How to fix NetBeans IDE when it has dark tabs

Sometimes on Windows, you can have Java configured in such a way that the NetBeans IDE (Integrated Development Environment) will use a dark background (like black) on all the inactive tabs, making them difficult (or impossible) to read. Here's an example of what this might look like:

Not good.

As it turns out, there is no way in NetBeans itself to fix this problem, at least that I've found.  You can't change the color scheme or anything.

A work-around for this problem is to change the Java theme for NetBeans IDE to be something else, like Metallic.

To change the theme, open the file "c:\Program Files\NetBeans x.x\etc\netbeans.conf" (where x.x is the version number) with a text editor and add this to the end of the netbeans_default_options line, before the closing quote:

--laf javax.swing.plaf.metal.MetalLookAndFeel"

Here's what NetBeans might look like after making this change:

You can now read the tabs!

Hat tip to Tushar Joshi for a description of changing the look-and-feel of NetBeans.

Adding Syntax Highlighting to Blogger

(Note: This article is somewhat dated because SyntaxHighlighter 2.0 was released in February 2009.  However, this article is still valid for those who prefer the older 1.5.x version or who don't want to upgrade)

As we all know, any self-respecting blogger needs some kind of syntax-highlighting plug-in before posting source code on a blog. I've been amiss in this regard, but decided it was high time to correct this particular deficiency.

From doing a little web searching, it looks like the favorite choice is a Java script tool called syntaxhighlighter. As of this writing, syntaxhighlighter hasn't been updated since version 1.5.1 was release in August 2007. It's been surprisingly robust all this time, except that it appears to have some trouble with scrollbars in the more recent Firefox versions, and Safari can be pegged at 100% CPU utilization. Also, the documentation is a little sparse.

That said, here are the steps I followed to make syntax highlighting work with Blogger (the host for this blog) using the syntaxhighlighter suite of javascript and css code.

In the blogger back end (reachable by logging into your blog and clicking "New Post" or "Customize", or other methods), click the"Layout" tab, then the "Edit HTML" sub-tab. Within the textbox within the "Edit Template" section, do the following:

1. Go to http://syntaxhighlighter.googlecode.com/svn/trunk/Styles/SyntaxHighlighter.css, then perform a "select all" and "copy". The css information is now in the clipboard.

2. Paste the css information at the end of the css section of your blogger html template (i.e., after <b:skin><!--[CDATA[/* and before ]]--></b:skin>).

3. [Updated March 25, 2009 to include closing script tags] Before the </head> tag, paste the following:

<!-- Add-in CSS for syntax highlighting -->
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shCore.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushCpp.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushCSharp.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushCss.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushDelphi.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushJava.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushJScript.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushPhp.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushPython.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushRuby.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushSql.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushVb.js' type='text/javascript'></script>
<script src='http://syntaxhighlighter.googlecode.com/svn/trunk/Scripts/shBrushXml.js' type='text/javascript'></script>

Feel free to remove lines for languages you'll never use (for example, Delphi) -- it will save some loading time.

4. [Updated to add final /script] Before the </body> tag, insert the following:

<!-- Add-in Script for syntax highlighting -->
<script language='javascript'>
dp.SyntaxHighlighter.BloggerMode();
dp.SyntaxHighlighter.HighlightAll('code');
</script>

5. Use the "Preview" button to make sure your website is correct, then click "Save Template".

6. When composing a blog entry that contains source code, click the "Edit Html" tab and put your source code (with html-escaped characters) between these tags:

<pre name="code" class="cpp">
...Your html-escaped code goes here...
</pre>

Substitute "cpp" with whatever language you're using (full list). (Choices: cpp, c, c++, c#, c-sharp, csharp, css, delphi, pascal, java, js, jscript, javascript, php, py, python, rb, ruby, rails, ror, sql, vb, vb.net, xml, html, xhtml, xslt)

For performing the HTML escaping, you can get a good list of tools by searching for 'html esaper' or a similar term. Here's the one I used while writing this post.

Let me know how it works!

Notes:

1. Step 2 is a work-around to accommodate Firefox browsers, which for some reason refuse to load the css when linked, because it thinks the type is mime/plain instead of mime/css (I don't personally understand this -- I'm just using a workaround recommended from elsewhere)
2. See full documentation here for Syntaxhighlighter.
   

