4.3 The TBYTE Data Types

HLA lets you declare ten-byte variables using the tbyte data type. Because HLA does not allow the use of 80-bit non–floating point constants, you may not associate an initializer with this data type. However, if you wish to reserve storage for an 80-bit variable, you may use this data type to do so.

The tbyte directive allocates ten bytes of storage. There are two data types indigenous to the 80x87 (math coprocessor) family that use a ten-byte data type: ten-byte BCD values and extended precision (80-bit) floating point values. Because you would normally use the real80 data type for floating point values, about the only purpose of tbyte in HLA is to reserve storage for a ten-byte BCD value (or other data type that needs 80 bits). The chapter on arithmetic will provide some insight into the use of this data type. However, except for very advanced applications, you could probably ignore this data type and not suffer.