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Bock's Birthday 2004 by SMS Power! [web]

Bock's Birthday 2004

Starting Up

1. Set up your Master System or Master System II as described in its instruction
   manual. Plug in Control Pad 1.

2. Make sure the power switch is OFF. Then insert the Sega Cartridge into the
   Power Base.

3. Turn the Power Switch ON. In a few moments, the Title screen appears.

4. If the Title Screen doesn't appear, turn the power switch OFF. Make sure your
   system is set up correctly and the cartridge is properly inserted. Then turn
   the power switch ON again.

*Important:* Always make sure that the power switch is turned OFF when inserting
or removing your Cartridge.

*Note:* This game is for one player only.

(1) Sega Cartridge
(2) Control Pad 1

  / |     [====]  /|


Welcome to Bock's Birthday 2004, the amazing new title for your Sega (R) Master
System. Heard of the awesome power of Sega's Mega Cartridge(R)? This is like
that, only more awesomely refined and concentrated so it'll fit into 3/8ths of a
Mega, so get ready for some 3/8ths hot 3/8ths action!

What's going on?

The year is 2005 AD. World-renowned electronic archaeologist Mr. Bock Lee Temjin
Omar Zoop Sega Cool Cornut-Kitty is making final preparations for the impending
anniversary of the opening of SMS Camp, his website devoted to mobile phone text
messaging in tents, which later changed its focus to Sega 8-bit preservation.

However, something is missing. Gnawing deep into his soul is the knowledge that
there is a gaping chasm in the fabric of the universe. Bock's Birthday 2002 is
well-loved and viewed in silence worldwide every SMSDay (the day after Friday).
Bock's Birthday 2003, bringing multiply slaughtered cloned Italian plumbers to
those with the ability to play Minesweeper, traditionally follows with its
awesome FM music and reminder that all our games are belong to SMS Power.

But what of Bock's Birthday 2004? What happened? Nobody knows.

Venturing into some kind of handy plot device, Bock meets an old woman in a huge
tree stump. "HEY BRAVE WARRIOR, LISTEN CAREFULLY" she shouts at him. She tells
him about the real story of Bock's Birthday 2004, about the space-alien
kidnapping, about the government cover-up, about the amazing battle through
space and time to save the universe. The story is almost unimaginable - almost,
that is, because I'm not going to tell you about it so you're going to have to
imagine it yourself. Stop being so lazy.

So anyway, that explains exactly what happened and why it's four months late. If
Heliophobe can come up with such a plausible excuse for his SMS Power birthday
demo being late (or not released at all, we're still waiting), I'd like to see
it. And it is surely more deep, multi-layered and culturally significant than
most game stories (which isn't saying much).


You betcha. Dance Dance Revolution may or may not be the original dancing game -
I don't really know or care, but you can be sure that there's nothing else like
it on the SMS. If you don't know how to play, here it is.

You've got a playing field with arrows on it, and music playing in the
background. The arrows are timed with the music so they map out dancing steps -
if you press the arrows on your dance mat at exactly the same time as the
corresponding arrows line up with the ones at the top of the screen, not only
will you be dancing in time with the music, you'll also be highly entertaining
to those around you and you'll be getting a huge score.

There are five possible ratings for you. They are:


The closer your timing is to the exact moment when the arrows line up, the
better your rating will be. Get Perfect or Great to line up a combo - and as
your combo length builds, your score will skyrocket!


Here's how the scoring works:

Step rating  Score      Combo length
Perfect      M * M * 3  +1
Great        M * M      +1
Good         M          Set to 0
Boo          0          Set to 0
Miss         0          Set to 0

What's M? Well, it's a multiplier that depends on your combo length. It is
calculated like this:

Combo length  M
0-3           1
4-7           2
8-11          3
12-15         4

...and so on: your combo length is only limited by how well you can dance! Get a
combo length of 10 and each Perfect step is worth 27 points. Keep going up to 20
and it's 108 points... get to 100 and a single step gets 2028 points. These are 
the highest scores possible:

Beginner   167892
Light      964965
Standard   964965
Heavy     2185461

If you can get even 10% of these you're very good. I normally get 15000-20000 
without trying very hard.

