Bruce Perens (who did Busybox and Debian as well as defining "Open Source") has created an Open Hardware Journal (http://openhardware.org/journal/). Check out the first issue, I've got two articles in it! Ok ok, probably he needed more submissions which is why my stuff made the cut :-). But hey I'll take it!
The first article "An Open Hardware Platform for USB Firmware Updates and
General USB Development" is about the USB interface on the Lightuino. I chose that topic because this interface is a cheap and tiny way to put USB in many of your projects. The interface will talk SPI to your uP or some SPI chip, or I2C (although I did not use that in the Lightuino). And it will do serial (USB CDC ACM if you need the formal acronym) or emulate an input device (USB HID). Read the article for more info, and check out my code on github here: https://github.com/gandrewstone/toastedCypressUsb
My second article "A Return To Open Devices" is about my ideas around the philosophy and driving forces behind the open hardware movement. I'm sure the people who come to open hardware do it for many different reasons; this is simply my perspective.
Wednesday, November 2, 2011
Friday, September 9, 2011
DIY Surface Mount Workshop
A few days ago I held a workshop on do-it-yourself (aka cheap) surface mount electronics techniques at a Boston artspace/hackerspace called sprout & co (http://thesprouts.org/). This was organized through the Boston Arduino meetup group. Participants got to mount a tiny QFN-24 chip (a PCA9555 io-expander) onto a QFN breakout board and then we tested them by connecting them up to an Arduino. There was one bad chip; but once that was replaced everybody's boards worked!
Here are my notes from the workshop. If you did not attend, these notes are a good tutorial on how to get started cheaply! Also, if you'd like some of the QFN breakout boards, please contact me and I will sell you a few.
Surface Mount Tools (homemade/modified):
Toaster Oven:
Got mine from the dump. Keep it simple; you don't
need to mod it with fancy temperature feedback like some web posts suggest.
Hot air “pencil”:
$30 used heat
gun (ebay) with aluminum foil to narrow and speed the air jet. Secure the aluminum foil by wrapping steel wire around the nozzle. Shape the hole in the end by forming it around a pen with your fingers. This tool is indispensable for removing and replacing chips (rework), and works great!
Cheap plastic Mechanical Pencil:
Pencil lead solder paste onto pins;
eraser dabs off too much.
PCB Vice:
You can use any clamp like this. You can probably get one for less then $10 if you look around. Just drill a hole in your desk slightly smaller then the clamp bar and stick it in upside down.
Here it is holding the boards we made, with my breadboard-to-IDE-or-RJ-45 connector in the background.
Here it is holding the boards we made, with my breadboard-to-IDE-or-RJ-45 connector in the background.
But once you do this fairly often you'll want to upgrade to a Panavise.
Soldering Iron:
You CAN use a standard cheapo wide tip soldering iron for SMT rework -- even though you can't touch just a single pin, it is sufficient to heat a single pin.
However, knockoffs of the "Hakko 936" soldering iron are pretty cheap at $50; check Amazon or ebay. And they are all you'll ever need...
Tweezers:
You use these to hand "pick-and-place" chips. Buy them from a drugstore. But don't buy the cheapest pair you can find. Buy a set that looks totally overkill for plucking nose hairs :-) -- like they were milled out of a block of metal.
Magnifying glass/bright light:
You may need these to peek at the board as it is cooking, and for rework. I'm sure you can do it on the cheap. I have a "helping hands" for the glass:
Supplies:
Solder wire:
Get thin rosin core solder
Solder Paste:
Solder paste are tiny balls of solder in a flux mix that is viscous like toothpaste. It can be very expensive and require refrigeration. Don't buy that. Buy this Lodestar paste from DealExtreme. It does not require refrigeration, however, as a hobbyist you should refrigerate it so it will last you forever.
Flux:
Flux is a substance that cleans your PCB and lets the solder flow better. It is also available at DealExtreme. They often mis-name it "paste" but you'll know it is flux only because it won't be grey. Get "no-clean" or "neutral PH" (its almost all like that now).
Solder Remover Braid:
This braid is necessary to remove excess solder when doing fine SMT work. Solder suckers don't work!
Step 1:
Use an oven to solder a QFN-24 part onto a breakout board.
Mix a TINY bit of solder paste and flux to about a 60/40 mix. You don't need much. Put any extra back into the container since it contains lead so its good to generate as little hazardous waste as possible...
