[LAU] [LAD] [OT] digital mixer losing its presets after battery replacement

[Ralf Mardorf]

On Thu, 17 Jan 2013 14:34:41 +0100, Dave Phillips <dlphillips at woh.rr.com>  
wrote:

> On 01/16/2013 06:14 AM, Dave Phillips wrote:
>
>> ... simplesysexxer seems to receive and transmit a bulk dump with no  
>> problems, but the units do not respond correctly. The first preset gets  
>> copied, then I receive an error code "cE". I could make good use of the  
>> machine's error code definitions now...
>
>  From the owner's manual: cE indicates a checksum error.
>
> Would that be an error on the part of simplesysexxer or the hardware ?

When I wrote sound managing software for the DX7 the checksum always was  
ok, but failed for one sound only. For this special sound I patched the  
Assembler code, to not calculate the checksum, but to use a fixed  
checksum. It wasn't a mistake in the code regarding to e.g. an overflow,  
it was Voodoo. However, old devices, not only the DX7, were able to use  
transmitted data with bad checksums. At least for old MIDI devices, it's a  
seldom, but known issue.

-- 
FreeBSD 9.1-RELEASE amd64