Where did you buy the parts for your first electronic project? That’s a question likely to prompt a misty-eyed orgy of reminiscences from many Hackaday readers, if ever we have heard one. The chances are that if you are from North America or substantial parts of the English-speaking world, you bought them from a store that was part of the Radio Shack empire. These modestly sized stores in your local mall or shopping centre carried a unique mix of consumer electronics, CB radio, computers, and electronic components, and particularly in the days before the World Wide Web were one of very few places in which an experimenter could buy such parts over the counter.
Sadly for fans of retail electronic component shopping, the company behind the Radio Shack stores faltered in the face of its new online competition over later years of the last decade, finally reaching bankruptcy in 2015. Gone are all but a few independently owned stores, and the brand survives as an online electronics retailer.
The glory days of Radio Shack may be long gone, but its remaining parts are still capable of turning up a few surprises. As part of the company’s archives they had retained a huge trove of Radio Shack products and memorabilia, and these have been put up for sale in an online auction.
There is such a range if items for sale that if you are like us you will probably find yourself browsing the listings for quite a while. Some of it is the paraphernalia of a corporate head-office, such as framed artwork, corporate logos, or strangely, portraits of [George W. Bush], but the bulk of the collection will be of more interest. There are catalogues galore from much of the company’s history, items from many of its promotions over the years including its ventures into sporting sponsorship, and numerous examples of Radio Shack products. You will find most of the computers, including a significant number of TRS-80s and accessories, tube-based radios and equipment from the 1950s, as well as cardboard boxes stuffed with more recent Realistic-branded items. There are even a few retail technology dead ends to be found, such as a box of :CueCat barcode readers that they evidently couldn’t give away back in the dotcom boom.
If you are interested in any of the Radio Shack lots, you have until the 3rd of July to snap up your personal piece of retail electronic history. Meanwhile if you are interested in the events that led to this moment, you can read our coverage of the retail chain’s demise.
Thanks [Mark Scott] for the tip.
What do you do when you decide that running CP/M on a Commodore 128 with a 5.25″ drive “Isn’t CP/M enough”? If you are [Chris Osborn], you reach for your trusty TRS-80 Model II, with its much more CP/M-appropriate 8″ drive.
There was one small snag with the TRS-80 though, its keyboard didn’t work. It’s a capacitive device, meaning that instead of each key activating a switch, it contains a capacitive sensor activated by a piece of aluminized Mylar film on a piece of foam. Nearly four decades of decay had left the foam in [Chris]’s example sadly deflated, leaving the keys unable to perform. Not a problem, he cast around for modern alternatives and crafted replacements from a combination of foam weather strip and metalized gift wrap.
Care had to be taken to ensure that the non-metalized side of the gift wrap faced the capacitive sensor pads, and that the weather strip used had the right thickness to adequately fill the gap. But the result was a keyboard that worked, and for a lot less outlay and effort than he’d expected. We would guess that this will be a very useful technique for owners of other period machines with similar keyboards.
What is CP/M, I hear you ask? Before there was Linux, Windows, and MacOS, there was DOS, and before DOS, there was CP/M. In the 1970s this was the go-to desktop operating system, running on machines powered by Intel’s 8080 and its derivatives like the Zilog Z80 in the TRS-80. When IBM needed an OS for their new PC they initially courted CP/M creators Digital Research, but eventually they hired a small software company called Microsoft instead, and the rest is history. Digital Research continued producing CP/M and its derivatives, as well as an MS-DOS clone and the GEM GUI that may be familiar to Atari ST owners, but were eventually absorbed into Novell in the 1990s.
We’ve featured a few capacitive keyboards here at Hackaday before, including this similar repair to a Compaq from the 1980s, and this look at a classic IBM terminal keyboard.
When you live in a totalitarian, controlled and “happy” society, and you want to be a hacker, you have to hack the social system first. Being just an engineer doesn’t cut it, you have to be a hypocrite, dissident and a smuggler at the same time. That’s the motto of my personal story, which starts in Yugoslavia, and ends in Serbia. No, I didn’t move, I’m still in Belgrade, only the political borders have changed.
Half a century ago, when I was in elementary school, I discovered the magical world of HAM radio. I became a member of two amateur radio clubs, passed all exams and got my licence and callsign, which was YU1OPC. I was delighted, but after five years, the party was over. What happened? Well, one day the police paid a visit to all registered owners of CB Band equipment and simply took that equipment away. No one knows why they did it, but it was probably off the books, as we never got any written confirmation, and no one ever saw their equipment again.
Continue reading “Hacking the Digital and Social System”
[danjovic] is a vintage computer enthusiast and has several old computers in his collection. Among them are a couple of TK-85 units – a ZX81 clone manufactured by Microdigital Eletronica in Brazil. The TK-85 outputs a monochrome video output. And when [danjovic] acquired a SyncMaster 510 computer monitor, he went about building a circuit to “colorise” the output from the ZX81 clone (Portuguese translation).
