Oscilloclock.com

Handcrafted Scope Clocks with circle graphics

Tag: CRT

  • Z Core makes Blanking easy!

    Z Core makes Blanking easy!

    Here at the Oscilloclock lab there’s nothing more pleasurable than helping put a cherished vintage oscilloscope back into action. A new lease on life!

    That’s why when [Chris] reached out about his early 1970’s Conar 255 oscilloscope, wanting to convert it into a Vectrex gaming machine, we were naturally excited!

    The Conar 255 – “space age technology” per NRI Journal Nov/Dec 1973
    Beautiful vector graphics! Image by When Chemists Attack

    The original Vectrex was an incredibly cool device. Instead of the pixelated, blocky graphics of the time (anyone remember Pac-Man?), the system used vector graphics to draw smooth line-art images. Each vector was a straight line, or a smooth arc, connecting point A to B. Vectrex games were true works of art, and the original hardware is quite rare (and $$$)!

    Scopetrex

    The Scopetrex

    Well, [Chris] caught the vector graphics bug. But he decided to build a Scopetrex – a hardware emulator that allows you to run Vectrex games on an oscilloscope! He would theoretically just connect this to the Conar 255’s existing X, Y, and Z (blanking) inputs.

    We like this “minimum invasion, maximum re-use” approach. We’ve gone down this route numerous times to craft Oscilloclocks out of still-usable hardware. (The alternative? Install a full set of modern boards that drive the CRT directly.)

    Sample specimens of “minimum invasion, maximum re-use”

    [Chris] got down to planning. He could interface the X and Y inputs easily. But he faced a problem with the Z (blanking, or intensity modulation) signal, which instructs the scope when to turn the beam on and off:

    • The Scopetrex outputs a 5V DC digital blanking pulse.
    • The Conar requires at least 20V peak-to-peak blanking signal – and employs analog AC coupling.

    We’ve solved this mismatch problem before using various non-standard Oscilloclock board setups and complex hook-ins to the existing circuits. Always on a case-by-case basis, always unique.

    But now, at last, it was time to standardise the process. To make it easy. To adapt any vintage oscilloscope for digital blanking from a microcontroller! We proudly announce the next member of the Core family: The Z Core!

    The Z Core (in this case, a Z Core 2 Ex) …

    … joins the Oscilloclock Core family!

    How to install it

    Believe it or not, the minimal installation requires just 3 steps. For almost any oscilloscope! The Z Core effectively sits in series between your device’s blanking supply and the CRT grid.

    1. Snip the wire connecting to CRT grid.
    2. Connect the orange wire from the Z Core to the circuit side of the cut wire.
    3. Connect the green/yellow wire to the CRT grid.
    Snip.
    Connect!

    Visit the Z Core Support Page for lots more detail, including the obligatory warnings about high voltage. There are also details on how to connect the Z Core to your controller, detailed specifications, and some fun Q&A to help answer your most burning questions!

    The Z Core 2 Ex!

    We’ve wanted to develop a dedicated, built-for-purpose Z Core product for a very long time. This would consist of a single, miniaturised, low-power board called (ingeniously) a “Z Core Board”, and a few harnesses.

    But [Chris] didn’t want to wait for Oscilloclock labs to work through its ever-growing bucket list. Could we deliver within 2024?

    Yes!

    In past retrofits such as the Kikusui 537, we’ve taken spare boards that were originally designed for fully-featured Oscilloclocks, and partially populated them with only the necessary components to serve the blanking purpose.

    Partially populated Oscilloclock Power Board

    For [Chris], we found an almost fully-populated new-old-stock Power Board v2.27 and compatible CRT Board v1.21 lying around, just dying to be used and loved by someone. Older revision boards do tend to be set aside, as folks want the latest and greatest.

    With just a few minor modifications, this assembly shipped – and is now branded as the Z Core 2 Ex. The “2” refers to the Power Board’s major revision, and the “Ex” stands for “external blanking amplifier” (the function of the CRT Board). The Power Board rev2.2x series boasts an on-board blanking amplifier, but this section wasn’t already populated. What a great opportunity to use up a stock CRT Board!

