Applefritter - Guide

Fixing the Epson 'Prints Blank Pages' Problem

Sat, 18 Mar 2006 21:08:02 -0800

Recently, after changing out the blank ink tank on my finacee's Epson CX5400 multifunction inkjet printer, the printer began printing nothing but blank pages. Even after doing multiple head cleanings and test prints, pages would emerge from the printer completely blank. After some research, a number of fellow CX5400 owners have reported having the same problems, to the extent that the term "design flaw" became a common theme. I've owned several Epson printers and have had, generally, good luck with them. I was always somewhat suspicious of Epson's philosophy of making the print heads a permanent part of the printer and having the only replaceable part be the ink tanks, but it produced good-looking prints so it didn't bother me. Now I know, unfortunately, that this system is both a blessing and a curse. Before we delve into how to fix your blank-page-printing problem, a quick explanation on how Epson's ink delivery system works (or, rather, how it appears Epson's ink delivery system works, because Epson isn't exactly willing to divulge its trade secrets) is in order. There are a few components to the delivery system. First, you have the ink tanks. Early Epson tanks were just that; plastic boxes with a sponge inside saturated with ink. Newer tanks have a small PCB with a flash chip on it, so the printer can tell if a tank is new or used, or if it's an Epson brand cartridge or a generic replacement. In either case, the basic functionality is that it's a holder for the ink. Next in the chain are the ink tubes and primer. I've heard conflicting reports on how Epson printers get the ink out of the tanks; some believe that the tanks are positively pressurized when first installed, so that ink shoots out of the tank when the printer needs it. Other reports say that the printer puts negative pressure on the cartridge to draw ink out of it. Once the printer has the ink out of the cartridge, there are two places it can go, to either the print heads or to the purge tube. The print heads are what makes the ink spray onto the paper; the purge tube is where the ink goes when the printer primes new cartridges and cleans dirty print heads. Many cases of the "prints blank pages" problem occur right after installing new ink tanks. People have literally removed empty tanks from printers that work perfectly, and installed new tanks to find that the printer delivers blank pages (this happened to me). Since it's highly unlikely that the print heads have become clogged during the 5 minutes it takes to swap out the cartridges, the problem has to be elsewhere in the ink delivery system. So here's what happens when you install a new ink tank: 1. The new tank is installed, the printer recognizes that it's a new tank, and begins the priming sequence. 2. The printer starts to prime the tank. Ink comes out of each tank and is directed to the purge tube. 3. The ink flows through the purge tube into the internal absorbent pad. 4. After a couple seconds, the printer stops the priming sequence and probably does a quick print head cleaning. Now, a few people have done some in-depth troubleshooting and found that the "prints blank pages" problem is actually caused by a clogged purge tube. While this may not immediately make sense (you may be thinking, "so what if the tube is clogged, the ink will just spill inside the printer elsewhere"), here's what my research suggests happens when the problem occurs: 1. The new tank is installed, the printer recognizes that it's a new tank, and begins the priming sequence. 2. The printer starts to prime the tank. Ink comes out of each tank and is directed to the purge tube. 3. The tube is blocked, so the ink has nowhere to go. 4. After a couple seconds, the printer stops the priming sequence. Epson's ink delivery system appears to be a sealed system, so when the ink has nowhere to go in step 3, little ink has actually escaped the new ink tanks. This means they're not primed correctly, and won't deliver ink as they need to when the printer goes to print. So unless the purge tube gets cleaned out, you can swap tanks and perform head cleanings until the cows come home and it won't do any good. Now that there's a basic understanding of what's going on, here's how to try to fix the problem. This guide is meant to be model-agnostic; I did this procedure to a Stylus CX5400 multifunction, but it should be similar for most Epson inkjets made in the past few years. It's unknown if new Epsons still have this problem, as it usually takes a year or more to surface. The first thing you need to do is prepare your work surface. You'll need a big table, preferably one you don't care too much about. If all you have is your good kitchen table, then it's a good idea to slice open a tall kitchen garbage bag to make one large sheet, and tape it to the table to protect it. Next, you'll need the following tools and supplies: You'll need: 1. Needlenose pliers 2. Philips screwdriver 3. 10mL syringe (preferably two) -- see note on this below 4. Superglue for when you break something (you probably will break something, like I did) 5. Paper towels, lots and lots of paper towels 6. Your sanity-maintaining drink of choice 7. Two plastic cups (one filled with water, the other empty, not pictured) 8. An assistant, if you have one (not pictured) 9. Several hours to spend wrestling with the printer and getting ink all over the place (and yourself) 10. The willingness to buy a new printer if you end up breaking yours attempting the repair, or if the repair doesn't fix the problem (this is a big one) Here's the note about the 10mL syringes: If you don't live with a chemist as I do, you can probably find 10mL syringes at a pharmacy or medical supply store. You need just the syringe itself; do not buy hypodermic syringes (the kind with the needle attached). You need to be able to attach the syringe to the tubing inside the printer. (I used a Becton Dickinson 301029 10mL Luer-Lock slip-tip non-sterile syringe, and found it to fit on the tubing well. The catheter-tip version may work better, though, as it ultimately has a narrower tip, which may allow it to be fitted to some of the smaller tubes.) So here's the step-by-step: 1. On your computer, tell the printer you're going to replace the ink tanks. This is to get the printer to move the tank/print head assembly out of its home position, and also allow you to remove the tanks. Once the printer has moved the assembly and is waiting for you to replace the tanks, unplug the printer. If you try to turn the printer off with the button first, it will move the assembly back, so what you need to do is simply pull the power cord. 2. Disconnect the printer from the computer, remove the paper from the printer, and put the printer on your work surface. 