Too much paste and the solder will not wick onto the pads (it will stay on the non-metal parts of the PCB or create bridges between pads -- "pads" are the metal parts of the PCB that you are trying to solder the chip's wires "pins" to)
Too much flux and the pins won't be soldered.
Apply with your mechanical pencil (click out the lead). For
tiny QFN leads, just draw your pencil straight across all the leads. That is, cover the entire surface including between the
leads. This is important so let me emphasize: Don't try to keep the paste out of the 6mil space between the leads! That is impossible & when heated the flux will cause the paste to flow to the pads anyway.
But if there is a center square pad, use the pencil to
draw around that pad to clean any paste that would bridge the center pad to a lead (it is
very hard to fix that issue).
You need to apply a thin layer. You should be able to see the shape of the pads under the paste, but they should be obscured. But if the paste goes on clear, with just a few "dirty" spots you have too much flux in your mix.
Next, put the chip on with tweezers. Positioning is not critical; you can be off by a half-pin in any direction. When hot, the chip will actually float on the flux layer and surface tension will actually cause the chip to be sucked onto the pads! But if you are off by more then a half-pin, the chip might be sucked onto the wrong set of pads.
Now bake your board. You need to bake the board in a particular fashion, but its not rocket science.
Here is an example provided by Kester paste. It works fine for any paste:
Basically, you want to raise the board to 150C in a minute or two. Then wait for another minute or two so the entire board gets to that heat. This bakes out any water and lets everything expand (if you chip pops like a firecracker its ruined. You have too much water in those chips and need to bake the rest at low heat for hours to evaporate it out; its only ever happened once to me).
Next, you
bring the heat up to a max of 220-240C rapidly to melt all the solder
paste. Excessive exposure to this heat can harm the chips or melt
plastic parts so you want to keep this brief. At this point, use your
magnifying glass and a bright light to watch the paste on the board. It
will go from grey to bright shiny silver when melted (bubbling is just the flux moving around). Wait 10 more seconds after you see no more grey to make sure solder you can't see also melts. Then turn the oven off.
Now you have a choice. You can either wait with the oven door closed so the oven cools down slowly (as shown on the heat profile). Cooling slowly will mean there are fewer mechanical stresses on the board.
Or if you see any problems, you can open the oven door, pull out the tray and
reposition “tombstone” (sticking up) resistors and caps. Also if a chip is out of alignment (off by one pin for example), you can “tap”
the chip to make it position itself! When doing multiple bigger boards, you'll often find a few issues.
I'd imagine that while this cools the board faster, it is probably still less stressful then heating a portion of the board with your "air pencil". That is the only other way to reposition chips.
Debugging
Now that your board is baked and cooled, you need to visually inspect it. Look for bridges (2 pins connected) and unsoldered pins. A bridge will look more shiny then the other pins since it is a bigger solder blob. Unsoldered pins will look darker.
Unsoldered:
Apply a tiny bit of paste to solder pins. Heat the pin (and perhaps nearby pins) with an iron to melt the solder. Often you'll have added too much paste, so now check for bridges.
Bridges:
Use flux to cause the bridge to flow onto nearby pads/pins. This only works if the bridge is not caused by too much solder.
Use copper solder remover wire (braid) to
remove solder. I guess this is often misused. This is how you do it:
Touch braid to you can of flux to get a tiny bit on it)
Put the braid onto the bridge part so it complete covers it (and probably a bunch more pins).
Heat the braid by using the iron to press
it into the bridge where you want to remove the solder.
The braid won't work if its not hot!!! So heat it and cause its heat to melt the solder.
If the braid is at all silver, clip it and throw that part away; it has already sucked up solder.
Speed solder headers
Next we need to solder long headers onto the board. There is a fast technique to do a row of pins that I will show. Eventually you should be able to do about a pin per second or two.
First, clip/break the pin header so it contains the right number of pins.
Next put the headers in the solderless breadboard; and put the PCB on top. This gets them aligned correctly. Use the PCB to seat them into the breadboard. This will keep the board steady as you solder it.
Now its often good to solder the ends to make sure the PCB stays firmly seated against the pin header, but as you get better you can skip this step.
Now use the speed solder technique to do the rest. Here's a video:
Here I am doing pins on both sides of the iron, so heating 6 pins simultaneously. But you should stick with one side for now.
