About Us

With a well-established track record, Abacus Systems reduces operational risk, develops robust business processes with risk-free solutions to protect our customers businesses from issues such as; data loss, data leakage, skills shortages, energy waste, overloaded legacy systems, and, ultimately, the failure of business processes. With leading technical expertise and practical management skills, Abacus Systems is your partner of choice for technology solutions. As a leading provider of quality services and products, combined with a proven record, we always aim to exceed our clients’ expectations when addressing their IT challenges.

We are known for extensive understanding in most major platforms and recruit only very experienced staff. Our expertise allows us to deliver bespoke service combinations, customised to provide the most effective solutions to meet your requirements.

As a leading, independent IT infrastructure solutions provider, Abacus Systems is a recognised partner of the world’s leading IT suppliers.


Derek O’Callaghan

Managing Director

Qualified Novell Certified NetWare Engineer (CNE), Compaq Accredited Systems Engineer (ASE). Derek has over 30 years experience in computer connectivity, with extensive knowledge of network operating systems, network communications, application packages and project management. This experience was gained working with Sharptext here in Ireland and later with BML in Kenya. Derek returned to Ireland in 1992 and formed Abacus Systems. in 2014 Derek graduated with BSc in Psychology.

Eoghan Johnson

Business Development Director

Eoghan joined Abacus Systems in 1996 and he holds a BBS, MBA and is a graduate of the Marketing Institute of Ireland. He has worked in Sales Management roles for almost 30 years and also holds certifications from Microsoft, Cisco, HP and other vendors. Eoghan is responsible for Business Development.

David McDonald

Sales Director

David has a BA from UCD and 19 years extensive IT experience working first with Dell Computers Management Information Systems team before joining Abacus Systems as a senior network engineer, pre-sales technical consultant and account manager. David is VMware Certified Professional and his main areas of expertise are project management, design and implementation, IT security, business continuity, enterprise switching and routing architecture, IP telephony and a storage area network specialist.

Stephen Mullin

Technical Director

Stephen joined Abacus Systems in 1997. Stephen is a Microsoft Certified Systems Engineer, VMware Certified Professional and Mitel Certified Professional with 20 years experience in Microsoft, HP, Dell and Cisco solutions. Stephen has been the lead engineer on most of Abacus Systems major projects, including IP Telephony, Virtualistaion, Network Infrastructure, Business Continioty, Storage Area Networks and WAN connectivity.