Graphics corruption when dragging windows

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    Hey all,

    Ive got an amiga 2000 set up with a retina z2 card. I was delighted to read that p96 supports this card, since Ive not been able to get retinaemu working.

    Anyhow, setup all went ok but Ive got this strange issue where in workbench windows initially render ok, however when I drag them they start to go all fuzzy. The more I drag them, the fuzzier they go.
    Ive attached a couple of screenshots of before and after dragging.


    Anyone got any ideas? The retina is set up with 4MB of memory, but only half the slots are filled if that makes any difference.


    before dragging:

    https://postimg.cc/Z9hB81tm


    After

    https://postimg.cc/v1L133bV

    The error pattern is too erratic to be software-caused.


    The Retina card has it's memory in sockets. You (or the previous owner) may have cheaped out and used slower RAM chips than recommended. Please check that.


    Jens

    It has TC5144AZ-80 chips installed, do you think 80ns is too slow for P96?

    It's not a question of "for P96" but "for Retina".


    The manual clearly states that 80ns is the minimum, and 70ns is recommended. Depending on the manufacturer, I'd avoid 80ns types. Back then, even the Retina manual warned about Goldstar memory chips, and pretty much everyone knew that Micron RAMs didn't deliver what the datasheet promised (they did improve since then, so this only applies to 1990s chips).


    The "every other socket free" is correct in the 4M configuration. Your part number doesn't appear to be complete, but the TC prefix may hint at Toshiba as manufacturer. If I remember right, both Toshiba and Siemens were produced in the same fab and even bonded+packaged at the same service company. All I know about Toshiba RAMs of the era is that they were slightly higher price, and considerably higher quality.


    However, you have to know that D-RAMs do age. They get slower over time, and if the manual is right about 80ns being on the edge, age might have pushed it over the edge in your case.


    It's really just a guess - though an educated one. My own Retina card is equipped with 70ns NEC RAMs. Quality-wise, they play in the same leage as Toshiba did.


    So in order to tell if you even have the right chips, we need the full part number (there should be two more digits after the 44). There are a couple of special RAMs available in the same package, possibly with the same pinout, but different features, such as EDO and Static Column. Both are definitely incompatible with the NCR VGA chip of the Retina.

    Jens

    Thank you for your time in writing such a detailed response!

    The full number printed on them is:

    TC514400AZ-80


    I’ll keep my eyes open for some reasonably priced 70ns chips.

    That part number is a standard D-Ram part, and should be compatible. However, the 80ns part has a painfully slow page mode cycle time of 50ns, which may already be the explanation for the errors you're observing.


    You might want to see if you can get TI memory chips with the "enhanced page mode": This will already start to evaluate the column address when it changes, not just when the CAS signal is going active. This gives the TI chips an advantag, even if they have the same access time. Timing-wise, they're a crossover between standard page mode and static column, but 100% compatible with the original D-Ram timing. These chips started hitting the market in 1995 and became more common in 1996. Couldn't find any info about them being available in ZIP package, though.


    The NEC chips on my Retina are UPD424400V-70. These are 10% faster on page mode cycle time - and they are the same speed for 80ns parts, so that "painfully slow" comment applies to them as well. Given that the circuit board of the Retina is really large and traces for memory are very long, there's an inherent disadvantage of the design already, which may make faster memory chips a requirement, just because of the long traces.


    Please let us know how it goes with faster memory chips. It's going to help other Retina users as well!


    Jens

    I’ve found the 60ns version of this toshiba chip on aliexpress for a very reasonable price - will see when it arrives!

    No luck unfortunately even with TC514400AZ-60 chips. Looks like Im stuck with retinaemu 😅

    Can you try a lower resolution? This will lower the pixelclock, and with a little luck, also lower the memory access speed.


    Jens

    Some important information seems to be missing here: Which A2000 revision is this (rev.4 or rev.6) and if rev.4, has a board upgrade been made? Second, which accelerator is used here, and which CPU is installed. Third, is the CPU overclocked?


    This does not look like a software problem. It looks like a hardware issue driving incorrect data (or addresses) over the Zorro bus, and the Zorro slot in particular on rev.4 boards is flaky.