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CP/M 8266 is a software emulator that runs a Z80-based CP/M 2.2 environment on an ESP8266 microcontroller. Its full-memory configuration targets 64 KB of emulated RAM and 15 simulated 250 KB floppy drives, but it gives up Wi-Fi to make that memory available. The project documents a separate Wi-Fi/Telnet build with substantially less RAM for CP/M programs.
What CP/M 8266 does
CP/M 8266 recreates a CP/M 2.2 computer in software; it does not turn the board into a physical Z80 machine. The project uses the ESP8266 as the host for the emulator and presents a CP/M system through a serial console. Its repository describes a full configuration with 64 KB of emulated RAM and 15 simulated floppy drives, each 250 KB. These are project configuration figures, not independent performance measurements. The CP/M 8266 repository contains the project’s source and build notes.
Memory and Wi-Fi trade off against each other
The project author reports that, under Espressif’s NONOS firmware, the heap remaining after Wi-Fi and TCP/IP load was below the 48 KB minimum target. The NoSDK approach provides more than 80 KB of heap for the 64 KB emulator, but does not provide Wi-Fi. This is the rationale for treating the two builds as different operating configurations rather than assuming the full-memory version can also use networking.
Full-memory configuration
The NoSDK configuration is the option for the project’s 64 KB target and 15 simulated floppy drives. It is the closer fit if the goal is to run CP/M software that expects the usual 64 KB memory space, but its described configuration sacrifices Wi-Fi.
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- Not only it is easy to program for this controller by using the CP2102-USB interface,but also unnecessary to press the flash and reset buttons before each flash operation.
- NodeMcu is an open source Lua based firmware for the ESP8266, ultra low cost wireless modules, development boards for rapid prototyping, integrated with ESP8266 chips.
- The ESP8266 has powerful on-board processing and storage capabilities, and can be integrated with sensors and other application-specific devices through its GPIOs.
- It is compatible with Arduino IDE,works great with the latest Mongoose IoT/Micropython.
- Modern Internet development tools can use the built-in API to instantly put your idea on the fast track.
Optional Wi-Fi and Telnet configuration
The README also documents a Wi-Fi build selected with BUILD=WIFI. According to the project author, it has about 36 KB of emulated RAM and one fewer floppy drive. The author reports roughly 5.9 KB free in MBASIC and says this configuration cannot run Turbo Pascal or Ladder. These compatibility and memory figures are project-reported, not independent benchmarks or guarantees for every board or build. The documented Telnet service listens on port 23 after the board obtains a DHCP address.
Hardware you need
The CP/M 8266 project page specifies one 4 MB ESP8266/NodeMCU board and says no other hardware is required. The best match is therefore an ESP8266 NodeMCU development board with 4 MB of flash. Check the exact board revision and flash size before buying: board designs and USB-to-serial implementations vary. A separate USB-to-serial adapter is only needed if the particular board does not include its own interface. The Hackaday.io project page lists the board requirement.
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Espressif’s ESP8266EX is a Wi-Fi system-on-chip with a 32-bit Tensilica L106 processor, on-chip SRAM, and interfaces including UART, SPI, SDIO, I2C, I2S, and GPIO. That describes the chip’s embedded capabilities; it does not independently establish that a given board revision will work with this project. See Espressif’s ESP8266 Hardware Design Guidelines, version 2.8 (2024.10) for chip and hardware design context.
Build and connect to the emulator
The repository documents a build based on ESP-Open-SDK and several utilities: z80asm, cpmtools, zip, and xxd. It notes that some Linux distributions provide xxd through vim-common. The instructions are repository documentation, so check the dependencies against your current operating system and toolchain rather than assuming the process remains turnkey.
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- Built-in Micro-USB, with flash and reset switches, easy to program
- Arduino compatible, works great with the latest Arduino IDE/Mongoose IoT/Micropython
- Data download access to the website: http://www;nodemcu;com
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Install ESP-Open-SDK and the listed project utilities, checking their availability and compatibility for your operating system.
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From the project source directory, run
make fullto compile and upload the documented full configuration.Rank #4
HiLetgo 3pcs NodeMCU GPIO Board ESP8266 NodeMCU Pin Out IO Out 1 into 2 for ESP8266 ESP-12E NodeMCU Development Board- NodeMCU GPIO expansion board
- NodeMCU can be connected through by Pin Header & Screw Terminal
- GPIO 1 INTO 2
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Connect to the board’s serial console with a terminal program configured for 8 data bits, no parity, and 1 stop bit (8N1). The README gives a standard speed range of 300 to 115200 baud; select a speed supported by your setup.
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For full-screen applications, configure the terminal for VT100 or ANSI emulation. Without a compatible terminal mode, screen-oriented programs may not display correctly.
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- Adopting the original brand new CP2102 chip with powerful functions, developing a complete set of tools for ESP8266.
- Built in Tensilica L106 ultra low power 32-bit micro MCU, with main frequency support of 80 MHz and 160 MHz
- Supports RTOS.
- Support many kinds of working modes like STAAP/STA+AP etc, support AT remote upgrade and cloud OTA , and upgrade for Smart Config function etc.
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To build the optional Wi-Fi configuration, use
BUILD=WIFIas documented in the repository. After the board joins the network and receives a DHCP address, connect to its Telnet service on port 23.
How CP/M 8266 compares with RunCPM
RunCPM is a related CP/M 2.2 project documented for ESP32 and other platforms. Rather than using disk images in the same way, it maps CP/M files to folders on the host. Its documentation says it requires substantial RAM, but does not establish that it is a drop-in replacement for CP/M 8266. Consider the distinction that matters to your use case:
| Factor | CP/M 8266 | RunCPM |
|---|---|---|
| Documented platform | ESP8266 | ESP32 and other platforms |
| CP/M file or disk representation | Simulated floppy drives; the full configuration lists 15 drives at 250 KB each. | Maps CP/M files to host folders rather than disk images. |
| Memory and networking trade-off | Project documents 64 KB of emulated RAM without Wi-Fi, or about 36 KB in the optional Wi-Fi build. | Documentation says substantial RAM is required; an equivalent memory figure or matching Wi-Fi trade-off is not stated in the cited documentation. |
| Setup | README describes ESP-Open-SDK and project utilities, with serial access or optional Telnet. | Platform-dependent; a directly comparable setup procedure is not stated in the cited documentation. |
RunCPM documentation is available at the RunCPM repository. Choose between the projects based on supported hardware, memory available to CP/M programs, network needs, how files are represented, and setup requirements—not an assumption that one can substitute directly for the other.
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