    [Chris] will be happy. And we’ll keep up this spirit of minimising waste. You’ll see some other Z Core assemblies popping up in future: a Z Core 1 Ex, a Z Core 2, and potential variations of Z Core 3’s.

    And finally, one day, a genuine dedicated Z Core will be born!

    Why your scope needs a Z Core …

    Many old oscilloscopes simply don’t have any input for Z blanking, Z axis, intensity modulation, or cathode modulation. (Look carefully – it goes by many names!) Or, the input may be there, but it’s not compatible with a microcontroller. Why couldn’t the designers offer a decent interface?

    Well, it all has to do with high voltage! To get there, let’s cover how CRTs work in just three short sections:

    Gun

    A cathode-ray tube (CRT) has an electron gun that shoots electrons at the phosphor molecules on the screen. The electron beam is deflected by putting positive and negative voltages into electrodes placed in the CRT’s neck, and this is how patterns are drawn on the screen.

    This is how a CRT works. It’s awesome.

    But the electron beam has to be turned on and off, to break the pattern and make meaningful images on screen. This is known as blanking.

    Blanking

    Oscilloscopes, particularly, have to blank the beam when it goes back (retrace), from the right to the left again. If there were no blanking, you’d see a retrace line – wickedly cool for us artists, but devastatingly distracting for engineers who want to focus on the waveform itself!

    Retrace lines – arty but not desirable

    Oscilloclocks also rely on blanking. In Circle Graphics, where all figures are composed of lines and circles, blanking is crucial to creating meaningful segments. For example, a “C” is readily created from an ellipse “O”, simply by blanking the beam at just the right place!

    A blanking pulse kills the beam to get a ‘C’

    Grid

    CRTs are designed for blanking. There’s a valve-like electrode called a grid that sits inside the gun, just in front of the cathode where the electrons are spat out. If you inject a negative voltage into the grid (compared to the cathode), it repels those electron babies and sends them back where they came from. They don’t bombard the screen, and no more light is emitted. Blanking in action!

    Titillating! Electron field density is reduced when a negative voltage is applied to the grid!
    A fuller explanation – from The Bible
    The bible

    A change in grid voltage influences the field distribution of the first lens, and in so doing controls the emission from the cathode. For any fixed value of voltage applied to anode 1, it influences the number of electrons which pass through the cross-over point. Let us see how this comes about. In Fig. 5-17 is shown the field distribution in the first lens for two values of grid bias, O and -30 volts, and a fixed value of voltage on the plate.? It is clearly evident that with zero bias, the area adjacent to the cathode, between the cathode and the control-grid aperture, has a comparatively high positive potential as the consequence of the field between the control grid and the first anode. Under such conditions of zero grid voltage, it has been found that the area of the cathode which is emitting corresponds approximately to a projection of the area of the grid aperture; the maximum number of electrons are passing through the grid opening and the beam-current density is high.

    When the control grid is made negative by an increase in the bias, —30 volts in the illustration, the field distribution in the vicinity of the cathode is altered so that only the center of the emitting surface is behaving as an emitter. The other areas are influenced by the space charge and effectively are not emitting. The result is a reduction in beam density and several other related effects.

    High voltage

    So – back to the high voltage aspect. The cathode and grid are usually about 2kV (that’s right – 2,000 volts!) negative compared to the rest of the circuits. If you connected an external input signal directly to the grid, something would fry.

    Old-school oscilloscope designers took a very easy (read: cheap) solution: they stuck a high voltage capacitor between the grid (or cathode) and the external signal. This is called AC coupling because the capacitor blocks the DC voltage (2kV), and only couples through the AC (the fluctuating blanking) component of the signal.

    AC coupled external intensity modulation in the Conar 255 (L) and the Trio CS-1554 (R)

    This method of intensity modulation was fine for the regular, repeating signals observed in old TVs and radios. But it isn’t what [Chris], or so many millions out there like him, needs! They need to send through an irregular, sometimes not-fluctuating-at-all (i.e., DC) signal. They need DC coupling! And it has to be isolated – standing off more than 2kV!

    And there’s another voltage related problem: the grid has to go substantially negative with respect to the cathode, in order to completely block the electron flow. We’re talking 20-50V typically. This is not a voltage that a modern microcontroller board will deliver! This requires an amplifier.

