Category Archives: DOS

DOS boot hang update

Additional information came to light regarding the hangs with DOS 2.x/3.x when booting from a disk with large number of sectors per track. The problem appears to have been noticed sometime in 1987—perhaps. The MS-DOS OEM Adaptation Kit (OAK) for … Continue reading

Posted in DOS, IBM, Microsoft | 4 Comments

From a Feature to a Bug

Sometimes the quest for backwards compatibility has unintended consequences. In some cases, the presumably beneficial backwards compatibility turns into a source of problems. The costs end up far outweighing the benefits, yet the “feature” may be difficult to get rid … Continue reading

Posted in DOS, PC history, Windows | 13 Comments

Lotus 1-2-3 R3 copy protection

Release 3 of Lotus 1-2-3 (1989) utilized a mild form of copy protection which relied partially on technology but primarily on shaming would-be pirates. 1-2-3 installed from copied disks prominently showed the name of the original owner every time the … Continue reading

Posted in DOS, OS/2, PC history | 9 Comments

What’s in a name… OS/2 or DOS?

There have been many rumors that the name “OS/2” was chosen only shortly before the product was announced. It’s not entirely clear what the name would have been otherwise, but quite likely DOS 5; certainly DOS in some form. There … Continue reading

Posted in Documentation, DOS, OS/2, PC history | 1 Comment

DOS/V graphics text modes and scrolling

I recently ran into an interesting difference in the way various DOS/V versions manage VGA memory. DOS/V of course refers to the Japanese versions of DOS which are capable of running on standard “Western” hardware. Microsoft has a very long … Continue reading

Posted in DOS, VGA | Leave a comment

Is it so hard to document things?

A few weeks ago I spent a bit of time debugging a program which mysteriously failed under DOS 3.3, although it worked without any apparent problem on DOS 4.0 and later, and there was no indication that it required anything … Continue reading

Posted in DOS | 66 Comments

Running 1-2-3 R3 in a VM

I recently tried to install the infamous Lotus 1-2-3 Release 3 from 1989 in a VM. The program disks included both DOS and OS/2 executables, and both were failing. The DOS version stopped with “Cannot initialize system driver” immediately after … Continue reading

Posted in DOS, PC history, VirtualBox | 3 Comments

Need for Speed SE video glitch

When attempting to play the classic racing game Need for Speed SE in a virtualized environment (VirtualBox), I was dismayed to discover that all the in-game videos were completely garbled. Curiously, the introductory video played when the game is first … Continue reading

Posted in DOS, VirtualBox | 7 Comments

WordStar needs address wraparound?

The CP/M compatible interface in DOS was initially documented, later forgotten, and then re-discovered every once in a while. In 1989, John Switzer described parts of the CALL 5 system call interface mechanism in a slightly hysterical article as a “back … Continue reading

Posted in DOS, PC architecture, WordStar | 11 Comments

Who needs the address wraparound, anyway?

The infamous A20 gate is well known and documented in hair-raising detail. What’s much less well documented is the real purpose of the A20 gate, that is, who actually needs the 8086 address wrap-around to be emulated in the first … Continue reading

Posted in DOS, PC architecture | 4 Comments