Posts by jlopez

    Gelegentlich mal zur Kenntnis nehmen, wie die Lage in Italien und Spanien ist, sollte den einen oder anderen wachrütteln.

    Daß die Leichen mit Militärlastern aus der Stadt gebracht werden, weil das sonst nicht zu bewältigen ist, gibt es sonst nur in Kriegsgebieten oder Hollywoodstreifen, die das US-Militär verherrlichen.

    Ob dieser Kelch an uns vorüber geht, ist noch längst nicht raus.

    *** Report from Andorra ***


    Infected: 224

    Healed: 3

    Deceased: 3


    The government is taking measures to protect foreign citizens with seasonal employment.


    *** Report from Spain ***


    Infected: 49844

    Healed: 9357

    Deceased: 4858


    The government has reacted too late, too little. It was not until a week ago that their president decided to create a comittee of scientists to help in the decisions.


    There's not anything related to the IQ of people... there are lots of smart people in Spain. The problem is culturally imposed: if Spain is known for anything is for its picaresque. If something is forbidden, then people will certainly do it; the "idiot" is the one who closelly follows the established conventions and then... the disaster happens. I still remember what happened at Totalán... that was pretty sad.


    Picaresque started to be important in society when the empire started to decline. The large amount of dissent, revolts and civil wars until the last century made it a desirable trait for common people to survive in those hostile environments.


    The following are some cases of the Spanish picaresque during this crisis:


    https://www.lavanguardia.com/v…allina-uga-lanzarote.html

    https://www.lavanguardia.com/s…saltar-confinamiento.html

    https://www.lavanguardia.com/s…bar-murcia-el-palmar.html

    https://www.lavanguardia.com/v…tado-de-alarma-salir.html


    People would do anything to get some fresh air. Some even react with violence when found by police or gc. In the (approximately) two weeks we've been enclosed I've seen lots of news like the four posted above.


    To close this post, the Darwin Award of the week... this guy (not Spanish) definitely deserves the award.

    https://www.lavanguardia.com/m…llenge-lamer-retrete.html


    Regards

    jlopez : Here in my region, the youth gathers at the evening at the playgrounds and other places drinking and having fun. For sure, school is closed like all recreation offers. So plenty of free time paired with lacking sense for responsibility. No accusation, 25 years earlier I would most likely have behaved likewise.

    I imagine so. :thumbup:


    But you know... that T-Rex and the dog-dressed-guy hurts the eye.


    Murcianic Park

    Walk time, Bobby!


    I hope if your young people doesn't care about their health, at least they do about their pride. People here in the South have shown no respect for neither of the two.

    Wie ist das in anderen Ländern?

    Both in Andorra and in Spain confinement was implemented last week. There are 50+ positives in my country with no casualties at this moment.


    Spain is, but the opposite. The government is scaling their measures to prevent people cheat the system. There were a few exceptions to the quarantine, one of them is walking the dog (just for hygienic purposes) or to go shopping. During those days I've seen things you wouldn't believe... things like:


    * People walking the dog all day

    * People walking a Guinea Pig

    * People walking a cat

    * People walking a goat

    * People walking a radiator

    * People renting their dogs

    * The skyrocketing number of dog walk services

    * Someone disguised as an inflatable T-Rex (Murcia, Spain)

    * Someone disguised as a dog (Escaldes Engordany, Andorra)

    * Confirmed cases of people who was infected (and knowing it) that travelled, sometimes in buses.


    The government measures came too late and while most people react as expected there are still a high number of people who seems allergic to follow instructions. It seems inevitable that the country will follow the Italian path... They have deployed police, Guardia Civil and also the army.


    I also have a friend in Milan who keeps me informed about how the whole thing is going there. Fortunately he seems to be fine.


    Regards,

    Jaume

    About the infection and mortality rate of Spain... It would be better for you to not extrapolate it with Germany. A lot of people reacted in an irresponsible manner to the warnings given by the local governments. Lots of them (mostly from Madrid) understood the quarantine as Holidays and travelled to coastal towns employing AVE, in effect crossing the country with it. Some of those people were infected. According to Murcia's president beaches and bars were full of Spaniards other than Murcians and decreeted the closure of any cultural site and cancellation of any event in order to discourage intranational tourism while the quarantine is enforced.

