AOS/VS II
AOS/VS II was an operating system for the Data General 32-bit MV/Eclipse computers.
It was released in 1988 and was originally to be simply rev 8.00 of the AOS/VS operating system. However, it introduced a new file system which was not compatible with the original AOS and AOS/VS file system and also contained new features like ACL groups. Since some customers did not want to upgrade to the new file system, or invest in new hardware, Data General agreed to continue bug-fix support of an “immortal” revision of AOS/VS, which became known colloquially as AOS/VS “Classic”, while new development would proceed as AOS/VS II, with revision numbers rolled back to 1.00.
Both VS-Classic (rev 7.7x) and VS-II (rev. 3.2x) were updated to survive the Year 2000 problem, although by this time both were obsolescent.
Among the other new features that were part of AOS/VS II were a full TCP/IP stack, NFS support, expanded kernel address space using ring-1 and a logical disk-level user data cache. /VS (classic) had a file system metadata cache, but no user data cache.
AOS
AoS or AOS may refer to:
Military, police and government
Schools and education
Science and academia
Data General AOS
AOS was the name of a family of operating systems for Data General 16-bit Eclipse C, M, and S minicomputers, followed by AOS/VS and AOS/RT32 (1980) and later AOS/VS II (1988) for the 32-bit Eclipse MV line.
AOS/VS exploited the 8-ring protection architecture of the Eclipse MV hardware with ring 7 being the least privileged and ring 0 being the most privileged. The AOS/VS kernel ran in ring 0 and used ring-1 addresses for data structures related to virtual address translations. Ring 2 was unused and reserved for future use by the kernel. The Agent, which performed much of the system call validation for the AOS/VS kernel, as well as some I/O buffering and many compatibility functions, ran in ring 3 of each process. Ring 4 was used by various D.G. products such as the INFOS II DBMS. Rings 5 and 6 were reserved for use by user programs but rarely used except for large software such as the MV/UX inner-ring emulator and Oracle which used ring 5. All user programs ran in ring 7.
Calculator input methods
There are various ways in which calculators interpret keystrokes.
One can categorize calculators into two main types: 1) single-step or immediate execution calculators and 2) expression or formula calculators.
On a formula calculator one types in an expression and then presses 'Enter' to evaluate the expression. There are various systems for typing in an expression: infix, postfix, natural display, etc.
On an immediate execution calculator, the user presses a key for each operation, by pressing keys to calculate all the intermediate results, before the final value is shown.
Immediate execution
With the immediate execution mode (also known as algebraic entry system (AES) or chain calculation mode) of operation each binary operation is executed as soon as the next operator is pressed, therefore the order of operations in a mathematical expression is not taken into account. Scientific calculators have buttons for brackets and these calculators can take order of operation into account. Also for unary operations like √ or x2 the number is entered first then the operator. Simple four-function calculators, such as those included with most operating systems, usually use this input method.
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