Sources:

1. Enjoy Web Tech - Publish Source code in Blogger
2. Using Syntaxhighlighter on Blogger

Keyfixer 0.4 for Firefox and Thunderbird

Firefox/Thunderbird keyfixer, starting with version 0.4, is now as a Mozilla Extension.

Keyfixer makes the keyboard bindings for Firefox or Thunderbird on Mac OS X behave like Windows. This is very useful for people who use both Windows and Mac (like I do), and don't want to have to continually remap your brain for each system

This new version is a regular Mozilla Extension (a type of Add-on), so now you don't have to uninstall and reinstall every time you upgrade Firefox.

Thanks to Jim Mendenhall of Starry Hope for the original version!

Let me know if you have any issues!

Cheers, -Matt

[Update: Version 0.4.2 is now available as a feature release to additionally bind the Control key instead of just the Command key. Some people prefer to use Control, and now you can use either...)

Joel Spolsky Co-Launches "Stack Overflow" programmer's forum

One of my favorite programming bloggers, Joel Spolsky, recently announced his latest co-project:  Stack Overflow.  This is basically a 'fixed' version of the question forum that you frequently encounter when searching for programming questions.  The improvement is that this is moderated, and the answer gets promoted to the top so that you don't have to wade through endless comments to find the answer (if you do find the answer).

It's still in beta, and it doesn't have too many users yet, so it's hard to say whether Google will give it enough PageRank to reach critical mass.  Just in case, I registered myself (using OpenID, with my blogger website -- this blog) so that I could get a low enough user number to have Web Cred.  I got #7448.  Not too bad.  If this ever grows to SlashDot proportions, people will be like "ahh, he's got a four digit user number -- he must know what he's talking about"  (says the 7-digit user number user).  Of course, it will be impossible to ever win the user number war against Jeff Atwood:  #1.

I browsed the site a little bit and couldn't find any big complaints about the user interface, although I haven't tried posting yet (I did get a 'bronze medal', though, for filling out my biographical information!).  They've got syntax highlighting on the code samples, so it can't be too bad...

I'm half tempted to move a bunch of the programming tidbits I've collected on this site over to Stack Overflow.  I just want to make sure that the answers still link over to this blog so that this blog can build web presence as well.  (One of the great things about posting useful answers in your blog is that it raises the blogs PageRank -- if these same answers are posted elsewhere, your blog doesn't improve).  Stack Overflow lets you link your website through your user profile, but you have to click the user profile first.  I've also noticed that the last person to edit the question gets the credit for asking it -- not the original asker.  This creates a situation like that game where you try to put your hand on top of another person's hand, who tries to put their hand on top of yours, until you both end up slapping each other instead of putting hands on hands...

In any case, I hope that this website builds to the point that Google gives it top PageRank for the questions it answers.  This would let me reap the benefits of this system without all the work... :)

Hiding Password in Registration E-mail for Joomla

I use Joomla 1.0 for the IEEE Security in Storage Working Group (SISWG) homepage, and discovered that when new users register, their e-mail addresses are e-mailed to them in clear text before being hashed using MD5 and stored in the database. Since SISWG is a security group, it's important to provide a little better security than for the usual Joomla user. Things like sending a plaintext password in e-mail are a no-no.

Unfortunately, it looks like Joomla 1.0 does not provide a way to disable having the users' e-mail sent to them if the admin chooses to require registration. The closest thing is to change "Use New Account Activation:" to "No" in the Global Configuration->Site tab, but then users can register without a valid e-mail address.

Fortunately, this is just a one-line change to the appropriate file, which shouldn't be a problem for those who don't mind getting a little dirty. Here are the edit instructions:

Open the file components/com_registration/registration.php and change this line:

154: $pwd = $row->password;

to

154: $pwd = "********";


If you're not using version 1.0.12, the line number may be a little different.

That should do it!

How to Prevent the Random Number Bug in Debian OpenSSL in Other Implementations

As probably the entire hacker community has heard by now, there was a bug recently discovered in Debian's OpenSSL implementation that crippled the random number generator. For background, see Schneier's Coverage, Slashdot's Coverage, Debian's Announcement, Ubuntu's Announcement, and a Cartoon.

On the surface, this just looks like a stupid mistake by one Debian maintainer. But if you look at the details, it's not that obvious. Here one of the two lines in question, within md_rand.c

MD_Update(&m,buf,j); /* purify complains */

This function seeds the cryptographically secure pseudo-random number generator, which then generates important things like cryptographic keys. The security of a cryptographic key is solely in the difficulty of an attacker to guess the value (like a house key's tumbler positions), and if it is predictable, there is no security. The maintainer removed this line because the Purify and Valgrind tools complained about uninitialized data.