    Yesterday my government made two public statements. The first one contained early measures such as cancelling all school trips to outside the country or aadvising not to exit the country. It seems that after that the government met as a crisys cabinet and by evening they stated that a case of a 86-year old woman was confirmed, her daughter is a teacher and also was close to her. As a result schools close from Monday on. Other closures include the ski resorts, without them our economy will suffer greatly. The nearest supermarket is empty and I cannot expect the other ones to be different.


    It's official, that crowned virus has finally arrived at Andorra.

    Char ROM was pulled from an (almost) working 8032 as unfortunately this computer came without its own. The replacement was known to be working. The VRAM was tested on that other board and found to be working too. Just as a curiosity, I recently found that they were made by Tesla, soviet-era Czechoslovak manufacturer; this means that the totality of its RAM ICs were from the Eastern Block.

    Hamsterkauf means "hoarding" or

    "stockpiling". Of course, and that is the joke, it could also mean "buying a hamster" .

    But that is not the real point. Have you ever seen a hamster or a sqirrel collecting comestibles? It has large expandable chops. That is, where the german meaning of Hamsterkauf comes from.


    Stefan

    It seems today I've learnt a little more.


    Thank you, both to you and yalsi

    Having removed both PIAs (they were pulling /IRQ down) and replaced B2 (7425) and H1 (74LS74) I can proudly say that after 40 years the /RAS signal is pulsing again. I have but the side effect that the screen is not erased anymore. The two (and a half) lines are permanently on the screen. Doesn't seem to react on /RESET. Next step, fixing the video circuit maybe?


    Regards

    Ah, ok. What I don't understand by lecture is translated using automatic translator... apparently Google's AI loves hamsters. :)

    Yes, I imagine that the Spanish level is difficult to beat. A lot of "miraculous" remedies are flooding the social networks.

    WAIT! Do people really think that hamsters will protect them??!!??

    That's just crazy! Completely irrational! In Spain there's dumb people in social networks that say drinking baby pee cures Coronavirus...


    I didn't know that modern medicine has been supplanted by witchcraft-era remedies... A general state of panic is being created and when that hapens, people lose their mind.

    Two days ago the spare parts I couldn't buy at Barcelona arrived. I still have no /RAS and /CAS, but I least I found the cause of the CPU being stopped: /irq is permanently down. Today's first test will consist in testing VIA and PIAs, which are the only components that can cause this signal to go low.

    Yes I know the name was for this reason. But again, the situation was completely different from now. The belligerents had banned any kind of publication about the disease and in that case the ban helped propagating it. It seems that we humans like extreme scenarios: a case of complete lack of information vs infornography. We always fail to adopt a correct attitude agains those problems and it seems we never learn. And that brings the next point...


    No, the world isn't smaller. That's the price we pay for globalization. Events in the other side of the globe can affect us directly. In the past, cost of travelling was high and therefore people didn't used to move from their countries very often. Nowadays, the cost barrier has been smashed and as a result transit among far countries increased dramatically. Transmission of diseases and introduction of invasive species of animals are a couple of side effects we experience.

    calm down please.

    I am absolutely calm ... no prob. I just want to participate in this discussion with you & everyone. Everything's fine ... there are no worries. :)

    Ok. I had a different feeling when I read the first post... anyway, glad to know it. :)


    Medical staff are getting really worried, but because both mass media and politicians are causing unrest. This morning I heard an excerpt (I think it was fromRadio València) where they jokingly said that the only news that the Spanish tv media were broadcasting was from coronavirus and Catalan independentists. And this evening... yes, coronavirus and catalans. At least they aren't monothematic anymore.;)

    Forist, calm down please. Things aren't as dark as they paint it. Everybody seems to be overreacting about this issue. Coronavirus is not new, but an old enemy we know since the sixties. During those 50+ years there have been a few outbreaks but the total deathtoll of all of them is nothing serious compared with a single year's mortality of normal flu. Just as Toshi said, it's just that the flu is so common that nobody cares about it.


    About the Spanish flu, both events aren't comparable in any way. Our sanitation level is high enough to help to avoid infection (althought not 100% guaranteed). Back in the times of the Spanish Flu, Europe was putting end to a 5-year war. Maybe Germany wasn't in ruins but the ever-decreasing rationing was making its population to starve; soldiers on both sides weren't better: they couldn't maintain any kind of hygiene in the trenches. That was the perfect scenario for a pandemic. Fortunately this is not the case today.


    My advice: don't worry, it's not worth it.

    I know it's Friday and already a week has passed since I got in possession of the following, but I'd like to present them to you.