Use an overhand grip on the iron so it can be placed flush along the pins.
Heat 3 pins simultaneously.
Preheat pin -- using iron tip
Middle pin -- focus on soldering it
3rd pin -- continue to heat to make a good solder joint
I noticed most people using not nearly enough solder. Feed the solder so fast that there is a large constant blob of solder on the iron. This solder blob is essential to transfer heat to the pins. As you push your iron across the pins it will actually clean up this excess solder (if not, your iron is too cold, or you aren't using rosin core solder). Actually you may end up with a few bridges, but those are easy (and quick) to fix once the job is done. Just hold a "dry" iron against the bridge and it should grab the excess. And look for any holes you missed; as a beginner you'll have one or two!
Testing: Hook up the breakout board
Read the spec to hook up the board. Really. This is a great exercise and very important to get correct. Because if you are trying a new PCB, new software, and a new chip you want to make sure you get something right! :-) But ok, Ryan Feeney was kind enough to help you out with this image:
In this image, GND are the blue rows on both sides and 5v are the red ones (connect them to GND and 5v on your Arduino).
One other trick; if you don't have a handy 3.3v power supply, you can use a red LED to reduce 5v to 3.3v. This will work up to about 20mA; beyond that your LED will burn out so use multiples!
Testing: The sample sketch
The sketch I used is located at: http://i2cdevices.svn.sourceforge.net/viewvc/i2cdevices/latest/ioexpander/pca9555/pca9555.pde?revision=1
Someday I might actually put other i2c devices in there too! :-)
It should blink the LED.
Hot air rework exercise
Some of you got to do or see this, because we had a dead chip.
In this exercise we'll use the hot air "pencil" to remove a chip and then replace it with a new one.
First, use aluminum foil and metal boxes to cover and protect other chips (and plastic headers). Well, there is nothing really to protect in the breakout board except for the plastic vise jaws -- but for a "real" board you'll need this.
Heat the chip with slow motions of the heat gun. When the solder on the edges goes shiny, pluck/knock it off with tweezers.
If there is a lot of solder on the pads then clean it with flux and solder remover. Put a little more paste on the pads.
Touch the new chip in the flux can to just get a TINY bit of flux on its pads
Place the new chip right near, but not on, the pads. This will cause the chip to heat up with the pads. The chip's leads have to be hot enough to melt the solder or the solder won't stick to it! Its the SMT equivalent of a "cold" solder joint.
Reheat with the hot air "pencil". When the solder melts (it goes shiny) it should wick to the pads so there is no bridges. If there are bridges you have too much solder or not enough flux. When it wicks correctly, tap the chip with tweezers to move it into place. You should see it "snap" or "pop" into place as the surface tension of each pad/lead pulls the chip. Heat for maybe 10 more seconds to make sure all the chip's leads were hot enough and then you are done!
Thanks! Please go forth and build open source hardware!!
Thursday, June 16, 2011
RSD GameMaker
Recreational Software Designs GameMaker product was a program that ran on the IBM PC machines around 1991-1995, sold in the USA, UK and Korea. I recently became aware of some efforts by the community at diygamer, specifically Eric-Jon to gather information about the program. He has written 20 or so posts about games that users created, see http://www.diygamer.com/author/eric/, and also created a wiki that attempts to capture the history about the community at
http://www.aderack.com/game-maker/index.php?title=Main_Page .
I was the creator and major author of the software, and was helped by my father who handled most business issues, my brother who also did some coding, and my mother who did GUI testing and made some games. We also had a friend of my father who graciously spent a few weekends sitting with me giving guidance (Thanks Pete!)
It was basically a toolkit that let you create your own platform-style (of course we did not call it that back then!) games.
As the creator of a very small piece of history (but one that seems to have a major effect on those who used it well, spawning passions and careers around programming, graphics, and games -- Google "RSD GameMaker"), I shall indulge in a very small soapbox so you can hear my thoughts and ramblings on the subject :-).
I think perhaps that in retrospect GameMaker's history may be interesting for a few reasons.
The first Game Creation Engine?
