Editing CDC Cyber (section)

===Cyber 180 series===
Cyber 180 development began in the Advanced Systems Laboratory, a joint CDC/NCR development venture started in 1973 and located in Escondido, California. The machine family was originally called Integrated Product Line (IPL) and was intended to be a virtual memory replacement for the NCR 6150 and CDC Cyber 70 product lines. The IPL system was also called the Cyber 80 in development documents. The [[Software Writer's Language]] (SWL), a high-level [[Pascal (programming language)|Pascal]]-like language, was developed for the project with the intent that all languages and the operating system (IPLOS) were going to be written in SWL. SWL was later renamed PASCAL-X and eventually became [[Cybil (programming language)|Cybil]]. The joint venture was abandoned in 1976, with CDC continuing system development and renaming the Cyber 80 as Cyber 180. The first machines of the series were announced in 1982 and the product announcement for the NOS/VE operating system occurred in 1983.

As the computing world standardized to an eight-bit [[byte]] size, CDC customers started pushing for the Cyber machines to do the same. The result was a new series of systems that could operate in both 60- and 64-bit modes.  The [[64-bit]] operating system was called [[NOS/VE]], and supported the [[virtual memory]] capabilities of the hardware.  The older 60-bit operating systems, [[NOS (operating system)|NOS]] and [[NOS/BE]], could run in a special address space for compatibility with the older systems.

The true 180-mode machines are microcoded processors that can support both instruction sets simultaneously.  Their hardware is completely different from the earlier 6000/70/170 machines.  The small 170-mode exchange package was mapped into the much larger 180-mode exchange package; within the 180-mode exchange package, there is a virtual machine identifier (VMID) that determines whether the 8/16/64-bit two's complement 180 instruction set or the 12/60-bit ones' complement 170 instruction set is executed.

There were three true 180s in the initial lineup, codenamed P1, P2, P3.  P2 and P3 were larger water-cooled designs. The P2 was designed in [[Mississauga]], [[Ontario]], by the same team that later designed the smaller P1, and the P3 was designed in [[Arden Hills, Minnesota]].  The P1 was a novel air-cooled, 60-board cabinet designed by a group in Mississauga; the P1 ran on 60&nbsp;Hz current (no motor-generator sets needed).  A fourth high-end 180 model 990 (codenamed THETA) was also under development in Arden Hills.

The 180s were initially marketed as 170/8xx machines with no mention of the new 8/64-bit system inside.  However, the primary control program is a 180-mode program known as Environmental Interface (EI).  The 170 operating system (NOS) used a single, large, fixed page within the main memory.  There were a few clues that an alert user could pick up on, such as the "building page tables" message that flashed on the operator's console at startup and deadstart panels with 16 (instead of 12) toggle switches per PP word on the P2 and P3.

The peripheral processors in the true 180s are always 16-bit machines with the sign bit determining whether a 16/64 bit or 12/60 bit PP instruction is being executed.  The single word I/O instructions in the PPs are always 16-bit instructions, so at deadstart the PPs can set up the proper environment to run both EI plus NOS and the customer's existing 170-mode software.  To hide this process from the customer, earlier in the 1980s CDC had ceased distribution of the source code for its Deadstart Diagnostic Sequence (DDS) package and turned it into the proprietary Common Tests & Initialization (CTI) package.

The initial 170/800 lineup was:  170/825 (P1), 170/835 (P2), 170/855 (P3), 170/865 and 170/875.  The 825 was released initially after some delay loops had been added to its microcode; it seemed the design folks in Toronto had done a little too well and it was too close to the P2 in performance.  The 865 and 875 models were revamped 170/760 heads (one or two processors with 6600/7600-style parallel functional units) with larger memories.  The 865 used normal 170 memory; the 875 took its faster main processor memory from the ''Cyber 205'' line.

A year or two after the initial release, CDC announced the 800-series' true capabilities to its customers, and the true 180s were relabeled as the 180/825 (P1), 180/835 (P2), and 180/855 (P3).  At some point, the model 815 was introduced with the delayed microcode and the faster microcode was restored to the model 825.  Eventually the THETA was released as the ''Cyber 990''.