Now, if for some reason the Init/ signal is never nbeing asserted, the CPU microcode program counter will not be cleared. I think, though, that no matter where the microcode starts, it will end up in the fetch-execute loop -- but the CPU registers will not have been cleared (thsi is done by the power-on self test microcode), so it's unlikely to run BAISC correctly. Maybem though ,the keydown routine, particularly if you pressed STOP. does intialise enough to get a display To the OP : After pressing STOP, does there appear to be any progrma in memory? I think this is unlikely. The trivial rason is that in genral capacitors dry up, so that the POR signa lwil lbe too fast, not too slow. The main reaso nis hat I can't see anyhting hat ath signal (ClrMark/ in my schematis) could not clear that STP/ would then clear. It is worth checkign the KeyDn/ interrupt signal after power-on. If it's asserted and stays asserted you need to find out why. I am sure htere are plentyy of other machiens htat need documentation... One day I must get roudn to gettign my Digideck to read nad write such tapes. It's muc hthe same mechansim and the encoding scheme is so similar (even down to the marker bit i nthe middle of each byte). and I ahve the full manual for said drive. -tony

Simply that the HP9800 series has been reverse-engineered alredy. There are plenty of machines that haven't been -tony

big to Christian, How about putting them on a white wall and making high-res pictures? I suppose there lots of people including me interested in getting a copy. -Rik

On Mon, 22 Jul 2013, Fred Cisin wrote: I had tried that in the past, but the result weren't satisfying at all. E.g. you'll never get the lines crossing the scan boundaries to match. And even fladbed scanners have a small "3D" component in the result that distorts the image especially around the edges of the scan area and where the paper has folds. Anyways, I'll try to scan at least those documents that fit on our A3 scanner/copier. Christian

Try to use progrms for stitchin images, it is usually good enough, straightens up the schematics and everything gets done easily.

["stitching" multiple pieces of a scan together] Does any software currently wexist that is specifically for that purpose? For analog images (photographs), there is some specific software available specifically for it. Look at gigapan However, successful results require overlap, and the amount of overlap needed might be an issue. In the case of Gigapan, where they are photographs, there can be some facinating artifacts wherever there was motion between one frame and another, often resulting in missing heads, extra arms (ala Zaphod Beeblebrox), etc. On a panoramic phot sequence, I tried the Microsoft Image Composite Editor, with mixed results. When there were a lot of images (high-res), it got confused and made some false matches, eliminating the Richmond refineries! Also, although it was JPG in and JPG out, the JPGs that it output were not accepted as input (I tried to combine the images in several groups, but it claimed that there were NO matches between the multiple groups). For schematics, or even text, there are different problems, and ideally, the software for stitching them should NOT be exactly the same algorithms as the search for overlaps in photo stitching. A mismatch is potentially serious, so I would suggest including in the image an overlay of a set of dotted? lines marking the edges of all overlap areas. After manually confirming that the traces line up properly, that overlay could be dropped. Perhaps specialized software could be written that would look for and flag any occurence of a line segment that ends without connection, particularly in the overlap regions. -- Grumpy Ol' Fred cisin at xenosoft.com

his itself Are you enjoying yourself ? As far as I can see you're right about the 18k2 resistor, but there is more. The 100k is changed from a feedback resistor to a parallel load of the inv. input and the Au is changed from 10 to infinitive. I've to look into it, maybe just removing the 18k2 resistor does the trick also. If you read the whole article, you'll see it's about the difference in behavior between normal LDR's and CDSe LDR's The last ones are almost unobtainable and sensitive to IR, standard LDR's are sensitive to visible light. The problem is they react different, you can't just replace a CDSe with a standard LDR that doesn't work. Also there is a big difference in resistance between light and dark between the two types, that's why you have alter the EOT-circuit. It needs to be more sensitive for smaller changes, and as it seems you can just remove the 18k2 resistor and not replace it. I wrote it because it's a working (tested) solution for an actual problem. AND you can't just replace the CDSe type with a normal off the shelf LDR that doesn't work, I tried.. So be careful before just shouting something without testing it! And about Tony, he did a lot of work making the diagrams available for everybody .. It's ok to look at his diagram and if you find an error, he'll be the first to admit it and correct it.. And don't throw his work away, it's a first class job, if you don't like the presentation that's on you. But reverse engineering so much HP hardware is hell of a job and he helped, by making them public, a lot of people. He reversed engineered more the 100 items, how much did you do? Everybody makes an error ones in a while I do, Tony does, and you?? -Rik

