OS/2 Museum

Sound Blaster 1.0 or 1.5?

Posted on May 16, 2015 by Michal Necasek

According to some sources, a Sound Blaster model CT-1320C is a Sound Blaster 1.5. But according to Creative’s own reference materials (which do contain many inaccuracies and cannot be taken as gospel), the only difference between a Sound Blaster 1.0 and a 1.5 is the presence of C/MS chips which provide Game Blaster compatibility.

For example this card is clearly a Sound Blaster 1.5:

Model CT-1320C, no C/MS chips, case closed. But what then is this one?

That’s another model CT-1320C, but with C/MS chips. According to Wikipedia, 1320C makes it a SB 1.5. According to Creative, C/MS chips make it a SB 1.0. How to tell who’s right and who’s wrong? Fortunately, there is a way. Continue reading →

Posted in Creative Labs, PC hardware, PC history, Sound Blaster | 19 Comments

Intel 420TX Chipset

Posted on May 9, 2015 by Michal Necasek

The OS/2 Museum recently obtained a somewhat unusual board: A 1993 vintage 486 PCI/ISA board equipped with the Intel 420TX chipset.

The 420TX chipset, codenamed Saturn, was probably Intel’s first PCI chipset available to customers. It was probably first sold in 1992. The 420TX consisted of three chips. 82423TX and 82424TX together formed what would later be called a northbridge, and 82378IB was the southbridge.

Identifying the board took a little while but in the end wasn’t too difficult as it has several very unusual features. A Socket 2 486 board with PCI slots, onboard SCSI controller, but no onboard IDE or floppy—that is a rare sight indeed. Continue reading →

Posted in 486, Intel, PC hardware, PCI | 43 Comments

Sound Blaster: The French Connection

Posted on May 1, 2015 by Michal Necasek

Ever been wondering why there are chips labeled MHS on many Sound Blaster cards, and why there usually was some chip with a © Intel marking? For example this one, on a Sound Blaster 1.5 (1991):

Or this one, on a Sound Blaster Pro 2 (1994):

I was wondering the same… Continue reading →

Posted in Intel, PC hardware, Sound Blaster | 16 Comments

Sound Blaster DIAGNOSE and Disabled MPU-401

Posted on April 21, 2015 by Michal Necasek

Today I finally solved a nagging problem that always seemed like it had to have some sort of reasonable solution. Creative’s DIAGNOSE.EXE utility is quite useful when working with any Sound Blaster 16 derivatives (Sound Blaster 16, AWE32, Sound Blaster 32, AWE64). But there’s an annoying oddity related to the fact that many SB16-based cards have an MPUEN jumper which can disable the MPU-401 interface, typically accessible at port 330h. This jumper is very useful when a SB16 is combined with something like a Roland SCC-1 or a Turtle Beach Maui.

When the MPUEN jumper is set to disable the Sound Blaster’s MPU-401 interface, DIAGNOSE stops working:

This seems very unsatisfactory; the MPUEN jumper is well documented, so why would DIAGNOSE refuse working when the default setting is changed? After all, a user might not care for MPU-401 compatibility at all, or might have a system where ports 300h and 330h are already occupied by other hardware (SCSI HBAs, network cards) and needed to force the SB16’s MPU-401 to be disabled. Well, there is a solution… Continue reading →

Posted in Creative Labs, Sound, Sound Blaster, Undocumented | 3 Comments

sips To the Rescue

Posted on April 17, 2015 by Michal Necasek

A few days ago I scanned a document and unwisely used MS Paint on Windows 7 to touch up a small selection of the scanned pages. Once the dozen or so files were re-touched, I combined them into a PDF together with the untouched originals. Today I tried OCRing the resulting PDF in Acrobat Pro, only to be greeted with an error message complaining that “this page” cannot be processed because it’s larger than 45 x 45 inches.

By now I’m used to the fact that Acrobat Pro oscillates between really wonderful and amazingly shoddy, so I wasn’t surprised that there was not the slightest hint which of the 302 pages might be causing trouble.

