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helocast

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About helocast

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  • Birthday August 17

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    Amarillo, TX

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  1. Extra was probably a poor word. I just saw an original provision was made for two not implemented. No clue if they represent anything in the GPL scan tables or TI just left them blank - didn't get far enough to research that. When I'm piddling around thinking out loud in ExpressPCB + designing stuff, not being a software/application guy, I try to include full use of assets and let the smart software/assembly peeps run with it. I merely figured if the hardware + 9901 reserved codes in the CRU bits was there, then why not shorten the space bar a tad and make them accessible to the world if someone tamed/altered GROM0? Doug Edit: No doubt with the two unused 9901 pins, this is how the 99/8's keyboard was able to accommodate 54 keys. Just add another scan line to the matrix and you get 8 "new" keys ... of course you have to make software provisions for scanning them.
  2. Here's what I had worked on several years ago (files has an Aug 2018 date) in ExpressPCB https://www.expresspcb.com/ (free but proprietary, let me know if you want the .pcb file). Diode in place to fix the caps lock/joystick up override and individual RGB leds per key for backlighting. Resistors were tiny 0805s if memory serves and nobody likes working with those. Standardized ribbon connector (would require a +5/GND tap added in the 15-pin bundle to support backlighting, but you could leave those off and go classic dark. I think the small SMT latching relay for the caps lock to simulate was solved, but I abandoned the project. When I put it to the group here for sounding and common sense check, there was a lot of pushback that it would be too expensive and I'm certainly too poor to bulk order Cherry brown, RGB PCB mount switches in that quantity to build them for the group. Doug P.S. Good luck on your project ... it has merit as you've already done the hard part.
  3. No problem, Ksarul. I probably should've just posted the whole clean 516-page PDF for anybody else researching chips of the era (it's a huge one): Fairchild_MOS_CCD_Data_Book (1975).pdf
  4. Here's the specs on your F4049BPC compliments of 1975 Fairchild Handbook. I also have several tubes of the 1052911-X if somebody is doing a group project. Doug
  5. I know there's tons of calculators online, but this has always been my go to for supply lines (had to find the website again). https://www.mclpcb.com/pcb-trace-width-vs-current-table/
  6. Not the best copy I've seen, but maybe this will help y'all fill out a few of the missing ones. I checked a few and they seem to match off the list CD+four digit number of TI's part number. Doug
  7. For this one specifically and to a couple previous posts: Again I have visually identified (desoldered the female GROM riser on a a dead QI board) and those two traces fly by the port without connection, unlike the earlier 4A. Not to raise what I believe a (possible) separate issue to explain the FG's behavior on a QI, but imho I really feel it is more related to how the 4A generates Vss pin 33 on the grom connector vs "real ground" as the QI is wired. What I can't explain yet is why the ~ -.7v bias difference still works on QI built-in groms interchangeable with 4A groms. I really hope I'm not following the wrong rabbit down the proverbial hole on this research.😅 Doug
  8. You're pretty close from what I've been able to deduce all these years focusing on Figure J of the QI schematic. Despite how it is drawn, the open collector pullup on GRDY does go to all three groms (physically checked best my eyes can do on a populated motherboard). I keep meaning to publish all the oops! I've found so far, but don't really have the software to make a professional presentation here to the collective. Way back when Tursi pointed me to the Hombre TAL stuff on WHT it became one of my main projects. CPURY is a fairly complex equation taking GRDY, GCS, and SYSRY into account driven/sampled on @CLK2 phase and then finally NANDed with three separate conditions off of the shift-hold 8/16-bit bus conversion logic circuit. Hombre Logic TAL004 Gate Array.pdf
  9. Yes, pin 4 -CRUCLK and pin 6 CRUIN have no motherboard connection to the GROM port/riser. Just happens I've been spending the past month going over trace/component by trace between both models for a project. What I have not been able to detail on the FG99 because I don't have the schematics is the use of Vss, GROM port pins 33 & 35 (the odd little -.72V used to pull the line slightly below system ground). The standard TI-99/4A used a cap, resistor, and diode to provide that, but to "save" cost didn't make the final QI design and they just tied both pins 33/35 to ground. I know in Ralph's own troubleshooting he noted the FG99 is doing what it is supposed to, minus making final menu visible/actionable. These are really the only differences between the GROM ports unless you want to discuss the way pin 1 RESET is realized between the two, but that doesn't apply here. I have to assume TI engineers kept timings identical between revisions, but we know GROMs are very poor drivers because of the single transistor managing both pull up and pull down on its data lines. I throw something together in the FG thread whenever I get this little project of mine finished. Doug
  10. I guess I should've sent this zipped when you bought my FinalGrom99 ... didn't think about it at the time. Consider my PC hard drive like the Wayback Machine when it comes to TI stuff, even though I never use 99.9% of the files I get/find through this forum. I snapshot'd this back on July 12, 2017, at least that's what the file(s) creation date tells me (well prior to the existence of Ralph's current updates folder published 13 months? ago). Maybe it contains the originals required (not responsible if people break things). As to "building" the cpld file, there seems to be instructions at the end of the README.md file but it's all alien👁️‍🗨️ to me. Hopefully it helps someone. Doug finalgrom99-master.zip
  11. helocast

    TMS9901

    Ebay funkward-tech https://www.ebay.com/itm/TI-TMS9901NL-TMS9901NL-40-TMS9901-Programmable-System-Interface-DIP-40-x-1pc/151076609192 has always been reputable to me. Only had one order out of probably two dozen where I was physically shorted DRAMs, but they made it up. I've had zero fakes in my dealings, but I'm about due. Doug
  12. Appreciate the offer. PM'd OLD CS1. I'll keep my reply short since I'm in Dev. I really wanted it to work ... if nothing else to have a piece of every tech offered here. I can't keep up, but retired pension/money permitting I try. Doug P.S. Brewing Academy on Ebay still swears up and down this combo "works" and I've sent them a message to alter their listing in that regard. ¯\_(ツ)_/¯
  13. Considering I only run/own V1 QI, I'm still wondering what to do with my FG purchased early in 2018? Can we get credit/trade-in against a future SDD99 sale if that will finally support the QI? Doug
  14. A little slower, 55ns vs 45ns and wider voltage supply range. Other than that it is also in the 44-pin TSOP II package. $6.92 AS6C8008-55ZIN https://www.mouser.com/datasheet/2/12/AS6C8008-1288432.pdf I haven't checked compatibility any closer than that. Doug
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