charge of the tape, while the source code was provided for free with other purchases. BASIC While FOCAL was becoming popular on DEC machines, BASIC was becoming a more popular alternative on other platforms. By the late 1960s, several companies were making inroads in DEC's minicomputer stronghold, selling similar machines running time-sharing versions of BASIC. Notable among these was the HP 2100 series, running HP Time-Shared BASIC. David H. Ahl had recently joined DEC's PDP-8 Group, just as the company became interested in selling the machine into educational settings. Due to the popularity of BASIC in the education market, especially with the growing library of BASIC programs from the Minnesota Educational Computing Consortium, Ahl found selling the machine with FOCAL was difficult despite its advantages. As he later noted: Ahl took it upon himself to produce a BASIC system for the platform, hiring a company he later learned was a single programmer in Brooklyn to produce a version for the 4 kWord PDP-8. DEC began selling packaged versions of the PDP-8 with terminals and the BASIC as the "EduSystem" lineup, with larger systems in the series having expanded versions of BASIC, and in some cases, also FOCAL and FORTRAN. Some PDP-11 based EduSystems were also created. Ahl then began porting programs from FOCAL to BASIC, notably The Sumer Game (which he renamed Hamurabi), a version of Lunar Lander, and many smaller FOCAL demos. Combining his ports with submissions from outside programmers, he managed to collect enough material to have DEC publish 101 BASIC Computer Games in 1973. The book was an immediate success and ultimately ran through three printings to 1975. By the mid-1970s BASIC was a standard feature of all DEC machines and FOCAL use evaporated. Rebirth in the Soviet Union The PDP-11 had been cloned in the Soviet Union in the 1970s for military purposes. In the 1980s, single-chip variations similar to the LSI-11 were produced that gave rise to a series of PDP-11 compatible home computers. Most notable among several models were the Electronika BK series, released in 1985. These were initially supplied with FOCAL on a ROM cartridge, while a BASIC cartridge was an optional add-on. Later models supplied BASIC by default. Language The following description is based on FOCAL-69 as seen in the FOCAL-8 language reference manual. Direct and indirect modes FOCAL followed the JOSS model for interaction via a command line interface. This allowed