You can keep track of your combo length and score near the bottom of the screen.

(1) Target arrows
(2) Rating
(3) Step arrows
(4) Combo length
(5) Score

|  /    |    ^    \   |
| (--  \|/  /|\  --)-----------(1)
|  \    V    |    /   |
|      PERFECT!----------------(2)
|                     |
|  /              \   |
| (--            --)-----------(3)
|  \              /   |
|         01-------------------(4)
|      00000003----------------(5)

But I don't have a dance mat!

Don't worry, nobody does. Maybe you could make one out of a PlayStation dance
mat. Maybe I could see if my proposed Playstation to SMS controller adaptor
(sold separately, includes free Intellivision Keyboard Component) would work if
I wrote a suitable driver function for it. Maybe one of those adaptors Lik-Sang
sells (http://www.lik-sang.com/info.php?products_id=3462) would work. Maybe if
they send me one, I'll put in an ad for them. All these possibilities :)

Alternatively, you can just play it using the ordinary controls. it's still fun
that way, and you are less of a spectacle.

Very minor compatibility warning

Before you go off and start on that: this program has a known compatibility
feature that results in partial lack of functionality on the Sega Master System
(and some emulators). Other systems are untested. In other words, it has a bug
so it doesn't actually work on a real system at the moment. Even if it did, you
wouldn't be able to hit opposite arrow directions on the joypad. A bugfixed 
version is in development, but don't hold your breath waiting for it.

Hints and Tips

- Try to listen to the music more than watching the arrows. You'll get better
  timing that way.

- When you have to press two arrows at the same time, the game will allow you to
  press one slightly before the other, and only register your input once both
  are pressed. So don't go nuts trying to hit them at the same instant.

- Remember, Good ratings are OK but they're not Good for your combo length.

Alternative titles

Shenmue 3:
  While I was working on it back in November 2004, Bock was trying to find out
  about it; he jokingly guessed that it might be Shenmue 3, so of course I had
  to make sure it was, even if in name only.

SMSPower 8:
  Since it became a dual-purpose demo for SMS Power's 8th birthday, I "borrowed"
  the title of Heliophobe's demo for the 7th birthday, continuing a fine
  tradition of incestuous content-copying within the SMS demo scene.

Copyright Violation Episode III:
  Heliophobe wrote Copyright Violation in 2002 for the SMS Power Rush Coding
  Competition #1 (not that anyone's recovered enough for #2 yet). Bock's
  Birthday 2003 was so full of other people's intellectual property that it was
  sub-titled Copyright Violation Episode II. So I may as well make this one
  Episode III: The Rise of the Arrows, for which I am eternally grateful to
  George Lucas for unknowingly choosing a subtitle for his crappy space-western
  movie in which a single word change makes it exactly describe this demo.

Bock Bock Revolution:
  Well, it is a Dance Dance Revolution clone after all. Full credit goes to
  Chris Covell for breaking open the vault of DPaint to convert my 24-bit
  original logo into a pixellated masterpiece (which, incidentally, looks even
  better on a real TV).

Things you may have missed

"xiao presents"

Nothing I ever do is without her support, criticism and interruptions :) She may
not like having her name drawn 150 pixels high throughout but I think it looks

"Press the button!"

Maybe someone is still sitting there looking at the "xiao presents" screen,
waiting for something to happen. How silly that would be!

"This is not a real scroller"

Honesty is the best policy.

The Making of Bock's Birthday 2004

Here's a little behind-the-scenes look at the magic of game making.

So it all started in March 2004 when the 2004 Minigame Competition kicked off. I
was thinking about possible options and I thought it might be nice to try for a
DDR game for the 4KB category; I worked on a super-simple music engine, and
spent far too long converting a crappy, but suitably cheesy, song (I'm not
telling which) to my format by studying some sheet music I found online. Anyway,
that was at the same time as doing my Masters' degree and it didn't pan out; I
just didn't have the time for it.

