user: Question: What is the value for the byte string when the memory map, decimal, and floating points are all standard and the max memory is smaller than 512?
Columns: ['Model', 'Floating point', 'Decimal', 'Byte string', 'Memory map', 'Max memory (kwords)']
Types: ['text', 'text', 'text', 'text', 'text', 'real']
Sample row: ['Sigma 7', 'optional', 'optional', 'standard', 'optional', 128.0]
SQL:

assistant: SELECT "Byte string" FROM "Table" WHERE "Memory map" = 'standard' AND "Decimal" = 'standard' AND "Floating point" = 'standard' AND "Max memory (kwords)" < 512.0;