    Do you remember the MSX-BASIC tutorial beta tape I found? Well, I'll be able to watch it.



    Seems to be working as far as I could test it. The mechanism was found pretty clean and did not destroy the tape as old VHS players do sometimes. When I opened it I found the whole assembly to be very well assembled, I smelt quality inside. Sometime in the past I opened 2-3 VHS players either to clean or to scrap them and I can assure that they were built cheaply.


    And, when things couldn 't get better...



    I acquired a Commodore PET-2001-8C. It's not working but seems that the video logic is fine. The cassette won't open but I think where I could find a spare unit. It came with a 16KB (unnoficial?) expansion board so this computer is 24KB + 1KB RAM. It wasn't cheap but in the Spain the CBM-PET line is almost nonexistent so it seemed fair.


    Its previous owner came to my grandmother's house (the nearest place from Barcelona at which we use to go) and delivered it himself. That's not the usual practice. And there was a good reason. He sold it using an app called Wallapop, which is a second-hand market portal. Very useful. But once he posted it, he received not only my request but the ones from other collectors and a flood of requests from speculators. The average price of a PET-CBM in Spain ranges from 800-1200€ and those people saw the advertising and wanted to make easy money with his computer. As he wanted the PET to arrive be at good hands (someone to repair and maintain it) he turned down their requests and started to be harassed by them. They insulted and threatened him in order to force a deal for the computer. In response he changed the status of it as "reserved" and considered retiring it. The only reason I have this nice piece of iron in my hands is that my father asked if it was still available, about one week after the change of status. Negotiations began and nearly a month later, when we went near Barcelona, he delivered it to us. I imagine the reason of bringing it to us instead of asking us to pick it up was to prevent us (or whoever) to know where he lives.


    We all know there is a speculative bubble around old computers, consoles and videogames but I wanted you to know that it doesn't affect all zones/regions in the same manner. South of the Pyreneés things are this bad... not to say about the flea markets. Last time I went to Arbeca they asked me 170€ for a broken breadbin C64. I love to go to flea markets, but after 3h travelling finding this kind of "offers" is infuriating. I'm considering if I'll ever return there.


    My region is :censored:.


    Regards

    I'm glad that I haven't scrapped the first prototype (the one which couldn't stop playing). I have some prototyping boards, like the one used for the patch.


    After the revision , the components for a single-pit board is of 6 ICs (74 series and PIT). Being an eurocard-sized board i'm sure that once the VCA is tested it would fit without issues.


    Thank you again, for your help and your patience. :)

    It is no problem if the DAC is selected as well, when the MIX-register is selected. The D-output of the day will just have a small voltage present. I have tested this and there is no problem with the circuit. Just leave the D-output open if you have the the mix-register on the same port.


    You don't really need the gate-inputs on the PIT for muting the sound. The DACs will make the sound inaudible when they are on 0V (value of 0x00h). The whole mix circuit is nice and all, but not really needed if you use the DACs. You will have to write a byte anyways if you want a single channel to be muted...


    -Jonas

    Dropping the mixer control, then. Having two 4-bit ranges simplifies logic, being from the same length means that they could be selected using a single 2:4 decoder from the '139. :thumbup:

    You have 2x 2to4 decoders per 74ls139 IC. Why do you need all the other logic?

    Using only the 2:4 decoders dring the issue that the DAC will always be selected when the mixer control register is selected. The nor circuits cuts the 4 bit range into 3 ports to the DAC and one for the register.


    I think I know now what you want to do... you want to integrate 2 cards into one?

    Only if IC count is low, it's not prioritary at this point. You proposed to use -A3, which increments range to 16 ports and that's why I tried to match. I would have preferred to use an 8 port range instead.


    You don't have to loose the fourth DAC-output. It may be good to have separate voice (like noise) and the DAC will allow the control of that voice...


    digital noise:

    I was thinking on adding noise, and that's the reason of choosing a 6-bit register instead of a 4-bit one to control the PIT's output.


    Thank you for the VCA circuit. I have no idea about audio, this is proving very interesting and useful. I'm learning a lot.


    Regards,

    Jaume

    :grübel: What about this?


    I revised the schematics for a new version of the board.


    The highest 5 bits of the port are not hardcoded anymore (farewell rewiring!), removed both '74 from the design, a single ic is used to control the channel's output. The DAC has been added, it's a 7226, as suggested. I also introduced the mixer between channels (which is also the speaker driver, was present in the patch board) and what I think would generate the audio signal using the output from the PIT and from the DAC (using transistors as switches).