Truthfully, if I were in the same position as a maintainer, there's a good chance I might have commented out these lines too. Code analysis tools are very useful in helping to maintain high code quality, and crippling these tools also has consequences. The right action is not always obvious, and when you go through hundreds of lines of code it's easy to forget the significance of a single line like this.

The fundamental issue with random number generators (RNGs) is that they are infamously difficult to test. A standard software regression test takes a known input to a program and checks for a known output. RNGs aren't like that -- at least when used with good seeds. A good seed never repeats and cannot be tested against known answers. Instead, you have to perform statistical tests on several samples from the seed source (examples: DIEHARD, NIST's RNG suite).

This problem is much more widespread than people think. This is also a very common problem in embedded systems. Many instantiations of SSL don't properly seed their RNG. This won't cause the system to fail, testers won't ever catch it, and customers won't complaint. So from the vendor perspective, there's really no incentive to make it work. Most of the engineers adding OpenSSL don't know much about cryptography, and often won't know to or even bother to hook up a seed. Some systems don't have a good way to generate this seed.

Even NIST' Computer Security Division (the owner of FIPS 140-2, a major cryptographic standard for government agencies) has mostly washed their hands of this problem. FIPS 140-2 used to include statistical tests on the entropy (i.e, 'randomness') source used to create the seed, but now the only requirement is that the vendor justify a certain entropy level.

To solve this problem, I think that OpenSSL (and other SSL implementations) needs to add some kind of sanity check to the seed to make sure this mistake doesn't happen again. Here's a rough outline of this test:

1. During OpenSSL's initialization, immediately collect several samples from the seed source. The number depends on the constraints of the system, but NIST's old FIPS 140-2 statistical test collected 20,000 bytes, which is a reasonable number.
2. Run simple statistical tests on these samples (see FIPS 140-2 for an example) and make sure the entropy source is reasonable.
3. Store the first 100 bytes or so of this sample set in non-volatile memory, (e.g, hard disk, flash), and keep a history of several thousand of these initial samples. Discard the other samples (don't use them as part of the real seed)
4. Run another statistical test on the series of first samples. If there is a correlation between these samples (i.e,. the values tend to be the sample after initialization), then fail with a big obnoxious error that you'd hope no distribution maintainer or embedded software engineer would miss.
   

This test would have caught the bug in questions because the same seed would likely have occurred across power cycles. The default for this seed is the process ID, which by default is at most 32,768. According to the birthday paradox, you will on average see a duplicate random number in the range 1 to N after roughly the square root of N samples. In this case, the square root of 32,768 is 181. Someone would have seen the horrible error message by then.

Caveat: Make sure that the files that store these seeds are properly protect from access and modification. If the entropy source is poor, it's possible to leak information about the rest of the system, or even give hints as to what the subsequent seed will be as used by the real random number generator.

When it comes to security, you really can't rely on people to catch these kinds of mistakes through code reviews. You need to have good tools to automatically catch this. Unfortunately, making the tools is difficult, which is why we still mostly rely on code reviews.

Although code reviews are better than nothing, and in this case, it sounds like even a code review would have helped...

Can Firefox keyconfig fix Home/End buttons in textboxes?

In poking around a little further with the problem of creating custom key mappings in Firefox for Mac, I found the plugin named keyconfig (see forum discussion). The plugin seems reasonable on the surface, but it's not actively supported, and its web presence is poor. The best article I found was here on random($foo). Unfortunately, the shortcuts it includes seem to be just for navigating, and not for text edit boxes. I suspect it's possible to add custom code to make keyconfig do what Starry Hope's Firefox keyfixer does -- remap the home/end keys to go to the beginning/end of the current line -- but I couldn't find out how without a lot of poking around.

Keyfixer is a patch utility that modifies the Firefox configuration file named platformHTMLbindings.xml (kept inside the zip file named /Applications/Firefox.app/Contents/MacOS/chrome/toolkit.jar) with the appropriate key board shortcuts. For example, these are the lines that change Home/End to go to the beginning/end of the current line instead of top/bottom of current edit window.

