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Data communication and interactivity: the first start

Around 1975, the data communication facilities of the Physics Laboratory TNO were very limited compared to current means. The available data communication controller could handle a maximum of eighth synchronous and/or asynchronous lines, provided that the total "baudrate" did not exceed 30-40 kbps. Above that rate, the very complex peripheral processor program (1MR) could not cycle fast enough to cope with the data streams. Both the LEOK, the IZF and the PML were connected to the PhL using 2400 baud and 4800 baud modems. The very expensive, many kilos heavy modems were full of coils and knobs to tune the interconnection characteristics. The Digital Equipment Programmed Data Processor- or PDP-systems at the previously mentioned institutes used a by the laboraties modified version of the UT-200 (UT200) (Mode 4) synchronous protocol. In that way, these institutes could deliver batch jobs ("card images") to the CDC system. The output was sent back as "print"-output that was collected in files on the PDP. This can be seen as the initial beginning of the network between the TNO Defense Research institutes, later called the DOnet.

Interactivity: synchronous hick-ups

Tektronix 4010 graphic terminal plus printer The terminal room on the Laboratory contained six synchronous 711-terminals. Synchronous means that the terminal is polled each second for a "send screen content"-command. Output was delivered in blocks. These 711-terminals were very delicate pieces of equipment weigthing about 15 kilos a piece. Per synchronous line, two or three terminals were connected. When your neighbour was paging through a lot of output, one's response time decreased a lot. At that time, one had to "reserve" the terminal for a block of a quarter hour. At the end of the quater, one was allowed to reserve a new slot.

To be less dependent on the availability of the large card reader and printer, the Laboratory bought a CDC 734 batch station: a console, small (and slow!) card reader and a small printer. This batch station used the UT-200 synchronous protocol as well for its communication.

A historic network overview of the Physisch Laboratorium dated April 1978 shows the connection of the Calma ("ECAD"-system), seven synchronous terminals (711's) sharing two lines, the PDP 11/45 of the PML, a 711-terminal at the Hogere KrijgsSchool (HKS) {Higher Military School}, the 734-batch station - all via 4800 baud synchronous ljnes - and the PDP at the LEOK via a 2400 baud synchronous connection. Apart from these terminals and systems, 8 Newbury terminals were connected using 300 baud asynchronous lines as well as a Silent 700, 12 kilos heavy "movable (they stated portable)" terminal and a Tektronix 4010 graphics terminal (1200 baud). Later in 1978, a Tektronix 4014 graphical terminal was connected. This terminal was used to display radar-coverage images calculated in the CDC system.

SUEDI: Single User Editor IWIS

The standard Control Data file editor was a multi-user, multi-threaded editor that occupied roughly 40000B words (123 KB) of memory. This was a burden for the system! The TNO Mathematics and Statistics institute (IWIS-TNO) had a CDC system as well. They developed the "Single User Editor IWIS-TNO" (SUEDI). This editor was written in a mix of Fortran (4) and assembler (COMPASS) code. This editor was faster, had more features, used far less memory and -above all- when a crash occured only the single user was affected.

About crashes: interactive work required reservation of a terminal for 15 minutes, hope for a fair response by the system and a synchronous 711 terminal that kept alive as well as no hangs of the operating system. A good habit was to save all changes each five to ten minutes to keep the losses low. During a couple of years, systems programming worked a lot on improving SUEDI by adding new features, improving the speed and the reduction of memory occupation. The latter required the split of program subroutines in even smaller modules that could be loaded as separate overlays. The largest overlay was the one who's size had to be decreased down to the next lower multiple of 100B words. It required sometimes multiple days to figure out a way to decrease the largest overlay by two words (4-8 hardware instructions). Often, a solution turned out to be a gain of 100-200B! At that time, of course one had to look at the next largest overlay with a fresh look... In a couple of years, the SUEDI program was halved to 2700B words (11 KB). Collegues at the computer centre of the Rijksuniversiteit Groningen added new, fast search methods for text strings, as for instance the Booyers-Moore algoritm. This resulted in a speed-up with a factor two to ten depending on the text fragment content.

Around 1980, a (almost) complete ASCII-version was developed by IWIS-TNO. Later on, Daan Sandee developed a fast and very small version of thsi editor: SUEDA. Two 6-bit "CYBER"-bytes were used for the storage of a single Ascii-character.
Because of their rich feature set, the fastness and the small memory occupation, the SUEDI and SUEDA programs became very popular at almost all Netherlands computer centers that used CDC-systems. New SUEDI-developments, system corrections and new "features" were exchanged during INFOSYS-meeting (Information exchange Systems programming) that were held bi-monthly. In this manner "sites" helped eachother. Interesting system and application code spreaded fast and was even developed further at other sites. One could actually regard part of the meetings as the first "shareware" sessions.

The by CERN, Schwitzerland developed SCAN-program was converted by the NLR to the NOS/BE-platform. The earlier mentioned Booyers-Moore algoritm was added to it by the Rijksuniversiteit Groningen and the Physics Laboratory RVO-TNO added the full-ASCII feature.

IWIS-TNO provided the text formatter TOI (Tekstopmaker IWIS) as shareware to the Netherlands computer centers. TOI used a kind of "HTML-lookalike" code formatted output.

Besides the INFOSYS-meetings, the heads of Operations met as well on a regular basis. They discussed problems with suppliers of computer media, print paper, operational problems, emergency support in case of a system break-down. Data exchange sometimes gave problems as well. Combinedly, they developed courses for new operators. These meetings were hosted on a round-robin basis by the various Netherlands sites using Control Data equipment (at that time): ACB, ACCU, CDC Nederland, ENR, IWIS, KEMA, Lips, MID, NIKHEF, NLR, RUG, SARA, STC, VROM.



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