SD81Booster: a complete expansion for ZX80 and ZX81
It includes microSD storage, 512 KB of memory, sound, expanded video, and new development tools for the Sinclair ecosystem without losing compatibility with the original machine.
SD81Booster is a project designed by Wilco2009 to greatly expand the capabilities of ZX80 and ZX81. Its SMD construction and exclusive case are ready to integrate with the casing of these microcomputers.
Storage and memory for working without limits
The interface allows loading and saving programs from microSD FAT32 cards using the popular format .P. It also incorporates common file and folder operations: list, copy, move, rename, delete, and manage directories.
The memory is expanded to 512 KB through block paging of 8 KB. The mapper allows querying which page is active in each block and executing code in the area between 32K and 48K.
microSD FAT32
Load, save, and management of programs and directories.
512 KB paged
Intelligent mapper organized in blocks of 8 KB.
Expanded graphics
Up to 128 customizable characters compared to the original 64.
Original compatibility
Tape and ZX printer routines preserved.
The board evolves
The current review focuses the design on a single more powerful CPLD and places the components on a single side. The goal is to simplify assembly and reduce production costs.
- check_circleProgrammable Atari DB9 joystick.
- check_circleEmulation AY and voice synthesizer compatible with Currah MicroSpeech.
- check_circleIntegrated real-time clock.
- pendingComposite video output, RGB, and color interface in development.
Faithful emulation and development tools
EightyOne CrossPlatform translates in real-time the accesses to the SD81Booster ports. The public version includes Z80 disassembler, register inspector, step-by-step execution, and execution control, pause, advance, and stop.
The extended snapshot format .z81 saves RAM, paginator, chip AY state, VGM player, and PEG virtual machine. A session can be saved and restored to the same point.
Emulated functions
- 512 KB of paged RAM.
- AY-3-8912 and ZON X compatibility.
- VGM player with loop and pause.
- Virtual PEG machine with three threads.
- CP/M disk images.
- Chroma81 and extended video.
- Voice playback and synthesis.
- Extended screenshots
.z81.
From emulator to real hardware
The first tests confirm that the software developed in EightyOne also works on a real ZX81 equipped with SD81Booster. Adapted versions of Manic Miner and Nanako demonstrate the potential to port ZX Spectrum games.
A growing ecosystem
The goal remains to take ZX80, ZX81, Timex Sinclair 1000, and compatible devices beyond their original limits. SD81Booster combines storage, memory, sound, voice, clock, joystick, and CP/M into an open platform for users and developers.