<!-- Additions to fix home/end -->
<handler event="keypress" keycode="VK_HOME" command="cmd_beginLine"/>
<handler event="keypress" keycode="VK_END" command="cmd_endLine"/>
<handler event="keypress" keycode="VK_HOME" modifiers="shift" command="cmd_selectBeginLine"/>
<handler event="keypress" keycode="VK_END" modifiers="shift" command="cmd_selectEndLine"/>

The question I have is whether similar changes are possible within the keyconfig firefox plugin. If this is possible, it would be much easier to maintain because you have to uninstall Firefox keyfixer before upgrading firefox.

I see a lot of potential in keyconfig because it's a firefox plugin, and is something that should be in Firefox anyways, but right now I can't make it work better than the keyfixer patch.

Ada beats Colossus in Cipher Challenge

I caught this article on Slashdot about an Ada program beating Colossus in a challenge to quickly decrypt messages from the Lorenz SZ42 cipher. The Ada program took 46 seconds versus what Colossus (the World War II machine in Bletchley Park that cracked German messages) solved in about three and a half hours.

Ada has me very fascinated because I'm interested in programming languages that lend themselves to computational correctness and high execution speed. I haven't used Ada, but I tend to hear good things about it, and would like to try using it next time I start a project. I'm particularly interested in how it would help programs that use cryptography and that are going through a Common Criteria evaluation.

According to the TIOBE Index, as of May 2008, Ada is sitting at #17 with 0.431% popularity and a rating of 'B'. From that point of view it doesn't look like the hottest thing out there, but it has Objective-C (Mac's darling) way out-ranked. Objective-C is #47 with 0.083% popularity, which makes me wonder if it's worth learning for writing Mac OS X Widgets. Fortunately, Mac's Xcode provides some good hooks for Python (#7, 4.6% popularity) and Ruby (#10, 2.85%)...

Fixing Home and End Keys on Firefox 3 for Mac OS X

[Update: Keyfixer 0.4 is now available; see new blog post]

Since I'm a heavy gmail user, I make significant use of the editor window in my web browser. Ever since moving to a Macbook as my primary computer, I've been struggling with re-learning the Mac navigation key shortcuts. Since I still use Windows a lot, I decided to instead reconfigure the Mac shortcuts to emulate Windows shortcuts.

This strategy worked well, except for in Firefox, which doesn't respect the Mac DefaultKeyBinding.dict file. For Firefox 2, I solved this problem by running Keyfixer as published by Starry Hope. Unfortunately, this stopped working for me when I updated to Firefox 2.0.0.14. I switched to Safari for a while, but Safari's other bugs and "features" started to annoy me. I wanted my Firefox back.

After digging into what Keyfixer does, I've put together an updated version 0.3 that should work for Firefox 2.0.0.14 and Firefox 3.0 beta 5 (tested on Mac OS X 10.5.2). The new solution performs patches instead of straight copies of the keymapping xml file, so I'm hoping it is more robust against future changes in Firefox.

Click here to get Firefox Keyfixer 0.3.

Compared to version 0.2, this new version has the following updates:

• Support for both Firefox 2 and 3 (versions on or after May 2008)
• Running the program twice will uninstall the patch. This is useful when performing upgrades (Firefox won't upgrade if Keyfixer has been applied -- you have to remove it first)
• PageUp and PageDown now moves the cursor instead of just moving the screen. This is more consistent with Firefox on Windows.

As a side note, it looks like there was an intention in Firefox to follow standard Mac behavior by mapping Command-Left Arrow and Command-Right Arrow to move the cursor to the beginning and end of line, respectively. However, this doesn't seem to work (at least when using gmail). I'm interested to know if anyone else has seen this issue, because it's a bug.

If you have any problems or questions with this version, please drop a comment and I'll see what I can do to help!

Fixing up the Mac Key Bindings for Windows Users

[Note: Edited on 2010-02 to switch the order of the shift and command key modifiers.  Apparently, Mac OS is particular about the order.]

[Edited on 2010-10-22 to describe how to use TextEdit to apply this key mapping]
[Edited on 2010-11-12 to mention that TextEdit sometimes adds a .txt extension]


I'm a longtime Windows user who recently purchased a Macbook. Overall I'm very impressed with the machine, but it does have a learning curve, especially for the key bindings.

The first thing I noticed was that the Macbook does not have the Del and Ins keys at all, and the Home, End, PageUp and PageDown keys require pressing 'Fn' and then an Arrow key (which is understandable because the keyboard on a small Macbook is somewhat cramped -- also, I've asked a couple users who have not used PCs much before using a Mac, and they did not even know these keys existed, or what they would do with them)

However, when I'm not on the road, I like to use a nice full sized Microsoft Natural Keyboard, to reduce tendinitis. As a (former) hard-core programmer, I very extensively use the Home, End, PageUp and PageDown keys to quickly navigate code or text documents. I was very dismayed to discover that Apple pretty much doesn't do anything with these keys.