    Summing it up

    So that’s it! Just three(?) words. We need an isolated DC-coupled amplifier. And it needs 2kV isolation with a 10x amplification factor.

    Welcome to the Z Core!

    Demo

    No assembly can leave our lab without being fully tested, and without a demonstration to ensure the customer’s utmost satisfaction. Here’s how the demo went:

    The host device: Trio CS-1554

    This venerable Trio (also branded as Kenwood) hails from around the same era as the Conar 255. It was attractive, had fairly good specifications, and a low(-ish) price tag, making it very popular both in Japan and overseas. Documentation is freely available and… more importantly, I had one lying around!

    Look carefully – it’s bulging and leaking!

    Of course this device is full of high voltage oil capacitors. These were effective in their day, but they break down over time, and things get very nasty. One particular HV capacitor in this unit was overheating to the point that the metal case had warped, and oil was even leaking out! Ick.

    A few modern-day capacitors hacked together replaced the leaky unit and saved the day. Onwards!

    The controller: Oscilloclock Connect

    Oscilloclock Connect

    As mentioned on the Availability page, one lovely Oscilloclock Connect unit is in stock. What better controller to verify the Z Core’s performance?

    The demo

    1. Connect Connect X output to Trio EXT HORIZ input at rear 1
    2. Connect Connect Y output to Trio CH1 vertical input
    3. Connect Connect Z output to Z Core input 2
    4. Connect Z Core outputs to Trio CRT grid and grid circuit (as shown in earlier section)
    1. Incompatibility! The Trio’s horizontal input seemed to want 10V peak-to-peak for maximum deflection (this is way off its original specs of 250mV/cm. I think it’s broken!) The Connect by default has only a 3V peak-to-peak output signal. The image is going to be small… ↩︎
    2. Trickery! The Connect by default is designed for a display device with a high-impedance Z input. The Z Core 2 Ex has a low-impedance input and 15mA drain at 5V. A temporary mod was needed in the Connect – which was promptly reversed after the test. ↩︎

    The result? A relatively clean image, albeit small! But the blanking works well. [Chris] was okay with the jagged edges and other blemishes; these are attributable to the Trio’s rough condition.

    Performance testing

    The Oscilloclock cave is not a precision testing laboratory. But we do have a significant collection of equipment, and every piece plays its part. In this case, we deployed a Hewlett Packard 1901A Pulse Generator.

    Choosing amongst a plethora of delightful old oscilloscopes, we stayed with the HP theme and used a venerable but still digital HP54615B.

    Yes! This HP has an undocumented Tetris game built in!

    The setup was simple:

    1. Set up the pulse generator for 100kHz square wave
    2. Set rise and fall times to minimum (around 10ns)
    3. Set output to 5V and connect to the Z Core’s input
    4. Connect a 20pF capacitor across the Z Core’s output, via the standard 200mm 22AWG harness
    5. Connect Ch1 of the scope to the input, Ch2 of the scope to the output

    Results

    MeasurementAssembly: Z Core 2 Ex
    Waveform base voltage-46V
    Rise time130 ±10 ns
    Fall time180 ±10 ns
    Propagation delay120 ±10 ns
    Effective bandwidthDC to 3 MHz
    (limited by rise/fall time)

    These results were satisfactory. But at some point, we’ll try the same with a Z Core 1 and a Z Core 3. And one day – a purpose-built pure Z Core. Stay tuned!

    In conclusion

    Well, that’s a wrap! The tested assembly has now shipped, and soon [Chris] will be able to try out a Scopetrex on his minimally-modified Conar oscilloscope. Fingers crossed!

    For more technical info, fun facts and Q&A, check out the Z Core Support page. And for a peek at our range of gadgets, be sure to check out the Gallery.

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  • OscilloChat!

    OscilloChat!

    Here’s a rare thing: Take the Toshiba ST-1612B Oscilloclock. Run the OscilloTerm VT52 terminal feature. Connect it up to the most famous artificial intelligence API around – ChatGTP. And what do you get? OscilloChat!

    Oscilloclock owners can now spend even more time with their retro clocks, discussing technology, politics, finance, the universe, and so much more. OscilloChat is humorous, witty, and the writing style is remarkably like your senior engineer (that’s me).

