Killer Cobra programmer Pete Wiseman SPEAKS!

[Xyphoe]

Hey guys!

Anyone remember my Killer Cobra longplay and review?


https://www.youtube.com/watch?v=3bGBgOzA1ZU

Well! As discussed at the time, it was believed that the listed programmer "Peter Wiseman" may have been a pseudonym for Richard Aplin (Double Dragon I/II, Shinobi, etc) due to his name being in the code if you crack it and the liquid smooth scrolling that Richard was able to master too in his games. I had a chat with Richard at the time but he couldn't remember coding it, but may have done the load protector.

So yesterday, a new comment appeared on the video, and it's from the real Pete Wiseman and it's very interesting! Confirmed, for example, that it runs at 50fps!
There's even some programming tricks there that might help some budding coders here!

Enjoy ....

Hi, It's the real Pete Wiseman here! I wrote this game when I was 16 years old and as was common in the good old days, was responsible for everything - all the coding, graphics and sound straight from my bedroom. I definitely didn't hide that message in the code so it must have been added by Rich Aplin in some kind of loader/copy protection if he worked at Mastertronic at the time. Anyway, I was extremely proud of this game so thanks for keeping the thing alive via your video. Definitely one of my best technical achievements on the 8-bit computers. I was particularly proud of how smooth I managed to make the scrolling when the Amstrad was notorious for clunky scrollers. Pity you couldn't manage to capture it properly in the video but it's tough to do, especially when the game was refreshing at 50fps and your camera might have been recording at 60fps and then YouTube does god knows what to it once you upload it. Anyway, It was essential that all my 2D games ran at a silky smooth 50fps and this was no exception. I actually read about this scrolling technique in an article posted in an issue of Amstrad Action magazine one month and I created Killer Cobra around it. I loved Scramble and was just obsessed with how smooth the arcade version scrolled and wanted to recreate that on a home computer. I was really into the TV series Airwolf at the time too so the helicopter intro sequence shows some similarities to the Airwolf intro sequence. The actual scrolling technique was quite simple once I knew how. There were some well known hardware registers that you could use to offset the screen and scroll it one 4-pixel block at a time but that produced scrolling that was just miles too fast for this type of game. The only other Amstrad game that I know of that used that hardware scroll was Tornado Low Level (TLL) by Vortex Software and all the videos I've seen on YouTube of TLL look really slow but if my memory serves correctly, you could fire up the afterburners on your jet at some point and it just ripped across the landscape at mind blowing speeds four directional scrolling as silky smooth as Killer Cobra but twice as fast because it was scrolling 4 pixels per frame, so pretty unplayable but very impressive in terms of smoothness nonetheless. Anyway, the technique published in Amstrad Action revealed a second hardware register that nudged the screen horizontally to the right by 2 pixels. I think it was some kind of screen centering register that wasn't documented but if you used this in conjunction with the hyperspeed 4-pixel scroll, you could slow the scrolling down to something more playable. To do that you would scroll the screen left by 4 pixels but also nudge it right by 2, effectively scrolling left 2 pixels. Then the next frame you could just nudge the screen centering register back to it's normal position scrolling left 2 pixels again. Then repeat and you'd end up with a 2 pixel scroll which although is probably twice as fast as arcade games like Scramble and Super Cobra, it's playable ... and silky smooth as it uses hardly any CPU. The only tricky part was rendering any moving sprites on screen because at some point they would wrap off the end of memory and drop vertically by 1 line or something like that but it turned out that a simple test of the overflow flag was all that was needed to make the necessary adjustments. I'm trying to remember why I didn't display any score or lives on the screen during game play and I can only assume that the scrolling would have required me to re-draw all the digits each frame and the CPU wasn't fast enough. I only had to re-draw the right and left edges of the horizontal fuel meter so that was fairly quick to do. Even though the scrolling is a little bit jumpy in the video, I enjoyed watching it as I'd completely forgotten some of the stuff I'd programmed into the game, such as the laser beam gates you had to shoot open, the stalagmite tips you could blast off and that little hovering space ship thing near the end. I tell you what though, you played the hell out of that game and have some mad skills hey? I don't think I ever managed to complete the entire game like you did but nice shooting! I made it hard as hell hey? Did you notice that Mastertronic printed the final screenshot upside down on the inlay card? D'oh!! After posting a copy off to Mastertronic I remember them giving me a bell and offering me a non returnable £2000 advance on royalties for this game. Then they said that if I'd written it on the Commodore 64 I'd be making three times that money. I learned a valuable lesson that day about coding for the hardware with the most potential customers! I never sold enough copies to earn anymore than the 2000 squids advance but at 16 years old in 1987 it was like seeing the booty at the end of the game .... only real. I ended up with a better telly and VCR than my mum and dad and invested in my next computer, the Commodore Amiga and a full set of programming manuals with it. Thanks for the memories and I'm happy to hear you enjoyed playing it so much!

