solidcorp

As I said in a previous post the game runs in two frames. I deliberately chose overbright colors on black because they appear to the eye (not the camera) to flicker the least and they best matched the coin op appearance. I tested my video timing with a white background and boy oh boy that was an epileptic flicker fest. One screen is a classic Atari 2600 kernel, it shows an 8x8 pixel ship, an 8x8 pixel fuzzball, and the three sparks or mines that follow the ship around. It is a double line kernel so looks more blockey. All image data is displayed directly from ROM. The other screen shows the cannon, shields, and the 3 player shots. Internally, logically, each shield is 12 bits in two bytes that rotate coarsely. There is another byte that has the fine angular position of each shield. Those bits are used to build the shield data into RAM during two vblanks and one overscan. The shield logic is EXTREMELY complex. It basically converts each set of shield bits into a bit-mapped line that it wraps into a circle and packs with other shield bits into about 60 bytes of RAM for display. Each shield ring has different sized shield segments. A later step or's the appropriate 16x14 pixel cannon frame into the center area. The shield screen has a top and bottom portion that simply display the shots where needed, but the 46ish double scan lines in the center center of the display is pretty intense. It's a double line kernel that does not loop, a 3k monolithic function that uses a number of hand optimized macros to construct the lines. It, like the title screen, uses what we used to call a modified Dave Stauguss 6 character score kernel, you probably know the same code as a 48 pixel sprite kernel. Using player 0 and player 1 in tripled mode interleaved with each other on the screen, you load graphics into the GRP0 and GRP1 in such a way as to spit out 48 pixels of graphics by rewriting or latching registers right ahead of the electron beam as its being displayed. It's very sensitive to timing. I use no wsyncs in that code, I sync at the top and it's 76 cycles per line. Each line starts by grabbing bytes out of RAM and masking (and-ing) them with immediate values specified per line in the macros. Those values are drawn into the shield/cannon area, then the graphics registers are cleared and the next scan line turns each shot on and off as needed. That is why the shots are smaller than the sparks (as in the coin op) and the shields appear to be louvered. It was very challenging to get them to work properly in the small amount of RAM and time allotted. There were at least 5 major revisions of the shield code, each previous revision was thrown away for the next. I applied way too many clever programming tricks and modern day game programming techniques, most got thrown out. On the 2600 straight tables are usually smaller and faster than any other cleverness. One classic example was the cannon frames. I only stored 90 degrees of cannon frames in ROM at one point, but the code used to vertically flip the frames was slower and larger than the frame data in the first place. I laughed my butt off when I figured that out. Timing was also a real problem. I wrote the shields first and like I said, they took 2 vblanks and an overscan (37+37+30=104) scan lines to prepare which only left one overscan or 30 scan lines to do all the game logic, including 3 shots that can each collide with the cannon, 3 spinning shields, and 3 sparks. I finally was able to shoehorn all the processing in at about 1am before the Video Game Summit. Placing all the tables (graphics, arc-tangent, sin, cos, etc) in carefully aligned areas of ROM that don't cross page boundaries bought back a lot of time. Sensitive display kernels also had to be sure not to cross page boundaries. To be a good 2600 programmer you have to be a master of both time and space. (and maybe a little bit of a masochist) D. Scott Williamson

Definitely two of the best games on that system (Toki especially). Aw Gee Wiz, thanks. I wrote S.T.U.N Runner on the Lynx too. I absolutely love that system to this day, it was way ahead of its time. I was the head of external Lynx development at Atari. I developed new technologies and supported external developers. It was one of the most exciting times of my life. I still work with John Sanderson who wrote Steel Talons and Hard Drivin' (and more? idk) at High Voltage Software.

I will soon, but I have a question. The game runs 30fps in two 60 Hz fields. One field draws the cannon, shields, and the shots, the other the ship, fuzzball, and three sparks. Using over bright colors on black makes the flicker on a phosphor television unnoticable, but stella flickers a lot. Do you have a suggestion for the best way to capture a video? D. Scott Williamson

Looks very nice, but I know of at least one or two people who thought it could be done... I knew I couldn't have been the first, my hat is off to those who have tried before me. D. Scott Williamson

FWIW I tried very hard to acquire the license. Without getting into the very interesting and sordid origins of the Star Castle coin op, it was released by Cinematronics, a company which was purchased by Tradewest and renamed Lehland Corporation, all of which was purchased by Midway, which as recently purchased by Warner Brothers Interactive. I know quite a few people at Midway/WMS and I was able to work with the interactive media liaison at WBI who is in possession of the formidable list of properties to which Warner Brothers possesses the rights. Curiously, Star Castle is not on that list. D. Scott Williamson

I don't like where this is headed....... I don't like where this has gone, it was never about money. I regret making that stupid joke that has taken the attention away from the work. I wrote the game because I am a fan and to prove I'm at least as good as one of the best Atari 2600 programmers there ever was. D. Scott Williamson