On 2013 Jul 25, at 2:48 AM, Rik Bos wrote: Yes, Rik, I read your whole article, and I don't see the point or necessity of the changes you made. The original circuit has a voltage divider for the LDR formed with the 18.2K resistor in the lower half and the LDR to +5V, feeding the negative input of the 741, with the positive input fixed at 2.5V. The result is the 741 (comparator) will trip when the LDR resistance passes through 18.2KOhms. By intention, you have changed the 18.2K resistor (as it really is, not per Tony's diagram) to 6.8K and added a 100K feedback resistor and 10K series resistor on the neg. input. This would actually reduce the gain of the 741, as well as lower the LDR resistance (increasing the illumination required) at which the 741 trips. Except that's not really what you did. The 100K resistor is actually going to ground (re the error in Tony's diagram). In addition though, the 6.8K resistor which you intended to be the lower half of the voltage divider, you have misplaced on the circuit board. It should be soldered on the two pins below the two pins you soldered it to. As it is, you have it soldered into the solenoid circuit where it is doing essentially nothing. The real result of your mods is a voltage divider formed with a 100K R to ground, and a 10K R in series with the LDR to +5. The 741 should trip when the LDR resistance is around 90K. The whole thing is a far cry from what you intended. In your simulation, you used resistances for the LDR of 74K dark and 4K illuminated. That should have worked just fine with the original HP circuit, although it wouldn't work with the way you have actually modded the board. I'm not shouting, I am being careful - far more than you, and I have repaired and done a fair degree of experimentation with these sensors (in one instance replacing the lamp/LDR pair with an IR LED/ phototransistor pair, and it didn't require any changes to the comparator circuit). Considering how many mistakes you've already made, I put no faith in your claim about the CdSe vs CdS making a difference of consequence, not without further details about your test conditions and outcomes. Measure your new CdS dark/illuminated resistances in-situ, with a cassette in place and the cassette door closed, and unplugged from the 741/comparator. Try simulating that with the proper HP circuit configuration. You're dealing with at least 4 circuits: - the proper, original HP circuit - the way you think the original HP circuit was, based on Tony's incorrect schematic - the modified circuit you intended to implement - the circuit you actually did implement with your on-board mods All 4 of these are different. You need to retract your article before other people hack up their 9830 circuit boards unnecessarily, go back to scratch and reassess everything you've done. Yes, it is up to me. Try paying attention to what was said: Tony didn't leave it up to me. If he had, I wouldn't have said anything. Tony is very knowledgeable about certain things and if you wish to support him and use his assistance you are welcome to do so, right up to the point you support him when he's being an ass. I have been on the list for well over a decade now. I have experienced Tony's attitude many times. The best I can say is he's not as bad as he used to be. And no, he won't be the first to admit he made a mistake. Again, if you paid attention to what I wrote, you would note that I made allowance for making an error every now and then in such a task. I haven't counted how many items I have reverse engineered, but it's many dozens, over a hundred I expect depending on what level of complexity one is including. I have supplied the resultant schematics to numerous people. I have also made gate-level simulations based on those reverse engineerings, and have them running successfully. And no, Rik, I'm not enjoying myself, it's all a nuisance. And before criticising me, try paying attention to not just what was being said, try paying attention to what you are doing. Normally I would be more gracious about something like this, but when people start criticising me when they're wrong, I feel no great obligation to be polite about it.

On 2013 Jul 26, at 3:35 AM, Rik Bos wrote: I was RE'ing the 9830 in the spring, so back then sometime. The past 2 months I have been distracted by getting some teletypes ready for a film production. (Aside from the stress, that was enjoyable.) Why does how long matter? I hope you don't mean to suggest that I'm bound and obligated to point out your mistakes to you. Or do you mean why would I bring it up now? Because it happened to flow out of the discussion. Maybe it seems a little harsh and you didn't like having the mistakes pointed out in public, but I'll point out that when I first mentioned you in this, I did not fault you - I pointed out the cascading consequences of an error that was not yours. You might even have appreciated that as you were the 'victim' of the error. I didn't point out the 6.8K error at the same time because I was being polite and wasn't out to fault you, and maybe figured you might find it of your own accord when you went back to look at the 18.2K issue. I did not interpret your response as being exactly polite. Maybe it's just language diffs and email, maybe it's not. Everything I've said afterwards was a response to something you said to or about me. If you're following things, Rik, I'm not about to contact Tony privately because he's been such an ass in past interactions on the list. For the most part, I try to avoid him on the list and limit interaction to technical matters. If he had limited his first response in this to technical matters I wouldn't have said anything, but he just had to drop in that comment about my RE effort. This isn't the first time this RE/schematics issue has arisen. A few years ago Tony threatened to take all his marbles (away from everyone) and go home because I was RE'ing some other piece of HP equipment and wasn't using his schematic, which I didn't even know existed until well into my effort. If that was the kind of attitude I got for NOT using his schematic, I could only wonder what sort of obligation would be incurred if I did. I have an answer to that but I'm trying to be polite and not say it here. As for contacting you privately, your email address is not in your article. A google search produces a whack of Rik Bos's. There's one at U of Utrecht in Comp Sci, but I have no indication that is you. I haven't run across a web site. And it just hasn't occurred to me to be scanning the list over the months to catch your email address as it goes by on some unrelated topic. How much effort do you expect me to go to to inform you of a mistake you made? Question my intentions or ethics? My sense of ethics is fully intact. I question the character of people who drop comments like that and then indicate their intention to run away (next quote) rather than sticking around to support (or apologise for) their statements. And as I said elsewhere, if you wish to discuss the technical matter of the sensor, I'm here.

