polling the UART for an input character arrived..
If things were healthy, init would have finished and the monitor would be running
waiting for you to hit a key to tell it where to book from.
If IORQ is not moving then something may have crashed the CPU.
I would like to know if you hit the reset does the IORQ pulse even once withiin
several seconds of that?
Douglas
On Feb 16, 2013, at 1:19 PM, rbruinsma <rbma...@gmail.com> wrote:
Hi douglas,
The pin 20 on the Z80 is the IORQ and pin6 on the z80 is the clock. Pin 6 does have a pulse, but I read in a thread that also pin20 needs a pulse on the z80. To be sure I did a resolder on pin20, but now I'am not sure if pin 20 needs a pulse or not? I did found this somewhere in this thread: https://groups.google.com/forum/?fromgroups=#!topic/n8vem/T5s7-N0VzPM
Ronald
Op zaterdag 16 februari 2013 21:58:10 UTC+1 schreef douglas_goodall het volgende:rbruinsmaIf pin 20 is the clock input to the Z80 (I think that's right), check with your logic probe to see if the heartbeatexists on the back of the board at pin 20. If not, check to see if you have continuity between pin 20 and theoutput of the crystal oscillator. If not you may have to run a wire from the oscillator to the Z80 clock input.It may be as simple as having to re-flow the solder on the pin-20 connection. I had this exact problem a while back.Let us know how this goes...DouglasOn Feb 16, 2013, at 12:12 PM, rbruinsma <rbm...@gmail.com> wrote:I have a little problem to get my SBC to run. I have read a lot of posts on this form and checked the most things that were suggested in these posts.
The only thing that I can find that is wrong on board is that I have no pulse on pin 20 of the Z80 IC. (tested with a logic probe)
What does that mean? What could I check next?
What I have checked so far:
- pulse on pin 6 of the cpu and pin 16 on the 16550
- VCC on all IC's
- solder work, re-tipped a few
- reburned my rom a few times, no errors and I use the ROMWBW
- tried two different max232: ADM232A and MAXIM 232CPE
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Note: I don't use messenger, or skype, or facebook, chat programs in general. Having always-on open communication links through massive public servers I don't have control over seems like too much of an invitation to be infected by a virus or bot. It is bad enough that my Mac wants to stay in periodic contact with Apple's cloud. Skype was tempting before Microsoft bought them. There have been too many examples of remote session links being abused by vendor employees. Even "back to my mac" makes me nervous. There was a recent episode where Apple cooperated with a social engineer and compromised someone's entire electronic persona. If you want to speak with me, calling me on the phone works well, and you don't have to wonder if the electronic mail got through or not. When I say "Hello, this is Doug", you know who you are talking to. Just in case you were curious.