When November rolled around, of course I was making plans for Bock's Birthday
2004. DDR was dusted off, and I decided to make a proper go of it this time.
Martin Konrad's MOD2PSG2 was in its beta phase and he was happy to let me use
it; I also got access to the playback engine so I could use it in my demo.

I've never actually played DDR; my wife had a knock-off PC-based version and a
dance mat pre-modded with a parallel port adaptor, which I had a go on and it
was fun, if embarrassing. However, she was rubbish, and threw the thing away (it
only cost something like ?.50 anyway) when we moved house. However, I
remembered that the Butterfly song was kind of cool in a J-Pop way. I'd also
heard a version of it come up on Gaming FM a few times over the summer. So I
went off a-searching for a MOD version of it on the Interweb.

Well, that wasn't successful. I found some MP3 versions, but even if I did
manage to get a sample player and good enough compression for it to fit into a
reasonable rom size, the difficulties of sample playback on the SMS would make
it almost impossible to have a game happening at the same time.

I did, however, manage to find a MIDI version of it. What's more, it was a
karaoke MIDI (can you imagine anything worse?) with timed lyrics which might be
useful for timing steps instead. So I went off and found every MIDI2MOD program
I could find. There hasn't been much innovation in the MIDI2MOD area since about
1993, and all the programs suck. I even managed to get the recommended one set
up with the sample banks the authors kindly refused to include, but it never
produced anything usable.

Martin Konrad saved me by suggesting ModPlug Tracker. This is a MOD tracker,
that runs in Windows, that can import MIDIs, even supplying its own samples. It
can perfectly create an XM format module from my MIDI file, and it plays back in
Winamp very nicely. But I can't save that to the required MOD format; when I
want to convert, it simply asks me which 29 of the 32 channels I'd like to throw
away. And some of the music sections that you might expect to be on the same
track are split over two or three.

But there is is solution. My dabbling in polyphonic mobile phone ringtones
(getting chiptunes onto my phone) meant I was familiar with a little program
called "PSMPlayer". It's a Japanese utility for converting between various
levels of the MIDI standard, including the SMAF format for mobile phones, and it
is able to do some simple editing and squashing-into-less-channels along the way
(for devices that can only handle 8-track MIDIs, for example). One of its output
settings is something to do with 3-track PSG so I went for that; it stripped
everything down to a single instrument and three tracks, losing percussion along
the way. But it still sounded like Butterfly. This was good. I converted it to
XM, and it still sounded good. Then I converted it to MOD, and ModPlug Tracker
screwed it up. The volumes almost seemed to be inverted, so full-volume notes
were silent and the lead parts were drowned out by the harmony.

So I spent hours and hours, carefully editing the music to try to restore some
of it. The repeated parts were OK, I could copy and paste them most of the time
and they worked out OK. Martin was kind enough to add a little extra
functionality to MOD2PSG2 to let it solve some of the other problems, too.
Eventually I got it so it sounded right; any problems caused by its messiness
could be dealt with later. (Much later, I figured out how to get the pattern
lengths sorted out and the resultant PSGMOD file almost looks good, except for
the way it totally fails to re-use patterns.)

The next step was to make a game engine. I found a screenshot of DDR, and made a
version of its arrow in Paint Shop Pro, and did a whole lot of editing to try to
make the top-of-screen sprite arrow mask (the arrows at the top of the screen
that don't move, which are implemented as stationary sprites against a moving
background). Problem was, even by cutting off some small parts of the mask, I
was only just able to get it done using all 64 of the system's sprites. I'd have
to reassign the sprite table in a horizontal interrupt routine to show anything
else, since the background layer would be constantly scrolling and thus a
useless place to display status information, or could I use the scroll lock to
deal with that? Ah well, it worked just enough and I could deal with any
problems later. I even had the arrows changing colour as you pressed buttons, by
updating the palette of course.

