The PicoMEM 2 will add emulated CD-ROM and CD Audio in the Next firmware revision.

It is based on the yyzkevin Panasonic/MKE emulation added in the Picogus

El Torito BIOS extension is also supported, allowing to Boot from CD or use ELTORITO.SYS [driver]
(https://gitlab.com/FreeDOS/drivers/eltorito/-/tree/master/BIN).

In El Torito mode, the PicoMEM transfer the data via the Shared RAM, for faster transfer.

It support both ISO and CUE/BIN files.
CD ROM emulation does require only I/O port, no DMA or Interrupt is needed.

CD images needs to be stored under the "CDROM" folder in the MicroSD.

Like the HDD images, the files names are limitted to 13 characters.
.ISO and ,CUE files needs to be renamed if they are too long, but .BIN files must remain unchanged.

CD image can be selected from the BIOS SETUP menu, or the OLED Front Panel.

The MKE interface needs to be enabled in the BIOS Setup page, Disk sub menu.
You can select its base port : 0x250 or 0x260

ElTorito interface is always active, then CD Boot and ELTORITO.SYS can work even if the MKE interface is disabled.

Vincent Besson added the support of CD Boot via the add of El Torito BIOS extension.
It is then possible to boot from Windows 95 install CD for example by pressing "C" during the Boot.

The PicoMEM will use the default 250 base address.

CD-ROM needs 2 drivers to be loaded:
The Hardware driver in the CONFIG.SYS
Then CD Filesystem driver in autoexec.BAT

Multiple CD driver can be load, then the DOS driver can use all of them and mount them on different drives.

CDMKE is a driver provided by Creative Labs to use a Panasonic CD reader.

The driver si available here (PicoGUS Site)

Add this line in the CONFIG.SYS:
DEVICE=CDMKE.SYS /P:250 /Q

This will create a storage device named MSCD000 by default, using the port 250.

ELTORITO driver can be downloaded from here

No hardware resource is needed in this mode, as data transfer is done via BIOS calls.

Add this line in the CONFIG.SYS: DEVICE=ELTORITO.SYS

MSCDEX is the DOS CD-ROM/DVD-ROM redirector driver, it is provided by default in DOS.

Add this command line in your AUTOEXEC.BAT:
MSCDEX /D:MSCD000

Detailed MSCDEX parameters can be found here: https://www.computerhope.com/mscdex.htm

SHSUCDX can also be used instead of MSCDEX, it can mount up to 10 Drives and use less memory.
Download from here

It is used the same way, adding this line in autoexec.bat:
SHSUCDX /D:MSCD001

It can be used for 386 or more, the Driver SHCDHD86 also exist for 8086/286.