The leasing was mostly in the older days. The 360 in System/360 stands for 360 degrees of coverage, meaning the machines were made to do all sorts of tasks. Before the workstation came into real power, mainframes had a significant portion of the CAD and simulation market. S/360s and S/370 found a few scores in the factory process control market. One mystery - what was the box that converted the Bus and Tag to signals the machines could use, before the S/1s were released? A 29xx or 39xx series box? I want to know! Here you will have troubles. The big IBM drives (DASDs) are almost all gone. The last of the really huge disks, 3390s, are just about all out of service. Just about everything else big, from early times, is gone, except for a few anomalies (like the recent 3350s out of Columbus, OH). For big drives, the CDCs seem to have survived the best. And oddly, old IBM tape drives - the 3420s - can still be found. DEC systems mostly just make a lot of sense. Try one, you might like it. If you are looking for a pre-S/390 big IBM, you have very few options. S/34 and S/36 are just about the only ones. S/1s are getting pretty thin. You can mostly forget about finding a pre-S/390 mainframe, like a 9121, 9221, or 43xx. There are very few of these left in the wild. That said, I am still looking for an ES/9000 (9021, 9121, or 9221). Or even 3090 or before. -- Will