I found some step diagrams on a DDR website, and transcribed them into my code.
It should be a simple matter of comparing the current inputs to the step data,

Next up was to get the arrows drawing and scrolling. Drawing is easy, you just
draw on the off-screen area so it looks like a smoothly scrolling larger
tilemap. But there are only four offscreen lines and my arrows are five line
high. I decided I'd come back to it.

Scrolling seems easy until you set the requirement that it has to scroll exactly
40 lines every 24 frames for this song (so arrows don't over-print each other,
and of course are aligned to the 8x8 pixel grid of the tilemap), and if I want
to include more songs, I'd better make it not hard-coded with that. So I went
off and wrote an implementation of Brenham's Line Drawing Algorithm, which is
ideal for plotting values from (0,0) to (24,40). It's actually really cool how
simple it is in Z80 assembler.

And... it was now about 10pm on 25th November. Bock's Birthday is here and my
demo is nowhere near finished. Still, I had to do something, so I made a VGM
version of the music and sent him that. I promised I'd do the rest later, and
made a mental note that I could easily get it done in time for Christmas. Or, if
not then, the SMS Power anniversary on March 27th would be plenty of time to get
it totally finished.

At least Charles would release the demo he'd been working on. I'd reminded a few
other people too, and they could do something too since I'd failed. They
wouldn't fail too, would they?


Well, I didn't do anything much in December. Or in January; I did try to
optimise that sprite mask to free up sprites, by cleverly overlapping and
aligning sprites, but that was really hard and I never made much progress. In
February I didn't do anything either. By the time March came around, I realised
I'd better pull my finger out (metaphorically speaking) and started to spend
time on it when I could; my wife's exam revision meant I had to clear out
anyway, so it was a good excuse. I spent a lot of evenings on it, but I was
unmotivated to get back into the source and Z80 programming is hard when you
don't have solid blocks of 4 or 5 hours to devote to it. So I found myself doing
all kinds of everything but working on it; Bock unwittingly helped by supplying
unprocessed video files, museum developments, etc, but it was all fun so I'm not
complaining. I did make quite a lot of progress. I made a flickering-sprites
function because that's better than a half-the-sprites-are-never-shown function,
and most emulators will allow it to work without flickering anyway. I eventually
threw away my entire arrows-drawing-and-scrolling code and did it again, this
time using precomputed tables for scrolling (24 bytes isn't a huge price to pay)
and making the arrows draw in two overlapping three-line phases, so the
scrolling was smooth and beautiful. It still didn't actually work though,
because I still didn't have anything parsing the step data to know what you were
supposed to be pressing; and getting everything properly synchronised was
turning out to be the most difficult part of it.

Just as I was starting to be afraid of missing my latest deadline, it turned out
that SMS Power's birthday was on Easter Sunday, which meant that the Friday
before was a Bank Holiday - that's what we call a public holiday/free day off
work here in the UK - so I had, in theory, three full days before the deadline.
In 72 hours, imagine what I could achieve! Well, I had to sleep, eat, be nice to
my darling wife, lose an hour as I sprung forward into BST (that's what we call
Daylight Savings Time, rest-of-world-who-don't-speak-proper-English), etc, but
it was a block of time to fit it into so I decided to go for it.

I re-implemented the top arrows using double-sized sprites, which neatly fit
into 24 sprites instead of 64-with-bits-missing, leaving space for other useful
stuff like ratings (coded, displayed, animated, but still no code to trigger
them) and a score (later on). I edited the background arrows to have matching
blocky white bits and for the first time the scroll-under-matching-sections
worked (well, almost). I got some code to track the steps that were supposed to
be happening, and it was indeed showing (in Meka's RAM Viewer, at least) the
"current" step that had been drawn a few seconds ago but was due to be pressed
in time with the music.

At this point I realised that my step data lasted about 90 seconds and my music
lasted about 150 seconds. After some frantic editing of both, I had it finally
figured out (IIIAABBCAABBDD, and IIIAABBCAABBDDBBBBDDO, or something like that),
the PSGMOD actually looked right, and it seemed to be lining up with the data.
The understanding of 2's Complement notation I'd got from my degree meant I
could implement abs() in a few opcodes and be calculating the accuracy of steps.
Some rapid kludges later to deal with timing accuracy, and with a non-kludge
modification to Meka for debugging them, I had ratings working.

