jmazo@casbah.acns.nwu.edu (Jacob Mazo) (04/08/91)
Just a couple of quick thoughts from a 28S owner... 1). Is it possible to multitask on 28S (or the 48SX, if I ever get enough money to buy one). If yes, how? 2). How does one open the case of the 28S ? just wondering, but I do not think I will mess with the hardware, as I would be too afraid (actually, careful?). I do not usually go beyond the SPEED program of making an OFF command. Also, suggested by a friend of mine, there may be the danger of using SPEED to set SPEED to 15 and generating heat that damages the chips inside... Or are HP's THAT durable? Thanks for answers, ******************ATTENTION******************** My regular mail should go to mazova@acns.nwu.edu However, it recently had a bad crash involving its hard drive, so you might have to try jmazo@casbah.acns.nwu.edu ************************************************ Any language problems or spelling are due to lack of knowledge of English Thanks!
lishka@uwslh.slh.wisc.edu (a.k.a. Chri) (04/12/91)
jmazo@casbah.acns.nwu.edu (Jacob Mazo) writes: >Just a couple of quick thoughts from a 28S owner... >1). Is it possible to multitask on 28S (or the 48SX, if I ever get enough >money to buy one). >If yes, how? Another person and I (a long time ago) had a discussion about trying to get the hp28s to multitask. I think the consensus was that it wouldn't be possible from RPL, and that we weren't sure about ML. Since the hp48sx has about the same tasking features, I would assume the same for it. The real problem lies in the "stack" nature of interrupting programs: i.e. you can interrupt a program, execute another program, and then continue with the original, but there is no way (that we could find) to resume an arbitrary interrupted program (you must follow the FIFO order of the program interruption "stack"). I hope this helps. I may be wrong, because the above was derived from educated guessing. .oO Chris Oo. -- Christopher Lishka 608-262-4485 It is not safe out here. It is wonderous, Wisconsin State Lab. of Hygiene with treasures to satiate desires both lishka@uwslh.slh.wisc.edu subtle and gross. But it is not for the uunet!uwvax!uwslh!lishka timid. -- Q
jthornto@ee.ubc.ca (Johan Thornton) (04/17/91)
In article <1991Apr8.013337.13760@casbah.acns.nwu.edu> jmazo@casbah.acns.nwu.edu (Jacob Mazo) writes: >Just a couple of quick thoughts from a 28S owner... > >2). How does one open the case of the 28S ? just wondering, but I do not >think I will mess with the hardware, as I would be too afraid (actually, >careful?). I do not usually go beyond the SPEED program of making an OFF >command. > Fairly simple to open it up: 1. Remove the metal plate thingie at the top, above the display. Put a jewellers' screwdriver underneath and lift it up; it's just glued on. 2. Take a drill (I think about 1/8" or so) and ***CAREFULLY*** drill out each of the "plastic rivet" doodads. Save the "HP dust", and sell it to your friends. 3. Remove the metal plate thing that sits on the keyboard. Use the same technique as above 4. Drill out the rivettes (as they're probably called), even more *** C A R E F U L L Y *** this time 5. Making sure you have the manual handy nearby, remove the upper part of the plastic. You will need the manual to put the keys that are about to fall out back in the right place. If this is a friend's calculator, don't worry too much about it. 6. Did I mention to turn the calculator off? At this stage the batteries will fall out since the lid doesn't have anything to hold onto. OK, now that you've done this, what will you see inside? Two blank shiny chunks of silicon, sans any labelling whatsoever, with ever so tiny wires emanating from their sides and connecting to the small circuit board. My guess is that one is the Saturn and the other is the ROM. There is also a 256K by 4 bit memory (in mine it was a Mitsubishi). There is very little else--just a bit of control stuff for the led and keyboard. I'm telling you this so that you don't do open yours. The following reassembly instructions are pretty scary. 7. Warm up a soldering pencil. Put the kids to bed, they shouldn't be watching this. 8. Facing the top piece of plastic down, reinsert the keys in whatever order you fancy. Come to think of it, it would have been a good idea to put a large piece of packing tape over the keyboard in the first place, to keep the keys in. 9. Book a flight on the next shuttle; this feat is much easier in a microgravity environment. Put the rest of the calculator down on top of the front piece containing the keys. Probably some of the keys will have jumped out, so this may take a few tries (but not if I had thought of that tape trick! Damn!) 10. Once the whole thing fits together, place it normal-like on a flat surface. 11. Pressing down on the top half, see how the buttons feel. Probably they're a bit mushier than before. Oh well, it's your fault. In any case, see if there's some crap in some of the rivette holes. 12. With the soldering pencil, re-seal the rivettes. Buy some HP dust from your friends in case you're not getting a good enough connection-- just sprinkle some on, and melt it in there. 13. Remove the metal panels from wherever they got stuck to. Clean the dirt from the back, and put them back in place. 14. See how the keyboard feels. It's not as good as before, is it? 15. Go to step 1 to open it up again, to try to fix that keyboard problem. In any case, I don't recommend opening the 28. It was the last thing I did with my 28 before I bought a 48. I ended up with an OK keyboard except for the top row of function keys. Sold it to my friend for CAN$100. -- Johan Thornton (but my friends call me jthornto@ee.ubc.ca)