https://community.element14.com/technologies/embedded/Embedded systems programming, design and products; also microcontrollers, programmable logic, memory, DSP and controllers. en-USTelligent Community 12https://community.element14.com/technologies/embedded/m/managed-videos/151212Fri, 17 Apr 2026 17:59:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:5c7f49e7-55c3-40c3-9932-9145b74fad38CatwellI always wanted to design my own operating system, so I finally sat down and did it. NostOS is intentionally not compatible with CP/M, but it's CP/M-like. NostOS features an inherently rommable operating system. There's an 8 KB kernel and an 8 KB ...https://community.element14.com/technologies/embedded/b/blog/posts/new-operating-system-for-the-z80-cpu---wowFri, 17 Apr 2026 17:58:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:dadb7b36-c331-49e4-9ffc-cf76629dc08eCatwellScott Baker’s RC2014 system featuring the Z80, CompactFlash, floppy, VFD, ACIA, and speech synthesizer. (Image Credit: Scott Baker ) We all know the Z80 system has a long list of operating systems available, and now, there’s another one. Scott Baker developed the open-source NostOS , the most recent OS for the RC2014 and similar Z80 and 8080-based systems. According to Baker, the NostOS is designed for nostalgia (think CP/M or HDOS) and retro computer fanatics in mind. He says that NostOS isn’t compatible with CP/M binaries or disks, and intentionally designed it that way. However, it still boasts some impressive features and functionality. NostOS runs entirely on ROM and can generate multiple ROM images. Each one is tailored to a specific UART, storage device, and memory configuration. It’s also compatible with 32 KB RAM/32 KB EPROM and 512 KB ROM/RAM banked memory, similar to RC2014, Zeta2, and other classic SBC builds, to surpass the 16-bit limit. In addition, NostOS includes native support for serial devices, such as ACIA, SIO/2, SCC, and Z180-ASCI, as well as the WD37C65 floppy disk controller. Alternatively, if floppy drivers aren’t available, storage can come from the Intel Bubble Memory or CompactFlash devices. It even features driver support that loads at runtime for VFD and LCD displays. Along with that, the operating system supports the SP0256A-AL2 speech synthesizer with built-in text-to-speech capabilities. Baker didn’t leave the retro gamers hanging, either. He added classics like Pac-Man, Zork, Tetris, and Star Trek. Other notable games include Chess, Life, Eliza, and Maze. Though he warned us that the computer in the Chess game isn’t very good, so don’t expect grandmaster-level play. As for ported 3rd-party applications, he added Nascom Basic, Fig-Forth, and Zealasm (8-bit assembler). Baker also included native applications like APPEND, DEBUG, ED, HEAD, XSEND, XRECV, and FORMAT. User programs can also be loaded by the NostOS, and they carry built-in relocation data. This allows them to move effortlessly between 32 KB and 512 KB NostOS systems while adjusting to memory shifts caused by TSRs. Baker included every technical specification in the GitHub documentation. He mentions that the NostOS should run on other CPUs like the 8080 or 8085. “Only Z80 is tested at the moment, but the code is written to be compliant with the 8080 instruction set only,” he wrote. www.youtube.com/watch Have a story tip? Message me here at element14.operating systemmakerhackopenembeddedz80osinnovationhttps://community.element14.com/technologies/embedded/m/managed-videos/151138Wed, 01 Apr 2026 15:04:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:0c7e6b6b-ee74-4d64-8a83-c9bb0ffa8cd3shabazhttps://community.element14.com/technologies/embedded/b/blog/posts/esp32-cheap-yellow-display-cyd-guide-with-a-jellyfish-exampleSun, 29 Mar 2026 18:15:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:b373b718-282b-48fa-9ac9-01f6c8638b5ashabazTable of Contents Introduction CYD Features Is It Any Good? CYD Connections Reference RGB LED Micro SD Socket UART and BOOT pin Audio Output Spare Input/Output Connections Touch Interface TFT Screen, Backlight and Light Sensor (Light Dependent Resistor) Install VS Code, and PlatformIO Extension Download the Jellyfish Project Open the Project Folder in VS Code Build the Project Uploading Firmware to the Board Summary Introduction The Cheap Yellow Display (CYD) is a very low-cost board with a 2.4” RGB TFT screen on one side, and an ESP32 module on the other! The formal name is ESP32-2432S028 but it’s known as the CYD for self-explanatory reasons. I recently saw a project on Hackaday.io (a site I usually ignore, because most projects documented there are incomplete, usually missing schematics or code) and was happy to see the author had provided a GitHub repository link to the code . The project