Category Archives: Intel

When Networking Doesn’t Work

Posted on May 4, 2026 by Michal Necasek

Last week I spent far too much time trying to get my Windows 11 machine to talk to an antique Tyan SMDC (Server Management Daughter Card) IPMI module over the network. At first, I tried Tyan’s own old TSO (Tyan … Continue reading →

Posted in Bugs, Intel, IPMI, Networking, PC hardware, TCP/IP | 2 Comments

Learn Something Old Every Day, Part XX: 8087 Emulation on 8086 Systems

Posted on April 24, 2026 by Michal Necasek

Not too long ago I had a need and an opportunity to re-acquaint myself with the mechanism used for software emulation of the 8087 FPU on 8086/8088 machines. As mentioned elsewhere, the 8086 CPU (1978) had a generic co-processor interface … Continue reading →

Posted in 8086/8088, Development, Intel, LSOED, Microsoft, x87 | 20 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

Minor 387 Documentation Mystery

Posted on January 10, 2025 by Michal Necasek

So here I am, writing a bit of test code to figure out the behavior of x87 FPUs with regard to saving and loading the FPU state (FSTENV/FLDENV and FSAVE/FRSTOR instructions in different modes and formats). The original real-mode only … Continue reading →

Posted in Documentation, Intel, x87 | 9 Comments

Learn Something Old Every Day, Part VIII: RTFM

Posted on August 22, 2023 by Michal Necasek

In my quest to understand the intricacies of x87 behavior and especially floating-point exceptions, I pulled out my trusty old Alaris Cougar board. The system board had a 100 MHz Intel OverDrive 486 DX4 plugged in and worked quite well. … Continue reading →

Posted in 486, Documentation, Intel, LSOED, PC hardware, x87 | 9 Comments

Failing to Fail

Posted on June 16, 2023 by Michal Necasek

The other day I was going over various versions of the venerable DOS/16M DOS extender from Rational Systems (later Tenberry Software). The DOS/16M development kit comes with a utility called PMINFO.EXE which is meant to give the user some idea … Continue reading →

Posted in Bugs, Intel, PC architecture, x87 | 13 Comments

Learn Something Old Every Day, Part VII: 8087 Intricacies

Posted on January 23, 2023 by Michal Necasek

The other day I investigated a report that a C runtime library modification causes programs to hang on a classic IBM 5150 PC with no math coprocessor. The runtime originally contained two separate routines, one to detect the presence of … Continue reading →

Posted in 8086/8088, Development, IBM, Intel, LSOED, PC history, x87 | 11 Comments

Undefined Isn’t Unpredictable

Posted on November 7, 2022 by Michal Necasek

The other day I discovered that 32-bit FreeBSD 11.2 has strange trouble running in an emulated environment. Utilities like ping or top would just hang when trying to print floating-point numbers through printf(). The dtoa() library routine was getting stuck … Continue reading →

Posted in AMD, Development, Documentation, Intel | 22 Comments

Does (E)IP Wrap Around in 16-bit Segments?

Posted on October 29, 2022 by Michal Necasek

The 8086/8088 is a 16-bit processor and offsets within a 64K segment always wrap around. If a one-byte instruction at offset FFFFh is executed on an 8086, execution will continue at offset 0. This is simply a consequence of the … Continue reading →

Posted in 386, 8086/8088, Intel, x86 | 9 Comments

IBM AIX for IA64 (Itanium) aka Project Monterey Runs Again!

Posted on October 3, 2022 by tenox

(This is a guest post by Antoni Sawicki aka Tenox) Project Monterey was an attempt to unify the fragmented Unix market of the 90s in to a single, cross vendor Unix OS that would run on the upcoming Intel Itanium … Continue reading →

Posted in IBM, Intel, SCO, UNIX | Tagged , , , , , , , | 11 Comments