Believe it or not, there is no MIDI buffer in the MK1 or MK2 at all.
Incoming bytes are handled as they arrive. That works ONLY if the rate of input is slower than the Poly can handle the MIDI interrupt.
Many new pieces of MIDI equipment can definitely send MIDI faster than the Poly can handle it.
So if there is no buffer then how does it handle the messages?
Well, each time a MIDI byte arrives the Poly gets an interrupt. The hardware interrupt causes the CPU to save its 8 registers on the stack.
Thus, the stack grows and grows and grows until it reaches right down into the top of the patch storage.
The MK2 is susceptible to the same problem but since there is an empty memory space above the patch storage and below the stack, a MK2 simply crashes instead of losing patches.
The HAWK fixes all of that with stack overflow protection, MIDI FIFO buffering and flash memory storage of patches.
Mike
From: Gordon JC Pearce <gordon@...>
To: korgpolyex@yahoogroups.com
Sent: Sat, March 27, 2010 5:10:53 AM
Subject: Re: [korgpolyex] Re: patch file of the presets sounds of the Poly 800 for Cubase
On Sat, 2010-03-27 at 06:56 +0000, zoinky420 wrote:
>
> --- In korgpolyex@yahoogro ups.com, Gordon JC Pearce <gordon@...> wrote:
> >
> >
> > >
> >> Do bear in mind that as soon as you send any MIDI traffic to the
> > Poly-800 you'll lose the top eight patches ∗anyway∗...
> >
> >
>
> why does that happen??
>
Firmware bug, only in the Poly 800 Mk 1. Basically if you fling a lot
of MIDI messages at it, the message buffer overflows and starts to
clobber patch data. It's fixed in the Mk 2, but it would be nice to
have a bugfixed Mk 1 ROM. One day...
Gordon MM0YEQ