3. Take out the ink tanks and set them on some paper towels out of the way. 4. Most likely you'll need to remove at least the printer's top cover in order to access the purge tube. If your printer is a multifunction, you'll have to remove the scanner assembly first. On the CX5400, it was a matter of removing two screws on the back by the hinges, then removing a panel on the left side and disconnecting the data cables. The scanner assembly then just lifted off and away. Your mileage may vary depending on the model you have, but I suspect the process is similar amongst the multifunction. 5. Most newer Epsons have two-part casings: a beige upper part, and a dark grey lower part. Usually it's just a few screws to remove the upper part. There may be a couple cables that need to be disconnected (for the power light and buttons, etc.) so check for this before you completely lift away the top cover. 6. You should, at this point, be looking at the printer's guts attached to the bottom cover. The purge tube is going to be on the right side of the printer (the right side is typically the home position; it's possible some printers may be different). On my CX5400, there's a white plastic tray that slides left and right based on which tank the printer is priming. Here's a pic of what the tray looks like when slid all the way to the right: Notice the black hose coming from the bottom, and the clear hose that the black one connects to. This is the purge tube. From now on, things will be getting messy. 7. Look at the routing of the purge tube. It should come out of the ink tray, probably loop around some stuff and eventually empty into a waste ink storage area in the middle of the printer. If you can't see the entire path of the tube, you'll probably need to disassemble the printer further. Don't try to remove or disassemble any part of the printer's guts; just remove the guts from the bottom casing (this is done easily by removing a few screws). 8. Disconnect the tube at the ink tray and discharge end, and if the tube is segmented and easily removed from the printer, remove it. In the case of the CX5400, there are three parts to the purge tube -- there's a small black tube from the ink tray that connects to a longer, thicker clear tube, which then connects to a thinner clear tube mounted in the bottom casing of the printer. The thicker clear tube connects to the bottom tube via a hose clamp, illustrated below: I had to remove the printer's guts from the bottom tray. I was able to remove the small black tube from the ink tray to the thick clear tube, but the thick clear tube was not removable. 9. Draw 10mL of water into one of the syringes. The thinner tubes are probably going to be too small to fit to the end of the syringe, but if you're careful, you can press the end of the tube up against the nozzle of the syringe and get a decent seal. Work over a sink, and shoot water through the hose. A surprising amount of ink may come out. 10. Repeat with whatever other purge tube segments you can remove from the printer. Keep moving water through the tube until the water comes out the other end clear. 11. If you can't remove a segment of tube from the printer, then you'll need to clear the tube in place. Attach a filled syringe to one end of the tube, and hold a cup under the other end. Slowly apply pressure to the pluger of the syringe. If you get resistance, apply more pressure. Be careful, though, because if you apply too much pressure, either the clog in the tube will clear in a rapid fashion and spray ink everywhere, or the syringe will fly off the tube and spray ink everywhere (both of which happened to me). If this happens, do your best to clean up what you can. If you regularly wear socks around the house, take them off -- I inadvertently stepped in some spilled ink and ended up tracking ink all over my kitchen floor without realizing it. Thankfully, Pergo laminate flooring doesn't stain easily, and I was able to wipe up the spilled ink without a problem. 12. If you can get water to move through the tube, continue to move water through it until it runs through clear. If you can get some water to move through it but it takes a good amount of pressure to do it, try reversing which end of the tube you attach the syringe to. You could also try attaching two syringes, one at each end, and move water back and forth in a push-pull fashion until the clog clears. 13. Once you have the tube cleared out, reassemble the tube pieces, and put the printer back together. 14. I made a mistake when putting my CX5400 back together and broke off a couple internal clips. The clips hold a plastic lever in place that tells the printer if the cover is open or closed. This is where you'll need the superglue. Here are the clips I broke off: 15. Put the casing back together in reverse order of how you disassembled it. Then reinstall the ink tanks and plug the printer back in. If all goes well, the printer will pick up where it left off -- it'll think you've installed new tanks and will run through the priming sequence. If not, either use the printer's control panel or the software on your computer to start the tank swap process again. 16. If you get error messages when you turn the printer on, check to make sure that all internal cables got put back where they belong. If that doesn't help, it's probably time for a new printer. 17. If the printer finished the priming sequence without a problem, try printing a test page. If it comes out blank, try cleaning the heads once. If that doesn't help, it's probably time for a new printer. 18. If you get output after printing a test page, then your problem was at least in part due to a clogged purge tube. If the output is poor, try removing and reinstalling the tanks again, or clean the heads a couple times. The output quality may return to normal. If that doesn't help, it's probably time for a new printer. In my case, I got output after reassembling the printer, but it was poor. I cleaned the heads a few times and got the black, cyan and yellow working fine. But no matter what I did, the magenta barely printed any, even with a new tank. After wrestling with the printer and making an inky mess of my kitchen, I hurled it into the trash with disgust. The next day I bought a Canon Pixma MP450, which uses traditional cartridges (with the print heads built into the tank). Ultimately, this technique can work for some, but not all. I read reports of it working successfully for some users, but not helping at all for others. Considering that the only other options are to replace the printer or take it to a repair facility (which would probably cost more than a new printer anyway), you don't have much to lose by trying this. Good luck!

