Mallard BASIC is a BASIC interpreter for CP/M produced by Locomotive Software and supplied with the Amstrad PCW range of small business computers, the ZX Spectrum +3 version of CP/M Plus, and the Acorn BBC Micro's Zilog Z80 second processor. In the 1980s, it was standard industry practice to bundle a BASIC interpreter with microcomputers, and the PCW followed this practice. While the PCW was primarily a dedicated word processor for business use running LocoScript, it was running on top of the CP/M operating system. There were many existing implementations of BASIC for CP/M, such as Digital Research's CBASIC and the third-party ZBasic, but they followed the earlier 1970s model of compilers that were fed source code prepared in a separate text editor. BASIC was not built-in in these cases, the user would prepare a program and then invoke BASIC to run it. In contrast, home computers of the era had moved to using BASIC as the primary interface for the machine. Instead of booting into CP/M or a similar OS, these machines booted directly into a BASIC normally stored on ROM. These also included a built-in screen editor. Mallard was based on this model, with an integrated editor that was tailored for the PCW's non-standard 90-column screen. Although the PCW actually had excellent monochrome graphics support for its time and specification, closely comparable to the Hercules Graphics Card for IBM PC compatible computers, Mallard BASIC had no graphics support whatsoever. Instead, Locomotive Software optimised it for business use, with, for instance, full ISAM random-access file support, making it easier to write database applications. It was also optimised for speed — it is named after the LNER Class A4 4468 Mallard locomotive, the fastest steam locomotive in the world, once again displaying the company's fondness for railway-oriented nomenclature. In fact, the Locomotive Software name came from the phrase "to run like a train" and it was this theme that was used to name Mallard BASIC — no other Locomotive Software product was named after anything railway-oriented. The Acorn version was designed simply to run the Compact Software small business accounting products Acorn was including to target its Z80 second processor at small businesses. Mallard's major innovation designed specifically for Acorn was the addition of the Jetsam B*-tree keyed access filing system to give similar (but superior) features to the Miksam product Compact had originally designed around. Graphics could be implemented