20-05-2022, 10:57 PM
(19-05-2022, 10:17 PM)CheshireNoir Wrote: Interestingly I dropped back in the RAM test ROM and I'm now seeing it fail at random locations while doing the RANDOM NUMBER test, somewhat, err, randomly. Certainly at different addresses each time.Interesting that you are now having random problems with the TEST ROM memory test. Do the random failure happen on one particular bank or pair of banks or across all banks?
Quite probable that you have some contact issues either with the 2x 25 way headers between the Main and Core boards or even your IC Sockets, have good look at you EPROM socket. The original ones were not meant for multiple insertion removals and can be a bit of a problem. Are your RAM chips socketed?
The fact that BASIC fired up OK is a good sign, as this takes out a number of variables, bank switching and FDC being two main ones.
When you are saying that the neither the BN5443 nor the BN55 are booting up, earlier you described it as "doesn't even get a video sync" is this still the case or can you get into the Monitor with the BN5443 by powering up with the M key held down? If it is trying to boot the floppy through the FDC, you should get a block cursor at the top left of the screen until the floppy starts to boot, however depending on your setup may end up being off the top of the screen if your monitor is over scanning.
Depending on if you can get into the monitor or not will tell us if it is a floppy disk booting issue or a more sinister hardware problem with the Coreboard.
I don't have a BN55 EPROM to see if we can do the same there, but I would expect so.
The best I can tell is the BN5443 is meant for the 5.25" ds40 drives and the BN55 was for the 3.5" ss80 drives. It is possible that the routines for the ds40 access may have been replaced by those for the ss80, but I'm only guessing on this.
I assume you are using a GOTEK for Floppy Emulation?
Ernest