First of all, it obviously was the "diygamer" tool of that time, so it anticipated the thriving community we have today with countless game engines, web sites and indie game companies. I hear that it was preceded by a game maker on the Commodore machine, but I had/still have no knowledge of that software. As far as I knew, we were the first game engine in existence and we allowed games to be built with absolutely no programming (and ran up against the limitations that imposed as well)! But in the interest of complete disclosure, I believe that at that time professional game companies were also buying game engines for major $ to aid in game development. Very little information is available about these professional engines since at that time -- a time of game-feature "brinkmanship" -- the information was closely held.
Anticipating Creative Commons and the Remix Culture
Second, we shipped the software with a bunch of sample games and encouraged users to borrow and reuse our content. We also worked with a BBS owner (bulletin board system -- it was a precursor to the internet) to have an "official" community sharing repository. Also, I deliberately (in fact I remember an argument about it) made no effort to protect a game's content -- anyone could load up anyone else's game in the editors. My feeling was that if you were sophisticated enough to build a game that really needed protection, you could wrap it in your own encrypted .zip file or something. This philosophy emerged from knowledge of shareware licenses, but AFAIK is probably the first adaptation of the philosophy for content, not code. Today, the "creative commons" has standard licenses covering all manner of content.
And a lot of people did reuse our stuff (and other game authors)! In that way it anticipated today's emerging remix culture. If I remember correctly (and I may not), I was the one who decided to share all of the content shipped on our CD and disks while my father should receive credit for encouraging the community, through user letters (yes back then we got HANDWRITTEN letters, I still have a huge stack of them), the community BBS, and the GameMaker Exchange (which was sort of a "mail us your game & we'll mail it to other people" thing). But of course as a family company these decisions were often made around the dinner table. We also decided to buy (and beg) some games from our best users and ship them with the 3.0 version of our product in a "remixable" license.
Teen Hackers!
Third it was really a major piece of software built by teenagers, mostly for teenagers. This probably makes it pretty unique, if not completely unique. It consisted of 16000 lines of "c" code, 2000 lines of hard core x86 assembler, and 1000 lines of C++ (versions 1 & 2 predated the emergence of C++). So about 20000 lines of code total. 'Sloccount' (a Linux software line counting program) puts this at 4.5 man-years of effort with a $600000 price tag (assuming developer salary $50k 2010 dollars). But we did it during high school and college.
Sure we had adult supervision (and funding and support -- I can't overemphasise how supportive my parents were!!!), but at the same time we wrote all the code and essentially came up with the content entirely ourselves (with our user's input of course). If GameMaker somehow fast-forwarded itself to 2010, it likely would have been entirely teenager-driven. However, in the internetless world of the '90's there were countless costs -- lots of expensive advertising, CDs to print (sorry no CD burners), boxes and user manuals made, mailers, and on and on. I remain amazed that my parents put that kind of cash at risk for this effort.
Breathing Life into the DIY Culture
GameMaker was part of the DIY and programming culture of the 90's. I would love to see what my users are doing now. You have to be a certain kind of person to look through a magazine full of ads for instant-gratification twitch games and pick the software that makes you WORK hard. I would guess that we managed to pre-select the most creative individuals; a feat that our educational system has a very hard time doing.
Also I think that it is probably possible to trace a certain (changing) subset of the population throughout US history. Call them tinkerers, creative minds -- just people who like to do their own thing. And I am proud to have been an enabler of this culture in the 90's.
I see it in automobiles and phone systems in the 50s and 60s to the transistor (hi-fi) radio kits (hobbiest electronics), to the early garage build-your-own computers of the mid-70s and early 80s, the software of the mid-80s to mid-90s, all the web software, blogging etc from the mid-90s to sometime in the 2000s, and finally the emerging custom open-source hardware culture of the 2010s (www.arduino.cc, www.adafruit.com, and my own www.toastedcircuits.com). I fully expect that 2020 will see ubiquituous desktop manufacturing with communities not focused on building desktop manufacturing machines (as exists today) but focused on what can be made. By 2050 we'll probably be designing our own plants and animals, probably with an incompatible biology for obvious reasons.
Software Archaeology
Finally, it is an interesting piece of computer archaeology as its "heyday" fortuitously happened at the end of the prehistoric times (as people years from now will see these dark ages before the emergence of the global hive mind and recording device we call the internet).