used the CYD, and I thought it would be a nice gift for my little niece. https://youtu.be/K31UgdS-Uqc This blog post describes the CYD, the connections present on it, and how to go about using the CYD! It's a very short process; about an hour from start to finish. In brief, using the CYD entails connecting it to the PC using the supplied USB cable, and then in terms of the software environment, one can install Visual Studio Code (VS Code) , and then withing that select to install an extension called PlatformIO, and that will provide task items in a list, that can be clicked to build code, and upload it to the board. All the steps are described further below. The example project will be the jellyfish project as mentioned above. CYD Features The CYD diagram here shows what’s on the board, and it can be used as a pinout reference when coding. The component side has an ESP32 module ( PDF Datasheet ) with approximately 4 Mbyte Flash, and about 520k RAM, 2.4 GHz wireless LAN capability, and Bluetooth Low Energy (BLE). There is also an RGB LED, a 1W audio amplifier, Micro SD card socket (very useful for logging or configuration files for projects) and very few spare GPIO connections brought out to a couple of connectors. The board I purchased had both USB-C and Micro-USB connectors, but they are attached to the same signals, so both must not be used simultaneously. Power entry can come from either the connector labelled P5, or either of the USB sockets. Software can be debugged using the USB Serial interface present on the USB connectors, or using an external USB-UART adapter connected to P5. There are boot and reset buttons, which are needed during device programming. The other side contains just the TFT touchscreen, and a little light sensor (Light Dependent Resistor). Is It Any Good? The board arrives with a USB-C to Type A cable (a USB-C to USB-C cable will not work), and a short 4-wire cable if required for any external UART or GPIO connections, and a little plastic stylus, although the touchscreen can be pressed with fingers too. The 2.4” 240 x 320 resolution TFT screen is very basic, the contrast is quite poor, but that’s to be expected at such a low price. I think it is very good value for money, and the board can be used for user interfaces (for example). The board I purchased has space for an additional Flash chip to be installed, but that was not fitted on the board; the only Flash memory present is that inside the ESP32 module. CYD Connections Reference There isn’t an official schematic, but it’s possible to figure out the connections. Here they are! RGB LED There is a large RGB LED near the ESP32 module. The GPIO pins need to be pulled low to turn on the LEDs. GPIO# Connection 4 Red Cathode 16 Green Cathode 17 Blue Cathode Micro SD Socket The Micro SD interfaces uses a Serial Peripheral Interface (SPI): GPIO# Connection 5 *CS 23 MOSI 19 MISO 18 SCLK UART and BOOT pin The serial interface connects to both the USB connector (via a CH340C USB-to-Serial converter ) and to a board connector P5, through 100 ohm resistors. A supplied cable can be used. ESP32 Signal Name Description RDX0 ESP32 Board Rx, and P5 pin 3 (Blue wire) TXD0 ESP32 Board Tx, and P5 pin 2 (Yellow wire) The detail for connector P5: P5 Pin Description 1 5V Board Power Input (Red wire) 2 ESP32 Board Tx (Yellow wire) 3 ESP32 Board Rx (Blue wire) 4 GND (Black wire) The ESP32 boot pin is GPIO#0, and it is connected to a push-button to the left of the ESP32. It may need to be held down, while tapping RST, when programming the board. The boot pin is also connected to the CH340C chip to try to automate the boot control from the PC during device programming, but it didn’t work for me, and I had to use the push-button. Audio Output One pin (GPIO26) is wired to an SC8002B audio amplifier IC, which is a 1W 8-ohm bridge-tied-load amplifier, wired to a 2-pin connector labelled SPEAK. The connection is through an RC filter. GPIO26 can be operated in a DAC mode (peripheral signal name DAC_2) or perhaps PWM could be performed (no idea). Spare Input/Output Connections A few GPIO pins are brought out to two connectors, called CN1 and P3. CN1: CN1 Pin Connection 1 3.3V 2 GPIO27 3 GPIO22 (also present on conn P3) 4 GND P3: P3 Pin Connection 1 GPIO21 2 GPIO22 (also present on conn CN1) 3 GPIO35 4 GND Touch Interface There is a resistive touch layer on the TFT screen, and it can be pressed by fingers or using the supplied stylus. The touch interface uses an XPT2046 IC ( PDF datasheet ) in a TSSOP package. GPIO# Connection 36 Touch *PENIRQ (input to ESP32) 32 Touch DIN (MOSI output from ESP32) 39 Touch DOUT (MISO input to ESP32) 25 Touch DCLK (output from ESP32) 33 Touch *CS (output from ESP32) TFT Screen, Backlight and Light