In hunting through all the configuration options, I noticed that you can reconfigure a lot of key mappings through the System Preferences utility (go to the apple in the upper-left corner, select System Preferences..., click on Keyboard & Mouse, and click the Keyboard Shortcuts tab). This was useful for a start, but I quickly determined that the Mac wouldn't allow me to bind keys to any of the 6 special keys (Home, End, PageUp, PageDown, Delete, Insert). This made me sad.

I did discover, however, that it is possible to switch the Control and Command keys. This is a big help because now all the windows favorites like Ctrl+c for copy, Ctrl+v for paste, Ctrl+x for cut, and Ctrl+z for undo now work the same on both systems. I still switch frequently between Windows and Mac platforms, so it's very nice to have the same key mappings.

Most recently, I discovered that there is a special file you can create that allows special mappings to the 6 special keys. This made me happy. I was now able to get much closer to having a unified key mapping. For more details, see this article.

To do this, create a new file called ~/Library/KeyBindings/DefaultKeyBinding.dict and put the following text into it (You'll probably have to create the directory the first time -- this is okay).

/* ~/Library/KeyBindings/DefaultKeyBinding.Dict
This file remaps the key bindings of a single user on Mac OS X 10.5 to more closely
match default behavior on Windows systems.  This particular mapping assumes
that you have also switched the Control and Command keys already.

This key mapping is more appropriate after switching Ctrl for Command in this menu:
Apple->System Preferences->Keyboard & Mouse->Keyboard->Modifier Keys...->
Change Control Key to Command
Change Command key to Control
This applies to OS X 10.5 and possibly other versions.

Here is a rough cheatsheet for syntax.
Key Modifiers
^ : Ctrl
$ : Shift
~ : Option (Alt)
@ : Command (Apple)
# : Numeric Keypad

Non-Printable Key Codes

Up Arrow:     \UF700        Backspace:    \U0008        F1:           \UF704
Down Arrow:   \UF701        Tab:          \U0009        F2:           \UF705
Left Arrow:   \UF702        Escape:       \U001B        F3:           \UF706
Right Arrow:  \UF703        Enter:        \U000A        ...
Insert:       \UF727        Page Up:      \UF72C
Delete:       \UF728        Page Down:    \UF72D
Home:         \UF729        Print Screen: \UF72E
End:          \UF72B        Scroll Lock:  \UF72F
Break:        \UF732        Pause:        \UF730
SysReq:       \UF731        Menu:         \UF735
Help:         \UF746

NOTE: typically the Windows 'Insert' key is mapped to what Macs call 'Help'.  
Regular Mac keyboards don't even have the Insert key, but provide 'Fn' instead, 
which is completely different.
*/

{
"\UF729"   = "moveToBeginningOfLine:";                       /* Home         */
"@\UF729"  = "moveToBeginningOfDocument:";                   /* Cmd  + Home  */
"$\UF729"  = "moveToBeginningOfLineAndModifySelection:";     /* Shift + Home */
"@$\UF729" = "moveToBeginningOfDocumentAndModifySelection:"; /* Shift + Cmd  + Home */
"\UF72B"   = "moveToEndOfLine:";                             /* End          */
"@\UF72B"  = "moveToEndOfDocument:";                         /* Cmd  + End   */
"$\UF72B"  = "moveToEndOfLineAndModifySelection:";           /* Shift + End  */
"@$\UF72B" = "moveToEndOfDocumentAndModifySelection:";       /* Shift + Cmd  + End */
"\UF72C"   = "pageUp:";                                      /* PageUp       */
"\UF72D"   = "pageDown:";                                    /* PageDown     */
"$\UF728"  = "cut:";                                         /* Shift + Del  */
"$\UF727"  = "paste:";                                       /* Shift + Ins */
"@\UF727"  = "copy:";                                        /* Cmd  + Ins  */
"$\UF746"  = "paste:";                                       /* Shift + Help */
"@\UF746"  = "copy:";                                        /* Cmd  + Help (Ins) */
"@\UF702"  = "moveWordBackward:";                            /* Cmd  + LeftArrow */
"@\UF703"  = "moveWordForward:";                             /* Cmd  + RightArrow */
"@$\UF702" = "moveWordBackwardAndModifySelection:";   /* Shift + Cmd  + Leftarrow */
"@$\UF703" = "moveWordForwardAndModifySelection:";   /* Shift + Cmd  + Rightarrow */
}

Remember: These key mappings assume that you've switched Control and Command. If you don't want to make this switch, replace each @ (command) with ^ (control).

