"Max Eskin" <maxeskin(a)hotmail.com> wrote: 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!