Sensor (Light Dependent Resistor) The TFT screen uses an ILI9341_2 software driver ( Driver IC PDF datasheet ). The reset pin is hard-wired to the board reset circuitry, i.e. a capacitor keeps it low at power-up briefly. The Light Dependent Resistor (LDR) is attached to GPIO pin that may need a pull-up configured in software, perhaps. GPIO# Connection 14 TFT SCLK 2 TFT DC (Data/*Command) 15 TFT *CS 13 TFT MOSI (ESP32 Output) 12 TFT MISO (ESP32 Input) 21 TFT Backlight PWM (High = ON) 34 (ADC1_CH6) Light Dependent Resistor to GND Install VS Code, and PlatformIO Extension To get going with the CYD, first install VS Code . Then, install the PlatformIO extension by following the steps shown in this screenshot: Then, restart VS Code! Later, you might see Installing PlatformIO Core messages at the bottom-right of the VS Code window at some point, such as when a project folder is opened. If you see that, let it complete, and then click Reload Now . Download the Jellyfish Project Create a general projects folder, for instance, C:\DEV\projects Ensure you have git installed (install it using https://git-scm.com/download/win ) Open PowerShell , navigate to that general projects folder, and type the following, which will create a folder called denki-kurage and the source code will be placed there by the command: git clone https://github.com/likeablob/denki-kurage.git Open the Project Folder in VS Code Go to File->Open Folder and select the downloaded project folder denki-kurage. Click to trust the folder if prompted. You can view the code, by clicking on the left side explorer view, for instance, click on src and select main.cpp . The code will appear in the main pane. You should see a load of messages appear in VS Code at the lower-right, regarding PlatformIO performing project configuration operations. It may take a quarter of an hour or so to complete, even on a fast PC, and it may well sit at 100% for quite a while, seemingly doing nothing, but let it complete. I wasn’t impressed by PlatformIO’s poor status messages and the crazily long install time. Eventually you should see this: Build the Project Click on the PlatformIO icon on the left side icon bar, it looks like an alien head. Then click on cyd->General and then select Build . You should see a load of messages appear at the bottom, followed by Success messages. Uploading Firmware to the Board Plug in the USB cable into to the board and into your PC. You should hear a Windows device installed sound after a few seconds. Windows Device Manager will show a port installed, in my case, it was COM3 but the number will vary. The display on the board should be lit up, and may display an image that is part of any factory firmware that may be in Flash memory. Look at the back of the board, and locate the two buttons. The top one is labelled RST (Reset) and the one below it is labelled BOOT . The plan will be to click on Upload in VS Code, and then when you see a Connecting… message appear, quickly press down BOOT, and while holding it down, press and immediately release RST. Then you can release BOOT. What this does, is essentially ensure that BOOT is pressed during a board reset. Click on cyd->General->Upload , and notice the Connecting… text at the bottom: Now, as soon as that text appears, hold down the lower button (BOOT), then tap the top button (RST) and then release BOOT. You should see some uploading messages appear, followed by Success messages: Take a look at the LCD on the board, and a jellyfish should be present! Tap the jellyfish to change its colour. The jellyfish happened to be on a white background which I didn't like, so I edited the src/config.h file, to add the following line: #define CYD_INVERT_DISPLAY After that, I re-built and re-uploaded the firmware, and all was well. Summary The Cheap Yellow Display is a very low cost ESP32 microcontroller board with built-in touchscreen TFT. To get going with it, VS Code was downloaded, a PlatformIO extension installed, and then it was just a matter of clicking to build and upload any code. My board required the BOOT and RST buttons to be used during the code upload process. For next steps, I'd like to personalize the display, and maybe get it to display the time at the bottom too, so it can function as a desk clock. For other unrelated projects, the code could perhaps be used as a template, for custom code. Thanks for reading!esp32platformioespressifCheap Yellow DisplayCYDESP32-2432S028https://community.element14.com/technologies/embedded/m/managed-videos/151081Sun, 29 Mar 2026 18:15:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:70969f06-d8f8-41fe-8165-b56ba702f71fshabazNot my project - see https://github.com/likeablob/denki-kurage for the details. I merely tried it out!