Author Archives: Michal Necasek

Frequently Given Misleading Answers

The other day I came across this FGA item describing how to detect virtualized environments. It includes interesting comments which make Microsoft, Intel, and AMD sound stupid, but perhaps only reflect on the author being either deliberately misleading, or trying … Continue reading

Posted in Corrections, Documentation, Virtualization | 5 Comments

Dumping Ensoniq Soundscape ROMs

Let us posit that one has a need to obtain an image of the instrument ROM of an Ensoniq Soundscape S-2000, Elite, or OPUS sound card. There are two basic approaches: A) Desolder or cut off the ROM chip, plug … Continue reading

Posted in Ensoniq, Software Hacks, Sound Blaster | 4 Comments

WordStar Again

While trying to work on my DOS 5.0 article, I looked at DOS 5.0 build 224 from June 1990, which is the oldest surviving beta of DOS 5.0. And the README contains the following intriguing text, which reminded me of … Continue reading

Posted in DOS, PC history, WordStar | 73 Comments

DOS 5: TMI

For several years now I’ve been trying to continue the DOS history series and write (or rather finish) a DOS 5 page. While tracing the history of DOS 1.0 or 2.0 is quite difficult and the amount of source material … Continue reading

Posted in DOS, PC history, Random Thoughts | 12 Comments

About That Warranty…

Readers have been wondering what kind of valuable warranty users of Microsoft’s Quick Pascal 1.0 (and other products) might be voiding by running it on top of DR DOS 3.3x or 3.40. I don’t have the original Quick Pascal 1.0 … Continue reading

Posted in Digital Research, Microsoft, PC history, Undocumented | 16 Comments

How to Void Your Valuable Warranty

Try installing Quick Pascal 1.0 on DR DOS 3.40: What is going on there? It’s a long story… In 1988, Microsoft became increasingly worried by a new upstart OS from an old rival, DR DOS. Over the years, Digital Research … Continue reading

Posted in Digital Research, DOS, Microsoft | 30 Comments

There’s Another Possibility

Four years ago we pondered why on Earth a DOS floppy boot sector might start with 69h, supposedly a “direct jump” opcode. Which is the IMUL instruction on 80186 and later, and not documented on 8086. In the meantime, it … Continue reading

Posted in DOS, Floppies | 46 Comments

AMD64 APM Archive Online

Thanks to Konstantin Belousov, the OS/2 Museum AMD64 APM (Architecture Programmer’s Manual) is now available online. Big thanks to blog readers who recently supplied several missing revisions of the documents. This is a nearly complete archive of all published AMD64 … Continue reading

Posted in AMD, AMD64, Documentation | Leave a comment

Undocumented 8086 Opcodes, Part I

This is a guest post by Raúl Gutiérrez Sanz This multi-part document is about undocumented 8086 processor opcodes and their behavior. Most of the document will likely apply to the 8088 processor as well, but this has not been verified. … Continue reading

Posted in 8086/8088, Intel, Undocumented | 7 Comments

How Fast Again?

Or, Yet Another Wikipedia Mystery Looking for something on the Wikipedia USB page, a detail caught my eye. In the version history section, both the table and the text claim that the original 1996 USB 1.0 specification defined 1.5 Mbps … Continue reading

Posted in Documentation, USB | 31 Comments