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jdgabbard

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About jdgabbard

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    Tulsa, OK

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  1. Not sure if anyone here has the knowledge to have a discussion on a technical level concerning the MSX standard. But I have a few questions concerning the various slot signals. 1) I see very few references to the SW1 & SW2 signals, other than they should be connected together on the cartridge pcb. However, no mention of where they go, or what they do. I'm assuming that there is some bit in some register set or reset. But I can't find any reference to it. Anyone have any idea? 2) As far as CS1, CS2, and CS12, I am assuming that these three select lines function independent of individual slots? I.e., they should be active on all slots at the same time, and not gated to specific slots? 3) SLTSL seems fairly easy to generate. My understanding is that the register A8h provides the 2-bit slot number for pages 0-3 of the 64k of memory. So I should be able to use a 1-to-4 decode on A15 & A14 to create my page select lines, and then just gate them properly with the A8h register to have the possible outcomes. (Been working on a truth table, but it going to be fairly extensive. This could probably be implemented with a fairly fast EEPROM for the logic). I understand how the decode works I think. I just want to verify I am not missing anything here. Any traps for noobs? If you're wanting more information as to the scope of what I'm doing, I am designing an expansion adapter for my MSX1 to open up Slots 2 & 3, possibly decoding one to the 4 secondary slots.
  2. I approve of this message. 😀
  3. Nice, glad to see it is well accepted. As for the replacement switch, what are people moving to? I could probably design it, but would need to know what I'm looking at. Let me know how it turns out. I'm limited by the capabilities of my printer, so if I need to make any changes, I'd like to know.
  4. I recently designed a replacement for the power switch for the TI-99/4A. And thought I would give it to the community. I have hosted it on Thingiverse here: https://www.thingiverse.com/thing:3697972 But I have also attached a photo. It's not perfect, but good enough compared to jamming something in the hole to turn on/off the computer.
  5. Finally got my 3d printer back up and working. So I have finished designing the case for the SNES-2-GP.
  6. I think there is a certain level of truth to this. One of the biggest problems I see in much of the vintage gaming and computing community, where it concerns people designing and selling projects of their own, is overestimating the market. They will have a good idea, and try to bring it to fruition, only to discover no one buys it. Why? Well, it could be due to price point...it simply isn't worth it's cost. Or it could be due to practicality. Possibly it is a redundant product, where another better or cheaper solution exists. Or maybe it simply fills a niche that the vast majority of gamers simply do not fall into. Whatever the case, as a gamer, it's easy for us to put the blinders on when we have something in mind that sounds like a good idea. Its much more difficult to take the Warren Buffett approach, and look at the product for it's potential.
  7. It's possible, I may look into it. If I were to improve this, I think simply adding a method for variable current sinking so that it could emulate true analog values would be a must. Which would go well with Playstation analog sticks. So it's possible I might do something like that in the future. But the cost of bringing a product to market can be high. You don't want to guess what the cost on this project so far has been....not even counting my time... It's definitely a labor of love, fueled by the desire to give back a little of what I have benefited from in the various computing communities on the web.
  8. Yeah, I saw that. It threw me off for a moment, as I got the notification of what it was after being notified of the dollar amount. Thanks for the support though! And Ill try to get them in the post this afternoon.
  9. To get a true analog feel youd probably need extra circuitry. The way this is design is to provide an analog equivalent of a digital value. So when in the idle state it is mid range. When a button is pressed the value either goes full swing sink or no sink. What you suggest would be possible, but youd need a digital potentiometer. But I dont think they make them that: 1) have the correct value, and 2) the results Ive seen show they are not precise.
  10. It is using the second axis. But there is a difference in how those axis work under the two modes. In the traditional mode, it is simply another 2-axis current sensing. However, in HAT mode, it is a 1-axis current sense line. So the two modes are fundamentally different, and require different circuits to operate. I got around this limitation with some clever design implementations, and a bunch of digital to analog circuitry.
  11. Possibly. I don't have an SNES mouse to test with. But at the end of the day it would just emulate a joystick.
  12. I thought that I might share this here, as it is relevant to the forum. I recently designed an interface for vintage PCs with a Gameport (either an analog card or soundcard with Gameport). I had been thinking about the idea for quite some time. But thought that I would sit down and put the idea together. What I came up with is the SNES-2-GP. I've added a write up on my website. Clint Basinger from LGR liked the idea, and I'm sending him one to play around with. If anyone is interested reading about it's development, the link is below. http://retrodepot.net/?page_id=1078
  13. Calphool, as I mentioned earlier in this thread, you'd need to strip the composite sync signals as a reference for the timing. The datasheet does talk about this, but they do not go very deep into the application. And as Tursi pointed out, there may be a bit of skew. I never got around to prototyping anything out, I always have too many projects going as is. But the LM1981 is where I would start for testing. In short, you'll have to play with it to know how well it will work.
  14. Here is one I did. Its a modified NES controller for use on a PC. Digital to Analog board consists of a few transistors and resistors. Wiring was done with a Ethernet cable (stranded, not solid core). It supports Analog 1&2, and 4 Buttons (Select=4 Start=3 B=1 A=2). Im looking at converting a SNES controller as well (can use analog 3&4 for use as HAT buttons) with a second converter board, but I cant seem to find any 10 wire cable that is small enough to fit the SNES hole. If anyone has a suggestion on cable selection, Id love to hear it.
  15. I dig it. I may print a few of these out when I have some black PLA.
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