Dr. Vanessa Freudenberg

If you got as excited as me about Dan Ingalls' live Smalltalk-76 demo on an actual 1970's Xerox Alto, you may have wanted to try it yourself.  For one, you could try my Smalltalk-78 VM. Smalltalk-78 is a leaner version of Smalltalk-76 but very much identical in syntax semantics.  It is also possible to run the full Smalltalk-76 environment, and here is how: First, you need an emulator for the Alto computer. Ken Shiriff posted a nice piece on how to run ContrAlto on Windows . It is written in C# and I got it to work on my Mac using Mono. So here's a step-by-step: Install Mono from  http://www.mono-project.com/download/ Download ContrAlto-mono.zip from https://github.com/livingcomputermuseum/ContrAlto/releases Download this Smalltalk-76 disk image: http://www.bitsavers.org/bits/Xerox/Alto/disk_images/chm/xmsmall.zip Unzip both  ContrAlto-mono.zip  and  xmsmall.zip  in the same folder. In a terminal, change to the ContrAlto directory and run...

While working on my  SqueakJS VM, it became necessary to deconstruct floating point numbers into their mantissa and exponent parts, and assembling them again. Peeking into the C sources of the regular VM, I saw they use the  frexp ()   and ldexp () functions found in the standard C math library. Unfortunately, JavaScript does not provide these two functions. But surely there must have been someone who needed these before me, right? Sure enough, a Google search came up with a few implementations. However, an hour later I was convinced none of them actually are fully equivalent to the C functions. They were imprecise, that is, deconstructing a float using frexp() and reconstructing it with ldexp() did not result in the original value. But that is the basic use case: for all float values, if [ mantissa , exponent ] = frexp (value) then value = ldexp ( mantissa , exponent ) even if the value is subnormal . None of the implementations (even the complex ones) re...

TL;DR:  Try Etoys in your web browser  without a plugin (still buggy, but even works on iPad). Feedback from more platforms is very welcome, and fixes to improve the compatibility, too. — Half a year has passed since my initial release  of SqueakJS. Now I can report on some significant progress since then. For one, I adopted a UI layout similar to Dan’s Smalltalk-72 emulator, where the debugger interface is only visible when the system is stopped. Now that the basics are working, there is no need to show the debugger all the time. Try it yourself at the Lively page . But more importantly, many more subsystems are working now. BitBlt is almost complete (all the important modes are implemented), WarpBlt works (for scaling and rotating morphs), the image can be saved, an emulated file system supports reading and writing of persistent files. This now is enough to not only run the very old and undemanding “mini.image”, but SqueakJS now can even run the very lat...

I'm proud to announce SqueakJS, a new Squeak VM that runs on Javascript: SqueakJS project page It was inspired by Dan's JSqueak/Potato VM for Java, and similarly only runs the old Squeak 2.2 mini.image for now. But I developed it inside the Lively Kernel, which allowed me to make a nice UI to look inside the VM (in addition to all the Lively tools): It represents regular Squeak objects as Javascript objects with direct object references. SmallIntegers are represented as Javascript numbers, there is no need for tagging. Instance variables and indexable fields are held in a single array named "pointers". Word and byte binary objects store their data in arrays named "bytes" or "words". CompiledMethod instances have both "pointers" and "bytes". Float instances are not stored as two words as in Squeak, but have a single "float" property that stores the actual number (and the words are generated on-the-fly w...

The Raspberry Pi is a cute little computer. Quite cheap at $35, you plug in USB keyboard+mouse and a TV as monitor. And it is surprisingly capable, even for running 3D games. One particularly interesting game is Minecraft: Pi Edition . As in other Minecraft versions, the main goal is to create a world. But unlike other versions, you can not only use the tools provided by the game, you can make your own tools! That's because it comes with a programming interface. The Minecaft world is made of little cubes, and you normally place or remove these blocks by hand, one after another. This is fun, but for larger structures also quite cumbersome. For example, this rainbow here might take a long time to construct manually: But I did not make the rainbow by hand. I programmed it, using the Smalltalk programming language. It's just these dozen lines of code in the Squeak programming environment: Squeak is already installed on the Raspberry Pi, because Scratch was made in Squea...

SJ brought a hand-assembled XO-3 prototype to the OLPC Community Summit in San Francisco (mass production only starts when someone puts in a large-scale order), and of course I tried to run Etoys on it. It's pre-installed (as on all XOs) and worked right out of the box. I was able to paint and drag objects, but since there is no right-click support yet there was no halo to bring up a new viewer. Also, touch targets are rather small for my adult-sized hands, and since there are no hover events, some features don't work correctly (as we found out with the iPad version two years ago). So more work is needed, as well as for the XO-4 which has a multitouch screen in addition to a keyboard and touchpad. Help welcome :)