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Hi. PDOS/386 (at http://pdos.org) now supports (to some - for my use sufficient extent) the Win32, OS/2 2.0, Linux 386, 32-bit MSDOS (can be quibbled) and PDOS-generic APIs. And I now provide a toolchain for those first 3 APIs so that you can rebuild gcc 3.2.3 with itself (or basically any...

If I have a PM16 OS and program (both written by me), so that I have 8192 selectors (including both GDT and LDT), and I tile them to the max, and sequentially, and run everything in privileged mode, but I need to also write and execute memory, in a simple manner, so two selectors for each memory...

I am writing a 16-bit (PM16) version of PDOS-generic using an OS/2 1.x executable as a pseudo-BIOS and running under Windows 2000 (also tried HX dpmild16 under Freedos). I got a protection violation and thought that I needed the equivalent of mprotect to overcome that. DosQueryMem and DosSetMem...

I have an 80386SX laptop, which works for a couple of minutes every now and then (days apart). I would like to boot from an external floppy as the internal floppy is giving issues and it might be the drive. Is this a standardized connector at all? If so, what is it called and can I connect...

PM32 of the 80386 allows you to set the D-bit on a segment to say it is 16-bit. There are some op codes that have changed behavior between RM16 and PM32. I can probably find an example if required. If you set the D-bit to 16-bit, do you get the RM16 behavior of those opcodes, or the new PM32...

Hi. I bought a Hand 386 second-hand since they were out of stock new. I was surprised that PDOS/386 didn't boot. It said that it couldn't read the VBR. At the time I didn't know that that was a message from the MBR code, but when I started the debug process I found this to be the case. The CF...

I only have a vague goal, so take this with a grain of salt. Basically with the benefit of hindsight, I would like to have bought (or rented time on perhaps - I had only just started working in 1986) an 80386 computer in 1986 or close, and written a Win32 clone (what PDOS/386 is currently). I...

I just bought Windows 95 on floppy disks. They are in DMF format (21 sectors per track instead of 18). I tried reading them with PDOS/386 and only got standard 1.44 MB. I figured that was because the BIOS was reporting 18 sectors per track in the Drive Parms call, so I modified PDOS to...

Hi. I just bought one of these NEW laptops that apparently contain a V20 chip: https://www.ebay.com/itm/134615009272 (it says 8088, but I can see from the photo that it is a V20 - although maybe mine won't have that) Assuming I get a V20, I was thinking of modifying PDOS/86 to run CP/M-80...

Hi. I have posted in these forums before about PDOS/386 for the 80386, but this is the first time I have mentioned that there is a PDOS for the IBM mainframe. Currently I build for S/370, S/390 and z/Arch using conditional compilation. But I believe it is possible to have a single OS with some...

Hi. I am interested in running 16-bit code in PM32. I may simply run PM16 or CM16, but I'd like to know if PM32 is an option (twice the number of selectors). I'm not definitely going to do this, I would just like to know if it is definitively ruled out. Assume a homebrew 8086 OS and a...

Subject says it all. New version of PDOS (both 86 and 386) was released a few hours ago at http://pdos.org

As of about a day ago, I fixed the last known reproducible integrity bug, and as a result, PDOS is now nominally stable, and able to reproduce both PDOS/386 itself, and the tools used to produce it, including GCC 3.2.3. Available from http://pdos.org

Circa 1994 I didn't know what "huge" memory model was, and selected "large" to write PDOS/86 in. I then found that my already-written memory management routines didn't allow me to manage more than 64k of memory. Rather than change my routines, I hacked PDOS/86 to get more than 64k of memory...

I have previously posted about trying to reach back to 1990. Since then I have transitioned to 1986 (when the first 80386 computer had a 40 MB hard disk) and today I have moved back to 1983 when the IBM PC XT came out. Although I'm using a 20 MB hard disk instead of the standard 10 MB. See...

Sometime around 1987 when I was about 20 years old, someone advised me to program in C if I wanted my program to last forever. C was standardized internationally in 1990. I was there, waiting to see if ISO was going to change anything that ANSI had done, but they didn't. Finally we had a decent...