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Kai Robinson

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    IT Support Technician

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  1. @quorten I think i just noticed something in the original Apple RTC chip....it looks to be a very early implementation of I2C (phillips brought it out in '82) - Rename the pins on the RTC from RTC.CLK to SCL and RTC.DATA to SDA and....well, there you have it...I2C serial data line is BiDirectional after all....would make sense, right?
  2. How many Custom Apple ASIC's are there? Hundreds, i bet! But, what i'm interested in, is the simpler stuff - in this case, the BBU, the SWIM, SND and RTC Chip from the SE to start with. Who's seen Ken Shirriff's blog posts before? The guy is nuts, but in the best possible way - take a look: https://www.righto.com/2020/08/reverse-engineering-8086s.html This is the sort of thing i'd like to do with the custom ASICS, but i don't want to sacrifice working ones if i can help it - so...if anyone has any one of the aforementioned chips that are DEAD - please could you donate them to me so i can have them imaged? The more chips of each type i can source, the easier it'll be to image, and ultimately, reverse engineer. One of the guys who's working in the same group as me on discord, for the A500++ project, Johan has been reverse engineering the Commodore C128 PLA in his spare time and has developed a process to decap and image most, if not all, of the die itself, so it can be analyzed. I may reach out to a few other people who might be interested, as well - but yes, this is the general idea. Of course join in, if you have the expertise! This gives a good overview of the process, and the site also has a collection of commonly available die shots for analysis. https://siliconpr0n.org/wiki/doku.php?id=delayer:wet And here's an example of Johan's work: https://chips.c128.se/8521R0/index.html
  3. You dont need to add the crystal - that's already on the board.
  4. Well it's that timer 1 has the option of the 128 prescaler, whereas timer 0 doesn't. The video I posted had all the details.
  5. @quorten - after looking through your code - could you try changing this: //set up timer bitSet(GTCCR, TSM); // Turns off timers while we set it up bitSet(TIMSK, TOIE0); // Set Timer/Counter0 Overflow Interrupt Enable // NOTE: 0b111 external clock, 0b011, uses 1/64 prescaler on I/O clock. TCCR0B = 0b011; // Set prescaler, 32,768Hz/64 = 512Hz, fills up the 8-bit counter (256) once every half second TCNT0 = 0; // Clear the counter bitClear(GTCCR, TSM); // Turns timers back on into this: //set up timer bitSet(GTCCR, TSM); // Turns off timers while we set it up bitSet(TIMSK, TOIE1); // Set Timer/Counter1 Overflow Interrupt Enable // NOTE: 0b111 external clock, 0b1000, uses 1/128 prescaler on I/O clock. TCCR1B = 0b1000; // Set prescaler, 128 x 256 / 32.768 = 1000 TCNT1 = 0; // Clear the counter bitClear(GTCCR, TSM); // Turns timers back on I'm not sure if i set TCCR1B correctly, but the prescale math lines up...
  6. Hmm. Possible - although i'd rather just use the proper connector at least for now: https://www.exxoshost.co.uk/atari/store2/ - Item 0084.
  7. @quorten I think the ATTiny 85 would suffice for most people - is the time drift realllly that significant? Btw i found this, might be useful:
  8. Yep. SGI Octane Part 2 - was my Octane i donated
  9. @Torbar Neil's a friend of mine - was up there a few weeks ago for my holiday, got drunk in his lounge - i took one of my dead ones to him for a wall art thing in the cave
  10. OK - i found a supplier of DB19F connectors for PCB's - exxos store! The Atari community use them, too - i bought a few from there for the SE's
  11. I also went all in and got 10 boards - so there's a few more that'll be free to go out - and there's still one piece of 'wall art' available
  12. Well, they're here.... GND tests show... THE EXCLUSION WORKS!!! The rear I/O should now be good to go, it's not shorted anymore, and the rear ADB and serial ports are grounded correctly now.
  13. DHL are due to deliver the new batch tomorrow - assuming customs charges aren't due...
  14. By all means feel free to use the ATTiny87 - i'd recommend prototype with a through hole, but if it works, i'd knock up an adapter for the TSSOP-20 package that can fit in the confined space.
  15. @buserror Show us what you do with it I have 4 more pieces of 'wall art' (failed blue pcb run), left. The new rev 1.4c boards are due in shortly, whih hopefully WONT be wall art
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