A tablet for Windows
Music out the front only
Screen scramble
Up the grade
Duelling buses: PCI versus VL
A battery breathes its last
Parity problems
Are hardware disk caches worth it?
I noticed the question in The Help Screen (August issue, page 204) about the "Inside-out Mouse" and would like to offer further advice.
Questions such as that are very common from readers of our magazine [Multi-CAD Magazine], as may be expected considering our speciality. It is a very common misconception that tablets can be used for tracing images with any CAD program that claims to support tablets. However, most of the low-cost systems and most Windows-based CAD programs only support tablets as mouse emulations; that is, in "relative" mode. They really just make them a foolishly expensive mouse!
In order to trace, "absolute" mode is essential, and also some means of calibrating the movement to known co-ordinates. Really, this needs specific tablet-tracing calibration commands in the CAD program. The expensive systems have such features, but few low-cost ones and few Windows ones at any price do.
There is a tablet Interface for Windows which goes a long way to adding proper tablet capability to any Windows program, not only CAD programs. It can add tablet menus to any Windows graphics program, but it still cannot properly calibrate. Tracing can be done but the user needs to figure out some scale-changing process, separately for the X and Y axes, to correct the traced image size and proportions, in the absence of proper calibration facilities in the software. I believe the next version is likely to add some support for this. The program is called Virtual Tablet and comes from a firm in Seattle, Washington. A crippled trial version of Virtual Tablet is available for downloading from our Multi-CAD BBS in the Windows file area. The phone number is (07) 3878 2940.
Apart from Virtual Tablet, which sells for about $95 I think, there are WINTAB drivers available for commonly used or emulated tablet types. This is a special type of tablet driver that allows Windows programs that support them to auto-switch between mouse-mode and tablet-mode as needed. So the one tablet device can serve, without any manual switching, as the Windows system pointer and the CAD pointer. Otherwise, users often find the need to have a mouse as well as tablet on two ports, and get frustrated by continually grabbing hold of the wrong one! There are several WINTAB drivers on the Multi-CAD BBS.
About the only lowish-cost Windows CAD I have found that has proper tablet calibration and tracing facilities is Drafix 3.0 Professional, about $850 from Mara Plan Print in Parramatta, Sydney [phone (02) 683 6800]. Low-cost DOS CAD with full tablet support is provided by Generic CADD 6.0 at about the same cost.
- Geoff Harrod
Q I have a query regarding sound output from CDs. First, some background information.
I have an Osborne 486DX2-66 with a Creative Technology internal CD-ROM drive and SB 16-bit multimedia audio card (Panasonic interface). There is a volume control at the back of the computer unit, and at the front on the CD-ROM drive is a headphone jack with a volume control.
I am extremely hard of hearing and use binaural hearing aids. The hearing aids have a Telecoil switch that enables me to use induction plates which, placed near the hearing aids, plug into the headphone jack on any device such as TV, radio, etc, and give clearer input to the aids, while also eliminating all other noise.
Now for the query. Using the induction plates plugged into the phones socket on the CD-ROM drive is terrific for listening to music CDs. But when I use any computer CDs which have sound, such as Microsoft Bookshelf, there is no output from the phones jack even though the sound is normal from the speakers.
Is there a simple reason for this, and is it possible to get the sound from computer CDs through the phones socket? What is the difference between the sound on a music CD and a computer CD?
If there is some setting that I can change to correct the problem, could you be as explicit as possible as I am afraid I am no technical wizard, although I will attempt anything if the instructions are reasonably clear. Obviously, I can't expect any help from Osborne now!
- Jeff Wishart
A Many people get caught out by the headphone jacks on the front of CD-ROM drives. Sure enough they do work with some CDs, such as the music variety, but if you want to get sound out of your headphones from all applications, you should plug whatever hearing device you may need into the audio-out jack on the back of your sound card. The Help Line at Creative Labs says that most modern cards have four jacks (line-in, line-out, microphone-in and speaker-out), in which case you can plug into the line-out jack.
Some of the older cards only have the speaker-out jack on the back of the card; in this case you would unplug the speakers and plug in your head phones, or your Telecoil switch or induction plates, and you should be on your way.
I read with interest the letter sent in by Ben Skeates (page 198, July issue) regarding his problem with his screen image scrambling on odd occasions. I have experienced seemingly identical problems with my home computer (486DX-66, 8Mb of RAM, Viewsonic monitor, Cirrus Logic video driver).
I was advised by "knowledgeable workmates" that it was probably a driver problem, so I sent away for and installed the latest Cirrus Logic driver - with no improvement.
