BIOS Setup usage - FreddyVRetro/ISA-PicoMEM GitHub Wiki

The PicoMEM has an internal BIOS Setup allowing to configure the board completely.

However, part of the settings, the one needing to be configured at the PC Start can be configured with a text file named "config.txt"
ROM Base Port, Setup menu startup time, IRQ...

Display the detected System (Before upgrade) RAM, Number of hloppy and HDD and Hardware IRQ.

If the PicoMEM IRQ say "0", there is no jumper on the Interrupt header.

• Fast Boot : Reduce the Wait time for the BIOS Setup and Boot when On.

In this Menu, you can visualize the Memory present in the PC (Conventional (DOS), ROM, UMB) and the reserved/ROM part.
The PC Memory is divided in Segment (Block of 64KB of Memory), and the PicoMEM can extend it in Block of 16Kb.

As the PicoMEM is a 8Bit ISA Card, it can see only 1MB of Memory, then 16 Segment in total (0 to F)

The only way to extend the Memory with a 1MB capable board is one of these 3 Method:

• Extend the Conventional Memory (The 640KB zone from Segment 0 to 9) Up to 640KB or 736KB.
• Add UMA/UMB (Upper Memory Area) on free zone in Segment A to E.
• Add EMS (Expanded Memory): This is a type of Memory using 16KB windows that can be mapped anywhere in a larger Memory. EMS Uses the Segment D or E.

The PicoMEM can use 128KB of the Pi Pico internal RAM or an External Memory Chip (PSRAM) connected via an SPI Link.
The Pico RAM is fast enaugh to have the RAM Emulated with No Wait State on the ISA Bus.
To Have the PSRAM (8Mb) working, Wait States are added to the Memory Read/Write, then, RAM emulation using the PSRAM is slower.
Then, you may notice slow down if you move heavily used TSR or part of DOS to PSRAM emulated region.

• Add EMS: You need to select an I/O Port and a base Address (EMS Port / EMS Addr).
  EMS can be used only if the Segment D or E are available.
  !! EMS can't be enabled if the PSRAM test fail or PSRAM is disables.
  The PicoMEM emulate the LOTech EMS Board, then, to use EMS, you will have to install the LTEMM or PMEMM Driver.
  

• Add Conventionnal / UMA: This is done with the PM RAM Extension and PSRAM Extension Options.
  You can select if you want to extend only with fast memory or extend all the PC RAM.
  

• Exclude Video Segment : EGA and VGA Memory (In Segment A) may not be detected by the PicoMEM. to avoid Conflict, you MUST Have this option On if you don't use a MDA or CGA Video card.
  

• Maximize Conv Memory : This Option ask the PicoMEM to extend the Conventionnal Memory Above the 640Kb. You can then have 736Kb of RAM with a CGA Video or 706Kb with an MDA.
  

If you want to be an expert in 640Kb Barrier breaking, you can consult the "Breaking the DOS 640k barrier" Video.

• ROM0 and ROM1 Image are menu that will allow to use files as an Option ROM. NOT IMPLEMENTED
  New: Menu removed on the latest firmware version.
  

The PicoMEM can use .IMG Files as Virtual Floppy and/or Hard Disk drive.
.IMG files are disk binary images, without aditionnal information: (Like Sector, Head, Track)

Important : The PicoMEM will set the correct floppy geometry based on the files size.
Hard Disk Geometry will be set as H:16, S:63, C:x
Then, Image of disk with different Sector or Head count will not work ! (Small Compact Flash Image)
Images with the same number of Sector per Cylinder may be able to Boot but will not work.

Warning : The files name (excluding .img) must not be longer that 13 Character.
You can select up to 63 FDD or HDD image, support for Sub directory is planned.

• FDD0-1 / HDD0-3 : Select the FDD or HDD Image to mount.
• PicoMEM Boot Code : If you want to use the PC Boot code, disable this option.
  It is recommended to keep it On, except if other Disk ROM is present in the machine (Like XTIDE)
• New Disk image : You can create a new HDD image with this menu, it will ask you for the file name and its size in Mb.
  The PicoMEM will clean the first Mb of the image and add a default MBR sector.
  

• NE2000
  

  Base Port : Disable or select the Base Port.
  Be carefull as the XTIDE use also the Port 300h by default. Some Real time Clock and XT HDD can also use these ports.
  

  IRQ : Define the Interrupt number to be used for NE2000.
  This Interrupt should be different than the PicoMEM Hardware IRQ, to allow other fonction to work.
  However, if you don't want to use other fonction with Interrupt, use the same IRQ will increase the compatibility.
  

To use NE2000 under windows, set the Pico IRQ to 3 and NE2000 to 3, network should be recognized (Windows 95/98)

NE2000 emulation is done through the Wifi : Place the SSID and password on a wifi.txt file on the SD ROOT.
The Pi Pico Wifi chip is not really strong and in case of metal case, the wifi signal is reduced.
It is highly recommended to have your wifi Access point close to the PC.

The PicoMEM BIOS Still contains some menu/Item not Active :
REMOVED in the latest firmware revision.

Memory:

• ROM Files not implemented yet.

Advanced:

• SD Speed and PSRAM Speed are not active, they will allow to adjust the respective devices clock frequency to adapt to different components.