Here are steps to take to apply these changes:

• Open TextEdit under the Applications folder.  If TextEdit was already open, create a new document using File->New.  There should be a window labeled 'Untitled'.
• Select the text within the window above, copy it, and then paste it into your new TextEdit window.
• In TextEdit, convert this to plain text (the default is rich text) by selecting Format->Make Plain Text.
• Next, select File->Save As...  In the "Save As" dialog box, navigate to your home directory (look under PLACES on the left side for a house picture that has your name next to it).  In your home directory, double-click on the Library folder.  If you see a KeyBindings folder then double-click on it.  If not, then click on "New Folder" (within the Library directory), name the new folder KeyBindings (with no space), and then double-click on it.  Type DefaultKeyBinding.dict for the filename (at the top) and then click Save.
• Warning:  TextEdit will sometimes try to 'help' you by appending a .txt extension to the filename.  Make sure this doesn't happen.  If asked to use a .txt extension, tell TextEdit to instead use .dict.  It will not work if you use .txt.  If you have trouble, see comment by Nathan below.
• Before these changes take effect, you need to log out and then log back in.

There you have it! I know this emulation isn't perfect (not all applications honor this mapping), but it's a good start. Please drop comments if you have any questions or suggestions for improvements.

The Microcomputer Trainer

Back when I was 7 years old, I wanted to buy a TRS-80 Color Computer, but my dad wanted to make sure that I was committed to programming before spending the $100 -- so he bought me a Science Fair "Microcomputer Trainer" and wanted me to learn to program that first. After I attempts to read the book with my second grade (or was it first?) reading level, I finally managed to do a little programming, but I ended up destroying the system by shorting the clock out with my fingers. My dad was satisfied and bought me the CoCo for Christmas later that year, and I've been programming ever since...

The microcomputer trainer used a simple 4-bit processor with 16 hexadecimal buttons, 4 control buttons, 7 LEDS, a 7 segment HEX LED, and a speaker. The CPU was a Texas Instruments TMS1100, which was based on the Speak and Spell's TMS1000.

I downloaded a copy of the manual here. The primary goal was to teach machine language programming to a young audience.

My question is whether it's possible to teach kids machine language in today's world by using a similar device. If so, what changes would be necessary to keep enough interest to teach a little bit about machine language and pointers? I think a small instruction set would be appropriate, but how small could you make it and still be Turing complete, and still make it fun to use?

To get the ideas started, here is the instruction set for the Microcomputer Trainer:

Main commands:

• 0: KA = "Key into Ar" - If a key is pressed, then set Ar to key value and set flag to 0; else set flag to 1.
• 1: AO = "A Output" - Displays contents of Ar on HEX LED and sets flag to 1.
• 2: CH = "exChange" - Exchanges the contents of Ar with Br, exchanges Zr with Yr, and sets flag to 1.
• 3: CY = "exChange Ar with Yr" - Exchanges the contents of Yr and Ar
• 4: AM = "Ar to Memory" - Moves contents of Ar to the memory location indicated by following nibble and sets flag to 1.
• 5: MA = "Memory to Ar" - Moves contents of memory indicated by following nibble into Ar and sets flag to 1.
• 6: M+ = "Memory +" - Adds contents of memory pointed to by Yr to Ar, stores the result in Ar, and sets flag to 1 if there is a carry.
• 7: M- = "Memory -" - Subtracts the contents of Ar from the memory location pointed to by Yr and stores the result in Ar. If an underflow occurs, flag is set to 1.
• 8: TIA = "Transfer Immediate into Ar" - Moves following nibble into Ar and sets flag to 1.
• 9: AIA = "Add Immediate into Ar"- Adds following nibble into Ar and sets flag to 1 if there is a carry.
• A: TIY = "Transfer Immediate into Yr" - Moves following nibble into Yr and sets flag to 1.
• B: AIY = "Add Immediate into Yr" - Adds following nibble into Yr and sets flag to 1 if there is a carry.
• C: CIA = "Compare Immediate to Ar" - Sets flag to zero if Ar equals following nibble; else sets flag to 1.
• D: CIY = "Compare Immediate to Yr" - Sets flag to zero if Yr equals following nibble; else sets flag to 1.
• E: CAL = "Call" - Execute extended command (see below) if flag is set to 1 in previous command; else do nothing.
• F: JUMP = "Jump" - If flag is 1, jump to byte address in following 2 nibbles; else do nothing