Now I was getting greedy. Ratings are nice, but what I want is scoring! A quick
Google found a website with algorithms for DDR scoring, and I implemented them
with modifications (not least, I stopped it multiplying your score by zero). The
fact that the score can exceed 64K and the combo length can exceed 256 made for
some fun, as I would be multiplying 16-bit numbers and adding the 32-bit result
to a 32-bit score, all on an 8-bit CPU, and then all I had to do was convert
that to decimal for display! Well, that was a fun, but I cracked it with an
interesting algorithm based on how Phantasy Star displays your money total,
extended to 32 bits and involving adding negative numbers to perform

At this point I ran out of sprites. My huge "PERFECT!" display took a lot of
them, and in the end I was left with 10 sprites to display both the score and
the combo total, so I did an 8-2 split, and made the scores 100 times less than
in the original DDR (3 instead of 300, 1 instead of 100) so a 100%-Perfect Heavy
game wouldn't exceed my 8-digit maximum.

A quick detour to ask Martin how to make his music engine tell me when it had
finished playing the song, and I had a playable game.

All that's left is:

1. An introduction to the game
2. Some way to choose the difficulty
3. Something at the end to tell you how well you did
4. Maybe I should implement the Pause button handler too
5. Making sure it runs on a real system is always a bonus
6. And if I really have nothing better to do, the Reset button could be made to
   do what it's supposed to do
7. More songs? Erm, no. Maybe in the next version, the engine is not hard-coded
   to anything (as far as I know). All you need is to provide music and steps.
   And do a lot of work to make them synchronise properly.

I had already made some artwork for the intros; artwork is easy when you wrote
BMP2Tile and implemented decompressors for Phantasy Star-type compression! Well,
the hard part is making it look good. I have techniques for reducing things
nicely to 16 of the SMS's 64 colours, but they tend to end up looking spotty as
they make a lot of use of error diffusion dithering; I haven't found an easy way
to do ordered dithering. Chris Covell didn't much like what I showed him and
offered to help; he converted my super-smooth 24-bit antialiased Bock Bock
Revolution screen using DPaint, and it looks kind of cool. I quickly ran through
what else I needed to display:

- xiao presents
- Shenmue 3 (I'd already prepared this, ripping graphics from the shenmue.com
  splash screen Flash and doing my usual conversion)
- Copyright Violation Episode III (not too bad, The Rise of the Empire seemed
  too good to be true)
- Bock's Birthday 2004 (cheesy montage of previous years' screens)
- SMSPower 7 -> 8 (ripping content makes life a bit easier)
- difficulty select

As I worked through the list, my head grew heavy, my sight grew dim, I had to
stop for the night... but I couldn't. It really sucks to feel quite so much like
you're about to flake out when you're coding, but be unwilling to stop; perhaps
I ought to start drinking coffee or something.

Obviously, as my brain blue-screened and glitched, the code flowing from my
fingers was decidedly buggy, and in my fragile state of mind I felt real pain as
the difficulty select turned out to be completely broken. It took me forever to
realise my mistake (inc c; and 3; will not force 0<c<3) but at least I got it
sorted. At this point, I had only done the first two things on my list, but I
could not go on, and it was at least presentable. I did a final check that it
actually worked, set the version to 1.00, recompiled, renamed, zipped, uploaded,
posted "I am dead" and went to bed, swearing not to touch any Z80 code, or the
game, for at least a few months.

The next morning, I was glad to see some positive comments, even if everyone
else's demos were not ready. As I did some online research for my wife, kind
comments and lame high-scores came through in the #smspower IRC channel, and I
was even happy to play my game, enjoying it for the first time, getting to play
it properly for the first time since the previous afternoon's breakthrough into
actual gameplay. It almost seemed worth it :)

Final words:

1. Happy birthday Omar!
2. Dedicated to poor little "why'd you put my name on it so big?" xiao.

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