Editing Antifeatures (section)

==== Unnamed Ye Olde Mainframe from the Bad Old Days of Heavy Metal ====

The CPU came in two flavours... cheap and slow vs  fast and 'spensive. 

Most victims (umm, customers), surprise, surprise bought slow and cheap... and found it too slow... and bought the upgrade.

So the field engineer would hove into view carrying a anti-static bag with a board inside saying, "Shutdown... your upgrade has arrived"

He would swap out the board, putting the old board into a spare bag, power up and off to the next vic..err.. customer.

On the way, he'd pull over to the side of the road, haul out the old slow board, flick a switch on the "maus klavier" (dip switch), and on to the next customer. "Tada... your upgrade has arrived..."

This was called a "screwdriver upgrade" -- on the IBM mainframes I saw upgraded the DIP switch was flicked in place and the customer was fully aware of the process. It depends upon the charging model as to if this was a anti-feature. For example, most IBM customers leased the mainframe per-MIPS. Upon requiring more MIPS they much preferred a screwdriver upgrade rather than the multi-year planning required for "forklift upgrade", where the entire machine had to be replaced and sometimes the software rebuilt (eg, the new mainframe hardware may have required a move from MVS/XA to MVS/ESA), with extended downtime and significant risk of deployment failure. Usually contracts for IBM-compatible mainframes explicitly requested the range of MIPS for the hardware, a mainframe with a lesser range being penalised as that implied a major upgrade would be required sooner.