[Coco] Deranging DW behaviour

[Gene Heskett]

On Saturday 16 November 2013 18:07:18 Luis Antoniosi (CoCoDemus) did opine:

> I have 3 cocos in my desk:
> 
> Coco3 HD63B09
> Coco1 HD63C09  (don't ask me why the coco1 has the C version) with a
> JEFT op-amp
> Coco2 6809
> 
> And i use a DW3CC2.ROM in a FD502 and it works in all three machines. As
> well in my superIDE I have the same ROM in one of the banks. The
> superIDE runs in DW mode in all three machines. For coco3 I have
> another bank on superIDE with the dw3cc3 in case you ask.
> 
> Then I got an old game pack Spidercide (ok it's a crime I confess) and
> removed the 28-pin EPROM and plugged the CC2.ROM to test in my Coco1.
> 
> Just to find out the rompak hangs on the coco1.  Tested on coco3 + mpi
> and got a worse hang (random chars on screen). Then thinking the rompak
> was bad I tried on coco2 to find out irt runs fine on it!
> 
> WTF: what could it be ? The CPU! I replaced the 6809 to a HD63C09 and
> bang: it hangs now.
> 
> Then I start to wonder: why in tha hell it works on all three computer
> using the FD502/SuperIDE but not the ROMPAK ?
> 
> What changes ? The HD is 100% compatible BUT....it does drain less power
> and the ROMPak doesnt' have the 2 grounding pads that Gene Hesket brags
> us all about when designing new boards.
> 
> Does it make any sense for you ?
> 
> Should we put grounding pads even in rompaks ?

I wouldn't make it an ironclad rule w/o making up two cards, one with, one 
without, the grounding ears.  Then after a good testing, I think we could 
make the statement with a bit more authority.

Cheers, Gene
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