use. A utility for this was provided with the Level II ROMS. Disk BASIC allows disk I/O, and in some cases (NewDos/80, MultiDOS, DosPlus, LDOS) adds powerful sorting, searching, full screen editing, and other features. Level II BASIC reserves some of these keywords and issues a "?L3 ERROR", suggesting a behind-the-scenes change of direction intervened between the creation of the Level II ROMs and the introduction of Disk BASIC. Microsoft also marketed an enhanced BASIC called Level III BASIC written by Bill Gates, on cassette tape. The cassette contains a "Cassette File" version on one side and a "disk file" version on the second side for disk system users (which was to be saved to disk). Level III BASIC adds most of the functions in the full 16 KB version of BASIC plus many other TRS-80 specific enhancements. Many of Level III BASIC's features are included in the TRS-80 Model III's Level II BASIC and disk BASIC. Level I BASIC was still offered on the Model I in either 4K or 16K configurations after the introduction of Level II BASIC. Other programming languages Radio Shack published a combined assembler and program editing package called the Series I Assembler Editor. 80 Micro magazine printed a modification enabling it to run under the Model 4's TRSDOS Version 6. Also from Radio Shack was Tiny Pascal. Microsoft made its Fortran, COBOL and BASCOM BASIC compiler available through Radio Shack. In 1982, Scientific Time Sharing Corporation published a version of its APL for the TRS-80 Model III as APL*PLUS/80. Other applications Blackjack and backgammon came with the TRS-80, and at its debut Radio Shack offered four payroll, personal finance, and educational programs on cassette. Its own products' quality was often poor. A critical 1980 80 Micro review of a text adventure described it as "yet another example of Radio Shack's inability to deal with the consumer in a consumer's market". The magazine added, "Sadly, too, as with some other Radio Shack programs, the instructions seem to assume that the reader is either a child or an adult with the mentality of a slightly premature corned beef". The more than 2,000 Radio Shack franchise stores sold third-party hardware and software, but the more than 4,300 company-owned stores were at first prohibited from reselling or even mentioning products not sold by Radio Shack itself. Green stated in 1980 that although "there are more programs for the