame to the screen. http://www.worldofspectrum.org/infoseekid.cgi?id=0021316 Amusement Park 4000 came second in the 2003 minigame competition and is basically Theme Park in 4K of RAM. I've since released a version with lots more rides so let me know if you want to see the source for the larger version. http://www.worldofspectrum.org/infoseekid.cgi?id=0014559 |
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| Author: | DavidB [ Mon Oct 13, 2014 10:39 pm ] |
| Post subject: | Re: Converting Spectrum Games |
Looking at the source code to Rallybug, it seems that Z80 code is almost completely alien to me. The closest thing to it I've seen is 8086 code, though ATmega code has some similar instruction mnemonics. Let's face it, there are only so many combinations of letters one can use. I think one approach would be to get an idea of the structure of the game and extract the algorithms used for key gameplay mechanics, then write the graphics and sound routines from scratch, converting the graphics and maybe touching them up for the different resolution and colour depth to be used. Something for the cold winter nights ahead, perhaps.
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| Author: | oss003 [ Tue Oct 14, 2014 7:33 am ] |
| Post subject: | Re: Converting Spectrum Games |
DavidB wrote: Looking at the source code to Rallybug, it seems that Z80 code is almost completely alien to me. The closest thing to it I've seen is 8086 code, though ATmega code has some similar instruction mnemonics. Let's face it, there are only so many combinations of letters one can use. I agree, I started to convert the AGD engine but you must forget all 6502 algoritms and think in Z80 algoritms which are not familiar to me and that's why I got stuck.I used this construction: Code: reg_af equ $80 This way you can set the individual registers and use the 16-bit address by using indexed addressing eg. reg_f equ reg_af reg_a equ reg_af+1 reg_bc equ $82 reg_c equ reg_bc reg_b equ reg_bc+1 reg_de equ $84 reg_e equ reg_de reg_d equ reg_de+1 reg_hl equ $86 reg_l equ reg_hl reg_h equ reg_hl+1 reg_ix equ $88 reg_x equ reg_ix reg_i equ reg_ix+1 reg_af' equ $8A reg_f' equ reg_af' reg_a' equ reg_af'+1 Code: ld l,(ix+6) This way I managed to convert FSPRITES to the Atom.ldy #6 lda (reg_ix),y sta reg_l Spectrum version: http://zxspectrumdev.blogspot.de/2009/0 ... -data.html Atom version: https://www.youtube.com/watch?v=qcQ-1NaPWno Greetings Kees |
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| Author: | tricky [ Tue Oct 14, 2014 1:25 pm ] |
| Post subject: | Re: Converting Spectrum Games |
From the very old days I remember writing a sprite routine on the z80 and having to store alternating bytes of data and masks. For blitting, pul groups of registers off the "stack" and then push them onto a different "stack". |
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