7. SYSTEMS SPECIFICATION

7.1 Criteria for Choice of Equipment

Inevitably, no piece of equipment is likely to meet the specification in all respects. The extent to which various parts of the specification are met will therefore have to be weighted in making a choice of computer. The Technical Group recommends the following as a technical guide to weightings:

Extremely important

That the system should have been proven in a engineering multi-access environment, because reliability and availability are at the very heart of a service to engineering users.

Very important

User acceptability of the command language and editor, because the failure of a number of services is clearly attributable to this factor alone.

Response time acceptable to users, because this is the factor responsible for the failure of some services.

Virtual memory, because of the considerable time that has to be spent on condensing programs into a limited space.

Important

Cost, Or more strictly, cost per simultaneous user channel appropriate allowance being made for relative power.

Fairly important

Re-entrant compilers with link loaders

Variety of terminal support

Not so important

Other features, including application packages.

7.2 Specification of the Chilton Machine

The following is intended as a guide to the specification of the Chilton System. A detailed document will be prepared as part of the invitation to tender including particularly a more detailed specification of the work load and a bench mark which will form part of the acceptance test.

7.2.1 User Work Load

The system is to support up to 60 simultaneous terminal users at peak times engaged in a mixture of editing, compiling, debugging and running of programs. Virtual memory is required. The typical user work profile during a 30 minute period at peak hours maybe expected to be as in Tables 7.1 and 7.2.

TABLE 7.1: Simultaneous Terminal Use at Peak Hours

Terminal Class	Number of Concurrent Jobs
Remote job entry requiring operation at 4.8 Kbits/sec	say 6
Graphics at 4.8 Kbits/sec	11
Graphics at 1.2 Kbits/sec	11
VDUs and Serial Printers at 1.2 Kbits/sec	11
Serial Printers at 300 bits/sec	5
Teletypes at 100 bits/sec	16
TOTAL USER JOBS	60
Overhead jobs (print spools, connection to 360/195 etc)	say 10
TOTAL JOBS	70

Support for a wide variety of terminals is required - including page mode, variable delays for printer carriage return, APL character set, etc.

TABLE 7.2: User Requirements In Memory Space and Processor Power

No. of Users	User Memory (Bytes)	Total Memory (Bytes)	User CP Usage (Atlas Units)	Total CP (Atlas Units)
1	1M	1M	0.4	0.40
2	400K	800K	0.2	0.40
4	250K	1M	0.1	0.40
8	100K	800K	0.05	0.40
15	50K	750K	0.02	0.30
30	25K	750K	0.008	0.24
TOTAL		5.1M		2.14

A high degree of correlation between user memory size and user CP usage should not be assumed (ie the user consuming 0.4 Atlas power is as likely to be one occupying 50 Kbytes of memory as one running in 1 Mbyte of memory). Similarly, a high degree of correlation between terminal input/output speed and memory size or CP usage should not be assumed.

Wide variations in usage profiles over successive 30 minute sampling periods must be anticipated and will be incorporated into the benchmark.

Memory sizes assume re-entrant editors, Fortran compilers and link loader.

Requests for CP usage (not disk or input/output limited) lying within the above user profile should demonstrate a 98% confidence factor of response within an elapsed time not greater than three times the CP time demanded. The distribution of such requests will be very highly skewed. Random, skewed distribution requests for CP will be incorporated in the benchmark.

7.2.2 System Configuration

Based upon experience of comparable interactive systems the configuration may be expected to be in line with the following. Manufacturers will be free to offer alternatives - supported by adequate justification.

1. Processor capacity 3 Atlas power
   • to provide approx 2.1 Atlas power at 70% loading in peak hours
2. Real memory 2 Mbytes
   • ie at least 40% of user virtual memory
3. Total virtual memory 10 Mbytes
   • To allow for unused areas of user working sets.
4. Separate swap channel
   • To avoid swap/file access clash on one channel.
5. Fast swapping media
   • Manufacturer required to demonstrate by Benchmark that access time/transfer rate in conjunction with specified real memory will meet response requirement.
6. File storage of 800 Mbytes
   • To meet 1 Mbyte per user 200 Mbyte library and system area.
7. At least one spare drive per 6 on-line
   • For standby and maintenance.
8. 4 tape drives with minimum 100 Kbyte transfer rate, industry compatible
   • For file security, intersystem communication, etc
9. Line printer 1000 lines per minute
10. Card reader 600 cards per minute
11. Fast paper tape reader and punch

7.2.3 Communications

The system will be expected to support the asynchronous terminals initially via a star network driven by its own front end processor.

