Boards for grabs

From: Frank McConnell <fmc_at_reanimators.org>
Date: Fri Jul 24 20:43:56 1998

"Max Eskin" <maxeskin_at_hotmail.com> wrote:
> What kind of boards? Was it single-board or backplane or what?
> Also, what are the key differences between Hp and PC?

Why not start with the key similarities, it's a shorter list.
They both had 8088s and ran MS-DOS. OK, there you go.

The original HP150 looks like a 9" CRT in a box, with a keyboard
attached via coiled cord that goes to the back. Typically there would
be an HP-IB disc drive of some sort (probably with a 91xx model
number) around, most likely using 3.5" stiffies because HP was an
early adopter of the Sony 90mm medium, but even without that the 150
can be used as a terminal (it mostly looks like an HP2623A monochrome
graphics terminal).

If you look at the back, you'll see two DB25S connectors that are
serial ports, an HP-IB connector, a modular phone jack for the
keyboard cable, a power switch, a battery holder, and a couple of
covered slots for expansion. You might also see a thermal printer
mounted in the top.

OK, now let's go for some of the differences. The HP150 is not at
all compatible with the IBM PC at the hardware or ROM BIOS level. The
base system runs the 8088 at 8MHz, which was "faster" than the IBM's
4.77MHz, but on the other hand most applications don't access the
display memory directly as on the PC -- instead they either call ROM
services directly or behaved as though the console was the
aforementioned 2623A terminal, which was being emulated by in-ROM code
run by the 8088. So some of that extra speed was used up already.

The HP150 is also called the HP Touchscreen, because it has a
touch-sensitive screen, implemented as an array of IR emitters and
receivers mounted across the screen from each other. You touch
something on the screen, and the application gets (if it had asked for
same) an escape sequence from the "terminal" indicating what region
you touched. I'm thinking that the touchscreen resolution is
something like 40x14 (about half the 80x27 character display
resolution) but might be wrong on that.

Touchscreen trivia: after a while the holes that the IR beams need to
pass through get clogged up with dust, and the machine will fail its
power-on self test with code F000 (I think, it's been a long time).
HP came up with a fix: a little clear plastic shield that sits across
the holes in the bottom bezel.

Some sharp cookie at HP wrote a couple of TSRs for the 150 that
emulated parts of the IBM PC ROM BIOS for video and INT 14H
communications, and with these you could get a lot of PC applications
to run -- for example, with those I was able to get WordPerfect 4.1 to
run and even print to an attached LaserJet.

Tony has a later version of the HP150, called either the 150C or the
Touchscreen II. It has a 12" display, the touchscreen is optional
(not too surprising, it turned out to be not real desirable because
people didn't like reaching up to the screen all the time -- they'd
rather rest their arms on the desk and use the keyboard and/or I guess
a mouse), and better yet the touchscreen IR stuff is hidden behind
smooth IR-transparent plastic that doesn't collect dust so well.

All in all it arrived just before the users where I worked let it be
known that they'd really rather have IBM compatibles so they could at
least exchange floppies with people in remote offices. Good thing
HP brought out the Vectra about that time, else we might have had to
do another maintenance contract with Big Blue or something.

-Frank McConnell

PS- Hey Max! Trim quoted text!
Received on Fri Jul 24 1998 - 20:43:56 BST