Found some stuff at the scrapyard

[tony duell]

> Original "A" version with HP-IB interface, useless for regular
>  PCs of course. Complete with the "SomethingJet" marketing

It's mildly easier to use with a normal PC than the -B model (HPIL,
battery powered). Interestingly the -A version has an HPIB-HPIL
interface feeding HPIL to the main board (the interface is a 
modified (different firmware) version of the HP82169 IIRC.

Interesting #2, the custom HP controller chip in these printers
has a built-in ROM with the control firmware, but external 
font ROM and RAM. These communicate over what is essentially
the Saturn bus, as found in the HP71, etc.

> name that has been with us since then. The key innovation of 

I read somewhere that the official reason for 'THINKJET' was
'THermal INKJET'. I suspect that is very much a backronym. It
is a thermal inkjet printer, the cartridge has little heating elements
that boil the ink and cause a drop to be squirted out.

> that printer was the disposable cartridge with the micro-
> machined nozzles, which they had a horrendous time
>  manufacturing at first. And for some incomprehensible reason, 
> you can still order brand new cartridges from... Staples! Just put
>  a new one in and you should be good to go.

A couple of words of warning about those cartridges. Firstly
the ink, at least in older ones, is ethylene glycol based. It's toxic
and attractive in taste to some animals. Keep those catridges
away from cats, dogs, etc.

The ink is also corrosive. It can corrode the metal faceplate
on the cartridge, then drip onto the flexible PCB that connects
the cartridge to the rest of the printer and corrode that too. 
If you ever have a Thinkjet with missing dots, that's what has
happend (at least 99% of the time). The only source for 
replacement PCBs now is other Thinkjets. So don't leave the
cartridge in the printer if you are not using it. 

Incidentally, if the 9153 is the drive unit I think it is, it has a 
very odd HP-interface hard disk in it. There is one ribbon
cable (40 wires I think) carrying power, control signals and
raw data. I seem to remember the head positioner is a 
stepper motor, but it does micro-stepping as part of the 
design. 

-tony