BEEP
One of the most surprising features of this thing is that it has a fully-functional 16-bit ISA card slot. It came with a unique AMD network card in the slot, an AMD (yes, they made network chips?) AM79C960. The card has "2100/1500T Compatible" silkscreened on it. According to Windows 95, that's the only usable network port on the machine.So, of course I yanked it out in favor of a generic 16-bit SoundBlaster compatible card from eBay!
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| Super Generic card, from the days when there were multiple "IDE" standards (the four big connectors on the left) and multiple audio cable standards (the white connectors in the upper right) for CD-ROM drives. |
Buying Was the Easy Part (Rant Incoming)
Fitting this card was... an adventure. The various mounting brackets and other cards inside the Internet Advisor were in the way of the card. The IDE connectors and two of the audio connectors would have to go, which is a bummer; I'd hoped to use the IDE ports to temporarily add a CD ROM drive for temporary software installation. I actually had to cut away one of the mounting ears for an internal bracket just to clear the sound card bracket. That'd be a problem if this thing wasn't built to survive World War III.
The other fact that I haven't really harped on yet is that the entire machine needs to be disassembled to do almost anything. Cards must be unplugged. Flat-flex cables must be detached (carefully!). Changing hard drive? Full disassembly. Changing ISA card? Full disassembly. Oh, you made a re-assembly mistake? Fun times! Full disassembly. This thing must have made HP repair technicians furious, which is odd, because much of the other HP gear I've taken apart over the years had maintenance in mind.
The AOYUE 474A++ vacuum desoldering tool that came in so handy for the Commodore 64 work I did last year made relatively painless work of the IDE connectors. I'll never need the Mitsumi, Panasonic, or Sony ones, but I may find a way to re-fit the generic IDE one someday.
After some bending and judicious application of the metal nibbling tool, the card was fitted. What new screw-up did I perform on re-assembly?
Cringe and Flip on the Power
Sometimes I forget that Plug & Play made even ISA card fitting a relatively painless experience: |
| No smoke this time! Win95 discovered the Sound Card, Joystick Port, IDE connector, MIDI port, and all of the other stuff shoehorned into sound cards 20 years ago. |
Updates and Stuff I Was Wrong About
Early on I mentioned that the little lithium backup battery had two cells. WRONG. It's a single cell, but extra thick, CR2354 (23mm in diameter, 5.4mm thick). It still measures nearly 3V, but it's 20 years old so I got a new one from DigiKey.Some Googling about PS/2 led me to a site which informed me I was wrong about something else:
The device always generates the clock signal.D'oh. I thought the chipset generated the clock. My oscilloscope showed no activity on either the clock or data PS/2 signals from a cold start, so I done goofed somewhere. Maybe it's disabled in the HP-customized BIOS? After all, they never intended it to have a functional port...
One thing I got right was the LCD voltage. Yes, I measured it, and yes, it was at 5V as I'd reasoned/hoped. I didn't measure the current, though. I'm enjoying the mystery. I'm not worried; the voltage drop across my hacked-in MOSFET is very small, which means the current through the MOSFET is also small. Most importantly, those two facts mean that the power dissipated in the MOSFET is very small, so it shouldn't be a problem unless I screw up the connector again.