After a few months of work and preparation, and after presenting the project on Saturday, June 3rd, at RetroReal (Ciudad Real, Spain), we are proud and excited to introduce:
What is ESPectrum?
ESPectrum is an emulator of the 48K and 128K models of the Sinclair ZX Spectrum microcomputer that runs on Espressif ESP32 microcontrollers.
A microcontroller is a small computer dedicated to specific tasks (usually industrial) with limited processing power, memory, and storage. Fortunately, even with its limitations, the ESP32 has proven to have sufficient processing power for the development and execution of various emulation projects.
The chip is offered to manufacturers and makers for integration into other boards, and luckily for us, there are boards on the market that, in addition to the ESP32, include the necessary electronics, components, and connectors for the perfect operation of our project. One of the most affordable options is the Lilygo TTGo VGA32 board.
This small board includes everything needed for enjoying an emulated Spectrum, at a price of around €15: a VGA connector, two PS/2 connections for keyboard and mouse, a pre-amplified minijack audio output, an SD card slot, and a microUSB connector for power and USB communication.
We have also collaborated with Antonio Villena, a well-known retro hardware manufacturer who has created a compatible board for the project, featuring some enhancements, including the ability to use a real Sinclair ZX Spectrum keyboard as an input device.
Therefore, if we have a board equipped with the necessary connectors, a keyboard that supports the PS/2 protocol or a real ZX Spectrum keyboard, a VGA monitor, and, although not essential since the ESP32 includes internal storage, a microSD card as a storage medium, thanks to ESPectrum, we can enjoy a mature and accurate emulator that perfectly implements features such as contended memory, floating bus, beeper and AY sound, cycle-perfect timing, and video generation identical to the real machine.
In its latest version, it can be connected not only to standard VGA monitors but also to CRT televisions through a simple modification to the Lilygo board (with direct support on Antonio Villena's ESPectrum board) and a quite affordable adapter using the exact video refresh rate as that of an original Sinclair ZX Spectrum.
Features:
- Emulation of Spectrum 48K and 128K (no PSRAM required).
- Accurate Z80 emulation (core by José Luis Sánchez AKA zx81, author of the magnificent ZXBaremulator).
- Standard VGA, VGA 50hz, and CRT 50hz video modes.
- Support for 16:9 and 4:3 aspect ratios (using 360x200 or 320x240 modes).
- Emulated multicolor attribute effects (Bifrost*2, Nirvana, and Nirvana+ engines).
- Emulated border effects (Aquaplane, The Sentinel, Overscan demo).
- Emulated floating bus effect (Arkanoid, Sidewize).
- Contended memory and contended I/O emulation.
- AY-3-8912 sound emulation.
- Beeper & Mic emulation respecting their relative output levels (Cobra's Arc).
- PS/2 keyboard support and real Spectrum keyboard support (using Antonio Villena's ESPectrum board).
- Kempston and Cursor joystick emulation.
- Full OSD menu in two languages: English and Spanish.
- Real-time loading of TAP files.
- Loading of SNA and Z80 snapshots.
- Saving and loading of snapshots (both 48K and 128K supported).
- BMP screenshot capture to SD card.
- Simultaneous support for internal storage (SPIFFS) and external storage (SD card).
You can find more information on the project's website (still in Spanish, there will be an English version soon): https://zxespectrum.speccy.org, and on the Github repository: https://github.com/EremusOne/ZX-ESPectrum-IDF
We have also opened a Patreon at https://www.patreon.com/ESPectrum in case you would like to support the project.
The binaries for the latest version and the instructions for flashing them are now available at https://github.com/EremusOne/ZX-ESPectr ... g/v1.0.rc1 , and here are the release notes:
Regards!New features:
- Support for the real Spectrum 48K keyboard using the new ESPectrum board by Antonio Villena. From now on, there will be two binaries: one for the Lilygo VGA32 board and similar ones, and another for Villena's board.
- Support for three video modes: Standard VGA (60 and 70hz), VGA 33-40k 50hz, and CRT 15k 50hz. For VGA 50hz modes, you only need a monitor that supports them. The CRT 50hz mode is supported on the ESPectrum board through Antonio Villena's VGA-Scart adapter (it also works on the Lilygo board, but a small trick is required, which we will detail on the ESPectrum website).
You can switch between modes using the following key combinations during the emulator's boot sequence, and later check the current video mode on the bottom bar of the help screen:
1 + Q -> Standard VGA 4:3 (60hz)
1 + W -> Standard VGA 16:9 (70hz)
2 + Q -> VGA 40khz 50hz 4:3
2 + W -> VGA 33khz 50hz 16:9
3 + Q -> CRT 15khz 50hz 4:3
3 + W -> CRT 15khz 50hz 16:9
(On PS/2 keyboards, you should alternate between the two keys. On the ZX Spectrum keyboard, you can keep both keys pressed.)
Changes:
- More optimizations: improved emulation speed.
- Improved menu system: you can smoothly navigate forward and backward in menu levels.
- Multicolor "ESPectrum" name in the main menu.
Known issues:
- In rare cases, the sound may not initialize when starting the emulator or may become corrupted or muted after loading an SNA, Z80, or snapshot. Restarting the ESP32 (using F12 or turning it off and on) always solves the issue.
