The HP-42S supports indirect addressing with which it is possible to implement a Universal Turing machine and therefore the programming model of the HP-42S can be considered Turing-complete.
32.
The DEC PDP-10 computer with 18-bit addresses and 36-bit words allowed multi-level indirect addressing with the possibility of using an index register at each stage as well.
33.
The unused half could be used for extra instructions, indexing, indirect addressing, or a second ( + 1 ) address to locate the next instruction, each of which could increase program performance.
34.
Setting the B digit has the effect of adding the contents of the memory address of the first instruction to the second instruction at execution time, enabling indirect addressing and other run-time instruction modifications.
35.
The "'FX-501P "'and "'FX-502P "'supported indirect addressing both for memory access and jumps and therefore the programming model could be considered Turing complete.
36.
This divided the address space into four 8 KB'pages', only the current ( i . e . the page the program was running in ) could be addressed directly, the others only by indirect addressing.
37.
Most machine language implementations and early assembly languages did not have special syntax for records, but the concept was available ( and extensively used ) through the use of index registers, indirect addressing, and self-modifying code.
38.
This failure except with the draconian use of G�del numbers in the manner of Minsky ( 1961 ) ) leads to their definition of " indexed " instructions ( i . e . indirect addressing ) for their RASP model.
39.
The major differences between the original 2116 architecture and the BPC microprocessor are a completely redesigned I / O structure, the removal of multiple levels of indirect addressing, and the provision of a stack register for subroutine call and return.
40.
The first microprocessor with a true index register appears to have been the Motorola 6800, and the similar MOS Technology 6502 made good use of two such registers . ( The earlier Intel 8080 did allow indirect addressing via a register .)
