!! Use the PicoMEM with an existing HDD was tested on few machines, this may not work yet.

When an existing Legacy HDD is present, it will be put as HDD0.
If you want to add a PicoMEM disk image, place it as HDD1.
In the recent firmware, you can replace HDD0 with an image, but the existing disk will no more be accessible.

For Firmware <= 28 June :
The PicoMEM Will boot only on the HDD0 and HDD0 is always the existing disk.
Then, if the computer disk is not bootable, it is not possible to Boot the machine on a disk.

You need to place the XTIDE BIOS (ROM Address) Before the PicoMEM BIOS.
Then, it is recommended to place the XTIDE at C800 and the PicoMEM at D000.
You can only Boot on the PicoMEM Disk as the XTIDE will place its Disk after the PicoMEM ones.

Note :

• You also need to disable the "Use PicoMEM Boot code" to allow the XTIDE to Start.
  

If XTIDE or MFM / SCSI BIOS start after PicoMEM one, add PREBOOT in the config.txt file.

XT Hard drive often use the DMA. It is then not possible to use the PicoMEM with these disk and emulated RAM in this case.

To allow the PicoMEM to Start, the PicoMEM BIOS setup must start before the XTIDE BIOS
To do this, add PREBOOT in the config.txt file in the uSD home directory.

It is recommended to add BIOS C800 to place the PicoMEM BIOS at the begining of the extension ROM Address Space.
A Book8088 config.txt example file is placed in the GitHub firmware directory

EMS : Select the port 388, default port (368) will not work.

For a Book8088 with VGA :
Enable the option "Exclude Video RAM* in the RAM emulation menu.

Note for the 8MHz Mode:

• It is not stable in Battery mode only, you must plug an external power.
  
• EMS and PSRAM emulated RAM Does not work.
  
• As the ISA timings are not standard in this mode, it is not guaranteed to work on all the Book8088.

The PicoMEM is tested successfully on my Commodore PC10-2.
Anyway, the EMS and PSRAM emulated RAM Does not work, only the PMRAM RAM Emulation (With the pico memory) is working.

On some PC10, it work only in "Turbo" or "Double" Speed mode (Ctrl Alt+D or +T)
New: You can also test the Fast RAM Mode firmware. (_FR)

Don't forget to disable the Upper memory zone where the PicoMEM BIOS is placed. (See the Issue #13)
(https://github.com/monotech/NuXT/)

Early verion of the IBM 5150 does not support optional ROM.
Then, PicoMEM (Or Even XTIDE) will not work work with it.

Minimal version : 10/27/82

References:
https://www.minuszerodegrees.net/5150/bios/5150_bios_revisions.htm
https://www.minuszerodegrees.net/5150/motherboard/5150_u33.htm

Add these lines in the config.txt file :
BIOS C800
PREBOOT

The PPC604/512 may work or not depending on the expantion slot board used.

Somebody recntly solved Boot issue by changing one capacitor on the ISA extention Board.
IF it can help someone else, here is the link:
https://github.com/FreddyVRetro/ISA-PicoMEM/issues/53

Some person got difficulties to have it working, you can find infos there :
https://github.com/FreddyVRetro/ISA-PicoMEM/issues/7

Tandy 1000 with Tandy Graphic (Before Tandy RLX) need a special parameter in config.txt
See this Wiki section for more infos :
https://github.com/FreddyVRetro/ISA-PicoMEM/wiki/Configuration-files#configtxt

Tandy 1000 ROM Address can be a little tricky, for Tandy TL, a working location is D800.
C000 or C800 work for Tandy 1000 HX (then probably SX)

It seems that some of these Tandy 1000 can't work with XTIDE and PicoMEM.
a New BIOS developped by "Cloudschatze" solve the issue :

https://forum.vcfed.org/index.php?threads/picomem-project-pi-pico-on-an-isa-board.1241199/page-17#post-1424729
https://forum.vcfed.org/index.php?threads/tandy-1000-rlx-and-rsx-bios-modifications.1246429/