Intel Mac mini: Take Apart Guide (RAM & HD)

Wed, 01 Mar 2006 22:42:45 -0800

The Intel Mac mini's case is just like that on the PPC model and can be opened by prying upward with a sharp putty knife while working your way around the bottom of the case: Once you have the lid off, you'll be presented with a very tightly packed computer: Beneath and around the optical drive is a black plastic frame, with a screw in each corner: This frame, which holds the hard drive and the optical drive, needs to be removed if you are replacing the RAM or hard drive. Three of the screws are easy to access. The fourth is covered by the airport antenna. To remove the antenna, gently pry inward on the two black tabs that hold it in place and lift upward: Next, there's a small cable on the front of the mini that needs to be disconnected: With this cable unhooked, the black plastic frame is only connected at the back and can be gently lifted out as if it were on a hinge, revealing the motherboard: You now have direct access to the two DDR2 SDRAM slots: If you want to replace the hard drive, turn your attention to the black plastic frame that's now lying upside down beside you mini's case. The drive is in it, held in place with four screws. Two are on the bottom: And two are on the side: With the screws removed, the drive can be easily slid forward and removed: The hard drive is Serial-ATA: When you reinstall the plastic frame, ensure that the interconnect board is properly seated in its slot: It's also likely that the audio board's cable became loose, so ensure that it's correctly seated: Given what a pain it is to remove the cover, power the computer up and test everything out before you snap the case shut again.

