These days, having a little computer in your pocket is par for the course. But forty years ago, this was a new and high tech idea. [The 8-Bit Guy] has a great video covering the state of the art in pocket computers and personal digital assistants from the 1980s and 1990s. You can see the video below.
There are a lot of familiar faces on the video including the Radio Shack pocket computers, Palm Pilots, and some more obscure machines of varying quality.
It might impress you to know that the Radio Shack TRS-80 PC-1 pocket computer actually had two CPUs. Of course, each CPU was a 4-bit processor running at 256 kHz, so maybe not as impressive as it sounds. Still, what a marvel in its day, programming BASIC on a 24-character LCD.
Continue reading “A Computer In Your Pocket, 1980s Style”
Before RadioShack decided the best business model for an electronics store was to harass its customers into buying overpriced batteries and cellphones, it was a great one-stop shop for most discrete components, knobs, resistors, radio equipment, and even a popular computer. That computer, the TRS-80, is a popular one in the retrocomputing world and if you can’t get original parts to restore one, you can always build your own clone.
This build comes to us from [Glen] aka [glenk] who is known for retrocomputing builds like this classic PET we featured a little over a year ago, and this TRS-80 is his latest project. He really gets into the weeds on the hardware, too. This isn’t an FPGA or Raspberry Pi running a TRS-80 on lookalike hardware. [Glen] has completely redesigned the computer from the ground up using modern CMOS components in order to make a modern, perfectly functional replica of the RadioShack classic.
Because of the level of detail [Glen] goes into, this one is a must-read for anyone interested in computing hardware (as opposed to the software, which you could learn about through a more simple emulator) and retrocomputing in general, and also brings most of us back to a more nostalgic, simpler time where a trip to RadioShack was fun and interesting.
Continue reading “TRS-80 Clone Uses Modern Parts”
Sometimes for a retrocomputing enthusiast it can be challenging to see a surviving machine gutted and used for another purpose. But in the case of [Tom Pick]’s Radio Shack TRS-80 based Steam Machine PC we can forgive him, because it began with a very unpromising machine that had most definitely seen better days.
The TRS-80 in question is a Model III, the all-in-one console device with a numerical keypad, CRT monitor, and dual 5.25″ floppy drives built in. This provided plenty of space for the components of a modern PC with a 12″ LCD monitor. The PC itself is a run-of-the mill 2.6 GHz Pentium and nothing exceptional, but its input devices are of note. The keyboard is a Red Dragon mechanical item which has been made to look the part in place of the old Radio Shack item with a set of custom colour-coded keycaps, while the pointing device in a particularly neat touch is a modern Radio Shack-branded mouse. The boot screen is the proper Radio Shack logo from the TRS-80’s heyday, meaning that if you didn’t know any differently you might think this was meant to be. Sadly the two floppy drives are unconnected, though we’re sure it would be possible to make a modern PC see them for a bit of 360k storage goodness.
We don’t see as many projects featuring the TRS-80 series as we should, and the model III is a particular rarity. Far more common in these pages is the portable Model 100, most recently gaining a cellular connection.
China, we’re told, can make anything. If you need some PCBs in a few weeks, there are a few factories in China that will do it. If you need a nuclear reactor, yep, there’s probably a factory in China that’ll do it because nuclear reactors are listed as one of the items facing new tariffs when imported into the United States. No, I am not kidding. What about LCDs? What about old-school character LCDs? Is it possible to find a factory in China that will make you the LCD you want? That’s what [Robert Baruch] will find out, because he’s repairing an old computer with new parts.
The object of this repair and restomod is a TRS-80 Pocket Computer (PC-1), otherwise known as the Sharp PC-1211. It looks like a calculator, but no, it’s a legitimate computer you can program in BASIC. [Robert] bought this computer for a bit more than $5 on eBay ‘for repair’, which means the zinc-air battery was dead, and unfortunately, the LCD was shot. The LCD technically works, but it just doesn’t look good. Sometime in the last thirty years, moisture got in between the layers of glass, polarizing film, and liquid crystal. This is not unique to [Robert]’s unit — a lot of these PC-1s have the same problem, many of these broken seals rendering the computers themselves useless.