    At best, this is eerily entertaining. At worst, it’s annoying and entirely untrustworthy! Let’s see what happened when I asked: “What’s your favourite Oscilloclock?”

    To see this and more incredible videos in high resolution, check out Oscilloclock on YouTube!

    They don’t call it generative AI for nothing. Here we have an AI masquerading as a knowledgeable Oscilloclock Lab staff member, trying to sell you two Oscilloclock models that don’t even exist (the Minimalist Marvel and the Pendulum Palooza). And when challenged with “Is it real?” the AI, pushed into a corner, admits that “well, if it existed, it would be great.” It’s like dealing with a child.

    The fictitious “Pendulum Palooza” Oscilloclock

    But like we do with children, let’s give OscilloChat a chance! Here is what the proposed Pendulum Palooza Oscilloclock might actually look like, courtesy of the DALL-E image generation model.

    Dear readers, please draw your own conclusions!

    How it works

    The OscilloChat experiment setup is simple. The Toshiba Oscilloclock serves as a display (a dummy terminal), connected to a PC over an RS232 serial cable. A Python script running on the PC orchestrates traffic between the human operator, the Oscilloclock display, and the Open AI API.

    Interaction with the GPT AI

    The Python script first creates a session with the GPT AI. It then sends an instruction telling the AI what it is; i.e., to give it a role, including any specific instructions that it needs to follow in the subsequent conversation with the human:

    "You are an assistant at Oscilloclock.com. You will be asked questions about any topic. Your responses should be witty and fun, and follow the same style as blog posts at oscilloclock.com web site. Responses should be short (within 512 characters). You can ONLY use ASCII characters! Do NOT use non-ASCII punctuation marks. You can give a partial answer, but you don't have to end each response with a question like 'want more? just ask!'"

    Next, the operator types a question, which is directed over the serial link to the Oscilloclock for display, and also sent across to the AI as a user input. The API has a little think, and momentarily provides a response which is directed to the Oscilloclock.

    Until the session is closed (e.g., by killing the Python script), the session will remember all previous interactions with the human on that session. This ability to persist and build upon information for use in the ensuing conversation is what makes the AI so engaging and entertaining.

    Delay effects

    Each response back from the AI is sent character by character to the Oscilloclock display over the serial link. But even at 9600 baud (a turtle’s pace, by any modern standard!), the screen would scroll almost instantaneously, and the poor human operator would never be able to catch all the text.

    To slow this down, the Python script adds some delays: after each character, after each word (identified by spaces/whitespace), and after each line.

    CHARACTER_DELAY = 1/120
WORD_DELAY = 0.3
LINE_DELAY = 0.8

    Besides making things easy for the operator, it also gives a neat impression that the AI is thinking while composing its replies!

    Lissajous Watermark

    Plain character displays can get boring. Happily, Oscilloclock Lab has a solution for every kind of ‘boring’! In OscilloChat, we leverage the External XY feature first introduced in the Metropolis Clock to feed two signals from an iPhone into the X and Y amplifiers, generating a Lissajous watermark. What a way to make a dumb terminal display look smart!

    Dissecting the dribble

    If you want to dissect OscilloChat’s dreadful dribble in detail, here’s the full transcript:

    Hi, tell me about yourself!

    Ochat: Well hello there! Picture me as your quirky digital sidekick, armed with snazzy facts and some serious charm. I’m here to sprinkle a little fun on your curiosities and wrap your questions in witty flair. Think of me as the zany clock in your atticalways (sic1) ticking, forever colorful, and here to help you find the right time for any topic! So, what tickles your fancy today?

    What is your favorite oscilloclock?

    Ah, the grand question of favorites! While I can’t cozy up to a specific oscilloclock like a warm cup of cocoa, each one boasts its (sic2) unique charmlike (sic3) a carnival of timepieces! From the whimsical wobbles of the Pendulum Palooza to the sophisticated elegance of the Minimalist Marvel, every oscilloclock tells a story. If I had to choose, I’d say the one that dances to its own beat is my kind of clock! Ready to find your oscilloclock soulmate?

