HP 16700A logic analyser.
A good ten minutes on the stock hard drive -- it cold-boots HP-UX from a remarkably slow Quantum Fireball SCSI drive.
It makes up for its slowness by being utterly unparalleled (at least without going all-in for a 16900) for reverse-engineering 68K system software.
Is that 10 minute figure accurate, or just a ballpark figure off the top of your head? I have never bothered timing it myself yet on a 16700 series.
I recently timed power-on to logic analyzer application fully up and running on a 16900A at 2 minutes, 10 seconds. That is a 1GHz PIII, 512MB running XP SP3 on the stock 80GB ATA drive with version 5.90 of the logic analyzer application. I haven't timed it on the 16901A or 16902B with the E8400, 4GB motherboard running W7 yet to see how that compares.
EDIT: I just timed a 16901A logic analyzer from power-on to logic analyzer application version 5.80 fully up and running at 1 minute 20 seconds. That is with the M890 motherboard version with a 3GHz Intel® Core™2 Duo E8400, 4GB running 64-bit Windows Embedded Standard 7 SP1 on the standard WD5000BPKX 500GB SATA hard drive. The M890 motherboard versions of the 16901A and 16902B were the final versions of Agilent / Keysight modular mainframes in the traditional form factor before they switched to AXIe modules.