HP-150 Touchscreen

At last a machine that I have heard of... Whcih amchiendo you have? The original HP150, or the later HP150-II? The obvious external differnces are : HP150 (Original) : 9" CRT fixed in the case 2 expasnion slots, the boards go in from the back of the machine HPIB and 2 serial conenctors on the back Power swtich, brightnes and focus (!) controls on the back Keyboard conencted by a 6p6c 'modular' plug External clip-in battery holder on the back Can take an internal thermal printer HP150-II 12" CRT in a tile mounting 4 expansion slots, boarfs go in from the top HPIB and 2 serial conencotrs bekind the clip-on back cover. Plugs go in Power switch is a button on the front under the CRT Brightness control is a knob on the left side (IIRC). Keyboard conencts via an HP-HIL connector No exernal battery holder. No intenral printer option I will assume from the fact you've inspected the pSU that you have the original machine. THat one is a lot easier to dismantle to get to the PSU. If this is the original version, the top case comes off with 2 quarter-turn fasteners on the bac. If you have the printer, it's best to take tht out first. With the top case free, unplug the fan fro mteh PSU board, do not forget to reconnect it. You wil lthen see 2 PCBS, one id the video montiro, the otehr is the PSU. It is obvious which is which. On the PSU board there are 2 large capactiros almost i nthe middle. These are hte mains smoothing capacitors. And they are just postioned right that if they decide ot burst they will break the neck of the CRT. So do inspect those carefully. The next trick is how to get to the logic boards. This is nto at all obvious. You can remvoe the tope cover if you wnat to, you don't have to. First unclip the battery holdre from the back of the machine. It contains 2 N-size cells ('Lady' size, LR1, etc). These are 1.5V each. Do _NOT_ put in the similar-sized 12V batteries used for soem car keys, etc. THey will wreck the real-time clock IC. Take out the expanison boards if you have any. There are 2 thumbscrews on the card reap plate, undo thoese evenly and the board slides out. Next unscrew the jackposts on the serial connectors (3/16" A/F) and the HPIB connector (9/32 A/F). Then remove the 5 screws on the cardcage rear panel and take that off. Inside yoy wil lsee the video board at the top of the cardcage. It comes out easily. TThe processor bord assembly coms out too. It has 2 daughterboards ('Mezzanine boards' in the HP manuals), one cotnains the memory (ROM and RAM) the other contains some of the serial port circuitry. Most machines have 256K on the memory board. I think there was a 128K version. Thers is a very cxommon expansion bord to ad 384K, bring the memroy up the the full 640K. There is a similar board that adds and HP-HIL port too. This lets you plug in a mouse. Others have mentioeed the Australian museum site as a source of manuals nad disk images. One manual that doesn't seme to be there, and which is very useful, is the Technicla Reference. This isn't quite as good as the IBM TechRef in that it doens't include the ROM sources, but it does contain all the BIOS calls (ntoe, the machiens is neither hardware not BIOS compatible wit hthe IBM PC) and the schrmatics of most of it apart it is fr too think to copy. What (if any) disk unit(s) do you have? THere is, of course, no internal disk on the HP150, you have to use an external HPIB unit. When you power it up, nothign wil lappear on the screen for quite some time. There are some LEDs on one of the boards, visible through a slot on the back, those should display changing patterns. At least that will indicate the PCU is running. -tony