HP110+ upgrade DOS2.11 to DOS6

[time27]

Hi

My resources
1. 2off HP47511 or HP110 Portable Plus

2. copy of DOS 3 to 7 version which I wish to install

3 ROM Burner - GQ-4X4 USB Universal 40 pin Programmer

4. I have M27C256B-12F1 - ST Microelectronics EPROM

Would love to do

Burn a upgraded copy of a DOS2.11 to DOS 5 or 6

What I have done so far:

I have taken out existing HP110+ software draw ROMs and read them.
First few lines of which is HP product number...

What I failed to find is a location of DOS2.11, I think it is soldered to the main board.
Did you guys ever upgrade the DOS??
I did try to load DOS3 by setting CONFIG.SYS to bypass PAM,
by using
> SHELL=A:\COMMAND.COM /P A:\
I used the HP9114B to load DOS3 into A: and I rebooted - I hope.
HP110+ hung, had to use battery reset...

What do you think of my approach?
Did you have a different approach?
https://photos.app.goo.gl/y5DYptc35sFsCvZK8

Regards Nick

[brouhaha]

The HP 110 and 100+ aren't PC-compatible. They run an OEM version of DOS specifically tailored to them. It's unlikely that they can run any version of DOS other than what HP supplied.

[time27]

Hi
Thanks for the thought

I looked at the software draw and I think the MS DOS is hiding in the main ROM.
To get to the that ROM I will have to take the HP45711 mother broad out and identify the ROM chip. I have 2 of those HP110+ computers.

Tried everything in way of loading an OS. so far but best option would be ROM based DOS5 as it has many extras such as ANSI.sys.

Alternative would be to create an edsk.sys command.com (DOS 5 ) and a path by creating a config.sys and autoexec.bat.

Many users of HP110+ have taken the path of creating a EPROM programs for images taken from a EDRIVE after trying software like "Pascal". If I can successfully boot from any other drive using config.sys and autoexec.bat creating an alternative path I can only imagen a success. I hope.

I noticed that after an alteration to memory size HP110+ reloads the DOS from B:\BIN\ directory...it also reads root dir of all the drives looking for config.sys before it loads the OS from a default location, If I can fool it once to use a different path I can perhaps load a command.com of DOS5. Alternative is fining a factory ROM on the motherboard and reprograming it.

Those are my thoughts on software before I am let loose on hardware with a soldering iron.
If you had hardware expereince with the HP110+ MB expereince is welcome.

Regards Nick

[Martin Hepperle]

.. as brouhaha said above, you first have to adapt the low level components of DOS to the HP hardware.

This part is required to access things like the mass storage (which typically is a combination of RAM and ROM disk), timing hardware (clock), keyboard and so on. In the old days, Microsoft supplied an OEM adaptation kit which contained the description and examples how to adapt MS-DOS to non IBM-PC compatible hardware.

This would require quite some effort and later MS-DOS versions would also use more RAM which is scarce on the Portable Plus.

If you want to use your soldering iron: a more interesting hardware development would be to design a large capacity RAM disks drawer.

[Sylvain Cote]

In the x86 BIOS pre-standardization world, all computers had a custom BIOS and manufacturer had to write their own IO.SYS file.
This is why MS-DOS is delivered with IO.SYS (computer-specific) and MSDOS.SYS (generic).
While this was somewhat easy for text mode, graphic mode was another thing. (CGA, EGA, VGA, HGC, HP-150, DEC Rainbow PC-100, etc.)