Repairing the PowerBook 5300

Fri, 18 Nov 2005 07:22:35 -0800

With flaming batteries, chipping paint, and pathetic performance, the PowerBook 5300 is not a computer many remember fondly. Worst of all was the power connector was poorly designed, such that every time an AC adapter was plugged in, pressure was placed directly against the solder joints. In time, the joints failed, resulting in an unreliable connection that made it impossible to charge the battery or run off AC without forcefully holding the power connector at just the right angle to reestablish the connection. Despite its shortcomings — actually, [i]because[/i] of its shortcomings — old 5300's are very affordable. The two PCMCIA slots make it possible to add modems, 802.11b cards, and various other devices. The infrared port, lacking on modern Macs, makes it possible to communicate with devices that newer machines cannot. Any paint that's going to chip has long since done so, the exploding batteries have been replaced, and the system become stable (if not particularly speedy) when upgraded to Mac OS 8. The only serious problem that remains is the solder joints. A few weeks ago I picked up a $15 PowerBook 5300c that was advertised as having just this issue. To repair the problem, first remove the motherboard by following the directions in Apple's Service Source for the 5300. Once you have the motherboard out, wiggle the power connector. It should be loose. Using a soldering iron and some desoldering braid, remove as much solder from each joint of the connector as is easily possible (see figure below). [center] The desoldering braid should be placed directly on top of the joint and the iron tip on top of the braid. The iron should be at about 800°F. The solder will melt and be pulled up into the braid. If it doesn't you're probably using a cheap 15-watt soldering iron. A 40-watt iron is ideal. Once you have most of the solder out, heat the component and board with the iron directly and solder each pin back in. You should now have a firm joint without movement. Reassemble the machine. Note that this process only fixes the immediate problem — it doesn't eliminate the cause. If you use the machine heavily, the joints will break again, so be prepared to repeat this process in the future.

