Author Archives: Michal Necasek

NetWare Pure IP on DOS

Posted on December 10, 2025 by Michal Necasek

It is fair to say that Novell struggled with moving from the IPX protocol to TCP/IP. Of course a big part of the problem was that IPX worked extremely well on LANs and IP brought absolutely no advantages for basic … Continue reading →

Posted in DOS, NetWare, Networking | 25 Comments

Wait here. No, wait here!

Posted on November 11, 2025 by Michal Necasek

While working on a hobby project, I set up an OS/2 MCP2 (Convenience Package 2 for OS/2 Warp 4) virtual machine with a debug kernel and an expectation that I’d reboot the VM a lot. I was disturbed to find … Continue reading →

Posted in Bugs, Debugging, OS/2 | 6 Comments

The OS/2 Display Driver Zoo

Posted on October 14, 2025 by Michal Necasek

I have recently explored (again) the possibility of writing a high-res display driver for virtualized OS/2. But I ran (again) into a dizzying array of possible solutions, each with its own advantages and a good deal of drawbacks. OS/2 display … Continue reading →

Posted in Development, Documentation, Graphics, IBM, OS/2 | 29 Comments

Messy Mastering

Posted on September 29, 2025 by Michal Necasek

Large companies like IBM, Microsoft, or Novell typically had a well defined process for releasing software on floppies. More often than not, files were not directly copied onto a physical floppy; instead, a tool was used to create an image … Continue reading →

Posted in Archiving, Floppies, IBM, Kryoflux | 18 Comments

8×19 Text Mode Font Origins

Posted on August 15, 2025 by Michal Necasek

I was recently made aware of something that I had noticed before, but never paid much attention to. Consider this screenshot of a BIOS POST screen: VGA text modes usually use 720×400 resolution and 8×16 fonts (expanded to 9×16). The … Continue reading →

Posted in BIOS, Computing History, Intel | 39 Comments

More than Two Hard Disks in DOS

Posted on July 22, 2025 by Michal Necasek

Investigating the rather odd behavior of the Microsoft OS/2 1.21 disk driver led me to Compaq and their EXTDISK.SYS driver. While experimenting with various setups, I realized that DOS versions older than 5.0 do not support more than two hard … Continue reading →

Posted in Bugs, Compaq, DOS, Microsoft, PC history | 84 Comments

Learn Something Old Every Day, Part XVII: DHCP and ARP Don’t Mix in WSA SMP

Posted on July 19, 2025 by Michal Necasek

I just spent an inordinate amount of time debugging a VM running OS/2 Warp Server Advanced SMP (WSA SMP). The VM was working fine (except for sometimes hanging very early during boot, a known issue with the SMP kernel), but … Continue reading →

Posted in Bugs, IBM, Networking, OS/2, TCP/IP | 3 Comments

1990 Networking: LAN Manager 2.0

Posted on July 16, 2025 by Michal Necasek

In 1990, Microsoft released LAN Manager (LM) 2.0, a member of a long line of Microsoft’s networking products that started with MS-NET circa 1984 and eventually morphed into Windows NT file sharing. LAN Manager 1.0 was released in 1988 as … Continue reading →

Posted in 3Com, LAN Manager, Microsoft, Networking, PC history | 10 Comments

Learn Something Old Every Day, Part XVI: DOS 4.0 SELECT Is Too Clever

Posted on July 2, 2025 by Michal Necasek

A while ago I discovered an antique pirated copy of IBM DOS 4.00 on 5.25″ media, which was something that was missing in my archive. And by antique I mean from August 1988, when DOS 4.0 was practically brand new. … Continue reading →

Posted in Archiving, DOS, IBM, PC history | 17 Comments

Where Did CP852 Come From Again?

Posted on June 27, 2025 by Michal Necasek

An earlier article explored the history of codepage 852 (Latin-2 PC codepage) in released and pre-release versions of DOS and OS/2. At the time of this writing (June 2025), the earliest OS/2 build with some form of CP852 support including … Continue reading →

Posted in DOS, I18N, IBM, PC history | 36 Comments