Patrick O’Beirne had already acquired an expertise in financial modelling when the first spreadsheet software appeared. For more than 40 years he has advised, trained and supported spreadsheet users. His company, Systems Modelling, also provided consulting services in software quality, application testing and spreadsheet risk.
He has served on the council of the Irish Computer Society and became a fellow of the association after leading its campaigns to prepare for the year 2000 date change and for the introduction of the euro currency.
This testimony begins in the ‘Minicomputer systems and software 1969-82’ archive. Click here to view.
Bord Gáis was my first customer, followed soon afterwards by the IMI and Ballyfree Farms. I developed decision support applications for Apple systems and moved deeper into training and consultancy.

Systems Modelling promoted decision support applications for both the Apple II and Apple III at Computex 1983.
Cartoon by Martyn Turner. Brochure created by Bennis Design.
A lot of smaller companies were buying microcomputers and starting to use spreadsheets at this time. I also sold the TABS accounting package, Pascal Payroll and Apple’s own text processing and mailing list software.
The Apple II did well for me. Systems Modelling sold dozens. The price of this computer in 1981 was around £1500 and buyers could double its memory for an extra £300. A copy of VisiCalc cost another £150.
I bought the Apple products from distributor Softech, where Jonathan Moss was my main contact, and from Leith Computers. I sourced third party add-ons from Pete & Pam Computers in Britain, from Softsel and directly from the USA. There were related hardware sales – Apple, Epson and Anadex printers, monitors from Transtec in Pearse Street, and supplies from Willis and QTH Electronics in Dun Laoghaire and Budget Computing in Malahide. I took a stand at the Computex exhibitions in 1981 and a couple of years thereafter.
Customers were good. There was only one occasion when I had to go into a company to retrieve an Apple when payment had not arrived on time; coincidentally, their premises burned down shortly after that!
The big limitation of the Apple II was its storage capacity. Its single-sided floppy disks held a mere 140 KB. Many customers bought two disk drives and some even installed four drives to handle their data. It was possible to use a hard drive with an Apple II, but this required the addition of a special board to the computer. A few of my bigger customers, including Waterford Glass and Pettitt’s supermarkets (later SuperValu), moved up to the Apple III in order to avail of a 5 MB hard drive.
The Apple III was less successful for Systems Modelling than the Apple II and the expensive Apple Lisa was definitely hard to sell. In 1984 I switched to MS-DOS-based machines, still concentrating on spreadsheets but now supplying Lotus Development’s products Lotus 1-2-3 and Symphony. MS-DOS had better device support and a faster growing aftermarket of applications. The PC hardware came from wholesaler HE Clissmann, which sourced systems from Compaq, Ergo and other vendors.
In June 1982 I teamed up with Tony Moynihan at the IMI to present the institute’s first training course in personal computing skills for business managers. We introduced the microcomputer as a calculator with logic and argued that users should acquire elementary programming skills in order to get the most from their systems. This course also included an introduction to VisiCalc, presenting spreadsheet packages as just one step removed from programming languages.
In subsequent years I gave courses in the IMI on Lotus and Excel and also delivered a module on statistics in a management course. Gus Liston at the IMI got me involved in these courses and my work there was enjoyable. From 1988 to 1991 I also lectured part-time in the Department of Management Science and Systems Studies in TCD, which was headed by Professor Gordon Foster. After leaving TCD I worked with Prof. Foster in EU sixth framework programme projects such as TRINET, which provided email services to remote parts of Africa via the POSAT low-earth-orbiting satellite.

Patrick O’Beirne pictured in 1988 with a Toshiba portable computer and an unidentified desktop PC.
Photographer unknown. Photograph courtesy of Patrick O’Beirne.
Systems Modelling continued to sell computer hardware until the arrival of mass market retailers like Dell in the 1990s, but software implementation was always my top priority. I wrote applications in dBase and Clipper for SMEs. I developed a room allocation system for the IMI in Clipper, a price list management system for Pettitt’s and other industry-specific applications like one for a meat processing factory.
My focus on Lotus spreadsheets ended when I began to use Microsoft Excel. I started with Excel 5.0 which came out in 1993 and went on from there. I kept moving deeper into Excel applications and invested in a lot of books on programming, software quality, statistics, and business. I became more interested in software quality and process improvement and more involved with the auditing and testing of applications, giving many presentations on spreadsheet risk. I developed and sell a spreadsheet auditing tool called XLTEST.
Spreadsheet consultancy, training, and Excel/VBA custom development for data analysis remains my present focus of work. Clients include private companies, insurance companies and a very large asset management organisation.
The late 1990s saw a great deal of involvement with the Y2K and Euro changeover campaigns where I was a member of the ICS teams that travelled the country to give advice. Stemming from that, I was awarded Fellowship of the ICS. I also had the opportunity of presenting worldwide in Europe, Asia, and America at Y2K and Euro conferences, was an expert adviser to the European Commission on euro conversion software, and wrote a series of articles in the Irish Computer magazine on those topics. I wrote a book, Managing the Euro in Information Systems, that Addison-Wesley published in 1999 and self-published Spreadsheet Check and Control in 2014. The latter influenced the development of the Spreadsheet Safe training and certification offered by Q-Validus in Dublin. I was a committee member of the Irish Software Testing SIG (SoftTest Ireland) for many years.
In 2000 I attended the first symposium of the European Spreadsheet Risks Interest Group (EuSpRIG) on spreadsheet risks. That interest has stayed with me and I am currently chair of EuSpRIG.
Last edit: October 2022
© Patrick O’Beirne 2022