    Tell me more about the Pendulum Palloooza (sic) Oscilloclock… is it real?

    Ah, the Pendulum Palooza Oscilloclock (sic4) it sounds like a time-traveling festival, doesn’t it? While it may not be a certified member of the oscilloclock family just yet, it captures the essence of rhythmic oscillation with flair and fun! Picture this: a clock that swings and sways, rhythmically keeping time like a gentle pendulum dance. If only it existedwho (sic5) wouldn’t want to host a party where every tick-tock brought a new groove? Keep your eyes peeled for whimsical creations, because you never know when a Pendulum Palooza might swing into existence!

    Nice! thanks for the feedback

    Anytime, time traveler! I’m always here to sprinkle some fun on your quest for knowledge. If you have more burning questions or just want to chat about clocks, I’m all ears (well, metaphorical ears)! Keep ticking and tocking along with curiosity!

    1. Missing dash (technically an em dash, Unicode U+2014). This should read “… attic — always …” ↩︎
    2. Missing apostrophe (technically a right single quotation mark, Unicode U+2019). This should read “… it’s …” ↩︎
    3. Missing dash. This should read “… charm — like …” ↩︎
    4. Missing dash. This should read “… Oscilloclock — it ….” ↩︎
    5. Missing dash. This should read “… existed — who …” ↩︎

    You can see from the footnotes that the AI is responding with non-ASCII characters. These cannot be displayed (yet!) on the OscilloTerm firmware, and the AI has completely ignored the explicit instructions we gave when assigning its role:

    ... You can ONLY use ASCII characters! Do NOT use non-ASCII punctuation marks. ...

    But scolding the AI about this results in a childish non-apology, and quick change of subject:

    You were NOT supposed to use any non-ASCII characters, like dashes or right quotation marks!

    OChat: Oops! It looks like I got a bit carried away. No special characters from now on, I promise. Just plain ASCII fun ahead! What can I help you with today?

    (Note: this interaction was not included in the video.)

    What’s Next?

    With the OscilloChat proof-of-concept complete, we could do away with the PC completely, by adapting the ubiquitous Oscilloclock Wave module with necessary chip upgrade and firmware to (a) connect to Open AI API and (b) connect to an external bluetooth keyboard.

    Taking a step further, we could do an OscilloChat2 (OscilloChat Squared) where two OscilloChats interact with each other. What would the conversation be like? Where would it lead?

    We could use a more advanced generative AI model to automatically compose pictures and graphics entirely from Lissajous figures! (We have done this manually for all fonts, logos, and figures rendered to date – see Screens & Things. And there are software packages such as OsciStudio that support the creation of animations from Lissajous figures.)

    Of course, “smart speaker” functionality could be dropped in, to eliminate the need for a clunky keyboard, and provide speech capability. OscilloChat could become OscilloChatty! How cool? How annoying? You be the judge!

    All excellent items to add to the ever-growing list…

    Credits

    [Eric], the protagonist of the recently published Zork on an OscilloTerm!, noticed this at the end of the post:

    He just couldn’t help pick up the gauntlet! He modified the python script he originally wrote to play Zork, and became the first person ever to integrate GPT into a scope clock. Check out his own video of Zork and GPT running on his OscilloTerm!

    Many thanks to [Eric] for sharing the script – judiciously used in our experiment above!

    Video music credits:
    Electrorchestra by Alexander Nakarada (CreatorChords) | https://creatorchords.com
    Music promoted by https://www.free-stock-music.com
    Creative Commons / Attribution 4.0 International (CC BY 4.0)
    https://creativecommons.org/licenses/by/4.0/

    Like what you see? Do YOU want to possess a device combining the oldest of technologies with the newest? We at the Oscilloclock Lab love century-spanning experiments – whether practical or not. Stay tuned for more!

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  • Made in Japan. Then. Now.

    Made in Japan. Then. Now.

    Here at the Oscilloclock Lab, we see a lot of vintage Japanese oscilloscopes made in the 50’s to 70’s. Most were purely utilitarian and austere, with little aesthetic appeal.

    But this Toshiba ST-1612B is different. It’s cute, compact, and culture-rich. Just when we thought Toshiba had exhausted its artistic reserves with their stunning ST-1248D, they managed to come up with THIS. Wow…

    Oscilloclock’ed!

