Laser-Engraving Hairlines: When A Line Isn’t A Line

May 29, 2022 by Donald Papp 8 Comments

When is a line not a line? When it’s a series of tiny dots, of course!

The line is actually tiny, laser-etched craters, 0.25 mm center-to-center.

That’s the technique [Ed Nisley] used to create a super-fine, colored hairline in a piece of clear plastic — all part of his project to re-create a classic Tektronix analog calculator from the 1960s, but more on that in a moment.

[Ed] tried a variety of methods and techniques, including laser engraving a solid line, and milling a line with an extremely tiny v-tool. Results were serviceable, but what really did the trick was a series of tiny laser-etched craters filled in with a red marker. That resulted in what appears — to the naked eye — as an extremely fine hairline. But when magnified, as shown here, one can see it is really a series of small craters. The color comes from coloring in the line with a red marker, then wiping the excess off with some alcohol. The remaining pigment sitting in the craters gives just the right amount of color.

This is all part of [Ed]’s efforts to re-create the Tektronix Circuit Computer, a circular slide rule capable of calculating all kinds of useful electrical engineering-related things. And if you find yourself looking to design and build your own circular slide rule from scratch? We have you covered.

Lotus 123 For Linux Is Like A Digital Treasure Hunt

May 23, 2022 by Al Williams 84 Comments

Ever hear of Lotus 123? It is an old spreadsheet program that dominated the early PC market, taking the crown from incumbent Visicalc. [Tavis Ormandy] has managed to get the old software running natively under Linux — quite a feat for software that is around 40 years old and was meant for a different operating system. You can see the results in glorious green text on a black screen in the video below.

If you are a recent convert to Linux, you might not remember what a pain it was “in the old days” to install software. But in this case, it is even worse since the software isn’t even for Linux. The whole adventure started with [Tavis] wanting to find the API kit used to add plugins to Lotus. In theory, you could use it to add modern features to the venerable spreadsheet program.

The $395 software development kit wasn’t very common and there was also a Unix version of Lotus 123, but no one seemed to have a copy of that. [Tavis] eventually found someone who ran a circa-1990 BBS and had the data on tape. Turned out there was a hot copy of the SDK that he was able to use. But he noticed something else in the BBS’s list of files: the long-lost Unix version of Lotus!

An investigation found the installer used TD0 files which took some research. Luckily, a utility exists that can convert these to raw disk images. Inside was a very large object file. Apparently, in the days without dynamic loading, that object would be linked with plug in modules to install them.

The object file had all of its debugging information intact which shed a lot of light on the program’s internal operations. The old executables used COFF format but it is possible to relink it to an ELF file. Of course, it isn’t just that easy. [Tavis] wrote a small program to remove the old-style Unix system calls so they could be rerouted to Linux system calls. Some calls just pass through, but others need some translation due to differences in things like structure layout, sizes, and alignment.

In the end, it all worked but didn’t have a valid license. However, [Tavis] felt like since he did have a license and the software is abandoned, he was within his rights to crack the license check.

We are well-known abusers of spreadsheets around here. Of course, we aren’t the only ones.

Continue reading “Lotus 123 For Linux Is Like A Digital Treasure Hunt” →

Building Your Own 8088 XT Motherboard

May 21, 2022 by Al Williams 47 Comments

There was a time when an XT-class motherboard — like the old IBM PC with an 8088 CPU — was a high-tech accomplishment. Now, something like that is easily within reach of the average hobby lab. [Homebrew8088] did it, and it looks surprisingly simple, especially compared to what passes for a motherboard these days.

The board will take an 8088 or one of the NEC chips and by default sports 512 K of RAM, a few ISA slots, a PC speaker, a USB hard drive, and a PS/2 keyboard connector. The board will fit in an ATX case. Not bad. You can see a video of the board below.

In fact, the channel has a lot of related videos and the main site has many interesting topics, like driving an 8088 or 8086 from a Raspberry Pi. The GitHub site has design files for KiCad along with a lot of other information. Some of this will be interesting even if you are just trying to repair an old motherboard or would like to design a new ISA card.

If you want to know why the PC used an 8088 instead of an 8086, we just covered that. What are you going to do with an old XT computer? How about IRC?

Continue reading “Building Your Own 8088 XT Motherboard” →

HP-200LX Runs Website Like It’s The 90s

May 21, 2022 by Donald Papp 20 Comments

The HP-200LX palmtop was a fascinating machine for its time, and [Terrence Vergauwen] proves that its time is not yet over, given that one is responsible for serving up the website for Palmtop Tube, a website and YouTube channel dedicated to vintage palmtops.