This is an ancient computer, and replacements for this LCD are impossible to find, but because the Sharp PC-1211 is well documented, it is possible to find the datasheet for the original display. With that, it’s just a question of finding an LCD manufacturer that will do it. So far, the costs look good — $800 USD ($300 for tooling and 10 samples, $500 for another 200 LCDs) is what it’ll take to get a few units. [Robert] already has a few people interested in repairing their own Pocket Computers. You can follow the eevblog thread here, or check out the video below.
Continue reading “Designing Custom LCDs To Repair Retrocomputers”
Around these parts, [Peter] is well-known for abusing the TRS-80 to do things it should never do. You can read Wikipedia on the TRS-80, you can look at Google Images, and you can browse the web. As with any retrocomputer, there are limitations for what you can do. To browse Wikipedia, [Peter] had to set up an AWS instance which translated everything and used serial to IP converters. It can be done, but it’s hard.
Now, after seeing a few interesting projects built around the ESP32, [Peter] built a network card for the TRS-80. It’s called the trsnic, and it’s a working network card for almost all the TRS-80s out there, with the eventual goal of supporting the TRS-80 Model I / II / III / 4 / 12 / 16 / 16B and 6000.
The idea for the trsnic comes from [Arno Puder]’s RetroStoreCard, a device that plugs into the TRS-80 Model III and connects it to a ‘personal cloud’ of sorts that hosts and runs applications without the need for cassettes or floppys. It does this with an ESP32 wired up to the I/O bus in the Model III, and it’s all completely Open Source.
[Peter] took this idea and ran with it. Thanks to the power found in the ESP32, real encrypted Internet communication can happen, and that means HTTPS and TLS.
Right now, documentation for the trsnic is limited, but the project does exist and building it is as easy as stuffing some headers and DIP sockets in a PCB and soldering them on. There’s a bit of work to do on the ESP32 code, but if you’re looking for a network card for your Trash-80, this is the one that works now.
We’ll forgive you if you were busy in the ’80s, and missed the TRS80 Model 100. It was a portable version of the original, ran on four AA batteries, and even had an integrated acoustic coupler which proved handy for workers on the go. However, time is rarely kind, and [Trammell] had come across a non-functional example for just $20. It was time to bring this relic screaming into the modern age.
The motherboard was toast, so [Trammell] decided to wire up a Teensy++ directly to the Hitachi HD44102 display driver chips. Being an older LCD, the display needed a negative bias voltage, so a few diodes, capacitors and a PWM line stepped in to create a charge pump. There was no character generator on board, so the heavy lifting is all handled by the Teensy itself. The keyboard was a simple enough matrix design, so that was wired straight up.
[Trammell]’s work with this iteration got as far as acting as a USB serial terminal, and there was some work done on VT100 emulation. However, according to Twitter, the next stage involves an iCE40 FPGA and some music with which we’re altogether too familiar.
[Trammell] owns a working Model 100, too – employed in some modem experiments, no less.
If you were lucky enough to own one of the crop of 1980s 8-bit computers, did you ever pause to consider how its graphics worked? Maybe the really expensive ones had dedicated CRT controller subsystems akin to the graphics cards you’d have found on a PC a few years later, but most of the affordable models would have stopped what they were doing every TV line interval period to allow access to their memory for their graphical output to be created.
The RC2014 retrocomputer dodges all this, by using a serial port as an interface and expecting your serial terminal to handle the screen. But what if it could produce its graphics directly as the machines of old did? [Rob Dobson] set out to achieve this, and not only did he succeed but he also found a way to directly emulate some classic machines along the way.
His RC2014 card which he calls the Bus Raider started as an attempt to use a Raspberry Pi to commandeer the RC2014 memory and read it via its GPIO lines, interpreting the graphics for its own screen. But even with bare metal Pi programming he couldn’t achieve the complex timing required for that, so he took an alternative approach. He ended up with an ESP32 that emulates a custom part of the RC2014 memory map and generates a display from there. Having created a custom memory map and hardware emulator for his RC2014, he then had the revelation that he could emulate any memory map, and thus he could make the retrocomputer perform natively as though it were any of a selection of classic micros. So far as well as a straight serial terminal he has a Sinclair ZX Spectrum and a Radio Shack TRS-80 running, as well as his own custom Z80 environment. And since the ESP32 also has WiFi, he can even connect to it through that medium.
Retrocomputers are something in which you might think that everything possible would already have been done, but projects like this one never cease to amaze us with their ingenuity. If you’d like to read more about the RC2014, we reviewed an earlier model back in 2016.