Building a Case for the Replica I

Tue, 22 Feb 2005 07:35:09 -0800

By Larry Nelson [center] As a person with multiple hobbies, I finally found a way to combine at least two of my part-time interests: namely, woodworking and the Replica-1 computer by Vince Briel. After buying the Replica, and adding the serial board, I made a box to put my Apple-1 Replica into. A few months later, Vince came through for the whole group of Replica enthusiasts with authentic ASCII keyboards. My old Replica case wouldn’t take the keyboard I bought from Vince, though, and I decided to build a case that would comfortably hold the new (old) keyboaof my system. Start out with a base of MDF (medium-density-fiberboard) cut to 18 1�?�4 inches by 14-3/8 inches. If 1�?�2 inch plywood is available, that could be used just as well. (The MDF was cheaper at the Home Depot.) Then make two sides from 15 X 5 1�?�2 X 3�?�4-inch pieces of walnut. These boards I cut on a band saw to the shape shown in the drawing. Lacking a band saw, one could cut the boards to shape with a handsaw, a scroll saw or a jigsaw. Carefully sand the rough-sawn edges smooth. Route a bull-nose on the two sides, using a 1�?�4-inch round-over bit. See the pictures for the placement of the round-overs. Don’t route the inside of the sides on the 1inch vertical front edge or the inside of the back edge. If you lack a router and round-over bit, use a wood rasp to round over the edges. [center] Now add a 1/2-inch rabbet to the bottom edge of each side piece. The rabbet is 3/8-inch wide (half the thickness of the side) and 1�?�2-inch deep for the base to fit into. Rabbet the back edge of the sides 3/8-inch by 1�?�4-inch to inset the back into the sides. Remember, the two sides are mirror images of each other. Be careful to correctly orient the two sides before rabbeting the edges, or you’ll wind up with two right or two left pieces. Don’t ask me why I bring this up, but my scrap-box seems to have a spare side in it. [center] The front edge is a piece of walnut wood 19 1�?�4 X 1 1�?�4 X 3�?�4. Shape it as shown in the drawing. Use a rasp to round over the outer edge of the front edge piece. The 15 o bevel on this piece will not properly shape with a round-over bit in a router. Notch the front edge piece on both ends as shown in the drawing. At the top of the back, add a piece of wood 18 1�?�2 X 2 X 3�?�4 to hold the hinges for the top. A 1�?�4-inch by 3/8-inch rabbet on the back side of this piece allows the back to fit flush. [center] The back of the case is a piece of 1�?�4-inch birch plywood, cut to size to fit into the rabbets. Before fastening the back in place, test fit the power supply and Replica circuit board in place. Mark the back to cut out access for the power cord, the PS fan, the monitor connection and the serial plug. Since placement of these holes may vary, I am not providing dimensions. After carefully marking the necessary holes in the back, drill and cut as necessary. There are three more pieces of wood needed to complete the case. Since I have a planer, I planed the wood for these three pieces to 1�?�2 inch thickness. If allowance for the difference in thickness is made, the top and front cross piece could be 3�?�4 inch thick. The key board however should not be thicker than 1�?�2-inch since the keys of the ASCII keyboard do not extend through 3�?�4-inch boards far enough. An alternate key board could be 1�?�2 thick plywood. [center] The top is 17 1�?�2 inches by 7 inches. The key board is 17 1�?�2 by 7 1/2 inches. These two pieces are maple in the original and are made by edge-gluing oversize boards together until you have sufficient width, then cutting the pieces to the correct width and length on the table saw. The vertical cross piece between the top and the keyboard is also 17 1�?�2 inches long. I started with a width for this board of 3 inches, but trimmed it to 2 1�?