Enclosed with this issue is a map showing the geographical distribution of the terminals in the pool. Any enquiries should go to Mike Jane who is now responsible for the management of the pool.
Oxford University has bought a VAX 11/780 to replace the PDP 11/45 (in the Department of Engineering Science) previously upgraded by ICF. The 11/45, its RK06 disk drive and the RK11 disc controller have been bought by ICF and installed in the Department of Civil Engineering in University College, Swansea to replace the ICF-upgraded PDP 11/40 there. Other peripherals from the 11/45 will be transferred to the VAX; also, the SI 9500 disk controllers at both sites will be upgraded to 9400s.
PRIME 550s have now been installed at City University (Department of System Science) and Surrey University (Computer Centre). The PRIME 400 at Chilton has been upgraded to a 750. A GEC 4000 series machine has been installed at University College, Cardiff.
Cliff Pavelin has moved to the Starlink project (see 'Rapid Response' No. 11, section 8). His place as manager of the ICF PRIMEs has been taken by Paul Bryant. Paul keeps his previous responsibility for the GEC machines and so is now in charge of all ICF multi-user minis apart from some of the upgrades.
The following is a list of the applications software made available through work programmes approved by the Interactive Computing Facilities Committee. GAELIC (see 'Rapid Response' No, 10, section 2) has been included for completeness. Much other software developed under SRC grants is also mounted on ICF machines but remains the responsibility of the groups which developed it.
The Sigma 5000 series (commonly called GOCs Graphic Opti Controllers) is a range of microprocessor-based raster scan display devices of various resolutions. This range has been developed over the past two and half years from a simple monochrome low-resolution (256 × 256) add-on for a Newbury VDU. It includes medium-resolution (768 × 512) complete terminals, both monochrome and greyscale, and sophisticated colour systems capable of hardware polygon fill. All the devices perform the usual graphical functions of line drawing and character plotting and permit graphical input via a cross-hair cursor. Also, graphics text and alpha text are displayed separately and solid or patterned rectangular blocks may be drawn. The power of these devices arises because, being refresh devices, selective erasure is possible. Thus, pictures may be modified without complete redrawing.
Three models from the 5000 series have been selected as "standard devices" for the ICF terminal pool.
Currently the GOCs are only supported by GINO-F but, since this was not designed to cater for raster-scan displays, it cannot give access to all their features. Some features can be accessed by interpreting GINO-F routines for such displays: eg, pen type 6 represents an eraser so that all actions with this pen are erasing actions. Other features, however, are outside the concept of GINO-F eg hardware polygon fill and plane selection; these can only be accessed by software on top of GINO-F addressing the device directly.
Consider hardware polygon fill. The device will on1y correctly fill a closed area lying within the domain of its bit map and so areas not lying completely within this domain need clipping. Since GINO-F only works with line primitives, not area primitives, an external clipping routine is needed which always produces a set of closed polygonal areas within the domain of the device. Such a routine is contained in the library, written in Technology Division at RL for use with GINO-F, to allow the more sophisticated facilities of the Sigma devices to be exploited. Other routines use the programmable colour map to simulate transparent and opaque overlays and allow easy selection of colours from a palette hue, using saturation, and intensity as variables. ICF support for this extra software is under consideration.
Details of facilities available through GINO-F are in the graphics documentation for the various machines. Further details can be obtained from Dale Sutcliffe. Details of the raster library are available from Mike Newman in Technology Division.
To achieve duplex data communications between ICF terminals and mainframes at medium/high speeds, asymmetric ("split-speed") operations have been utilised: 75 bits per second (bps) into the computer and either 1200 bps or the speed of a synchronous modem channel, typically 2400 bps, out to the terminal.
A synchronous modem channel does not coexist happily with asynchronous data transmission. The data is likely to be corrupted when low speeds are used. A 2400 bps channel will only support 600 bps for error-free graphics output. Post Office dial-up operations are straightforward as the modems are designed to handle asynchronous data at 1200 bps.
600 bps is too slow for large-scale graphics and a poor return on terminal, line and modem investment. To solve the problem, the Rutherford Laboratory's Telecommunications Group designed a device we call an "Asynchronous-to-Synchronous Retiming Buffer". It is interposed between computer and modem to capture the asynchronous data from the computer. This data is then controlled through the modem and line system by the modem clock. In this way, asynchronous output is transmitted to the terminal at the speed of the synchronous modem channel. Incoming data at 75 bps obviously requires no assistance; this speed allows more than thirty clock strobes per data bit on a 2400 bps synchronous channel!
The "standard" for asynchronous data communications has therefore been 75/1200 bps via Post Office dial-up modems and 75/2400 via synchronous modems on Post Office private lines. There have been some variations, such as 150 bps and 2400/2400 bps with re-timing buffers at both ends to satisfy individual terminal idiosyncrasies.