All by itself a HP-200LX doesn’t have quite what it takes to act as a modern web server, but it doesn’t take much to provide the missing pieces. A PCMCIA network adapter provides an Ethernet connection, and a NAS contains the website content while networking and web server software run locally. Steady power comes from a wall adapter, but two rechargeable AA cells in the 200LX itself act as a mini-UPS, providing backup power in case of outages.

The HP-200LX was a breakthrough product that came just at the right time, preceding other true palm top computers like the IBM PC 110. In the early 90s, it was unimaginable that one could have a fully functional MS-DOS based machine in one’s pocket, let alone one that could last weeks on a couple of AA cells. It didn’t have some proprietary OS and weird ports, and that kind of functionality is part of why, roughly 30 years later, one is able to competently serve up web traffic.

A video overview of the machine and how it all works is in the video embedded below. And if you’re more interested in what an HP-200LX looks like on the inside? This video is all about taking apart and repairing a 200LX.

Continue reading “HP-200LX Runs Website Like It’s The 90s” →

The Thin-Film Flexible 6502

May 21, 2022 by Jenny List 13 Comments

While our attention is mostly directed towards ever smaller-integrated silicon circuits providing faster and faster computing, there’s another area of integrated electronics that operates at a much lower speed which we should be following. Thin-film flexible circuitry will provide novel ways to place electronics where a bulky or expensive circuit board with traditional components might be too expensive or inappropriate, and Wikichip is here to remind us of a Leuven university team who’ve created what is claimed to be the fastest thin-film flexible microprocessor yet. Some of you might find it familiar, it’s our old friend the 6502.

The choice of an archaic 8-bit processor might seem a strange one, but we can see the publicity advantage — after all, you’re reading about it here because of it being a 6502. Plus there’s the advantage of it being a relatively simple and well-understood architecture. It’s no match for the MHz clock speeds of the original with an upper limit of 71.4 kHz, but performance is not the most significant feature of flexible electronics. The production technology isn’t quite ready for the mainstream so we’re unlikely to be featuring flexible Commodore 64s any time soon, but the achievement is the impressive feat of a working thin-film flexible microprocessor.

Meanwhile, if you’re curious about the 6502, we took a look at the life of its designer, [Chuck Peddle].

How The IBM PC Went 8-Bit

May 17, 2022 by Al Williams 52 Comments

If you were around when the IBM PC rolled out, two things probably caught you by surprise. One is that the company that made the Selectric put that ridiculous keyboard on it. The other was that it had an 8-bit CPU onboard. It was actually even stranger than that. The PC sported an 8088 which was a 16-bit 8086 stripped down to an 8 bit external bus. You have to wonder what caused that, and [Steven Leibson] has a great post that explains what went down all those years ago.

Before the IBM PC, nearly all personal computers were 8-bit and had 16-bit address buses. Although 64K may have seemed enough for anyone, many realized that was going to be a brick wall fairly soon. So the answer was larger address buses and addressing modes.

Intel knew this and was working on the flagship iAPX 432. This was going to represent a radical departure from the 8080-series CPUs designed from the start for high-level languages like Ada. However, the radical design took longer than expected. The project started in 1976 but wouldn’t see the light of day until 1981. It was clear they needed something sooner, so the 8086 — a 16-bit processor clearly derived from the 8080 was born. Continue reading “How The IBM PC Went 8-Bit” →

LED Backlight Brings Vibrant Colors To Classic Palm PDAs

May 17, 2022 by Robin Kearey 10 Comments

Back in the days before the widespread adoption of smartphones, Palm was the market leader in PDAs. If you had one of those you’ll probably remember taking notes by writing those funky “Graffiti” characters and tapping your stylus onto, usually, a green monochrome screen. Some models even came with a battery-hungry backlight, but for the ultimate display experience you had to buy the Palm IIIc that came with a backlit full-colour display.

While revolutionary for its time, it was hampered by the technology available: the CCFL backlight took a second to start up, and even with the screen at full brightness it was rather dim by today’s standards. [TobleMiner] fixed these issues by designing a module to retrofit an LED backlight into your Palm IIIc.

The new backlight consists of a long, thin PCB designed to fit exactly where the CCFL tube sits. The PCB holds twenty-one white LEDs along with their current-limiting resistors to provide even illumination from top to bottom. A little MOSFET soldered onto the mainboard ensures the new backlight also correctly responds to the device’s “brightness” setting. [TobleMiner] recommends to remove the bulky CCFL transformer from the Palm’s mainboard to disable the corresponding circuitry and save a bit of weight.

The end result is understandably hard to capture on camera, but apparently gives the screen more vibrant colours. In any case, this might be a useful hack for anyone with a Palm IIIc with a broken backlight, though we can’t remember if that was a common issue. If you’re among those who still use original Palm devices, you might like this Palm-compatible Bluetooth keyboard. Don’t have a classic PDA? You can also run PalmOS on modern custom hardware.