    We discovered our protagonist some years back – dirty, dusty, and destined for the trash heap. For aeons, it sat in stock, patiently waiting its turn.

    “Oh, when can I transcend test equipment mundaneness, and reach nirvana like my brethren?” screamed our protagonist.

    During our COVID-era hiatus, this unit’s pitiful wail fell on deaf ears. But with a strong recent recovery in parts availability, shipping routes, and other stabilizing factors, the Oscilloclock Lab has begun to thaw. Spring has arrived!

    And what better way to mark the occasion than to grant our Toshiba its wish?

    Done.

    And yes – it was made in Japan. Again.

    Exquisite exterior

    The case and knobs were in reasonably good condition and polished up very nicely…

    One knob is NOT original. Can you pick it?
    Class and style – even down to the model number plate at rear!

    Sadly, the leather carrying strap had seen better days. Yes, you read that correctly! This was designated as a portable oscilloscope, although it weighed in at more than 10kg, and had no battery supply!

    Nice leather. But was it really… portable?

    We love this adorable hatch compartment and secret patch panel. So utilitarian! Whole tribes of radio servicemen must have stashed their valuables here for safe keeping, before going away on holiday. Sadly, there was no jewellery or secret documents to be found in our unit…

    Take a look at this CRT hood. The phosphor screens in cathode-ray tubes are sensitive to external light, so many ‘scopes employed hoods or shades to keep ambient light out. This improves screen contrast for the lucky operator. Kudos to you if you can recognise the material used our Toshiba’s hood:

    Yes, it’s rubber. Solid rubber, with no metal tube inside. And while it’s a little banged up on the surface, it’s not disintegrating or brittle! It’s firm, yet still sufficiently flexible to support the CRT. And a little plastic polish did wonders. Good for another 60 years!

    Incredible internals

    Unlike many other scopes of the era, opening the case is easy. Just turn the latches with a coin, a single revolution. Voila!

    A nice complement of 12 tubes. Toshiba made them accessible for easy replacement

    As with its Toshiba brother and several other units crafted to date, we carefully installed amber LED lighting to simulate the original warm, gentle glow of electron tubes. This generates a beautiful, peaceful ambience.

    XY Input inspires!

    Avid readers may recall the XY Input feature first introduced in the Metropolis Clock, and included in several models since.

    This ST-1612B unit features a neat set of banana jacks in the rear hatch compartment, where the oscilloscope probes used to plug in. We repurposed them as X and Y channel signal input connectors.

    Driven by function generators, preamps, or even a mobile phone, we can explore an entirely different level of visual imagery!

    A function generator app
    A scene from “Planets” by Jerobeam Fenderson, played on the Toshiba

    A just-fit retrofit

    The ST-1612B was an engineering marvel. They packed an amazing amount of circuitry into a very limited space.

    But we needed to find space for two 100 x 80mm Oscilloclock boards. With legroom to isolate high voltage and provide circulation. And where controls can be reached. Not easy!

    Well, removing just a few bits and pieces* revealed two nice big cavities. And the best part? There were already access panels, complete with ventilation holes! What foresight those Toshiba designers had!

    A perfect fit! * Which bits were removed? Subscribe and await the “Making of…” post!
    In situ adjustments, made easy

    Control Freak

    You can’t beat vintage test equipment if you like controls: toggle switches, slide switches, rotary switches, potentiometers, trimpots – these guys have it all!

    But at Oscilloclock.com we target simplicity. There is only one control you need to turn the clock on and off, change faces, change settings, and generally play with your precious. Here, the focus control (焦点) gives you this authority. Who would ever guess?

    And for that most discerning owner, keen to install her beloved Toshiba ST-1612B in a moody environment such as a bar counter, living room, or bedroom: the intensity control (輝度) dictates the velocity of the electrons, as they smash haplessly into the phosphor. Okay, okay – it’s just a brightness control!

    Finally: we’ve wired up the frequency range switch (周波数範囲) to switch something on and off. We haven’t decided what. Let the Toshiba’s future owner decide its fate!

    What does this DO? You decide!