There is now a gradual shift away from asymmetric speeds. Terminal switching systems are utilised more and more, allowing the user to connect his terminal to a chosen computer by a command to the switching system. The Private Automatic Computer Exchange (PACX) at RL and Imperial College's Terminal Access Controller (TAC) are examples; both operate at symmetric speeds. Also, the ICF's GEC 4000 series computers offer a choice of only four speeds so it made sense to scrap 75 bps in order to provide a more useful, higher speed. To make this possible, the Telecommunications Group designed another device which allows continued use of 75 bps on the modem systems but steps this up to the appropriate symmetric input speed required by the computer/PACX interface. We call this device an "Up-timer". It handles either 75 or 150 bps input and outputs 1200, 2400, 4800 or 9600 bps to the interface. An up-timer with 75/1200 bps dial-up gives interface speeds of 1200/1200; a re-timing buffer in combination with an up-timer on a private line using synchronous modems gives the higher symmetric speeds.
When more than one terminal needs access on a private line synchronous modem channel, we have installed statistical multiplexers. These devices offer the channels bandwidth only to the terminals which are currently active. The devices are substantially buffered with provision of "handshaking" to allow control of data flow in case of impending buffer overflow. These are symmetric speed devices and thus fit into the scheme.
Finally we are planning to install most if not all of RL's dial-up lines onto PACX. We have had to design yet another device to do this! This device allows a Post Office modem to connect to its exchange line when called, and also closes down the call correctly. The device will thus provide low speed (110 and 300 bps) control, and in conjunction with an up-timer will provide a 75/1200 bps service presented as 1200/1200 to PACX. We plan to start making the change during April. It will enhance the service. The user will need to know only one telephone number each for low and medium speed operations, He will have access to the whole range of ports on ICF and batch computers at Chilton; he will also be able to logout from one machine and connect to another without having to re-dial the telephone call. These features should improve the user's access to the machine he wants when he wants.
Details of the dial-up changes and copies of the PACX User Guide are available from Mrs Steve Woodward.
The successful first FE Library course was held at Rutherford last October and the second at Glasgow in March. Others will be held in Manchester (30 June - 4 July) and (probably) in southern England later this year.
Following suggestions at last September's User Meeting, more specialised meetings will be held in future, forming an FE Colloquium series. They should provide a forum where experienced users can describe their approaches to specific problems and discuss the pros and cons of different techniques; also, researchers new to the field will be able to improve their understanding and also make useful contacts.
The first meeting is a "pilot" for the new format and. is entitled "Finite Elements in Fluids". It will be held at Rutherford on Thursday 15th May. The following talks are planned:
Lunch can be provided by SRC but other expenses must be borne by the visitors themselves. However, free transport from Didcot station or Heathrow airport is available if requested in advance. Anyone interested in attending should contact Ken Robinson or Chris Greenough for details.
Suggestions of topics (and speakers!) for other FE Colloquia would be welcomed by the Finite Elements Steering Group.
One-day tutorials are being held on the use of the NAP-2 package (see section 2. above). The first is on 21 May with a repeat on 22 May; both will be held at Chilton and both are already over-subscribed. Further tutorials will be arranged. Any reader who has not received information about the DACD work should contact John McLean at Rutherford.
The Special Interest Group for Computer-Aided Architectural Design has finalised its proposals for software development over the next five years. A draft paper was circulated to interested research workers in late January with a request for Comments by the end of February. The SIG met early in March and modified the draft in the light of comments received by them. The revised proposals were considered by the Interactive Computing Facilities Committee on 28 March. Details will appear later.
The Electron-Beam Lithography Facility (see 'Rapid Response' No. 10 ) at Chilton, which provides an integrated-circuit mask-making service to universities and polytechnics, is now operational; 25 mask plates have been delivered to customers. The GAELIC system for integrated circuit design, as supplied by Compeda Ltd, is used by designers to prepare the data defining their masks. A Compeda engineer, Bill Savage, is now working full-time at Chilton to assist users of GAELIC. New enquiries from potential users should still go to the Co-ordinator, Bill Turner.
The GAELIC Club, an association between Compeda, the SRC and the Post Office, has been formed to ensure that future development of GAELIC is both coherent and in the best interests of all concerned. Two members of Technology Division at Chilton represent SRC, and through SRC the universities and polytechnics. at formal meetings.
A meeting will be called shortly for university and polytechnic researchers developing integrated-circuit CAD tools and for potential users of such tools. They will be able to meet the SRC staff representing them in the GAELIC Club. Anyone wishing to attend should contact Mike Newman (for details see section 3, above).
The AUTOPROD 3-D drawing package is currently mounted on the PRIME at Chilton for demonstration purposes only; interested readers should contact Paul Nelson.
SRC has set up a working party to investigate the needs of its users for databases, database management systems, information retrieval and any related facilities such as long term data storage. Members of the Working Party are distributing a questionnaire to their colleagues in an attempt to collect this information. However there may be scientists not yet known to us who are contemplating SRC-sponsored research which will need a database management system. If anyone reading this would like to help us by completing a copy of the questionnaire please apply to Mrs Judy Lay.
