[Coco] Help with Nitros9 on SDC?

[Rick Ulland]

Tested, Can confirm.

EOU doesn't run on my shop CoCo with Tandy AXX-7117 upgrade installed. 
DECB is fine, even at dblspd. To deepen mystery, this AXX-7117 has 
Fujitsu 120 ns chips.

To cloud waters, this CoCo has other issues but it is supposed to crash 
near the end of OS9boot, not stop above the fold.

Gonna have to play with this also! My hobby needs a formal bugtracker. 
Maybe KanBan?

In closing,  AXX prefix is Tandyspeak for 'sketchy new part'. Might be 
best to put this one in a game machine?

-ricku



On 1/26/22 5:08 PM, L. Curtis Boyle wrote:
> On Jan 26, 2022, at 5:01 PM, Don Barber <don at dgb3.net> wrote:
>> Hi folks, wanted to send an update. I narrowed it down!
>>
>> Basically, I got another coco3, and bought a 512k sram update and 6309 for it.
>>
>> When I put the 512k sram into my existing coco, EOU6 boots up great!
>> When I put the old 512k card into my new coco, I get the same behavior!
>>
>> So clearly the old 512k card is faulty. This is despite passing every single ram test I throw at it.
>>
>> The old ram upgrade is a Tandy AXX-7117. I can't find any reference to it online, but its identical to the picture in https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/512K%20Expansion%20RAM%20Card%20%28Tandy%29.pdf which is part no 26-3334.
>>
>> As the 6809 EOU boots fine on the old RAM upgrade, I suspect its something specific that EOU is doing when using 6309 instructions...perhaps the TFM instruction? Maybe the old RAM just doesn't switch fast enough? No idea, just thinking out loud.
>>
>> So...curious if anyone has any advice on testing the old ram card and determining whats going on there? The chips on it are MT 1259-15. There are also several capacitors and one resistor. Nothing looks blown or anything. The card does get warm. Not a big deal to simply buy a new 512k upgrade but willing to try to a few things to get this one working too.
>>
>> Thanks,
>>
>> Don
>>
>     It could very well be RAM speed. 6309 EOU runs in 6309 native mode, which does run faster including a cycle out of accessing the RAM. I do remember that 150 ns RAM chips were hit or miss on the Coco 3 - some would work ok, others would have lock-ups, junk on the screen (especially when using hardware scrolling,etc.) . Once RAM upgrade manufacturers upgraded to 120 ns most of those problems went away. I know we had to take a few minor speedups out in the final versions of the original NitrOS-9 (back in the early 1990’s) because the GIME itself had difficulties with faster access to it’s registers while in the middle of the vector page RAM and/or GIME I/O access.
>
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