What can be recovered by reaching back across the curtain? This is quite an interesting question and many scholarly articles have considered it (I have read several articles in Scientific American on this subject over the past decade for instance). These articles tend to warn against electronic media for pretty obvious reasons. Quick summary: Your grandkids find a 3.5" floppy (or CDROM) in the attic. Will they even recognise it as electronic media? How will they read it without a disk drive? Even if they manage to get the bits, will modern computers be able to run the programs, read the documents, play the movies?
Well, for GameMaker, it turns out that quite a lot is possible! You can even play the created games in a Java simulator called "DOSbox" in the wiki posted in the first paragraph of this article. For me, it was quite a trip to play games (and see the GameMaker software on Youtube) that I created 15 years ago. You results may vary. Remember, these were games built 15 years ago mostly by teenagers! Please don't go in there expecting amazing stuff -- go in there amazed that these kids could put together this stuff at all! But if you hunt for gems of creativity I promise you'll find some.
Software Obscurity
And what did I do after GameMaker? Have I been washing windows for 20 years? No I've been writing vast quantities of code in various startup companies which have been sold for a sum total of approximately a half billion dollars. But all that code is gone. A company gets sold, the product is either canned or is successful for a few years. Then it is done. Can I get my code for the next project? No.
I have even attempted to purchase some from prior employers. No dice, price does not matter, the company is not in the business of selling its software, so its just not possible to find a manager willing to even consider the proposition. Because what if hidden in that chunk of software is something really important?
So if there ever was an argument for open source software and open source content then this is it! As engineers in corporate America (and elsewhere) we build machines for obscurity. We write novels to be read by no-one. We architect palaces of structured information that shall soon disappear.
Let's try to do that as little as possible.
G. Andrew Stone
2011
---
The next episodes of this little blog may delve in more detail about RSD and GameMaker's history, etc. Perhaps only interesting to those who actually used it.
http://www.aderack.com/game-
I was the creator and major author of the software, and was helped by my father who handled most business issues, my brother who also did some coding, and my mother who did GUI testing and made some games. We also had a friend of my father who graciously spent a few weekends sitting with me giving guidance (Thanks Pete!)
It was basically a toolkit that let you create your own platform-style (of course we did not call it that back then!) games.
As the creator of a very small piece of history (but one that seems to have a major effect on those who used it well, spawning passions and careers around programming, graphics, and games -- Google "RSD GameMaker"), I shall indulge in a very small soapbox so you can hear my thoughts and ramblings on the subject :-).
I think perhaps that in retrospect GameMaker's history may be interesting for a few reasons.
The first Game Creation Engine?
First of all, it obviously was the "diygamer" tool of that time, so it anticipated the thriving community we have today with countless game engines, web sites and indie game companies. I hear that it was preceded by a game maker on the Commodore machine, but I had/still have no knowledge of that software. As far as I knew, we were the first game engine in existence and we allowed games to be built with absolutely no programming (and ran up against the limitations that imposed as well)! But in the interest of complete disclosure, I believe that at that time professional game companies were also buying game engines for major $ to aid in game development. Very little information is available about these professional engines since at that time -- a time of game-feature "brinkmanship" -- the information was closely held.
Anticipating Creative Commons and the Remix Culture
Second, we shipped the software with a bunch of sample games and encouraged users to borrow and reuse our content. We also worked with a BBS owner (bulletin board system -- it was a precursor to the internet) to have an "official" community sharing repository. Also, I deliberately (in fact I remember an argument about it) made no effort to protect a game's content -- anyone could load up anyone else's game in the editors. My feeling was that if you were sophisticated enough to build a game that really needed protection, you could wrap it in your own encrypted .zip file or something. This philosophy emerged from knowledge of shareware licenses, but AFAIK is probably the first adaptation of the philosophy for content, not code. Today, the "creative commons" has standard licenses covering all manner of content.
And a lot of people did reuse our stuff (and other game authors)! In that way it anticipated today's emerging remix culture. If I remember correctly (and I may not), I was the one who decided to share all of the content shipped on our CD and disks while my father should receive credit for encouraging the community, through user letters (yes back then we got HANDWRITTEN letters, I still have a huge stack of them), the community BBS, and the GameMaker Exchange (which was sort of a "mail us your game & we'll mail it to other people" thing). But of course as a family company these decisions were often made around the dinner table. We also decided to buy (and beg) some games from our best users and ship them with the 3.0 version of our product in a "remixable" license.
Teen Hackers!
