[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [N8VEM-S100:5868] strange problem with dual IDE card

Can you add/more I/O wait states to the cpu

John Monahan (mon...@vitasoft.org)

On Dec 20, 2014 10:52 AM, "norwestrzh via N8VEM-S100" <n8vem...@googlegroups.com> wrote:
>> Roger I'm traveling so I cannot check but if you look at the source code you should see that what
>> is sent to the cf card is the same as that sent to the hex display.  You can check by outputting to
>> the 8255 port yourself from your monitor

Yep ... I did the little exercises that David Fry (I think it was him?) suggested (pushing out bit patterns to the hex digits, just to see that they are all working correctly).  All of that worked fine.  I forgot to mention that I also made the mods. that he suggested (switch S03's for the LS03's, and change the SIP to 330 ohms (from 680(?) I believe) -- that was *really hard* to do!).  Once SIPs are soldered in place, removing them is quite an effort.

I also forgot to mention that the CPUZ that I'm using is 4 MHz (apparently there is a 6 MHz version, but (sigh) I don't have that one).  I also changed out the 8255 a few times.  I tried the CMOS 8255 (82C55A-2), but it didn't help.  Not only that, but I got some actual glitches in the data being written into sectors on the compact flash.  I think that a sector full of 7's (37h) came out as a repeating pattern of 37ff, or something like that.  I also tried a straight 8255A, and now I'm using an 8255A-5, and it seems to work the best of all.  That got me to thinking last night that I ought to look at the TTL on the card.  I used 240 and 244 HCT, so this morning I changed those out too.  Haven't fired up the card yet to see if that helps.

Thanks for helping me look at this!!


You received this message because you are subscribed to the Google Groups "N8VEM-S100" group.
To unsubscribe from this group and stop receiving emails from it, send an email to n8vem-s100+...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.