Agreed [...] I fial to see why you need to 'simulate' this circuit. The actual comparator circuit, whether the origianl HP one iwth no feedback or the intended modification is simple enopug hthat you can understand it in your head. The dificult part is the sensor itself. Yes, you can measure the ligth and dark resistances (and if they really are 74K and 4K then it should work with an unmodified comparator circuit). But I don;t think you cna simulatre the sensor more than that. There are too many unknowns. Where are youre results/descriptions of this? Rik has desciribed what he did, you have (quite probably correctly) found errors in it. But I don't see your work published anywhere. Is that all :-)? -tony

I am going to try to stick to techncial comments only... No. This is a pblic mailing list, I am addressing whoever it was who simulated the circuit. In some cases I feel that simulation actually obscures an understanding of the circuit, in that your simulation program may well give voltages/waveforms that agree with what you measure on the real machine, but you don't really know wy. If we take the H Pcircuit, it's jsut a pair of potential fividers with the mid-points compared by an op-amp. A sort-of whaatstone bridge if you like. One potential divider has 2 equal-value resistors and is across the 5V line, so the midpoint wil lbe at 2.5V. The other divider is the LDR and soem other fixed resisotr, the voltage at its midpoint depends on the resistance of the LDR. I think it is reasonable to assuem the op-amp is 'ideal' here. Certainly the departures from perfection are not going to make much differece. So basically what you are looking for is when the midpoint of the second divider crosses 2.5V. [Yes, Brent, I am sure you knew all this and understnad it. I am not 'teaching you to suck eggs'. I am hopefully providing some information for others] As an aside, I feel it is unwise to base a modification solely on a schematic (where revers-engineered, in a commercial service manual, whatever. There might be several verisons of the device, there may be errors in the schematic (as here -- but I've come across plenyu of others as I am sure you have), whatever. To check that the actual unit agrees with te scheamtic doesn't take long and might save a lot of time. Yes, agreed I should have checked it. But, actually, is it totally ridiculous as I've drawn it (meaning 'should my bogometer have hit the end stop'>). I know nothign about the characteristics of the LDR. So suppose it's very high resistance. We agree that the +ve input of the op-amp is helt at 2.5V. So if there was a -ve feedback resistor as I drew and the LER was high resistace, the output would eb essentially at 2.5V so as to make the -ve input at 3.5V also (it would be a voltage follower, followign the 2.5V on the +ve input). As the LDR resistance dcreases, the output would have to swing towards the -ve reail so as to keep the -ve input at 2.5V. The (zener) diode on the outptu would prevent it going very far -ve. So the ouput of the circuti as I drew it (albeit not the circuit HP used) could have given a TTL signal with a suitable LDR. So I feel there is nothing that should instantly have said to me 'This must be wrong'. But anyway. It is wrong. The resisotr goes form -ve input to ground, not I do agree with you that in Rik's photos he seems ot ahve connected a resistor from LSolenoid to chassis ground. Which will hae no effect at all... I am not asking for every reapir you have ever done. It's just that you said you had done varios repairs and modifications to this sensor circuit. I am interested to know what you did, and IMHO it is relevant to this discussion. Well, I would like to discuss the techncial aspects -- publically. It seems a lot more valuable than us flaming each other. I do not dispute this at all. The original LDR seems to be unavaialble. I do have what I believe to be the part number for it, I can look it up if you want. I believe it was made by a company called 'Quantarol' or something similar. No, this is not in any HP manual that I've seen, but a very similar mechanism was used in a thing called a Racal Thermionic Digideck P72 and I have the component-level manual and parts lists for that. In the absense of further information it would be reasonable to use that as a starting point. However, I did try looking up tyhis part number on google and various data sheet search sites and came up with nothing. So, since these LDRs do fail, finding suitable substitues which need only minor modifications to the circuit would be a Good Thing. That is waht I am asking about . -tony

