TELECOM Digest Editor noted in response to a writer:
Applesoft BASIC = Microsoft 6502 cassette BASIC + Apple graphic commands It took 10KB (5x 2KB ROMs) and used 5 byte floating point numbers.
The OSI Superboard had an 8KB Microsoft 6502 cassette BASIC and used 4 byte floating point numbers -- same range (up to 10**38 if I recall) but less accuracy. The funky 2 character error codes were due to an oversight -- the high bit of the second character was not cleared resulting in a graphic symbol instead of the appropriate letter (it should have been "NF" for NEXT without FOR and "/0" for division by zero etc).
Apple DOS was written in house at Apple and added disk commands (in a rather unique kluge due to the cassette BASIC not having any DOS hooks built into it).
David Wilson School of IT & CS, Uni of Wollongong, Australia