Navigate/Search

Dropping the ball

That usually happens with me over the summer .. not much gets done in the hobby space as we are outside enjoying the sunshine … or trying to  … it was quite the rainy summer up in TO this summer.

Uthernet update – I have just received another shipment of modules, so some back orders are going out.   I have been advised that the module I use is being discontinued.  In the short term I plan to stock upon another 50 modules. That should hopefully see me through a decision on what to do next.

The options are

  1. Make my own version of the module
  2. Redesign the card as an all in one (perhaps add some ROM to it)
  3. Replace it with a completely new design (Silabs CP2200 perhaps)

If you have any input I’d like to hear it

Stay tuned …

//cmxp update– When the ball went bouncing down the road back in May, I was stuck on a glitch that still has me scratching my head …. This appears to be random but perhaps my analyser sample isn’t large enough for me to see the big picture.  Something is causing the data-bus to load up with all FF’s prior to it settling down on the vaule i actually want to write and that somehow triggers the address counter to increment prematurely. I have been staring at timing diagrams trying to make sense of it.

Today I recalled that memory cards built for the original //c could not be used in the IIc+ due to a timing problem. I had originally decided to test on the IIc+ so that once i had things down, I figured it should be backward compatible with the original memory expandable //c. On a hunch or perhaps an act of desperation I decided to un-mothball a //c and plugged my memory card into it.  I fired up the diags ($C40AG) and crossed my fingers .. the line of dots kept going and going and going … it made one complete pass .. I let go of my breath then .. I think I was blue  … I kept watching and it didn’t fail … after 10 passes I knew I was out of the woods … so far it has made a total of about 250 passes and no failures yet .. whoopee

Clearly I now have to figure out whats different with the IIc+ from a timing perspective as far as this glitch goes .. at least I know what I have works so far and that’s a step in the right direction. Bring on winter … it’s back to Apple ][ land.

Cheers

One Response to “Dropping the ball”

  1. Nick Westgate Says:

    Great to hear about the //c breakthrough! Sometimes leaving a problem and coming back to it later is the best way forward. The old less is more thing …

    I look forward to your updates as winter sets in!

    Cheers,
    Nick.

Leave a Reply