    Circle Graphics – with a caveat

    Oscilloclocks employ Lissajous figures to generate smooth, curvy artwork and characters on the screen. No pixelated, chunky graphics! But fastidious followers may spot that on the Toshiba ST-1612B’s screen, circles are not as perfect as advertised in our Circle Graphics post. And there are some jagged edges on the segments.

    This is because we’ve installed some prototype boards. These are early revisions of the yet-to-be-announced New Design, and the circle generator and deflection amplifier circuits aren’t quite right. But they’re too good to waste.

    Earlier prototypes of the New Design. – not quite right, but not wrong either!

    But we think it’s just fine! Tube amplifier enthusiasts understand: vinyl records and tube amplifiers actually sound better than digital devices, for some music. And our Toshiba here is 50 to 60 years old. A few kinky curves only add to its grace.

    The Toshiba ST-1612B Oscilloclock is in stock and ready to perform. Want to customize the screens? Decide on the secret switch’s secret? Work up some crazy XY effects? Check our Availability page!

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  • British Beauties

    New stash!

    These beautiful vintage British* CRTs have travelled the world over the last half century. And like homing pigeons, they have found their way at last to the Oscilloclock Lab!

    From left: SE5F/P31, DHM9-11, E10-12GP, SE4DP31, SE5F/P7. Brands: Brimar, GEC, Valvo

    Here, each piece of glorious glassware will receive the attention they have craved for years. They will be cleaned, rejuvenated, and start their latter-day lives performing retro electronic miracles for loving new owners from all over the world.
    * In fact, one of these CRTs was not made by a British manufacturer. Can you spot which?

    From Unloved to Loved

    This SE4DP31 is brand new, complete with protective paper sticker that was attached at the factory to protect the front glass. It’s never been loved. Such a waste, and we will certainly rectify that, as we have done previously for similar CRTs:

    Unloved…
    Doubly loved!

    Two is better than One

    These bad boys are dual-beam CRTs. They have two electron guns and two sets of deflection plates, meaning they can display two completely independent figures at the same time.

    Valvo E10-12GP
    GEC DHM9-11

    We used one of these in the custom Aftershock Clock, to overlay standard clock faces against a map hewn entirely from Lissajous figures. The intensity (brightness) and positioning of each beam can be independently adjusted to get the overlay effect just right!

    But importantly – the innards look so cool!

    Feeling Blue?

    We’ve talked before about rare blue phosphor finds. The newly landed Brimar SE5F/P7 will one day boast both presence and persistence:

    Presence. A strong physicality, tempered by a dappled blue light ambience
    Persistence. A visual expression of impactful new, awash with memories and traces of old

    With thanks…

    We dedicate this post and the promise of seeing these CRTs reincarnated to [Atif]. Many thanks for helping these pigeons find their roost!

    Are you in a state of cathode-ray rapture? Check out other CRT related posts, and see the Gallery to see examples of vintage glassware objects given new leases on life!

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  • Zork on an OscilloTerm!

    Zork on an OscilloTerm!

    Today’s story began with a mail from [Eric], who’d read up on the Oscilloclock 3-inch VGA Assembly and wondered if it could be used to create an old-school serial terminal display on a vintage oscilloscope CRT.

    Yes it could! In fact, the Oscilloclock Lab did one better. Instead of just a VGA display controlled by an external device, we developed native terminal firmware that accepts DEC VT52 compatible commands over a serial port, and renders all text and graphics using beautiful, curvy Lissajous figures.

    The stuff of dreams. The OscilloTerm Exo B7S4.

    Demonstrating basic terminal features, connecting to a PC via serial cable
    Oh, did I mention? It’s a clock as well!

    Zork, anyone?

    Ultimately, [Eric] just wanted to play Zork. And together we made it happen.

    The CRT. The Case.

    [Eric] wanted a sleek ‘skeleton’ look. His choice of a gorgeous B7S4 CRT, mounted in custom-machined cast acrylic supports, exposes all glassware and allows for a titillating rear viewing experience.

    CRT rings and supports – originally introduced for the Oscilloblock “Summer Dusk” edition

    And with a high-transparency cast acrylic case housing the electronics, the OscilloTerm Exo can be enjoyed from every angle!