[ivarf]

That could have been part of an Retrogamer article. Thank you 

[mr_lou]

Very nice!

I just wanna comment on your trouble regarding smoothness in the video.
Because it is one of the (many) reasons I'm targeting Blu-ray for my project 8-bit Memoirs.

The CPC sends out about 50hz. So when you record a video, it will be a 50 fps video.
In order for a 50 fps video to look good, it needs to be displayed on a screen that updates with a frequency of 50hz or 100hz or 150hz etc.
And there's your trouble: Most PC monitors updates at 60hz.
Therefor, you will never be able to make a 50 fps video look good on a standard PC.

But if your put your 50 fps video onto a Blu-ray disc, and play it this way using a Blu-ray player, then your TV will switch to a 50hz mode (or compatible), and everything will look awesome!

[Xyphoe]

I just wanna comment on your trouble regarding smoothness in the video.
Because it is one of the (many) reasons I'm targeting Blu-ray for my project 8-bit Memoirs.

Cheers, yea... problem is YouTube encodes it again at around 30fps (actually I think it's 29.7fps annoyingly!!) for standard definition, but if you up it in the playback settings to 720p or 1080p (if you've made it that size) then it will allow 50fps or 60fps. So you have a potential mix there, and hope people watch in HD by default. The mobile app defaults to standard 480p I believe.

Also many camcorders, cameras and even mobile default camera apps don't allow you to specify the FPS annoyingly. Most will allow you to choose the size (eg 1080p) but not the FPS or even the codec used.

I got a new camera that records in 50fps but it was by pure luck - it didn't advertise what FPS it used, nor was it in the instructions. Sadly, for some reason Sony Vegas has a complete hissy fit over the codec used and rendering always results in glitches. ARGGH.  (I use Sony Vegas to edit and encode all my videos ... there's not many video editors out there with the level of features it has, and despite it being a bug ridden mess that constantly crashes I can't afford new software). And yea there are mobile apps out there (I think Open Camera is one) that allow you to mess about with FPSs.

[Xyphoe]

More from Pete this morning!

I asked him about the 2 other games we have listed for him on the CPC-Power website...

Wriggler was my first Amstrad title and was published by Blaby Computer Games who had published my previous two Dragon 32 games, Olympia and Kamacarzy. They used to buy cheap 1/8th page advertising space in popular computer magazines displaying an Uncle Sam guy pointing at us saying "We Want Your Games" instead of "I Want You For U.S Army". There was another Wriggler floating around on CPC but mine was the Centipede clone. It was a pretty decent clone and got fairly high scores in Amstrad Action magazine. I would have made the centipede turn the corner in an arc like the arcade version if I'd played it more but my parents used to take me to Blackpool as kid a couple of times a year and I'd get to play the arcade games there a few times and then go home with short memories and just a desire to have these games on my computer. There was no internet back then for reference. Anyway, after Wriggler I wrote Doodlebug, a Ladybug clone which was also published by Blaby but I think they were going down the bog at that point as they didn't even design a proper cassette inlay for it. Shortly after that they went out of business and I regained the rights to both titles and let Players publish them. The main release was Doodlebug but I let them put Wriggler on the B side of the cassette as a freebie. They didn't exactly flaunt this freebie and I doubt anyone really knew it was on the B side unless they read the small print. They certainly didn't splash the extra cash for a B side label on the tape saying "hello ... Wriggler here". I think I got an advance of 200 quid for both games and never saw another penny in royalties. Anyone who thinks that the 80's "whiz kids," working from their bedrooms, were all driving around in Lotus Turbo Esprits like Eugene Evans is sadly mistaken. His massively publicised playboy ;-) lifestyle is what inspired me to write my own games as a teenager though. I'm finally doing pretty good on iOS 30 years later so no regrets 

[mr_lou]

Cheers, yea... problem is YouTube encodes it again at around 30fps (actually I think it's 29.7fps annoyingly!!) for standard definition, but if you up it in the playback settings to 720p or 1080p (if you've made it that size) then it will allow 50fps or 60fps. So you have a potential mix there, and hope people watch in HD by default.

What I'm saying is that even if you upload a 50 fps video, it will still look jerky from a standard PC, because most monitors has a refresh rate of 60 hz.

The only way you can watch a 50 fps Amstrad CPC video without any jerkiness, is to use a screen that has a refreshrate of 50 hz or dividable by 50.
Therefor it doesn't matter much that you do actually upload a 50 fps video in 720p or 1080p, because (most) people will be watching it on a 60 hz display regardless, resulting in jerkiness.
Because extremely few people use a monitor with a refreshrate of 50 hz or 100 hz.

[ukmarkh]

Absolutely amazing! I watched the vid also, brought back wonderful memories. That's an awesome insight into Killer Cobra, what a legend!


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