I have a schematic for the IBM 5160 XT, drawn by Sandy? & Dave Thompson. Pin connections are in logical rather than pysical arrangement on the chips. It is 24" x 36" fold creases FPUIB (Want it?) -- Grumpy Ol' Fred cisin at xenosoft.com

On 2013 Jul 28, at 11:09 AM, Tony Duell wrote: The input transition is coming from a slow mechanical process (along with typical LDRs not being exactly speedy), and with the 18K resistor in feedback it's essentially a varying-gain amp (from some gain to near unity) during the transition region, so some of that slow transition will appear on the output. Plus the output is on the low end of the TTL output level when it doesn't need to be, there's 2V of unnecessarily unused noise margin there. It may work the way you drew it but it begs the question of why a designer would do it that way when it has poorer performance than the 'typical' (and actual) way. Speaking of response times, going from Rik's info that a CdSe cell was originally used, I wonder if faster response time is the reason HP selected the CdSe over CdS LDR. Some web info suggests the CdSe are faster although I haven't found categorical specs.

On 2013 Jul 25, at 1:19 PM, Tony Duell wrote: Try being ingenuous Tony. You had two opportunities to ask. You didn't. You implied, not a question, but what I should do. Funny. It wasn't excellent a short while ago. Nothing like trying to backtrack out of your comments. I made no claim to perfection. Don't suggest I did. While one may want to communicate with an author about more subtle aspects of their work, this is such a basic thing I see no need for asking, and waiting, for an answer about it. I can't say it would even occur to me to ask, as if you have a convention about it, it could simply be noted at the beginning or end of the work, along with such things as source material identification, dates, table of contents, etc. As a matter of preference, when working on something, I don't want to have to go from the schematic, then to a pinout to interpret what pin is being ref'd, and then to the device. Here are some disadvantages to hand-drawing, aside from basic clarity: 1. The low density means the schematic is spread across more pages. 2. The difficulty of modifying and manipulating a hand-drawing, along with the low density, results in more symbolic connections. Symbolic connections, while of course useful, are disadvantageous in that it is not readily clear where all the uses of a signal are. 3. (2) is compounded in that the drawings are unsearchable. With a computer-based drawing, if one wants to find every reference to some signal/symbol, one just walks through it with a search. 4. I don't expect OCR to be a remedy to (3). You have your preferences and conventions, I have mine, some may prefer yours, some may prefer mine. This wasn't really about your schematic, it was whether it is acceptable for anyone else to RE something Tony already has.

On 2013 Jul 26, at 3:21 PM, Tony Duell wrote: I have never seen it used previously. That's a lot of ambiguity and non-obvious rules for a de-facto or unwritten standard. I understand that, it can be nice to see the logic without the clutter of pin numbers. It means, however, you end up with unnecessary line crossings as the input order on the page is determined by the physical implementation of the IC. I take the position that the primary point of a schematic is to elucidate the functional, electronic organisation of the device. The physical implementation is important, but a secondary consideration. For somebody repairing a unit, which they are probably doing on a one- off instance for an RE'd item, the first priority is still that functional understanding. So the schematic gets organised with signal flow left to right and electron flow up the page (for +V systems) as much as possible, and functional associations as close together as possible, even if that means bits of one board end up on multiple pages. All within reason as there are always exceptions. The physical implementation is still present and recorded in full in the form of IC pin numbers and connector pins along signal lines, and there are pages with all the connectors pins laid out if one wants to go from the physical to the functional. If you want all the physical associations as close together as possible, prioritised over the functional, it becomes a wiring diagram. (The pages you are looking at are old, it has since been encapsulated in a single PDF, updated now.) Yes, you did. You first raised the issue of your "reverse engineering" in relation to my efforts. If you hadn't, I wouldn't have said anything about your RE/schematic. Ingenuousness, Tony.