    Astute readers may wonder about the 2.1 kilovolts of high voltage coursing through their innocent-looking device. Rest assured! All internal wiring is sealed off, and Oscilloclock CRT harnesses are hand-crafted with heavy insulation and precautions taken against dust, prying fingers, rats, and even salivating cats.

    Safety in action! Mil-spec connector (left); custom-designed acrylic cap on the CRT connector (right)
    An O-ring blocks dust from entering the CRT/socket gap (picture from the Oscilloblock)

    This case and CRT mounting variation is branded the Oscilloclock Exo, and has proven its wow-factor at several public exhibits to date. We certainly love it, and [Eric] did too!

    The Terminal.

    This post would never be complete without showing you what real serial terminals from the 1970’s looked like, and explaining what they actually did! Here goes…

    DECscope VT52 (1974)
    ClickRick, CC BY-SA 3.0, via Wikimedia Commons
    ADDS Regent 40 (1979)

    Terminals such as the above were physical input/output console devices, back when computers were the size of massive refrigerators, and the operator would sit remotely – at a desk in a separate area, or even a different room.

    Gregory Lloyd, CC BY 2.0, via Wikimedia Commons

    The terminal and the remote computer were connected via a cable, and would communicate each other by sending data back and forth across the cable; mainly terminal commands and ascii encoded text. Most commonly, a serial communication protocol was used to get the data safely from one end to the other – and hence the devices were known as serial terminals or even serial consoles.

    Amusingly, they were also called dumb terminals, because they had no computing power of their own; they were only extensions of the computer to which they were connected.

    The OscilloTerm Terminal.

    [Eric] wanted a special Oscilloclock that he could also operate as a terminal, connecting it to a remote computer via cable. The remote computer would control the display, using the same serial protocol and commands as an ancient dumb terminal.

    But an Oscilloclock is anything but dumb. [Eric] wanted to keep all the standard exciting screens and features of his Oscilloclock active, and only display the special Terminal screen when the remote computer started to send commands. Then, when the commands stopped, the Oscilloclock should go back to the screen it was on!

    His wish was our command! Here’s a demo of smart screen switching in the final product:

    Some technical Comments

    Naturally, the terminal emulator firmware was written entirely in assembly language.

    PIC18F2680 – the Oscilloclock workhorse.

    We use assembly mainly because the minimalist PIC microcontroller used in the current Control Board revision has only 64K ROM, and an unbelievable 3328 bytes (yes, BYTES!) of RAM. To squeeze all the lovely Oscilloclock features in, while driving Circle Graphics real-time processing, the code and memory space has to be clean, tight, and heavily optimized at the machine code level.

    Assembly. It’s the ONLY way to squeeze it all in!

    For even more technical details, such as the list of VT52 (and VT100) commands supported by the OscilloTerm, and the various configuration parameters that can be tweaked to make the terminal emulator more ‘friendly’ when connecting to a specific device, check out the Support page. Worth a visit!

    Why Zork? And HOW?

    Zork is an interactive adventure game. But it’s old. And it’s text-based, because it was run on computers long before fancy graphics capabilities were widely available. The player explores mysterious locations, solves puzzles, and collects treasures while avoiding various hazards and creatures. All by reading text and typing commands and responses!

    [Eric] was able to play Zork by loading the game’s Z-code into a Z-machine interpreter known as Frotz, on a PC connected to the OscilloTerm. But there was trickery involved!

    1. He had to recompile a version of dfrotz (the dumb terminal version of frotz) to remove the status bar and audio from the game.
    2. He needed to wrap the dfrotz output with a custom Python script to support the OscilloTerm’s 16×8 screen and simulate the required baud rate.

    But now that’s done, he can play any Infocom game that runs in dfrotz on his OscilloTerm!

    What’s next?

    Readers would probably agree that adding a generative AI feature would be incredibly cool. For example, the War Games feature is great, but the text on the screens is all pre-programmed. What if you could interact more naturally with your Oscilloclock?

    Another one for the list!

    Are you a serial serial terminal collector? Do you want to play Zork on the oddest device imaginable? Or, you fancy a clock in the Oscilloclock Exo range? Contact us and let us know!

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