Additionally the manufacturer will be required to provide support as part of their standard operating system for the existing SRC owned RJE terminals (GEC2050). Communication to these terminals will be via a single high speed connection to a node of the network connecting all the terminals. The node is expected to be either a GEC2050 or a GEC4080.

The manufacturer will also be required to undertake that, in the event of a National Computer Board/SRC network being established using a Post Office supplied switching network, they will provide support for connection to the network and for the high level protocols adopted.

7.2.4 Operating System

An easy command language is considered an essential feature of the system and indications of those features characterising the language as easy will be incorporated in the tender document. In addition the system must provide the following:

1. Full user interaction with running programs (user written).
2. Access control and user accounting (to stage of producing sorted monthly summaries of usage by user, with facilities for modification of accounting units).
3. Reloading and restart of system not to exceed 3 minutes.
4. Ability to reconfigure system (memory size, number of disk drives, numbering of disk drives) without reloading operating system.
5. File housekeeping, copying, archiving.
6. Ability to set up multiple batch streams.
7. Full transferability between interactive jobs and batch stream with compatibility of command language between both.
8. Ability for user to create command macros and command lists.
9. Tuneable schedulers.
10. Performance measurement facilities.
11. System management facilities (permissible user memory size, file storage allocation, etc).

7.2.5 User Software

A combined text and line editor to be available. Compilers to be provided for the following languages:-

• FORTRAN IV
• ALGOL
• APL
• POP
• LISP
• BCPL

All of the compilers to be re-entrant and to provide link loading facilities except APL or other languages that are provided as interpreters.

At least FORTRAN to be provided with source level debugging aids and excellent chaining/overlay facilities notwithstanding the virtual memory requirement.

7.2.6 Other

Manufacturer to undertake full maintenance responsibility. No routine maintenance requiring system close down to be undertaken during prime shift.

Major system incidents (resulting in system reload) to be guaranteed at less than one per hundred hours operation.

7.3 Specifications of the Enhancements to the UMIST and Edinburgh Facilities

The UMIST and Edinburgh PDP 10 systems should be enhanced on the lines of the items listed below. As the existing systems were supplied by DEC the items are shown in terms of DEC equipment.

Some of the items are only available from DEC. However, both main memory and disc drives for PDP 10 machines are available from alternative suppliers, and the possibility of obtaining some of the equipment required for the upgrades from these sources should be investigated.

UMIST

1. Addition of 128 Kwords of memory including 4 port access and cabling
2. Addition of four 50 Mbytes discs (DEC RP03) including cabling
3. DC76 front end processor with 16 asynchronous lines. Modem control for asynchronous lines. One synchronous interface. Special interface between DC76 and a GEC 2050

Edinburgh

1. Exchange existing KA10 processor for a KI10
2. Addition of 128 Kwords of memory including 4 port access and cabling
3. Addition of two 50 Mbytes discs (DEC RP03) including cabling
4. Special interface between DC75 and GEC 2050
5. Link to the Scottish Regional Network.

7.4 Specification of New Multi-User Mini-Computers

7.4.1 Processing

1. Processor capacity ≥ 0.5 Atlas power
2. Sufficient main memory to support at least 6 concurrent users
3. Arithmetic accuracy (by hardware) 64 bits or better
4. User address space of at least 150 Kbytes

7.4.2 File Storage

1. Exchangeable disc storage of minimum 70 Mbytes capacity.
2. Minimum of 2 disc drives

7.4.3 Input/Output

Hardware and software support for:

1. 6 simultaneous user channels
2. Mixed terminal types
   • Data rates of 100, 300, 1200, 2400, 4800 and 9600 bits/sec
   • with dial-up for speeds up to 1200 bits/sec
3. Post Office EPSS connection (or to its successor)
4. Local 200 lpm printer, 400 cpm reader and paper tape facilities

7.4.4 Operating System

1. Response times 1n accordance with detailed profile to be drawn up
2. Full user interaction with running programs (user written)
3. Command language tolerable to unskilled remote users
4. Reloading and restart of system not to exceed 3 minutes
5. File housekeeping, copying, archiving
6. Batch stream capability
7. Full transferability between interactive jobs and batch stream with compatibility of command language between both
8. Ability for user to create command macros and command lists
9. Tuneable schedulers
10. Performance measurement facilities
11. System management facilities (permissible user memory size, file storage allocation, etc)

7.4.5 Other

Manufacturer to undertake full maintenance responsibility. Major system incidents (resulting in system reload) to be guaranteed at less than one per hundred hours operation.