Recent content by daver2

Good point, I was going to mention that a while ago and forgot. The probes cone with plastic attachments. They cover the GND ring of the probe to protect it from shorting against things. In addition, one of the plastic attachments helps the probe to stay on IC pins and not slip. Are you using...

Can you video the following signals please and indicate the frequency (if the signals are stable). B2/6. A3/11. A4/1. A3/10. A4/3. A4/6. Dave

They are fine. Dave

Yes, You can also check A3/4 and B2/5 at the same time. These are an inverted BA11 and can be tested at the same time. Thanks for posting the image, that helps me help you! Dave

They look fine. I am not sure why your frequency meter is not stable. The oscilloscope trace is rock solid though. You may need to read the manual to identify how the internal frequency meter works and whether there is any specific set-up required for it (e.g. oscilloscope Y position or...

I fully agree. Dave

Are you reading the frequency from your inbuilt frequency meter or the oscilloscope trace? How is the frequency changing on A6 / UD9 pin 2? Are the other address pins indicating a stable frequency? Can you post a video from the oscilloscope for A5, A6 and A7? Dave

Self-modifying code is the spawn of the devil and should be avoided at all costs! However, if you must do it, you must do it... I suppose my dumb question would be "why not use page 0"? That is what it is there for... If you must use self modifying code, try and use a 'generic' subroutine to...

Correct. You either must use page 0 or self modifying code. Those are your only two options I am afraid. Dave

Just got back from my business trip... If you go back to post #1,584 I asked you to measure the frequencies. ScottishColin was kind enough to test his machine and post the frequencies that he observed from his machine (1,591). You have the correct equipment to perform the test now, so why are...

There is a 6502 BASIC memory test somewhere. You can specify the start and finish address. For the SP9000 the start address would be $9000 and the finish address would be $9fff. You can select the bank of 4K out of 64K by poking the memory address for the bank switch register and run the memory...

I am looking at your posted photographs and seeing the duplicated text and error messages that are displayed. This is indicative that something is clearly amiss between the SP9000 and HOSTCM to me. I am sure you have read this...

I have checked myself, and the firmware for UD9 that has been burnt looks correct to me also. Based on that we are looking at the CPU -> ADDRESS BUFFERS -> ROM (UD9) -> DATA BUS -> CPU interface, along with the UD9 address decoding - and any potential bus contention. Assuming the CPU address...

OK - I understand more now... So, I am not sure what you are using the waterlooMonitor 'p' command for? It looks like you are trying to start HOSTCM on the remote machine via the SuperPET using the serial port. Is this correct? If so, you are trying to use the serial port for two different...

You go into the Waterloo Monitor and type 'p'. You log into your remote machine. What do you then type to perform the load? This is why I am suggesting using HOSTCM on your remote machine, that is guaranteed to work (he says)... Dave