ICL Series 39 facts for kids

The ICL Series 39 was a type of powerful computer system made by a company called ICL in the UK. It was released in 1985. These computers included both very large ones, called mainframes, and slightly smaller ones, known as minicomputers. A special feature of the original Series 39 was its "nodal architecture." This meant the computer was made of several smaller parts, or "nodes," that worked together.

How the Series 39 Started

The Series 39 computers were built using ideas from ICL's older 2900 line of computers. They also used the VME operating system, which is like the main program that runs the computer.

ICL introduced the Series 39 in two main types:

• Series 39 "Estriel" systems: These were the bigger computers. They replaced older, large machines from the 2900 series. These powerful computers needed a special room with controlled temperature and other equipment, like a dedicated computer room.
• Series 39 DM1 systems: These were smaller computers. They were designed to replace older, smaller ICL machines. The DM1 systems were special because they brought the power of a mainframe computer's operating system into a regular office environment for the first time.

How the Series 39 Was Designed

The first Series 39 computers used special "S3L" processors and a unique way of connecting parts called "nodal architecture." This design allowed different parts of the computer, called "nodes," to be up to 1000 meters (about 3,280 feet) apart!

The Series 39 introduced a clever way for computers to share information. It was like a mix between one big computer with many parts and a group of separate computers working as a team. Each machine had several "nodes." Each node had its own processor (the computer's brain) and its own memory.

Even though a program usually ran on one node, it could move and run on any other node if needed. Things like hard drives and other equipment were shared among all the nodes.

The nodes were connected using a very fast optical bus system called "Macrolan." This system used multiple fibre optic cables, which are like super-fast glass threads that carry data using light. This connection allowed the applications to share information as if they were all using the same memory.

When information was marked as "shared," it was copied to every node. If one node updated this shared information, all the other nodes would get the update. However, if information was not shared, it stayed private to its own node, keeping processes separate.

Special instructions, like "semaphores" in programming, helped control access to the shared information. They made sure that different parts of the computer didn't try to change the same shared information at the same time.

Overall, a well-set-up Series 39 computer with the VME system was very reliable. Its design helped protect against major problems, meaning the system was less likely to completely stop working if one part had an issue.

All Series 39 computers used special 'Cabinets' to store data. These cabinets were about waist height and connected to the main computer using fibre optic cables.

• Cabinet 2: These were the main storage cabinets. They held two 330Mb "Swallow" hard drives.
• Cabinet 3: These were extra cabinets that could be added to Cabinet 2. They could hold up to four more 330Mb "Swallow" hard drives.
• Cabinet 4: This cabinet acted as a link. It allowed the Series 39 to connect to older storage systems from the 2900 series.

The main part of the smaller DM1 Series 39 computers (like the Level 30 and its variations) was called Cabinet 1.

Every Series 39 computer also had a "Node Support Computer" (NSC) built into its storage system. This NSC was like a small computer itself. It allowed support staff to manage the main computer nodes from a distance, even letting them stop and restart the main nodes if needed.

How the Series 39 Changed Over Time

In the mid-1980s, a new version of the Series 39 Level 30 was made, called the Level 20. This was basically a Level 30 that was intentionally slowed down.

Later in the 80s, these were replaced by the Level 15, 25, and 35 models. These new versions also had different speeds but came with more memory. They could also be fitted with extra processor and input/output boards for even more computing power.

Around 1990, the Series 39 got a big upgrade with new "S3X" ("Essex") processors.

• SX systems: These were introduced in 1990 to replace the older "Estriel" systems.
• DX systems: These came out in 1993 to replace the DM1 systems.

What Replaced the Series 39

The Series 39 SX/DX computers were eventually replaced by a system called Trimetra. Trimetra (which included SY/DY, and later DL/SL ranges) used more standard computer parts. This allowed it to run both Windows and VME operating systems on the same machine.

Trimetra was then replaced by Fujitsu's mainframe platform, called Nova. Nova could act like a Trimetra system but ran on standard Intel-based servers.

Nova itself was phased out in 2007 and replaced by SuperNova. SuperNova runs the OpenVME operating system on top of Windows Server or Linux. It can even run on regular Wintel server hardware using just two main processors.

This change meant that the "ICL mainframe" became mostly a software product. This allowed Fujitsu to focus on supporting and developing the VME software without having to constantly update the computer hardware.