Sometimes identifying old hardware is a bit tricky. Consider these two graphics cards:
The PCB is the same, the BIOS chips look the same, the DAC is slightly different but an 80 MHz part in both cases, memory is the same… but wait—the graphics controller is different! The top specimen is equipped with the original S3 86C911 accelerator, while the bottom one uses the newer and improved S3 86C924 with added 24-bit true color acceleration. Continue reading
Many or most readers of this site probably know that most chips (and PCBs) have the date of manufacture stamped on them, almost always indicating the year and week (usually not the actual date) they were made.
Especially with PCBs, there is no standard for whether the year or week comes first. For pre-millenial hardware that’s not a problem, because it’s unambiguous what’s the year and what’s the week. It’s a bit tricker when something like 0403 is stamped on a PCB—is that week 3 of 2004 or week 4 of 2003? In such cases, both might be plausible and one has to look further.
Chips more or less universally use the year/week convention, but some manufacturers label their products with a two-digit year and others only use a single digit. Intel is of course in the latter category. The above image shows a typical vintage Intel chip with a date code stamped on the bottom side of a chip and etched on the top (a 90 MHz Pentium, manufactured in week 15 of 1995). Note that there are actually three date codes, 515 on top, and 501/515 on the bottom of the chip. Intel makes things slightly difficult by often embedding the date code in a longer string, with the three-digit date code starting at the second position (the first might be a digit or a letter).
Most of the time, it’s easy to tell whether a date code like 927 means week 27 of 1979, 1989, 1999, or 2009. But sometimes the answer is not so obvious. Continue reading
After more or less accidentally coming across a BBS listing of various high-capacity floppy formatting programs, I began wondering: How much data can really be stored on a diskette in a PC floppy drive? And what’s the relationship between formatted and unformatted capacity? When I started doing the math, I realized that the problem is both simpler and more complex than I had thought. And that one megabyte is not like another.
Note: This discussion is limited to 3½” high-density floppies, by far the most common format, unless otherwise noted.
Since floppies store essentially analog signals, how is their theoretical capacity calculated? There are no addressable memory cells like those in RAM chips, so how does one arrive at 2 MB? The math is actually remarkably straightforward and has little to do with the medium and everything to do with the floppy controller (FDC) and drive. Continue reading
An interesting question recently popped up: How exactly did IBM build the ROM BIOS for the IBM PC? Knowing what tools were used should make it possible to use the ROM listing published in the IBM PC Technical Reference and reproduce the ROM image.
Only one thing was clear—the PC BIOS wasn’t developed on a PC. With later IBM PC/AT and XT/286 ROMs, the situation is simple because the published listings identify IBM Macro Assembler 2.00 as the tool used. With the PC BIOS (and early AT BIOS), there’s no such identification.
The PC BIOS source code is remarkably straightforward. It is a single source file which does not use any macros. The one telltale marker is a $TITLE directive at the very beginning. No known version of MASM accepts this syntax… but at least one other assembler does. Continue reading
One of the better PC magazines back in the day (that is, in the 1980s) was PC Tech Journal (or PCTJ for short), a sister periodical of PC Magazine published by Ziff-Davis. While PC Magazine was targeted at the general computer-buying public, the PC Tech Journal‘s audience were computer professionals—software developers and information systems managers.
PCTJ had a fairly high content to advertising ratio and the issues ran to around 200 pages rather than 300+ of the more ad-heavy magazines. Every issue contained several in-depth technical articles, as well as product reviews and product comparisons. Among the focus areas were development tools (assemblers, C/Fortran/Pascal/Basic etc. compilers), database managers, and networking software. Continue reading
One might think that for example a ThinkPad Power Series 850 is an uncommon system, but such things are relative. The OS/2 Museum recently learned of not just one but two very rare Power Series systems, one of which is virtually a complete unknown. Both now live in the UK and both had been manufactured there (in Greenock, Scotland). The machines are a Power Series 800 and a Power Series 600.
In 1994, IBM started producing several PowerPC systems on a small scale and distributed them to software developers as part of the PowerPC development program. The most common was the Power Series 440 (6015) aka Sandalfoot, a desktop machine equipped with an early 66 MHz PowerPC 601. Operating system developers however also needed a portable in order to develop support for PCMCIA, LCD screens, and so on. That was the Power Series 800. What exactly the Power Series 600 was is less than obvious, but the system will be described in detail below.
I recently attempted to install RedHat Linux 3.0.3 (that’s the one from 1996, not RHEL 3.0) in VirtualBox. I thought I’d use the BusLogic SCSI emulation and the newer 1.3.57 Linux kernel. It did not work at all.
The problem was that the BusLogic SCSI driver, version 1.3.1 by the late Leonard N. Zubkoff, wouldn’t load. It failed with the following error message: ‘INQUIRE INSTALLED DEVICES ID 0 TO 7 FAILED – DETACHING’. That in turn caused the kernel to panic as it was unable to mount the root filesystem. The real problem turned out to be caused by a rather interesting collection of bugs in the Linux BusLogic driver. Continue reading
A recent inventory at the OS/2 Museum revealed that two seemingly identical sets of Microsoft OS/2 1.30.1 disk images were in fact not identical at all. Probably thanks to the twilight status of OS/2 at Microsoft in the days of OS/2 1.3, Microsoft managed to confuse things to the point that it had to issue KB article Q99245 explaining the differences.
The trouble was that all the versions reported themselves as 1.3/1.30.1, and the SYSLEVEL.OS2 file which is supposed to differentiate between minor patch versions was exactly identical in all cases. However, timestamps and sizes of many system files (including the kernel, OS2KRNL) were not identical. Continue reading
The OS/2 Museum recently acquired this mystery 386 board (click on the image to see a high-resolution photo):
This is in theory a killer 386 board: onboard Am386DX-40, a socket for a replacement 386 or 486DLC processor, a FPU socket, 256KB cache, 8 SIMM slots for up to 32MB RAM, six 16-bit ISA slots, and best of all, a clock chip that can be set via jumpers to 16/20/25/33/40/50 MHz. Anyone familiar with typical 386 systems knows that such boards with user-selectable clock frequency are rather uncommon. Changing the clock speed normally involves replacing the crystal, which is hardly something one would want to do regularly. Continue reading
The following picture shows four essentially identical Intel processors in the top row:
The real difference is that some of them are fabricated on an older process and thus sport a larger die size than others. (They’re also not all rated to operate at the same frequency, but that is not a design difference).
The more obvious difference is the labeling. From plain chips to i386 to i386 DX. The chips neatly illustrate an important chapter in Intel’s history. The leftmost chip was manufactured sometime in early 1988 and doesn’t look very different from the original 386s, or any other Intel chip of the era. It’s simply a slab of gray-brown ceramic with etched markings. The only noteworthy feature is the double-sigma (ΣΣ) marking indicating a 386 which reliably performs 32-bit operations. Continue reading
