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OCM firmware 3.9a version 1 for SX2 w/ Franky Sound

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@ducasp ducasp released this 15 Apr 13:53
· 75 commits to master since this release
SX2_OCM3.9a_v1
21c28fa

SX2_FRANKYSND

ko-fi

PLEASE DON'T USE THIS RELEASE, THE FULL RELEASE IS AVAILABLE, IT IS KEPT HERE FOR HISTORY REASONS.
CHECK FOR OCM_SM 3.9a - Oficial Release instead.

IMPORTANT! READ THIS AND BE CAREFUL! BRICKING SX2 ISN'T FUN! IT IS A PAIN TO
RESTORE IT USING JIC / USB BLASTER AS YOU WILL NEED TO CONNECT IT TO AN USB
BLASTER TO RESTORE IT. YOU HAVE BEEN WARNED! REALLY!

ONLY USE SMXFLASH.COM to update your SX2. ONLY USE A FIRMWARE THAT IS MEANT TO
SX2. NO, SMX-HB firmware IS NOT COMPATIBLE. SM-X MINI firmware IS NOT
COMPATIBLE. SM-X firmware IS NOT COMPATIBLE. IF THE FIRMWARE IS NOT SAYING IT
IS FOR SX2 STAY AWAY FROM IT.

The version of SMXFLASH.COM that is sent along with the firmware file also
works on NEXTOR. Older versions of SMXFLASH.COM requires MSX DOS 2 Kernel to be
loaded. Why would you use other version? I have no idea. Read this fully and
be carefull to not have any issues. Command line to update:

SMXFLASH OCM_SM.PLD

Wait until it quits to the dos prompt telling it is done. If there is an error
message after it started erasing or writing, try again until it works, as if
you power it down with an unfinished update, it will BRICK and you will need
to use an USB Blaster and JIC file to restore it, like said above, a pain!

Also, be aware that if power fails during update, you are most likely to end up
with a bricked unit and you will need to use an USB Blaster and JIC file to
restore it, again, a pain!

OCM-PLD v3.9a is an extension on KdL OCM release v3.9. What this extension
brings to the table on this frankysnd version:

- Extra: I've added partial support to a built-in Franky. That partial
  support is good enough to work with SG1000, COL4MMM (using COM\Franky
  versions) VGMPLAY and Sofarun (remember to set it to use MSX VDP and
  Franky's PSG). As Franky sound uses I/O ports 0x48 and 0x49, and those
  ports are part of the switched I/O, it is usually disabled, as OCM IPL
  loader will leave switched I/O selected after booting. There are 
  different ways to enable Franky sound:

    - VGMPLAY will automatically disable switched I/O, so you can play a
    VGM song that uses SN76489 and after exiting VGMPLAY you can use other
    software.

    - De-select the internal switched I/O by sending the basic command
    OUT &H40,0

    - Use SETSMART -8C to enable the I/O ports 0x48 and 0x49 for that, so
    any program relying on reading OCM information on those ports won't
    get it.

- Fix: I've fixed OPL3, it had two issues that prevented it to work with
  the latest VGMPlay version:

    - IRQ was not connected, so timers programmed wouldn't trigger,
      instead only the VDP interrupt, to slow, so music would play darn
      slow with VGMPlay.

    - Even after fixing that, playing speed was almost half of the correct
      speed for VGMs. The timer scaler was not properly set causing it to
      trigger slower than programmed.

  Since VGMPlay 1.3 relies on OPL3 timer when present to drive a high speed
  interrupt, not having IRQ and not having the proper scaler for timer
  caused its timing to be slow, darn slow...

  • Planned for the future SM-X, SM-X mini and SX-2 will have a franky build:

    • Missing: FPGA in those devices can't fit OPL3 along with Franky VDP and
      PSG, so that build won't have OPL3 support.

    • Extra: this is a WIP, please wait, but it will have Franky VDP :P

All source code and binaries:
(c)2022 Oduvaldo Pavan Junior - ducasp@gmail.com

All code can be re-used, re-written, derivative work can be sold, as long as the
source code of changes is made public as well.

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