I have found a "rough and ready" solution that, although inelegant, works with a minimum of fuss and (get this!) no cost whatsoever. I simply run a DOS prompt in the background and, whenever the prob-lem occurs, <Alt>+<Tab> to the DOS prompt and <Alt>+<Tab> straight back to my work and, hey presto, everything is fine again!
I have been told that this solution works because switching to the DOS prompt changes to text mode, and the switch back to Windows resets the graphics mode. I cannot say for sure if the explanation is correct, but the solution is 100 times easier than re-booting every time.
All the usual warm fuzzies about the wonderful Help Screen section, which has taught me more about hardware and other mysteries than any other source I have used.
- Sue Burn
Q I recently purchased an SX2 OverDrive chip for my Osborne 486SX computer. As this computer is based on an Intel Classic motherboard and the labelling on the OverDrive advised that it was suitable for any 16 or 20MHz Intel system, I thought the upgrade would be an easy procedure. (The designation of this chip is SX20DP50.)
On installing the chip, I was first met with a blank screen, but on changing the jumper settings on jumper 19 to 1-3 and 4-6 (from 1-3 and 4-5) I was able to get the machine to boot up and run.
On running the diagnostic software that shipped with the OverDrive, the program advised me that it could not locate an OverDrive processor on my system. I then ran the System Summary and Benchmarks program in the System Information Program from Norton Desktop for Windows, which advised that my system had a DX2-50 processor with a performance rating of 108.2 (double that of the system without the OverDrive).
To try to find out whether the OverDrive was indeed operational, or if the jumper settings were correct or needed to be adjusted, I contacted the Osborne Help Line (Osborne did not supply any system manuals with my system) on three separate occasions. This provided three non-functional solutions, the last of which was that the Intel OverDrive SX2 Processor was not compatible with the Intel Classic motherboard with an existing SX25 processor. The final Osborne advice was that this motherboard would only accept a DX OverDrive.
I next contacted Intel direct after having no success with its faxback system (based on American computer brands), and again received no satisfactory assistance or offer of who in that company would be of assistance. As their final advice was to contact the retailer who sold the unit, the next call went to Harvey Norman's Fyshwick store.
Their advice was even less valuable, being to play with the jumper switches until the problem was resolved. If that didn't work, they said to contact them again.
I hope that you may be able to offer some solution to my current impasse, and advise me whether Norton Systems information is right in identifying the new chip, or is the Intel setup program correct?
If the latter is the case, what is needed to make the new processor fully functional? My system appears to be functioning normally, and the OverDrive processor is generating heat, indicating that it has current passing through it.
- Steve Nichols
A From the facts that the system appears to be working well and System Information returns twice the previous performance rating, I'd say your upgrade is a roaring success. You should also notice an improvement in the "feel" and speed of the system, such as when you scroll through a word processing document. It's a worry that the OverDrive diagnostic software failed to find the chip, so I've passed your letter on to Intel for advice, just in case.
The reason why you got little help out of them is that Intel doesn't sell or maintain PCs - the Intel motherboard business is strictly OEM and supported by the box makers. However, we may be able to find someone in the organisation who happens to know the board concerned. Best of all, the mighty Help Screen Fan Club is now in possession of your facts and I wouldn't be surprised if it includes owners of Osborne 486SX systems with manuals.
Here's a bit of advice that's a bit late for you, but might help others about to step into the same boat: let your PC dealer know that no manuals means no deal. And if you open the (delivered) box and find no manuals, demand your money back. A computer system without manuals can't be held to meet the legal definition of "merchantable quality", so you can insist on cancelling the deal.
Q What's the difference between a PCI and VESA local bus (VLB)? Which is better? And why do Pentiums always seem to have PCI buses?
- Ken Harrington
A Both VLB and PCI are 32-bit buses that run at a maximum speed of 33MHz (a few systems have 50MHz VL buses). VLB runs at the processor's I/O speed - the processor's interface speed with the motherboard - while the PCI bus is currently fixed at 33MHz, meaning it's not a true local bus. Thanks to additional logic and buffering, however, PCI boards generally run a bit faster than VLB devices.
The answer to your question about the link between Pentiums and PCI buses is pretty simple. Because the I/O speed of Pentium processors is generally 60MHz or higher, a VLB board (unlike a 33MHz PCI board) would have to run very fast - faster than most peripherals can handle.