On 2013 Jul 28, at 11:19 AM, Tony Duell wrote: If we piece back together my sentence you split, it says: The physical implementation is important, but a secondary consideration. I didn't say the physical details were irrelevant or to be discarded (from the schematic). ... Yes, it can be used for both, as I indicated in my sentences you snipped: The physical implementation is still present and recorded in full in the form of IC pin numbers and connector pins along signal lines, and there are pages with all the connectors pins laid out if one wants to go from the physical to the functional. But I've certainly seen wiring diagrams where figuring out the functional is torturous. The machine itself can be used for a functional understanding of how it works but it usually becomes pretty awkward. It's what one chooses to prioritise in the representation (schematic), which is not the same as relevance/irrelevance. It's on my AL-1000 page.

OK, first question. Is STOP the only key to do this? WHat happens if you Nest disconnect the keyboard (paddleboard in front of the display PCB -- I will have to try that when I get back as well. Thanks! Dave

subscription actually am I learn effect. operator behavior on it give and, for What I don't get, the compleet 9830 is on the HPCC DVD, and that's not the DVD from the HP calculator museum. But you also can download all the diagrams form the hp computer museum site, www.hpmuseum.net. What's also very helpful was for my, when I was (with the help and advice http://www.brouhaha.com/~eric/hpcalc/patents/ The patents tells you a lot about how the machine works and how the firmware and routines are build and what they do. -Rik

Thanks for those links, Rik.? The hpmuseum.net site is a tremendous resource, along with the others you mentioned Dave Dave

I will check this out, hopefully this weekend.? Out of curiosity, is there an extender or some other way of probing these boards while powered up?? By the way, does anybody know the number of the mating plugs to make a cable for the 9866A printer?? It looks like a 19-pin cannon connector.? These seem expensive, so at least it would be nice to be confident I'm seeking the right model.? Any info on plugs and cable would be welcome. Many thanks, Dave?

Actually, Iv'e yet to find one that will not run OK with no load at all. If it does need a load I'd rather use a 6V bulb than a part-set of HP9830 boards :-) Incidentally, yuo do not have to screw the PSU heatsink to the chassis for testing. Yes, if the machien is being rund for a longish time you should -- it's part of the heatsink for the power transitors on the PSU board. But for tesitng it will not overheat without being screwed down. [...] My expeirience is tha the most unreliable pwats in an HP9800 re the 74Hxx ICs. But those can't be the fault here. -tony

Extender boards are very rare. JHP never intneded thse machiens ot be reparied to compneent-level in the field so there was no official set of extender baords. And they carefully put the conenctors for different boards in differnet positions so you would really need an extender for each board. However, there are several workarounds. The PSU will run with nothing else in the machbine -- and with the other boards removed it's easy to get to the track side of the PSU PCB. For times when you have to work o na board with those around it fited, what I do is to solder a few wires onto lilely testpoints, put he board in the machine and porbe the free ends of the wirs. It _is_ a standard connector. I haev seen it described as a 'MIL-C-26482' connector with a size 14 shell and 19 contacts. They are still available, for example Farnell sell them in the UK), but they are NOT cheap. If you have the machine and the 9866A printer you basically have 2 options. Bite the bullet and buy a couple of the plugs and wire them together. Or wait for a cable to turn up on E-bay and hope it doesn't sell for more than the cost of 2 plugs. The formwer is generally easier... -tony

Quite possibly. I don't know all the part numbers, but the '14-19P' souggests a size 14 shell with 19 plug contacts which is certainyl what you need. All I can say is that I needed ome of the panel-mounting socketts, I ordered the 'obvious' one from Farnell and it was perfect. If you need any help with the printer feel free to ask. I've doen a little owrk on them. As regards the HP9830, I find it best to take everything out of the case and give it a good clean. The memroy boards, both ROM and RAM contain MOS ICs -- and MOS ICSs that are difficult to get (the ROMS are custom, worse they are strange HP things so no normal EPROM will drop in; the RAMs are Itell 1103s which are not common now), so take anti-static precautions when removing said boards. I find it a good idea to remove the reap panel, strip the cooling fan and give it a few drops of machine oil (sleeve bearings). The tape drive is pretty reliable, being a reel-drive unit, there is no capstan nad pich roller, so the latter can't trun to goo ;-). The only mechanical parts that often fail are the O-ring 'tyres' on the drive wheels, these are a standard size and easy to get and fit. Electrically, the main problems are the optical EOT sensor, the bulb does sometime fail (it is still avaiallbe), and Rick Bos has reported problems with the LDR (I can't commonet on his repair as I've never needed to do it, but it looks very sensible). The dismantling procedures for everyything are in those HPCC Datafiel articles. -tony

each: selecting one board 17-or-so common. Yeah, great engineering isn't it ? -Rik