"One Million Dollars!" (read like Dr. Evil from Austin Powers) Just kidding. I'm sorry guys, I'm really really genuinely flattered and I don't want to come off as a jerk (although it may be too late ) but I really just want to finish the one game cartridge and show it off right now. I'd be happy to talk about the technical aspects of making of the game though if anyone has any questions. D. Scott Williamson

Thanks for the callout CPUWIZ. That was an oversight on my part, though I did remove the email addresses FWIW. I hope he doesn't mind, everything he said was very nice and I hope he doesn't find any harm in my post. BTW, you can call me Scott if you like - or SOLIDCorp or whatever. D. Scott Williamson

Thanks Dan, You really put on a great show and I thought it would be a great place to let people see Star Castle for the first time. I had no idea how it would be received or if people would even care (as much as I did )

Albert of Atari Age contacted me Sunday and was generous enough to offer to help me promote and potentially sell Star Castle. I am repeating my heartfelt reply here for those of you who are interested. ----------------------------- Why thank you so much, and thank you for the tremendous resource Atari Age is. I will not be attending this years Classic Gaming Expo and while I greatly appreciate your offer to demo the product, I don't think I am ready to exhibition this work at that level quite yet. I'm not sure what you've seen so I'll give you a little back story... I'm a professional game developer who has been making video games for over 20 years, I used to work at Atari in Lombard Illinois in the late 80's, I've always been a fan of the video game industry and its history, and I was an Atari zealot as a kid. When reading the book Racing the Beam, a fantastic book by MIT press about the history of the Atari 2600, its games, an developers and how their interactions influenced the fledgling industry, I was struck by the chapter "A Yar Is Born", in which Howard Scott Warshaw, describes the circumstances that led to the development of Yars Revenge. He was originally asked to port the coin op Star Castle to the 2600 and he is quoted as saying "I soon realized that a decent version couldn't be done..." which has always stuck with me. He has made similar statements other interviews (DP interview http://www.digitpress.com/library/interviews/interview_howard_scott_warshaw.html , Atari times interview http://www.ataritimes.com/article.php?showarticle=522, Game career guide interview http://www.gamecareerguide.com/features/378/on_game_design_the_.php?page=2) so I decided to prove it could be done and done very well. Star Castle is an 8k cartridge using standard F8 bank switching (for the time being), the same size as Asteroids. To be fair, Yars' Revenge is a 4k cartridge but as far as I know size wasn't a limiting factor when Howard said it couldn't be done. I don't want to suggest that I think any less of Howard Scott Warshaw, he did great things during a great time in our industry and was fortunate enough to be part of it's history. (Check out his DVD Once Upon Atari it's a great insight) Even though there is no RAM and under 30 bytes of ROM free, there is more I would like to do to the game software and hardware before I call it done. Not shown at the AVC Video game Summit is the physical Atari 2600 cartridge I designed and built. It's configurable for 4K, 8K, 16K, 32K, or 64K ROM and features game controlled LEDs in the cartridge. I'm also planning on machining a custom engraved clear acrylic case for the cartridge with my home made CNC machine. I don't have any plans to put Atari 2600 Star Castle cartridges into production as I didn't set out to port a 30 year old coin op game to a 33 year old platform to fill a market need. This game is the result of many months of very hard work and for that I am not inclined to share the code or binary. I will likely put up a website telling a more detailed story than the one here and look for a little publicity. But who knows, if there is a wealthy collector out there who wants it bad enough maybe I'd let my one and only copy go for a small fortune Feel free to share this story, the pictures, and videos freely, I'll be posting some eventually. Thanks so much for your interest, and once again thanks for AtariAge, a wonderful place for everything Atari. D. Scott Williamson SOLID Corp. P.S. I still am making games as the head of the Advanced Technology Group at High Voltage Software. If you want to know more about me or my recent projects, check out my picasa web album here http://picasaweb.google.com/spot1984 (there are pictures of some of the making of Star Castle and the cartridge in there and lots of other fun stuff) ----- Original Message ----- Sent: Sunday, July 18, 2010 4:44:38 PM Subject: Star Castle Greetings! I just saw a video that was posted on AtariAge of what appears to be a most excellent port of Star Castle to the Atari 2600. Congratulations on such a great job as well as keeping it secret! It's always nice to see such polished efforts come out of nowhere to surprise everyone. AtariAge is going to have a huge presence at the upcoming Classic Gaming Expo at the end of next week. I'll have a large number of game systems set up and will be demoing several upcoming homebrew games for the 2600. I was wondering if you might be interested in having Star Castle available for people to try? I'm sure it'd be a great hit at the show! And while I have your ear, if you're interested in making Star Castle available in cartridge form at some point, please let me know as I'd love to help you with that. Thanks and take care, ..Al

I wrote S.T.U.N. Runner too :-) Thank all of you, and the people at the AVC Video Game Summit so much! Your kind words made this very difficult effort pay off. D. Scott Williamson