1. Epoch Overlap The four epochs of HIS systems (mainframes, shared, mini and micro) overlapped quite a bit over the four decades of our HIS-tory. The Mainframe movement was strongest in the 60s, led by IBM’s breakthrough 360 system, and lasted well into the 70s when almost every large hospital had a mainframe in their basement. In the 70s, some started migrating to shared systems, and in the 80s, minis grew in power to erode mainframe presence. Only in the 90s were mainframes becoming scarce. 60s 70s 80s 90s Mainframes (eg: IBM, “BUNCH”) ++++ +++ ++ +

2. Shared Systems Sharing of mainframes started in the late 60s with IBM’s SHAS (Shared Hospital Accounting System), which enabled many vendors and Blue Cross plans to share a costly mainframe among smaller hospitals. By the 70s, thousands of hospitals were sharing systems, from giants like SMS, McAuto and Tymshare. It took decades and the growing power of minis and micros before shared systems lost their market dominance, although SaaS and “Cloud” computing may mark its resurgence… 60s 70s 80s 90s Shared (eg: Blues, States, Commercial…) ++ ++++ +++ ++

3. Minis go Maxi! The first minis were developed in the 60s, such as DEC’s PDP-1, but they didn’t gain much market share in the HIS market until the 70s with pioneers like McAuto’s (yes, the shared system giant!) HDC & MHS, HBO’s MedPro & IFAS, and SMS’ ACTIon series. Minis totally dominated the 80s with “Total HIS” offerings such as Dynamic Control on IBM’s Sys 38 and AS/400. Only in the 90s did they lose some ground to the next upstart: 60s 70s 80s 90s Minicomputers (eg: DEC, DG, HP…) + +++ ++++ +++

4. Micro Monsters It’s hard to remember just how amazing the PC revolution was in IT back then, but Apple IIs were looked upon with derision in the late early 80s when they first popped up in ancillary departments. Ironically, it was IBM who legitimized the genre with their PC circa 1982, and their later PS/2 suite. On the software side, DOS devotee’s resisted GUIs right up until Windows 95, by which time even shared and mini vendors adopted PCs as terminals, and pioneers like HMDS offered an HIS! 60s 70s 80s 90s Microcomputers (eg: Apple, IBM…) + ++ +++

5. H.I.S. Epochs So here’s the full picture: how platforms rose & fell like the tide. The hardware line today has blurred completely as “servers”… 60s 70s 80s 90s Mainframes (eg: IBM, “BUNCH”) ++++ +++ ++ + Shared (eg: Blues, States, Commercial…) ++ ++++ +++ ++ Minicomputers (eg: DEC, DG, HP…) + +++ ++++ +++ Microcomputers (eg: Apple, IBM…) + ++ ++++