bits of mantissa and twelve bits of exponent. This allowed for both significantly higher precision and a significantly wider range of values than most contemporary interpreters, making FOCAL a reasonable choice for serious numerical work. This high precision, and good choices for default decimal output formatting, meant that difficulties with binary-to-decimal rounding were not evident to beginning users. For comparison, Microsoft BASIC initially used a 32-bit format, while later versions expanded this to 40-bits. Most BASICs had problems with rounding that led to simple equations resulting in tiny non-zero remainders. It is generally agreed that FOCAL was more efficient in its use of resources than comparable BASIC systems. On a typical machine of the day, often with 6 to 24 kilobytes of magnetic-core memory, FOCAL could handle larger and more complex programming tasks than BASIC. Versions and spinoffs The Coca-Cola Corporation used a customized version of FOCAL called COKE. FOCAL was later implemented on the PDP-7, PDP-9, PDP-10, PDP-11, PDP-12, PDP-5 and LINC-8. The FOCAL manual showed how to add commands to the FOCAL parser, so many sites added specialized commands for operating custom hardware. The Digital Equipment Computer Users' Society collected many patches and enhancements for FOCAL. There were even major enhanced offshoots of FOCAL, such as FOCAL-W, which added many features, including better mass storage file I/O and even virtual variable memory. In the mid 1970s DELTA was a more sophisticated version of FOCAL. Program line numbers went from 00 to 99 "parts" and 000000 to 999999 "steps" executed in alphanumeric order. DELTA had some specialized commands for the Tektronix 4010/14 display scope. In Russia, it saw use as late as the early 1990s in mass-produced home computers of the Electronika BK series. Microsoft sold a version of FOCAL supplied on paper-tape. According to Raymond Chen, the master tape is missing and FOCAL is no longer available. Example code The original Lunar Lander makes an excellent example for examining FOCAL code, as it uses most of the features of the language. This code is from the original, found on Jim Storer's Lunar Lander page. T "CONTROL CALLING LUNAR MODULE. MANUAL CONTROL IS NECESSARY"! T "YOU MAY RESET FUEL RATE K EACH 10 SECS TO 0 OR ANY VALUE"! T "BETWEEN 8 & 200 LBS/SEC. YOU'VE 16000 LBS FUEL. ESTIMATED"! T "FREE FALL IMPACT TIME-120 SECS. CAPSULE WEIGHT-32500 LBS"! T "FIRST RADAR CHECK COMING UP"!!!;E T "COMMENCE LANDING PROCEDURE"!"TIME,SECS