Search results
Results From The WOW.Com Content Network
Synthetic programming (SP) is an advanced technique for programming the HP-41C and Elektronika B3-34 calculators, involving creating instructions (or combinations of instructions and operands) that cannot be obtained using the standard capabilities of the calculator. [1] Some HP-41C instructions are coded in memory using multiple bytes.
Finally, the first half of page one held the "subroutine entry pool", a list of addresses in program memory. These were stored with the high bytes in locations 0 to 31, and the low bytes in 32 to 63. Using these slots, branches and subroutine calls could also be reduced to a single byte opcode.
The high-order byte of the instruction specifies the operation. Bits 9 through 15 are the op-code, and bit 8 is the value of the condition code calculation which results in the branch being taken. The low-order byte is a signed word offset relative to the current location of the program counter. This allows for forward and reverse branches in code.
Here is a sample program that computes the factorial of an integer between 1 and 69 (70! needing an exponent greater than 99, the calculator's maximum). The integer is entered in the X register and passed as an input parameter when the program is run. The program takes up two registers, which is ≈14 bytes.
The integer data that are directly supported by the computer hardware have a fixed width of a low power of 2, e.g. 8 bits ≙ 1 byte, 16 bits ≙ 2 bytes, 32 bits ≙ 4 bytes, 64 bits ≙ 8 bytes, 128 bits ≙ 16 bytes. The low-level access sequence to the bytes of such a field depends on the operation to be performed.
In computer science, arbitrary-precision arithmetic, also called bignum arithmetic, multiple-precision arithmetic, or sometimes infinite-precision arithmetic, indicates that calculations are performed on numbers whose digits of precision are potentially limited only by the available memory of the host system.
The format of data on the tape is: 100 bytes with the value 0x16 (SYN, Synchronous Idle), one byte with the value 0x2A (*), the record identification number, the start address (two characters for the low byte of address, two characters for the high byte), the end address (in the same format), the actual data, one byte with the value 0x2F ...
The technique is called multiple-precision arithmetic. Thus, it is possible to perform byte-wide addition on operands wider than a byte: first add the low bytes, store the result and check for overflow; then add the high bytes, and if necessary add the carry from the low bytes, then store the result.