CALL commands (preceded by 'E'):

• E0: RSTO = "Reset port O" - Turns off the HEX LED.
• E1: SETR = "Set LED" - Sets LED according to number indicated by Yr (0-6)
• E2: RSTR = "Clear LED" -Clears the LED according to number indicated by Yr (0-6).
• E3: Not Used
• E4: CMPL = "Complement" - Replaces Ar with its ones-complement (i.e. result of F - Ar)
• E5: CHNG = "Change registers" - Exchanges Ar, Br, Yr & Zr with Ar', Br', Yr' & Zr'.
• E6: SIFT = "Shift" - Shifts the contents of Ar one bit to the right and sets the flag to the opposite of the least significant bit of Ar before shifting.
• E7: ENDS = "End Sound" - Emits an 'end' sound
• E8: ERRS = "Error" - Emits an 'error' sound
• E9: SHTS = "Short Sound" - Emits a 'blip' through the speakers
• EA: LONS = "Long Sound' - Emits a long sound through the speakers
• EB: SUND = "Sound" - Emits a note according to value in Ar (0 = no sound, 1 = la, 2 = ti, 3 = do, ... E = sol, F = no sound)
• EC: TIMR = "Timer" - Pauses for the following number of seconds: seconds = (Ar + 1) / 10
• ED: DSPR = "Display on port R" - Displays contents of memory locations E and F in binary on the 7 LEDs. Memory F contains the right-most 4 LEDs and memory E contains the leftmost 3 LEDs.
• EE: DEM- = "Decimal conversion of M- result" - similar to DEM+, but subtracts instead of adds.
• EF: DEM+ = "Decimal conversion of M+ result" - Adds together the decimal contents of Ar and the pointed address to give a decimal answer and stores that answer at the pointed address. If there is a carry, 1 is added to the pointed address less 1. After the command has been executed, the pointer is left pointer one address below the pointed address (If the number to be added is in 54, the answer is put in 54 and the pointer is reduced by 3. If there is a carry, one is added to 53)

iDrone reprint: Writing an accumulator generating function in Ruby

[This is an iDrone reprint, Written by Mark W on Feb 9th, 2007]

Talking with Matt, this morning, our conversation turned to the very large differences in power between various programming languages. While most would readily agree that higher level programming languages are far more expressive than assembly, many people draw the line there. Java, C++, VB, Python, Fortran are all “about the same” to quite a few people, including ,unfortunately, most of my previous bosses.

One example Paul Graham used to illustrate differences between higher level programming languages is how difficult it is to write a function that generates accumulators— a function that takes a number n as a parameter, and returns a function that takes another number i and returns n + i.

In Python, he said the commonly accepted solution was as follows:

def foo(n):
 class acc:
   def __init__(self, s):
     self.s = s
    def inc(self, i):
      self.s += i
      return self.s
  return acc(n).inc 

In Javascript, a surprisingly powerful language, considering it’s almost completely ignored outside of web page development, the solution is shorter and cleaner:

function acc(n) {
  return function (i) {             
    return n += i 
  } 
}

One language Paul Graham did not mention, was Ruby. I’m still fairly new to Ruby, but the solution was not difficult. Due to the power of blocks in Ruby, this sort of functional programming is extremely clean. Here is the accumulator generating function:


def acc(n)
  lambda {|i| n += i}
end 

Here’s a quick example of it in use:


f1 = acc(3)           # a function that increments by three
f1.call(5)            # returns 8
f1.call(-1)           # returns 2
f2 = acc(1.5)         # a function that increments by 1.5
f2.call(1)            # returns 2.5
f2.call(3)            # returns 4.5
f2.call(f1.call(1))   # returns 5.5 

In some less expressive languages, such as VB, C++, Fortran or Java, it isn’t even possible[1] to write a simple function that can generate accumulators. Obviously since each of those languages are Turing complete, the problem would be solvable, just not with a simple function. You could, given enough time, write a Ruby interpreter in C++, and then input


def acc(n)
  lambda {|i| n+i}
end

to get your accumulator.