�4-inches after experimenting with the fit. The angles involved make calculations hard to do. Into this board you will mount the power (on-off) switch, the RESET switch, and an LED for power indication. [center] You will have to drill three holes centered in the board for these switches and light. First mark the location of the three holes, drill 3�?�4 inch holes to within 3/16-inch of the front face, then switch to the finish bit size to complete the holes. This will allow the locknuts to be recessed into the vertical cross piece. Drill a 1/4 inch hole, 1/2 inch deep in the center of each end of the top back piece. Drill matching 1/4 holes, 3/8 inch deep in the sides. We will use two pieces of 1/4 dowel, 7/8 inch long, to hold the top back piece in place. Dry assemble the base, the two sides, the front edge and the top back piece to check for proper fit. Then glue the five pieces, clamping the assembly and checking for square in vertical and horizontal directions. Set the assembly aside. Round the top of the front edge of the top piece using your 1�?�4 inch round-over bit or wood rasp. [center] Cut two triangle pieces of 1�?�2inch scrap wood or plywood into triangles with a 15 o angle. Glue and clamp them onto the inside of the two sides of the assembly. These triangles go to the front of the cabinet and support the key board. The key board is not fastened to the case itself but just rests on the triangles. I found that the best way to cut the key board inlet was to make a cardboard template, test-fitting it over the ASCII keyboard until satisfied with the fit. Center the cardboard template on your case key board, draw the outline, and carefully cut out the pattern with a scroll saw or jigsaw. Smooth the cut edges with a rasp and sandpaper, test-fitting the key board onto the ASCII keyboard until it fits with enough clearance to allow all the keys to move freely. When satisfied with the fit, set the key board aside. Don’t attach the ASCII keyboard until after you have applied your finish. [center] The vertical cross board attaches to the top piece with 4 - #6 X 1-inch screws, glue and the support piece cut as shown in the drawing. If you have cut it to the proper width, the vertical cross board will contact the key board with its bottom edge and hold the key board in place. Now add hinges to the underside of the top piece to attach it to the top back piece. I inset the hinges, using a chisel to cut the inlets, but this is not necessary. With all the pieces finally done, you are ready for sanding and finishing. Sand away all scratches and rough edges with 80 grit sandpaper. Then progress through 120, 180, 240, 320 and 400 grit sandpaper until the surfaces are as smooth as possible. Clean off all dust and fingerprints with mineral spirits. Allow the surface to thoroughly dry, and then rub on two or more coats of Danish Oil or other finishing oil. Allow the oil finish to dry for 24 hours. Assemble the ASCII keyboard by screwing it onto the back of the finished key board. Mount the switches, LED, power supply and circuit board as previously explained. Connect all the wiring. This is not a wiring manual. If you have questions about wiring the Replica, refer to the instruction manual. Contact Vince Briel if necessary. Add four feet to the bottom of the case. I used stick-on felt pads available at the local hardware store. Fasten the back to the case with small screws. Plug it in. Load Microchess. Have Fun. [b]Materials:[/b] [list][*]Back: 18 1�?�4 X 4 1�?�2 -- 1�?�4-inch Birch Plywood [*]Base: 14 3/8 X 18 1�?�4 -- 1�?�2-inch MDF or 1�?�2-inch plywood [*]Front: 18 1�?�4 X 1 -- 3�?�4-inch Walnut [*]Sides: (2) 15 X 5 1�?�2 -- 3�?�4-inch Walnut [*]Key Board: 17 1�?�2 X 7 1�?�2 -- 1�?�2-inch Maple [*]Top: 17 1�?�2 X 7 – 1�?�2-inch Maple [*]Vertical Cross: 17 1�?�2 X 3 – 1�?�2-inch Walnut [*]Back Top: 17 1�?�2 X 2 – 3�?�4-inch Walnut [*]Triangles: (2) 6 1�?�2 X 2 – 1�?�2-inch MDF or 1�?�2-inch plywood [*]Hinges: 1pr. 2-inch X 1 3/16-inch, Brass[/list] [b]Miscellaneous Materials:[/b] [list][*]1�?�2-inch X 4 wood screws (6) [*]1-inch X 6 wood screws (4) [*]Wood Glue [*]Sandpaper in 80, 120, 180, 240, 320 and 400 grits [*]Danish Oil Finish [*]Felt feet for case (Set of 4)[/list]

