Author Archives: Michal Necasek

Missing Intel SDM Documents

Posted on December 30, 2015 by Michal Necasek

I’ve been trying to complete my archive of Intel SDM documents circa 2000 and later. I have most of the editions archived but a few are missing. Readers of this blog could have something stashed away too, so perhaps someone … Continue reading →

Posted in Documentation, Intel | 11 Comments

Lies, Damn Lies, and Wikipedia

Posted on December 26, 2015 by Michal Necasek

While researching the history of 486s for a previous article, I came across a fascinating Wikipedia entry and its associated talk page. It’s a nice showcase of inmates running the asylum, and a reminder that Wikipedia can’t be considered an authoritative … Continue reading →

Posted in 486, Intel, PC history | 38 Comments

Intel OverDrive Part I: 486 OverDrive

Posted on December 13, 2015 by Michal Necasek

Intel had a long history of offering retail processor upgrades for PCs. The last and by far the best known of those were the Intel OverDrive processors. But let’s start with the earlier history. In 1987, Intel released the Inboard 386/AT, … Continue reading →

Posted in 486, Intel, PC history | 6 Comments

Intel 486 Errata?

Posted on December 6, 2015 by Michal Necasek

There don’t seem to be any specification updates or errata lists for any Intel 486 CPU anywhere. It’s odd because there are specification updates for 386s (and of course Pentiums) from Intel, and because the embedded 486s continued to be … Continue reading →

Posted in 486, Intel, PC history | 22 Comments

MS C 4.0 Documentation Added

Posted on November 27, 2015 by Michal Necasek

Another library expansion. This time it’s Microsoft C 4.0 documentation (1986)—because it’s not available online, is not easy to find offline, and because Jeff asked for it. MS C 4.0 was an early Microsoft compiler, implementing first glimpses of the not-yet finalized … Continue reading →

Posted in C, Documentation, DOS, Microsoft | 7 Comments

More on the C&T Super386

Posted on November 20, 2015 by Michal Necasek

Since last week’s post, more information about the Chips and Technologies C&T has come to light. It now appears that at least some 38605DX processors were made. Whether there is any surviving working system is still an open question (since … Continue reading →

Posted in 386, C&T, Documentation | 32 Comments

The Forgotten 386

Posted on November 13, 2015 by Michal Necasek

The CPUs that fit into a 386 socket are well known: Intel’s original, AMD’s exact copy, and Cyrix/TI upgrades. There is also IBM’s 386SLC which is close to a 386 but can’t be plugged into a standard 386 socket. The photo below … Continue reading →

Posted in 386, C&T, PC history | 25 Comments

More ISA VGA Benchmarks

Posted on November 6, 2015 by Michal Necasek

After establishing that Trident VGA cards are indeed very slow, the natural follow-up question is: Are there cards even slower than that? But not some 8-bit VGA card from the 1980s (or a Realtek from the 1990s), and not some … Continue reading →

Posted in Cirrus Logic, IBM, S3, VGA | 9 Comments

About Those Trident VGAs…

Posted on October 30, 2015 by Michal Necasek

An earlier post mentioned that the performance of Trident-based ISA VGA cards leaves much to be desired. A reader pointed out that such cards tend to have switchable 8-bit/16-bit bus width and performance might suffer if the card is incorrectly jumpered. … Continue reading →

Posted in Trident, VGA | 18 Comments

Fast Unaccelerated VGA?

Posted on October 26, 2015 by Michal Necasek

For the purpose of comparing the relative real-world performance of various processors, it’s useful to run CPU and graphics-intensive benchmarks such as 3DBench or DOOM. To avoid benchmarking the graphics card instead, the VGA has to have enough headroom so … Continue reading →

Posted in 386, ATi, S3, VGA | 27 Comments