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About Waynetho

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    Space Invader
  1. Interesting side story about a conversation I had with Wes Newell in the mid '80's regarding my plans to make a triple OS board similar to his Ramrod XL. He told me it would be impossible to make a 3-OS board unless I could source the special three position switch (ON-ON-ON) that he used with his board. I proved him wrong. I used a PULL-UP resistor for the CS pins on the first and third chips, and a PULL-DOWN resistor for the CS on the middle chip. I used a DPDT "Center-OFF" switch to GROUND either #1 or #3 chip's CS in their respective switch position, along with pulling the middle chip's CS "HIGH" when in either "ON" position. In the CENTER-OFF position, the board defaulted to the #2 chip active due to #1 and #3 being pulled HIGH and the #2 chip being pulled LOW by resistors. The switch used five wires (CS-1, CS-3, GND, and CS-2, +5V). This was accomplished with a switch readily available from Radio Shack. For the record, I didn't mass-produce the board or even give it a name. I made one for my 800XL and I believe two more for friends, all hand-wired. I wish we had 27512 chips and the mod discussed in this thread back then as the OS daughter board required three separate 16k OS chips.
  2. Upon reflection, I see that the DP4T switch option gives a more streamlined approach than my 74LS02 solution. The DP4T chip method only requires three wires and two pull-down resistors and no additional circuitry (74LS02). The NOR or OR gate solution makes the switch more logical in it's hookup but it requires more components to make it work. Additionally, it will work with the board that is already in this thread rather than creating a new board with the logic circuitry. I bow to a more elegant design.
  3. Using the NOR gates (or OR gates) will eliminate the need for the second pole on the switch, simplifying the wiring to the switch considerably. The OR and NOR will be inverted results (1234 vs 4321), One of the inputs of each OR or NOR gate will be connected together and connected to position #4. The other input for each OR or NOR gate will go to either position #3 or #2 respectively. Position #1 is "NC" The leads to #2, #3 and #4 switch positions should be pulled DOWN via suitable value of resistors (3.3K, 4.7K, etc) Output of one OR or NOR gate goes to A15 and the output of the other one goes to A14. This means with four wires to the switch (three inputs and one +5v), one can switch between four separate OS's. Edit: I forgot to mention that in my circuit design, the other four inputs for the other two gates are tied to ground so they aren't floating.
  4. I have a circuit (heretofore untested) that uses three pull-down resistors and two NOR gates from a 74LS02 TTL chip that will allow the use of a single pole 4-way switch (rotary or slide switch) for OS selection instead of the 2-bit binary switching. It uses a 4 to 2 encoder circuit with NOR gates. Position #1 is open (NC) because the three inputs on the encoder are pulled down. As a result, in position #1 pins A15/A14 on the eprom are set High/High. When switching to positions 2, 3 or 4, either A15/A14 are High/Low, Low/High or Low/Low. I need to acquire an eprom programmer or at least the temporary use of one, before I can build the circuit and test it but I'm over 99% certain that it will work as designed. I think it might be possible to nest the 74LS02 inside the socket area of the board above or one similar, along with the three resistors for the 4 to 2 encoder. No pull-up or pull-down resistors are needed for the eprom pins because the 74LS02 provides the distinct logic states needed by the pins. Has anyone else considered something similar to eliminate the need for the pair of binary selector switches?
  5. YES - 100% digital. Some monitors are a bit finicky about the signal though, so a cheap monitor, dedicated to the Atari (or time-shared as a second display) is what I ended up choosing. I bought an AOC 20" monitor with HDMI input at a Micro Center store in Dallas TX USA for $65.00 (64.99) USD, +tx. Due to lack of a physical control to switch inputs, I chose to set it up as a second monitor in a DUAL MONITOR configuration on my PC. I'm receiving a VGA AB switch box today that I will use to turn off the second video source from my PC which will revert my PC to single video mode, leaving my Atari to take advantage of the second monitor's HDMI input, unfettered.
  6. My HP s2031, although not liking the video signal, said the input signal was H: 62.8KHz and V: 60Hz. I still do not know exactly what the HP monitor didn't like about the signal since 62.8KHz is well within its supported horizontal frequencies. And YES, it is an ALL DIGITAL signal but the monitor still requires a horizontal frequency otherwise as I understand it, you would have a straight vertical line instead of an image.
  7. Compatible monitor with HDMI port: AOC E2070Sw +/? (NTSC works, PAL unknown) One caveat, this monitor has no controls other than power so switching between the VGA and HDMI ports is a bit difficult. I have my PC's VGA going to the monitor through a VGA extension cable and I"m unplugging the extension to break the VGA so I can use the Atari. Conversely, the HDMI signal has to be cut before it will switch back to VGA.
  8. Obviously twisting the in and out pairs (separately) is best to reduce induced noise from other circuits on the motherboard. Right?
  9. I see now that this mod uses the LUM/CHROM signals already existing on the board. Let me ask this, without the mod, will I see the trash visible in the images above (color distortion and jumping/flickering)? My cable just comes off of the existing CH and L pins on the AV jack and goes straight to the S-Vid connector.
  10. Update on my off-topic search for a scaler to resolve my monitor's issue with Sophia: The cheap Bytecc HDMI Scaler does NOT work. It doesn't even come on when in circuit, possibly because it's not a true HDMI signal but rather the DVI data moved to the right pins. I'm going to try a cheap AOC monitor next, fingers crossed. Magic Knight, is there any benefit to using board level S-video mod over the CHROMA/LUMA signals? Of course my outputs are polluted so if the board level signals are clean, that's a definite plus but I wonder if the mod actually duplicates circuitry that's already on the separated video on the board or if it's an improvement over the included signals.
  11. Still willing to provide pictures if you want them (when I get home). Just figured you were thinking it might have been the work done to install the Sophia mod was responsible for the video issues. That being said, if I choose to keep the RF mod, does anybody know if there's a place to get a good replacement RF for the 130XE, or perhaps a way to bypass the RF Mod and re-create the composite signal circuitry without it?
  12. The 600/800XL P/S that I have is the one in the lower left of that picture. I just associate the white one above that with the 65/130XE because the color matches.
  13. The problems shown above in the composite and chroma/luma images were present before the Sophia mod was installed. They weren't present in 2001 after the SIO2PC was installed because that's what I used to load programs (exclusively) since I never bought a drive or disks when I got the 130 back then. All of my original 800XL and 400 equipment was either sold or given to my nephew in the late 80s or early 90s. When you mention the chip defeat, are you referring to the Sophia mod or the SIO2PC? I'm not familiar with that. If you're referring to mods mentioned in my comments in another thread, those mods are not in this computer. They were part of my 800XL that I gave up about 30 years ago.
  14. Yes, the Sophia is in the same machine. I added those pictures for reference even though I know there's an out of range error, since the image is crisp. I've already been looking at options for getting Sophia to work with this monitor. It works with my Samsung 48" HDTV. I'm probably going to get an UP/DOWN-SCALER to pass the signal through. When I go to the info screen on the monitor, it displays CURRENT: H=62.8KHz V=60Hz, RECOMMENDED: 1600x900, 60Hz
  15. Regarding the power supply, it's the black brick that's labeled for use on 600XL and 800XL. It's not a 130XE (bone colored) P/S.
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