---

[1]: Ken Anderson did offer an example of a way to kludge together an accumulator generating function in Java in Graham’s essay above. He used an integer to integer interface. Naturally enough, it fails to work for anything but integers. Generating a polymorphic function in Java, similar to the functions listed in this article would be a Sisyphean undertaking. If you can do it, I’d love to see a link to it in a comment.

iDrone reprint: How to Make a CSS Menu Bar

[This is an iDrone reprint, written by Mark W sometime in 2006; I'm posting it now because I finally got the syntaxhighlighter tool working]

Last week, a friend of mine asked how I made the CSS menu bar on my blog. Though it may seem a bit daunting to those who haven’t been using style sheets, it’s actually very simple. First, I made a list in my HTML:

<div id=”menu”>
 <ul id=”navlist”>
   <li><a href=”/”>Home</a></li>
   <li><a href=”/chinese-tools”>Tools</a></li>
   <li><a href=”/archives”>Archives</a></li>
 </ul>
</div>

Notice that I put the list inside <div> tags. That’s important. It’s also important that the <div> block and the <ul> have IDs, “menu” and “navlist”, in this case. After adding the above to my HTML, I had to add the following to my style sheet:

 /* Horizontal Menu */
#menu {
         height: 20px;
     margin: 0px 0px 6px;
     background: #eec;
}

ul#navlist {
     margin: 0px -15px 6px -15px;
     padding: 0px;
     white-space: nowrap;
     font-weight: bold;
}

#navlist li {
     display: inline;
     list-style-type: none;
     float: left;
     padding: 0px 0;
}

#navlist a {
     padding: 5px 12px;
}

#navlist a:link, #navlist a:visited {
     color: #246;
     background-color: #eec;
     text-decoration: none;
}
#navlist a:hover {
     color: #fff;
     background-color: #369;
     text-decoration: none;
}

The #menu portion just sets the height and background of the menu, the ul#navlist aligns the list to fit nicely with my layout, #navlist a determines how much space is between each item in my menubar, and #navlist a:hover is what causes the color and the background of each link to change when you hover your mouse over them. Voila, a navigation menu that changes colors when your mouse is over it. Best of all, there’s no Javascript involved. Idrone also uses a very similar CSS menu bar.

iDrone reprint: The Perfect Programming Language

iDrone reprint: The Perfect Programming Language
By Matt Ball, written some time in 2006

I’ve recently become interested in finding the ‘perfect’ programming language. This is mostly because I use one of the more out-dated languages, “C”. I work as an embedded software (firmware) engineer, where I create firmware for tape drives. Embedded systems is one of the few industries that hasn’t switched wholesale to Java or one of the .NET variants. As a result, I’m stuck in a sea of developers who have been programming C and nothing but C for the last 20 years. Just to retain my sanity, I’ve got to look at other approaches.

The idea of a ‘perfect’ language is a little far-fetched, but makes a good started point for knowing what to look for in a new language. If a perfect language existed, it would likely have some of these features:

• Compiles to code that runs as fast as C (or even faster). This removes the excuse to ever use C (or C++).
• Does not use a pre-processor
• Contains built-in garbage collection
• Allows creation of low-level data structures and data types.
• Natively supports integers of any size, between a single bit and an arbitrary large number of bits (BigNum). Along the same lines, natively supports modulo arithmetic to facilitate RSA and D-H cryptography (e.g. X * Y mod Z).
• Supports all the ‘good’ object oriented features, including single inheritance (not multiple like C++)
• Provides a build-in mechanism for determining whether parameters and data can be trusted.

The list goes on from there.

Relating to this subject, I found an interesting Slashdot article talking about someone from IBM that is doing a series on a similar topic. He’s approaching the problem from the perspective of a Java programmer looking at other languages, but the goal is roughly the same: look at several programming languages and find their strengths and weaknesses.

One good language that I found is the “D” programming language. This language is meant as an enhancement to C and C++, and provides several of the things in the list above. Unfortunately, D is still in the beta stage, so it’s not possible to use this in a real product. It also doesn’t have any books that I know of (having a book is one of Paul Graham’s requirements for a good programming language).

Of course, there are many other good programming languages out there, like Ruby, Python, and Lisp, but none of these languages compile tightly enough, or provide enough low-level control for embedded systems. This ‘perfect’ language needs to have the ability to compile small, if needed.

Finding the perfect language will be a long journey, but in the end I expect it will be well-worth the time, and if nothing else, will provide insight into how to use existing languages more effectively.