Jon Peddie’s The Graphics Chip Chronicles On Graphics Controller History

January 1, 2026 by Maya Posch 3 Comments

Using computers that feature a high-resolution, full-color graphical interface is commonplace today, but it took a lot of effort and ingenuity to get to this point. This long history is the topic of [Dr. Jon Peddie]’s article series called The Graphics Chip Chronicles. In the first of eight volumes, the early days of the NEC µPD7220 and the burgeoning IBM PC.

Texas Instruments TMS34020 (Source: Wikimedia)

These are just brief overviews of these particular chips, of course, with a lot more detail to be found when you go digging. Details such as the NEC µPD7220 being the graphics chip in Japan’s PC-9800 series of computers which are famous for the amazingly creative art and games that this chip enabled.

While the average Hackaday reader is likely familiar with the IBM PC side of things, Texas Instruments’ graphics controllers, including the very interesting TMS34010 and successor TMS34020 which can be called the first proper graphical processing units, or GPUs, effectively a CPU with graphics-specific instructions.

Although it’s tempting to see computer graphics as a direct line from the days of monochrome graphic controllers to what we have today in our PCs, there were a lot of companies and countless talented individuals involved, including companies who built clones that would go on to set new standards. If you’re into reading through a few years worth of computer history articles by someone who has been in the industry for even longer, it’s definitely worth a read.

Thanks to [JohnS_AZ] for the tip.

Top image: NEC µPD7220 by Drahtlos – Own work, CC BY-SA 4.0)

Trace Tracing To The Tunes

January 1, 2026 by Al Williams 2 Comments

Some kind of continuity beeper has been a standard piece of gear since the dawn of electronics. Sure, you probably have an ohm meter, but sometimes you don’t care about the actual resistance. You just want to know whether something connects or doesn’t, especially with a PCB trace or a cable. But what if your beeper could tell you more? [Nick Cornford] asks and answers that question with a beeper that lets you estimate resistance via pitch.

The circuit is relatively simple. A short to ground causes a voltage divider to produce a fraction of the battery voltage and a FET to conduct that fractional voltage to a VCO via a high-gain amplifier. The VCO converts voltage to frequency, and an audio amplifier feeds it to the speakers.

The two amplifiers and the VCO require two dual op-amp chips. The original schematic sends the output to some relatively high-impedance headphones. To drive more practical ones, the circuit can drop one op amp and use another FET and a separate battery.

Of course, you have many design choices, especially for the audio amplification. There are plenty of VCO circuits, or you could probably substitute a small microcontroller with an A/D converter and PWM output. Yes, you can also make a VCO with a 555.

VCOs are common because they are at the heart of PLLs.