This is a total rewrite of the ZX Spectrum ROM in 16384 bytes of Z80 assembly language.
The original ROM contained Sinclair BASIC, which while versatile was not suitable for writing games due to its lack of speed. It was also impossible to type quickly on the machine due to the ROM keyboard routines' insistence that the first key must be released before the second is pressed. This ROM remedies these problems.
The ROM contains editors for blocks, sprites, screen layouts, map, objects, text messages and sprite positions. There is a code editor that uses a simple scripting language inspired by BASIC. There is also a compiler to turn the commands into lightning-fast machine code and a game engine that is copied to RAM on initialisation.
Games created using this ROM will run on Spectrums with the original ROM and it is easily capable of producing games that would have been of commercial quality in the 1980s and early 1990s.
Assembler source of the text used in the ROM. If you would like to translate the ROM to another language, feel free to edit this and send me your version. Individual sections can be larger or smaller but the assembled size of your translated file should be no longer than that of the English file, 933 bytes. Let me know of any font changes you require too. There's a challenge for you...