Robert, IMHO operating system issues represent only a very tiny fraction of all the problems seen on ATM's, most problems arise due to hardware and immature device driver issues.
I disagree. The hardware used is very very very basic and with well supported drivers for the computer portion of them. As for hardware failure, that was few and far between "back in the day" - we were expecting (1997) minimal hardware failure related service calls (based off previous track records). So, though we were expecting them to be one of (if not
the) largest support issue, it was expected a staff of 3 people could cover Florida to Maine. Not a really big issue considering BoA (and their subsidiaries we would also be covering) was the 2nd or 3rd largest bank at the time.
In addition, I've found more blue-screened, compromised and other software related issues on the Windows ATMs than I ever saw on the OS/2 machines (which I've been using since the 80's when I was an employee at CitiBank and they'd rolled out their ATM cards on the Cirrus network). If that's related to driver issues, it's baffling as to why considering the XP platform and the hardware/drivers for these devices are quite equally mature in comparison.
Banks were also unhappy in the early days of the DOS to OS/2 migration, but most problems were to blame on device driver instabilities and the switch from the old DOS-style applications to the then-new OS/2 message-driven application programming paradigm.
Yes, but long since resolved. And in the Windows world, device driver issues for such computers are near non-existant for the hand selected, standardized hardware out there. It's not like someone took the OS/2 ATM and simply overwrote it with Windows XP or Vista.
Now we see a shift from serial to USB ATM devices and the newly-developed drivers for these new devices also have their share of problems.
These are not newly developed drivers. IBM's been using such on similar hardware for many many years, such as on the AnyPlace Kiosk sitting next to me (which is very similar to their other POS and ATM style offerings - including magnetic card reader, touchscreen and such - just leaving the cash dispenser/deposit input tray). NEC fits in the same boat on this as well. Oh, and a large portion of the devices in question simply respond as a keyboard or mouse.
So I'm not convinced that you will achieve a significant increase in ATM availability by replacing one OS with another one.
Funnily, history has proven otherwise already. A "support region" for a bank's ATM setups nowadays is often defined as a county - or even sometimes a portion thereof. It is no longer defined as 4-7
states. The number of ATMs has not increased nearly enough to account for the tremendous increase of support personnel. It's just pure, simple math.
Best,
Rob