Emax

You can look at both the binary of the OS and the EPROM in hex editors  
of course.

I have done so. Some parts are recognizable, some not. But perhaps for  
someone more versed in 6800 Assembler, this would make more sense.

Regards,
Ted

On Nov 5, 2008, at 12:23 PM, esynthesist wrote:

But the 5 minutes load time may have been reality...

This can explain why I don't know anyone and find no reference at all
of anyone who actually used this CD-ROM drive with the Emax. If this
5 minutes load time is true, this must have resulted in a commercial
failure for OMI when they launched the Emax OMI cd disks... but they
probably released these disks also in Mac/SD format ?

And yes, Emu has done strange things. E.g. the EII cdrom kit
supported a "folder" or "category" system: the banks on a disk could
be put in folders (like bank "piano" in folder "acoustic keyboards")
to make navigation much easier. This feature was not available on the
Emax and EIII harddisks. Maybe Emu considered this to be a feature of
OMI and not of Emu themselves, but they could have learned from
that...

RS422 Communication with the Emulator was designed based on following
key principles:
- all communication, including request/reply for parameter changes,
occurs at 500 Kbaud
- a whole bank can be downloaded/loaded with one special designed
type of command (a command which actually directly reads/writes the
RAM memory segments in which the bank data is residing)
- bulk data load/unload occurs with data packets sized 256 bytes, of
which each byte represents 1 sample point (data is transferred in
compressed format)

On the Emax, they seem to have decided that choosing for a *standard*
medium speed protocol was more important than choosing for a
*proprietary* high speed protocol. So they went for the MIDI
SYSES/MMA approach:
- all basic communication, including all commands/instructions,
occurs at 31.25 Kbaud, no matter if the DIN5 MIDI sockets or the DB9
RS422 port are being used.
- loading/unloading banks requires the full set of SYSEX commands.
Hence to simply download the parameters of just one voice of just one
preset, already multiple commands must be exchanged with the Emax.
This is due to the fact that in general only one parameter can be
transferred per command. And this must be done at the slow 31.25
Kbaud speed...mmmm...
- bulk data (sample) load/unload occurs with data packets sized only
120 bytes (MMA standard). Moreover each sample point requires 12 bits
now instead of 8 bits on the EII since data is transferred in linear
format instead of compressed format.
As a consequence, loading/unloading banks is much slower than on the
EII. Of course, once they released the Emax-II, they would have faced
problems anyway. This machine could have up to 8MB banks and doesn't
use compression, so even at full 500 kbaud speed and using only one
command - which is impossible in reality - the Emax-II would require
at least 2.7 minutes for loading/unloading banks. Fortunately there
was something invented called SCSI :-)

Nevertheless I will still do some experiments to find out if the Emax
OS doesn't have any "fast bank load" commands...
By the way: does anyone know whether the binary code of the Emax OS
can easily be de-compiled/disassembled in some way in order to get
some kind of source code ? Is a simple Z80 disassembler sufficient ?

///E-Synthesist

--- In emax@yahoogroups.com, tu@... wrote:
 >
 > That seems excessively slow, as the EII could load a similar sized
bank from the same CDROM
 > drive in 12 seconds. Its hard to imagine Emu would not have
implemented a similar load time on
 > the Emax if all it took was adding a software routine. But then
again, stranger things have
 > happened...
 >
 > /Tristan
 >
 > Quoting John Silveria II <john@...>:
 >
 > > Somewhere, and I can't remember where, I read that the CD-Rom
drive
 > > took
 > > up to 5 minutes to load a bank. I wish I could remember where. So
 > > indeed
 > > it was not only as slow as typical SYSEX load, it could actually
take
 > >
 > > longer.
 > >
 > > --
 > > Yahoo! Messenger: EmaxJS
 > > The Silveria Family Website and Emax and Emax II User's Group
 > > http://www.silveriafamily.com
 > >
 > >
 >






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