Question: Timing Changes

[sharpie7]

Hi David - hope you are good.

I am thinking about updating my MiSTER core to catch-up with your last round of updates to BeebFPGA. I am trying to get a handle on what you've changed and why.

One specific question: commits a9cf3b5 and 65cd9ac mention changes to sub-cycle timing to align to the Master. Would these also be applicable to the classic Beeb, or does that have a different sub-cycle timing that would best be handled differently in the emulation?

Thanks as always.

[hoglet67]

That set of changes was pretty hairy!!

Sorry, the comment is very confusing. The sub-cycle timing is the same on the Beeb and the Master, it's just I was using the Master at the time as the demos that were failing were Master only. There is a whole thread on these changes, see this post for the sub-cycle timing one:

https://stardot.org.uk/forums/viewtopic.php?p=359176#p359176

The test case that was failing is known as the "upside doom" test case, and can be found in this post:

https://stardot.org.uk/forums/viewtopic.php?f=3&t=22008&p=312652#p312652

Do you have access to a real Master?

It would definitely be worth you running through each of the demos / test cases. Somewhere I have an MMB image that contains all of them.

[sharpie7]

Hi David

It would be really helpful if you can find the test cases. I don't think common games are going to really test this level of detail.

I have a real BBC B, but not a Master.

Thanks for the clarification on the timing. I will take a look at the threads.

[hoglet67]

There is a build script for the MMB file in git: https://github.com/hoglet67/BeebFpga/blob/master/test/build.sh

This needs mmb_utils on your path: https://sweh.spuddy.org/Beeb/mmb_utils.html

Here's an actual BEEB.MMB file in case you struggle to build it: https://www.dropbox.com/s/nh0cw9dtb9adan1/TEST_BEEB_MMB.zip?dl=0

There are some notes here: https://github.com/hoglet67/BeebFpga/blob/master/test/NOTES.txt