    I revised the decoding logic, I know it's not elegant, but I haven't found a way to build it with less than three ICs (current design uses only two). It's not causing any trouble at this point, so I think it will be maintained.


    P2 - Shakuhachi Mk. III.pdf


    Regards,

    Jaume

    That's how things were left yesterday, with no change today, for board nº2.



    If you make a new revision of the card you could maybe add a prototyping area?

    What kind of bus are you using? Is it a common 96pin bus like the ECB?

    Are there any clock signals on the bus, that may be used to synchronise the address-decoding and may be used to replace the crystal?


    -Jonas


    Yes, I was thinking in adding a prototyping area to every available zone after optimizing this a little. I'm Using SKS's MC80 bus, present in the SKS KISS, Alphatronic P1, P2 (except P2L), P3, P4, P30, P40, HELL DS2038, DS2069.


    There is, according to docs, a clock signal of 3MHz but every peripheral card that requires clock uses its own crystal. I was thinking in keeping the current crystal but drop the D flip flop and allow the PIT to run twice the frequency for more precision.


    Regards,

    Jaume

    I'm finishing the schematics of the current version (board nº 2), changes on the design were made on the fly and written in paper. Following, the board nº1, which is the minimal test.





    Red spots on the component side are the points where the daughterboard was soldered. As it was reused to patch board nº2 it is not in attached there anymore. On the pictures, the traces cannot be seen, but they can be easily spotted when working on the board. The white coating was chosen because I can use then my permanent markers on it to signal where I should solder a wire.


    Its current status will be made public in a while, while I gather the notes and modify the schematics.

    Did you use the DAC08 ? They are a bit hard to master. Pullups or pulldowns are needed to make the H/L transition fast and reliable. The 74LS273 should be good for the input stage but there may be a situation where for a very short amount of time the 74LS273 is latched while the data-bus is not ready. As the DAC08 has a <100ns (>10mhz) setting time, even short digital blips can result in a recognizable reduction in output-voltage.


    As i said earlier: I like the TLC7226 Quad-DAC with MCU-Interface because it is easy to use and has a small decoder integrated :-) it has a "slow" 5us setting time (200khz) which is more than good enough for audio. This may filter some of the potential blips in a computer system.


    -Jonas

    I still have no envelope generator, the output is similar to the one present in the original IBM PC; I have done only half the job. Prior to decide what I'm going to use I'd like to consolidate what I learnt from this frankenstein-monster-like board. Some parts of the design aren't useful and some even cause trouble. For instance I hardwired the port, I think I also wired it wrong and decoded to another, used one (floppy?). I must rewire every one of my prototypes from this batch as a result. In a Harting-96 connector it doesn't look that good. I also have a daughterboard containing the patch made... Had I known a little more back in September/October, this first batch would have been completely different. Only if I had placed a DIP switch there... :wand:



    The sound card is the top one, that one with a yellow LED. I had to install it because I couldn't introduce my probe there and needed to check if the tested channel was active.


    I have some DAC08, but I'd like to try other options, including that other one you propose (in preference over the former), before heading for a final design.


    Thank you very much,

    Jaume

    I use the remaining D flip flop from the '74 responsible of halving the clock plus an additional '74 to use those inputs. It was a bit annoying to have that thing making loud tones without control. :D

    It's all under control now.:thumbup:

    I have heard some reduction on volume randomly... noise? I imagine that the amount of wiring to make it work is introducing it.

    Yesterday I built and patched board nº2. The patch was completed today after lunch. Board nº1 was built having in mind a minimal test, so I cut traces from both 7474 to the PIT and forced them to be high. This way there was always output from the PIT. The issue was that once the chip was programmed, there was no way to stop sound to be generated. To enable data to be stored by the 7474 a revision of the decoding logic has been done, and the required patch has grown considerably.


    Today's test: https://youtu.be/LvucYHNCRVo


    The current boards are obsolete. I knew that they had issues to work when I ordered them, but I guessed (correctly) that could be made work and now that this has happened, I'd like to integrate the changes from the patch into the board, remove the known failing sections, add debug parts and make the rest of the board (approx. >50% of the surface) as a prototyping board to ease construction and testing of an envelope generator.


    Regards

    I remember having revised all traces from /RAS, /CAS0 and /CAS1 up to the CPU. I imagine some ic is rot... that or rust that impedes contact.