No current 486 processor talks to its motherboard faster than 33MHz (the DX2s and DX4s run faster internally), and all VLB boards can operate comfortably at that speed. VLBs and boards are also slightly cheaper to manufacture, which complements the dirt-cheap prices of 486 PCs. Figure 1 shows which bus generally goes with which processor.
Interestingly, the new Pentium 75s have an I/O speed of 50MHz, which means manufacturers can use slightly less expensive secondary caches and motherboard components while still achieving speeds higher than that of a 66MHz Pentium. Once these systems are commodity items, no-one will have any reason to consider a 486, and the VLB will fade into history.
Q Recently, when I turned on my computer I received the message "CMOS time & date not set", after which it prompted me to either run my system setup utility or press <F1> to resume. I did the latter and the system booted normally. But the date read "01/01/80". Since then, the date and time have been wrong whenever I start up my system. What's going on?
- Troy Sica
A Inside your PC, a small battery maintains a tiny quantity of RAM called CMOS memory, which holds important information about your system when your PC is turned off. Sad to say, your battery is beginning to die. Sooner or later information about your drives and system memory may evaporate, and your system will refuse to boot until you run your setup utility and enter your hard disk's parameters from scratch. So run your system setup utility now and write down these parameters: the number of cylinders, the number of heads, the preformatted capacity, the number of sectors per track, and - on older drives - the landing zone and the starting cylinder for write precompensation.
Next, contact your system manufacturer or consult your PC's manual to find out which type of battery your system takes. You'll probably be able to find a replacement at a nearby computer or electronics store. With new battery in hand, turn off your machine, open it up, and follow the replacement instructions carefully.
Q My uncle replaced my 386 motherboard with a 486SX-25. Now whenever we run a program, we get a parity error message and the system freezes. We replaced all four 1Mb SIMMs, but it didn't help. What should we do?
- Matthew Daniels
A You might have to replace those SIMMs again, since you may have purchased the wrong type. Most 486SX-25 systems take 80-nanosecond (ns) SIMMs, while most 386 systems use 100ns or 120ns SIMMs. If you bought new SIMMs identical to those in the old 386, that would account for the problem: your memory is too slow to catch up with the current processor, and parity errors are the result.
If you have the right type of SIMMs, I suggest carefully removing them and taking a rubber eraser to their gold-edge connectors. Sometimes the contacts oxidise a little, and removing the oxidation with an eraser restores the proper contact between SIMM and socket. Make sure, of course, to leave no eraser shavings on the SIMMs.
It's also possible that you damaged a socket when reinstalling the SIMMs - easy to do in some systems. Replacing SIMM sockets is a difficult, expensive repair best performed by a qualified technician - and it's not worth it, considering the low price of 486 motherboards. If you broke only a plastic SIMM holder, you could try using a twist tie to hold the SIMM in contact.
Finally - and worst - your uncle may have a bad motherboard. Some poorly designed motherboards are extremely sensitive to heat, and if your old 386's casing has less ventilation than the casing in which the 486 motherboard used to live, the added heat could cause errors. The good news is that you can pick up a new 486SX motherboard (without the CPU) quite cheaply.
Q Here's an issue I've been wondering about: how much can a cache controller card enhance a PC's performance?
- Brian Moss
A A cache controller, a board that connects to your hard disk and has its own RAM for disk caching, can speed things up a lot - provided your PC isn't already running some form of disk caching software. The speed comparisons you see in advertisements for cache controllers generally make this assumption, which is unrealistic, since Microsoft's very capable SmartDrive is installed by default on nearly every PC.
In my experience, the performance difference between a hardware cache on a controller card and a software cache such as SmartDrive is small to non-existent. The boards cost money over the worth of the RAM installed, while SmartDrive is free.
Yes, software caches steal valuable RAM from main memory, but a well-built caching program like SmartDrive gives the RAM back to Windows applications when it's not in use. In my opinion, if you have a 16Mb system, a cache controller won't buy you much of anything for ordinary Windows applications - including multimedia.
Eric Knorr
Figure 1: Guide to CPUs and their buses. The VL bus speed is tied to the CPU's speed, while the PCI bus's 33MHz speed is independent of the processor's
CPU type Internal I/O speed Usual local bus processing MHz) type/speed (MHz) speed (MHz)
486DX2-50 50 25 VLB/25 486DX2-66 66 33 VLB/33 486DX4-75 75 25 VLB/25 486DX4-100 100 33 VLB/33 Pentium-60 60 60 PCI/33 Pentium-66 66 66 PCI/33 Pentium-75 75 50 PCI/33 Pentium-90 90 60 PCI/33 Pentium-100 100 66 PCI/33