The SyncMaster 510 supports 15kHz RGB video refresh rate, so he thought it ought to be easy to hook it up to the TK-85, which internally has the video and composite sync signals available. So, if he could lower the amplitude of the video signal to 0.7Vpp, using resistors, and connect this signal to one of the primary colors on the monitor, for example green, then the screen should have black characters with a green background.
Before he could do any of this, he first had to debug and fix the TK-85 which seemed to be having several age related issues. After swapping out several deteriorating IC sockets, he was able to get it running. He soldered wires directly to one of the logic chips that had the video and sync signals present on them, along with the +5V and GND connections and hooked them up to a breadboard. He then tested his circuit consisting of the TTL multiplexer, DIP switches and resistors. This worked, but not as expected, and after some digging around, he deduced that it was due to the lack of the back porch in the video signal. From Wikipedia, “The back porch is the portion of each scan line between the end (rising edge) of the horizontal sync pulse and the start of active video. It is used to restore the black level (300 mV.) reference in analog video. In signal processing terms, it compensates for the fall time and settling time following the sync pulse.”
To implement the back porch, he referred to an older hack he had come across that involved solving a similar problem in the ZX81. Eventually, it was easily implemented by an RC filter and a diode. With this done, he was now able to select any RGB value for foreground and background colors. Finally, he built a little PCB to house the multiplexer, DIP switches and level shifting resistors. For those interested, he’s also documented his restoration of the TK-85 over a four-part blog post.
1977 was a special year for computing history; this year saw the release of the 8085 following the release of the Z80 a year before. Three companies would launch their first true production computers in 1977: Apple released the Apple II, Commodore the PET 2001, and Tandy / Radio Shack the TRS-80 Model I. These were all incredibly limited machines, but at least one of them can still be used to browse Wikipedia.
[Pete]’s TRSWiki is a Wikipedia client for the TRS-80 Model I that is able to look up millions of articles in only uppercase characters, and low resolution (128×48) graphics. It’s doing this over Ethernet with a very cool Model I System Expander (MISE) that brings the lowly Trash-80 into the modern era.
The MISE is capable of booting from CF cards, driving an SVGA display and connecting to 10/100 Ethernet. Connecting to the Internet over Ethernet is one thing, but requesting and loading a web page is another thing entirely. There’s not much chance of large images or gigantic walls of text fitting in the TRS-80’s RAM, so [Pete] is using a proxy server on an Amazon Web Services box. This proxy is written in Java, but the code running on the TRS-80 is written entirely in Z80 assembly; not bad for [Pete]’s first project in Z80 assembly.
If you have an old computer you’d like featured, just load up the retro site, snap some pictures, have them developed, and send them in.
The lowly TRS-80 doesn’t get much love in most circles; it’s constantly overshadowed by the popularity of the Apple II or computers that had graphics that weren’t terrible. For [Mike Loewen]’s VCF exhibit, he’s turning his TRS-80 into something good with SD card disk drives and custom graphics adapters.
The -80 in question is a Model 4, the fancy all-in-one version that could run CP/M. The disk drives in this computer were replaced with half-height 5 1/4″ drives, the 200ns RAM was replaced with 100ns RAM and modified to get rid of the wait states, and a hard drive is emulated on a SD card adapter thanks to an add-on from [Ian Mavric].
[Ian] is somewhat prolific in the world of TRS-80s; he reverse engineered the original hi-res graphics board and reimplemented it with video RAM chips of a more modern vintage.
Continue reading “VCF East X: The Not Trashy Eighty”
While the vintage computer festival in Wall, NJ had just about every vintage app you could imagine – multiple varities of *NIXes, pre-Zork Dungeon, BASIC interpreters of all capabilities, and just about every game ever released for 8-bit Commodore systems – there was, perhaps unsurprisingly, a distinct lack of modern programs written for these retro systems. Yes, despite there being people still curled up to keyboards and writing games for vintage systems, modern software was a strange oddity last weekend.
There were two wonderful exceptions, however. The first was Fahrfall, a game for the TRS-80 Color Computer. We’ve seen Fahrfall before when [John Linville] wrote it for the 2012 RetroChallenge Winter Warmup. The game itself is a re-imagining of Downfall for the Atari Jaguar, with the graphics scaled down immensely. The basic idea of the game is to jump down, ledge to ledge, on a vertically scrolling screen. Hit the walls or the bottom, and you’re dead. It’s a great game that probably would have sold well had it been a contemporary release.
Next up is a rather impressive port of Flappy Bird for the TI-99. The video does not do this game justice, although part of that might just be the awesome Amiga monitor used for the display. This game was brought in by [Jeff Salzman] of Vintage Volts who isn’t the author of the game. Honestly, the video doesn’t do the graphics any justice. It really is a great looking port that’s just as addictive as the Android/iDevice original.
Continue reading “VCF East: Old Computers, New Games”