This period was marked by a cross-culture exchange in the software area between the GE600 world, the S/360 influence on Bull designers and the Burroughs culture that predominated in ASTO, the name of Jack MERNER one of the key architects of the B5000 and that of Mauro PACELLI, head of this ASTO unit should be mentioned.
The Bull initial interior decor was then complemented by the implementation of a stack mechanism handled by firmware for parameters passing, while the arithmetics remain in S/360-like registers.
The general conventions of a static linkage mechanism were established. The introduction of the "process" concept in the interior decor was confirmed, although many designers from GECOS3 and MULTICS were very reluctant to freeze the software design of those architecture elements .
Note that L178 Processes are called threads in recent Operating systems terms.
The concept of Process group and its identification as job steps' occurrences were introduced during this period.
A "Smart indexing", i.e., indexing modulo a length dependent upon the operand type was introduced.
Retrospectively, it appears that too much importance was given to the ease of implementation of some languages' features by compilers at the expense of CPU performances for high end machines. It was assumed that all the machines would be micro-programmed (in PROM), at the difference of the S/360 decor where the assumption was that the upper end should be wired-on for the majority of instructions.
Use of the ASCII code was planned at that time because IBM was then to have an ASCII mode on S/360 and because the overall culture of GE Computer Division was extremely reluctant to target any kind of IBM compatibility, such as the EBCDIC encoding that was selected later.