Richardson, M. (1964), User’s experience of CLEO. An analysis carried out by Richardson of the Board of Trade, Central Office, Lime Grove, Eastcote, Ruislip, Middlesex, of the use of CLEO. The analysis refers to an article in Volume 5, Issue 3, November 1962 of the Computer Journal by T.R. Thompson entitled Fundamental Principles for expressing a procedure for a computer application.
User’s experience of CLEO – By M. Richardson*
The Board of Trade Census Office has used CLEO for preparing Annual Inquiry registers, and issuing and processing the 1963 returns. We have also used CLEO for a register of new companies and are now in course of applying it to all new jobs. Comments made here relate to the first seven programs written, which were analysed in some detail.
The first CLEO compiler did not become available until the end of 1963 and is still not on general release
1. General comments (a) Adequacy
So far CLEO has covered all our programming requirements since these needed only integer arithmetic. It has not been found necessary to enter the lower language,
i.e. Intercode.
The major extension of facilities to floating-point values, etc., will cover all future requirements; there will be no need to know Intercode.
Facilities are to be extended to cover function calls and floating-point working within the next three months. In general, most of the features mentioned in T. R. Thompson’s paper in this Journal have been included in the system or will be included very shortly. At present the major limitation is on editing values for printing; this has been covered by a CLEO subroutine.
(b) Ease of learning, etc.
The CLEO conversion course provided for the first team of Intercode programmers occupied one and half days. There is no doubt that CLEO is easy to learn and with the compiler checks provided it is easy to use correctly.
(c) Debugging
Amendments are very simple to make in CLEO. The trials data system now being provided is even simpler than the Intercode system. It was difficult to locate logical errors in Intercode, but it is easy to do this in CLEO. Desk checking becomes more effective.
(d) Compiler problems
Only one minor imperfection appeared in the first version; this is now being put right.
2. Satisfactory features
The following table gives some idea of the reduction in programming time made possible by CLEO.
RELATIVE PROGRAMMING EFFORT (TIME UNITS)
INTERCODE CLEO
Flow charting 10 0
Coding time 55 10
Data description 10 2
Checking 10 2
Proving 15 2
Board of Trade, Census Office, Lime Grove, Eastcote, Ruislip, Middlesex
