Tutorials!

[BasariStudios]

Rob Sherratt

Pa2x/Pa800 SSD, RAM and ROM Internals

Power-up
The Pa2x/ Pa800 OS powers up in two stages. There is a 2 Mbyte NOR Flash Eprom device
(Macronix part number MX29LV160CTTC-70G). This contains the power-on-reset code and
device drivers that allow the CPU to manage the more complex SSD NAND Flash memory
in which the rest of the OS and musical resources are stored.

SSD-S and SSD-U
The internal SSD within the Pa2x and Pa800 is a single 256 Mbyte NAND Serial Flash device.
It is divided by the Korg OS into a system partition called SSD-S and a user partition called SSD-U.
It is made by Samsung semiconductor and has part number K9F2G08U0M.

The SSD-S stores the main part of the Korg OS and also the musical resources comprising the
Factory Programs, Styles, and Sounds. The system partition SSD-S also has a hidden folder in
which user samples are stored when the power is switched off. When the system powers up and
does a PCM autoload, the user samples are copied from SSD-S to RAM.

Sample Playback
The SSD is not capable of playing back user samples in real time. It can burst data at rates up to
200 Mbytes per sec, a bit like a disk drive because the bits are clocked in and out of the memory
a sector at a time. But each sector can not be directly addressed to retrieve sound samples when
they have to be played back in real time. The "random read access time" is 25 uS.

For playing back samples, a designer has to use memory whose access time is about 10 nS
(ie 2500 times faster than the SSD), and which can be directly addressed. Only very fast RAM
or mask programmed ROM can do this.

And even the fastest possible RAM is sometimes not fast enough as we learned on the forum
because some 64k RAM chips in some early Pa800 keyboards have had to be replaced.
They were "out of tolerance" causing the "disappearing RAM" problem.

Neither Korg nor any other keyboard manufacturer wants to implement the Factory Samples so
they can never be updated. It's just a current semiconductor technology limitation that forces it
to be this way. So, the factory Samples are stored in ROM. They are instantly available.
There is no load time. But they can not be updated.

Sample ROM
There are 8 chips forming each of the 8 bits of 128 Mbytes sample ROM. The chips are ROM chips
made by Macronix, part number MX23L12811TC-10 and you can download the datasheet from lots
of web sites if you do a Google search for it. These chips are manufactured using a photographic
mask in accordance with a one-off specification that Korg provide to Macronix. They are not reprogrammable.
The ONLY way to replace the factory Samples is to desolder the 8 surface mount IC's and replace them with
8 replacement chips. No-one wants to do this because of the risk of writing off the keyboard.

Even OS2 can not replace the factory ROM samples. Instead, OS2 introduces new software algorithms called
DNC that make fuller and better use of the samples that are there in your ROM already.

Sample RAM and the SSD
If you want to "update" the factory samples then you have to do it using "User Samples" that are held in SSD
when the power is off and which have to be copied to RAM before they can be used. Loading 128 Mbytes
of user samples takes about a minute, so there is a down side!

Disclaimer

The above information was compiled by Rob Sherratt, and is not officially released by Korg.

[BasariStudios]

Rob Sherratt

Notes about loading and merging .SET files

a) Loading .SET files from unknown sources and older keyboards is dangerous and can lead to data corruption and faults on your keyboard.

b) The only safe .SETs are those developed and saved from the same keyboard and OS version as you are using. They must not contain GLOBAL or SONGBOOK sub-folders or else you will have problems with your own important data being overwritten.

c) There is no automatic way to merge the contents of two or more .SET files, and loading .SET files developed by unknown people will usually overwrite your own data. See exceptions which follow below.

d) If User sounds are developed to use only factory samples, then these can be saved in a .SET file and given to other people and they can merge them with their own Sound data by using the OPEN procedure to find and load the individual sounds within the PCG file in the SOUND subfolder.

e) If user styles are developed to use only factory sounds, then these can be saved in a .SET file and given to other people and they can merge them with their own Style data by using the OPEN procedure to find and load the individual styles within the STY file in the STYLE subfolder.

f) Merging of .SET files containing User Sounds or User Styles which make use of User Samples is almost impossible for most users to do. It can be done if you have a lot of patience and experience with the Pa keyboard and if you are very technically minded.

g) Replacing factory Sounds or Styles with user Sounds or Styles is not recommended. You will lose all your work when the next OS upgrade is installed. There is no way to save and restore any of the work you have done.

h) One forum member, MickB (Mick Barry) is developing software in an attempt to solve some of the above restrictions and do the merging of .SET files automatically and safely. Due to lack of assistance from Korg for this, the development is going very slowly.