Third it was really a major piece of software built by teenagers, mostly for teenagers. This probably makes it pretty unique, if not completely unique. It consisted of 16000 lines of "c" code, 2000 lines of hard core x86 assembler, and 1000 lines of C++ (versions 1 & 2 predated the emergence of C++). So about 20000 lines of code total. 'Sloccount' (a Linux software line counting program) puts this at 4.5 man-years of effort with a $600000 price tag (assuming developer salary $50k 2010 dollars). But we did it during high school and college.
Sure we had adult supervision (and funding and support -- I can't overemphasise how supportive my parents were!!!), but at the same time we wrote all the code and essentially came up with the content entirely ourselves (with our user's input of course). If GameMaker somehow fast-forwarded itself to 2010, it likely would have been entirely teenager-driven. However, in the internetless world of the '90's there were countless costs -- lots of expensive advertising, CDs to print (sorry no CD burners), boxes and user manuals made, mailers, and on and on. I remain amazed that my parents put that kind of cash at risk for this effort.
Breathing Life into the DIY Culture
GameMaker was part of the DIY and programming culture of the 90's. I would love to see what my users are doing now. You have to be a certain kind of person to look through a magazine full of ads for instant-gratification twitch games and pick the software that makes you WORK hard. I would guess that we managed to pre-select the most creative individuals; a feat that our educational system has a very hard time doing.
Also I think that it is probably possible to trace a certain (changing) subset of the population throughout US history. Call them tinkerers, creative minds -- just people who like to do their own thing. And I am proud to have been an enabler of this culture in the 90's.
I see it in automobiles and phone systems in the 50s and 60s to the transistor (hi-fi) radio kits (hobbiest electronics), to the early garage build-your-own computers of the mid-70s and early 80s, the software of the mid-80s to mid-90s, all the web software, blogging etc from the mid-90s to sometime in the 2000s, and finally the emerging custom open-source hardware culture of the 2010s (www.arduino.cc, www.adafruit.com, and my own www.toastedcircuits.com). I fully expect that 2020 will see ubiquituous desktop manufacturing with communities not focused on building desktop manufacturing machines (as exists today) but focused on what can be made. By 2050 we'll probably be designing our own plants and animals, probably with an incompatible biology for obvious reasons.
Software Archaeology
Finally, it is an interesting piece of computer archaeology as its "heyday" fortuitously happened at the end of the prehistoric times (as people years from now will see these dark ages before the emergence of the global hive mind and recording device we call the internet).
What can be recovered by reaching back across the curtain? This is quite an interesting question and many scholarly articles have considered it (I have read several articles in Scientific American on this subject over the past decade for instance). These articles tend to warn against electronic media for pretty obvious reasons. Quick summary: Your grandkids find a 3.5" floppy (or CDROM) in the attic. Will they even recognise it as electronic media? How will they read it without a disk drive? Even if they manage to get the bits, will modern computers be able to run the programs, read the documents, play the movies?
Well, for GameMaker, it turns out that quite a lot is possible! You can even play the created games in a Java simulator called "DOSbox" in the wiki posted in the first paragraph of this article. For me, it was quite a trip to play games (and see the GameMaker software on Youtube) that I created 15 years ago. You results may vary. Remember, these were games built 15 years ago mostly by teenagers! Please don't go in there expecting amazing stuff -- go in there amazed that these kids could put together this stuff at all! But if you hunt for gems of creativity I promise you'll find some.
Software Obscurity
And what did I do after GameMaker? Have I been washing windows for 20 years? No I've been writing vast quantities of code in various startup companies which have been sold for a sum total of approximately a half billion dollars. But all that code is gone. A company gets sold, the product is either canned or is successful for a few years. Then it is done. Can I get my code for the next project? No.
I have even attempted to purchase some from prior employers. No dice, price does not matter, the company is not in the business of selling its software, so its just not possible to find a manager willing to even consider the proposition. Because what if hidden in that chunk of software is something really important?
So if there ever was an argument for open source software and open source content then this is it! As engineers in corporate America (and elsewhere) we build machines for obscurity. We write novels to be read by no-one. We architect palaces of structured information that shall soon disappear.
Let's try to do that as little as possible.
G. Andrew Stone
2011
---
The next episodes of this little blog may delve in more detail about RSD and GameMaker's history, etc. Perhaps only interesting to those who actually used it.