After pinning down the troublemaking manually, it of course turned out to be one of the edited ones… and the problem was that MS Paint somehow butchered the DPI values stored in the file. Oops… Continue reading →

Posted in Graphics, OS X | Leave a comment

OS/2 on ThinkPad T23 and T30

Posted on April 11, 2015 by Michal Necasek

Recently I had a need to install IBM’s OS/2 on real hardware rather than in a VM, and for various reasons I wanted “genuine” IBM OS/2 and not eComStation. One of IBM’s older ThinkPads was a logical choice. A T42p would have been nice, but mine is currently out of action, awaiting EEPROM hacking. The next choice was a T30 and then a T23. The T30 and T23 ThinkPads are notable for being among the last machines on which OS/2 was officially supported by IBM.

The operating system was the refreshed MCP2 (Merlin Convenience Pack 2) from early 2002. Installing the OS itself was relatively easy, but there were some interesting challenges along the way.

It appears that the refreshed MCP2 is a must, since previous versions reportedly fail on Pentium 4 systems with more than 512MB RAM. But I didn’t try those. Continue reading →

Posted in OS/2, ThinkPad | 11 Comments

SC-8820 Gripes

Posted on April 3, 2015 by Michal Necasek

After a long while, I dusted off my Roland SC-8820 sound module which I bought used about 10 years ago. The goal was to drive it from an older PC via MIDI. This turned out to be a lot harder than expected, all because of a power supply.

The last time I used the SC-8820 was at least two moves ago and either I never had the matching power supply or I had lost it. But the SC-8820 can operate on USB power, so a missing power supply is not a problem, right? Wrong… Continue reading →

Posted in MIDI, Roland, Sound | 12 Comments

IBM XENIX: One Step Forward, One Step Back

Posted on March 29, 2015 by Michal Necasek

A while ago I wrote about why IBM PC XENIX 1.0 can’t work on any CPU other than a 286. But not content to leave well enough alone, I attempted to patch this version of XENIX so that it would run on a post-286 processor.

While doing that, I had to change my original assessment of the problem. IBM PC XENIX does not put garbage into the reserved word of a descriptor table entry, it actually stores data there! That makes the behavior much harder to excuse, and also much harder to fix.

After some quality time spent with a disassembler, greatly aided by the symbol table included in the xenix and xenix.fd kernel files, I established that XENIX stores the segment size in the reserved descriptor word (this is the size in the file which may differ from the segment limit). Unfortunately, all my attempts to patch the XENIX kernel failed and I could never get the installation floppy to boot.

Or so I thought. A few days ago, I more or less by accident booted the patched XENIX floppy, and lo and behold:

It actually worked! It turned out that in my previous attempts, I assigned 8MB RAM to the XENIX VM. That was a mistake, because IBM PC XENIX 1.0 crashes with more than 4MB RAM! Duh… such a common problem which in various incarnations plagues many, many old operating systems (for example OS/2 1.0 crashes with more than 8MB RAM). Continue reading →

Posted in 286, 386, IBM, VirtualBox, Xenix | 5 Comments

The DOS 4.0 Shell Mouse Mystery

Posted on March 21, 2015 by Michal Necasek

Several years ago, I noticed that in some virtual and physical environments, the DOS Shell in both IBM’s and Microsoft’s DOS 4.0x has a very odd glitch: the mouse pointer moves, but does not register any clicks… except on scroll bars, and even then only partially.

On and off, I tried to find the source of the problem. I suspected the keyboard controller (with PS/2 mice), keyboard BIOS, PS/2 mouse BIOS… but never found any bug. Not long ago I finally found the cause of the problem, and it was not at all what I had expected. Continue reading →

Posted in DOS, IBM, PC hardware, PC history | 28 Comments

Do You Know These Peripherals?

Posted on March 18, 2015 by Michal Necasek

After a long pause, here’s another guessing game. Do you recognize the five peripherals below? This should be very easy since the manufacturers’ names are clearly visible, only the model numbers got “lost”.

This is all 1980s-1990s hardware from (obviously) Roland and Yamaha. The oldest module was made in 1987 or so, the newest is 1999-ish.

At least three of these modules are explicitly supported by some/many DOS-based games from the late 1980s and early 1990s. The remaining two work more or less very well by virtue of backwards compatibility with one of the others.

Posted in MIDI, Roland, Sound, Yamaha | 10 Comments