Dr. Dobb's Blogs

Expanding VTACH

Sun, 19 May 2013 22:49:00 -0400

The last few weeks, I've been building vtach — a Verilog implementation of CARDIAC, the old paper-based demonstration computer from Bell Labs.

Aliasing Is Particularly Troublesome With Vector Elements

Thu, 16 May 2013 22:28:00 -0400

I would like to continue our discussion with a particularly nasty case in which the result is not well defined.

Troubleshooting Verilog

Sun, 12 May 2013 15:31:00 -0400

I want to squash a bug as a way to show how you "debug" Verilog hardware designs (or, at least, one way to do so)

Some Subtleties of Aliasing

Thu, 09 May 2013 19:27:00 -0400

Aliasing can cause paradoxical behavior.

The CPU Crawl

Tue, 07 May 2013 21:00:00 -0400

I want to talk a bit more about Verilog and how it is different from simply writing something using software.

Sometimes, Making a Program Clearer Makes It Faster

Wed, 01 May 2013 21:15:00 -0400

We can "optimize" our code by removing requests for operations that our data structures do not really need to support.

The Heart of a CPU

Sun, 28 Apr 2013 18:47:00 -0400

A paper computer is certainly novel, and the spreadsheet version lets students get familiar with the architecture without having to write on cardboard. I wanted to go further, though.

Some Optimizations Are No-Brainers

Fri, 26 Apr 2013 14:53:00 -0400

Kernighan's rule for optimizations (Don't do it) is good advice. But as with most rules, there are exceptions.

CPU Design on Paper

Tue, 23 Apr 2013 12:57:00 -0400

FPGAs are great for experimenting with CPU designs.

BodyCom Development Kit

Tue, 23 Apr 2013 07:27:00 -0400

Use your body's electric field to authenticate

Java SE 8 Schedule Update

Fri, 19 Apr 2013 12:49:00 -0400

Yes, the release of Java SE 8 (JDK8) has slipped again. But it's for good reason: platform-wide security enhancements.

Sometimes Optimizations Cancel Each Other

Wed, 17 Apr 2013 14:43:00 -0400

Two rights can make a wrong in the software-design world.

More Conversions

Mon, 15 Apr 2013 10:45:00 -0400

Many processors now have built in analog I/O and that certainly makes things easier. But it is still worthwhile to understand how at least some of these devices work.

Optimizing a Program Means Making It Run Faster, Right?

Wed, 10 Apr 2013 14:18:00 -0400

People often use optimization to mean changing a program in ways that they think will make it run faster, but that casual definition is far from complete.

Roll Your Own Analog Input

Tue, 09 Apr 2013 11:35:00 -0400

Modern computers are inherently digital devices. However, we live in a decidedly analog world, so many systems (including systems on a chip) have methods to generate and read different analog quantities.

Optimization Versus Flexibility — An Example

Thu, 04 Apr 2013 15:04:00 -0400

Last week, I discussed how optimization can sometimes mislead programmers into writing code that works better in the lab than in the field, perhaps because the problems that programs encounter in the field are larger than those that are used during testing. As luck would have it, since I wrote that article, I encountered a real-world example of that phenomenon.

Game of Life — Using Threads and Lists, Part 1

Wed, 03 Apr 2013 05:56:00 -0400

I'm still looking at the Game of Life simulation.

Making Contacts

Mon, 01 Apr 2013 12:42:00 -0400

Many designs that aren't reliable blame relays when, in fact, they should blame the poor choice of relays instead.

Is Optimization Immoral?

Thu, 28 Mar 2013 07:50:00 -0400

Dynamic memory allocation in C++ (and C) can be surprisingly expensive.

Periodic Thread Processing in Java

Mon, 25 Mar 2013 01:00:17 -0400

In an earlier blog where I discussed how to handle uncaught Java exceptions in other threads, I had a minor bug in my example code.

The Mortal (Relay) Coil

Fri, 22 Mar 2013 16:56:00 -0400

Relays aren't (and shouldn't be) as ubiquitous as they once were, but there are still a few reasons you might need to put a relay in a modern circuit.

If Order Relations are Such a Pain, Why Bother?

Fri, 22 Mar 2013 05:30:00 -0400

Whenever a problem turns out to be harder to solve than we expected, it makes sense to ask whether perhaps we were solving the wrong problem in the first place.

Game of Life — Using Lists to Focus Processing

Tue, 19 Mar 2013 16:28:00 -0400

Let's discuss the basic parts to code the Game of Life using list data structure to hold the sets of grid points that may become alive or may die in the next generation.

Relay Race

Fri, 15 Mar 2013 15:22:00 -0400

New technologies may make older things less common, but sometimes the old things fill a niche that the new technologies can't replace.

Comparing an Integer with a Floating-Point Number, Part 2: Tactics

Thu, 14 Mar 2013 21:27:00 -0400

We continue last week's discussion by getting down to details.