A quick Mac battery replacement

Sun, 13 Jun 2004 13:53:48 -0700

I attempted to power up my RackMac TZ today after not using it for several months. The system was dead - nothing. Disappointed, I removed the battery for inspection: [image:3230] 1.52v was definitely low for this 4.5v battery, and certainly low enough to prevent the computer from booting up. Nonetheless, I still wondered about the potential for other problems and was loathe to order an expensive replacement battery that would take days to get here. There was only one thing to do... [image:3236] [image:3231] 4.5v is three AA batteries, so I dug this battery holder out of the trash (it was part of a cheap light) and broke the frame down to size. [image:3237] Next, I soldered the dead battery's cable to the holder's sockets. Red goes to positive. This case holds four batteries, so I bridged the last battery slot with a wire. I took the velcro off the old battery and glued it to the back of my new holder. [image:3238] Next I installed batteries and checked the voltage. It was 4.73v, so I hooked the unit up to the RackMac. Everything works perfectly. The official battery for these units is supposed to last several years. I have no idea how these AA's will do long-term, but I'll report back when they die.

How to Use IRC

Sun, 16 May 2004 18:25:28 -0700

[h1]Downloading a client[/h1] To join Applefritter IRC, first download a client. A few Mac OS X clients to choose from are: [url=http://colloquy.info/]Colloquy[/url] [url=http://www.ircle.com/]Ircle[/url] [url=http://www.snak.com/]Snak[/url] [url=http://xchataqua.sourceforge.net/]X-Chat Aqua[/url] IRC software for other platforms: Mac OS Classic: [url=http://www.shadowirc.com/]ShadowIRC[/url] Newton: [url=http://www.tactile.com/chatBuddy.html]ChatBuddy[/url] Apple IIgs: [url=http://www.ninjaforce.com/]Samurai IRC[/url] BeOS PPC: [url=http://classic.tucows.com/beos/preview/4460.html]Birch[/url] BeOS Intel: [url=http://classic.tucows.com/beos/preview/4462.html]Felix[/url] Linux: [url=http://www.xchat.org/]xchat[/url] Amiga: [url=http://www.vapor.com/amirc/]AmIRC[/url] Atari ST: [url=http://www.bright.net/~gfabasic/html/atarirc.htm]AtarIRC[/url] PalmOS: [url=http://epix.pda.tucows.com/palm/preview/34464.html]PalmIRC[/url] EPOC: [url=http://epix.pda.tucows.com/epoc/preview/11483.html]nICQ[/url] OS/2: [url=http://www.os2ss.com/select/internet/chat/ezirc.html]EZ IRC[/url] Windows: [url=http://www.mirc.com/]mIRC[/url] [h1]Connecting to Rizon[/h1] Now that you've installed your IRC client, you need to connect to a Rizon IRC server. A complete list of servers is available here. A web interface is also available. The recommended server is irc.rizon.net, port 7000. Enter this information into your irc client, along with your desired nickname. Connect. Once the client has connected, type "/join #applefritter" in the input box to enter the channel. For more information, see the [url=http://www.irchelp.org/]Internet Relay Chat Help Archive[/url].

Expanding Your Mac - A Rundown of Macintosh Slots

Sat, 29 May 2004 12:50:43 -0700

[i]Computers were designed as general purpose machines with the ability to do anything in the digital world that one can imagine. The standard configuration of a machine may not suit the mind of a creator or artist, so they'll add something to it. Their are many different types of boards available and they can fit into different types of slots. The type of slot dictates how many things work inside of a machine. The most common features are integrated onto a computer's motherboard but they are addressed virtually as if the functionality were an expansion card.[/i] [b]ISA - Industry Standard Architecture[/b] The ancient Intel design for expansion cards. Developed in the 1980's by computer giant IBM, it quickly became the standard in PC's. The 8 bit ISA bus is limited to 8 MB/sec bandwidth with the 16 variant offering twice that. The bus design works in tandem with the old IDE devices, floppy, PS/2, serial and parallel ports often found on PC's. That pretty much covers all the legacy ports the PC industry. The ISA standard has evolved a bit over time but not at the same pace as the various components an a motherboard. As processors continued to become faster and data traffic between devices exploded Intel created another standard - PCI. Why is the ISA important to Macintosh users since Apple never made a machine with an ISA slot? While a Mac never shipped with an ISA slot on the motherboard, the ISA bus have been used for communication between devices on the motherboard. PC Cards (aka PCMIA Type I and Type II) were designed around 16 bit ISA bus protocols. [b]NuBus[/b] Originally designed by MIT and then trade marked by Texas Instruments, the Nubus design was chosen by Apple for expanding the Mac II line. At its heart, Nubus is a 32 bit slot running at 10 Mhz for 40 MB/sec of bandwidth. For its time, it was a relatively fast bus. Since Apple was the only major company to adopt the standard, pretty much every Nubus card was proprietary to the Mac. With the Mac in a niche market meant Nubus cards carried a price premium. To keep Nubus competitive, Apple increased the clock speed of Nubus to 20 Mhz, but that wasn't enough. As Nubus showed its age, Apple wisely adopted the faster, more industry standard, and cheaper architecture of PCI. [b]PCI - Peripheral Communication Interconnect[/b] Intel, using its juggernaut control over the industry, guided to a new bus design called PCI to market. Intel made it industry standard and was adopted as such quickly. Apple wisely decided to follow the industry's decision. Being 32 bits wide and running at 33 Mhz provided 132 MB/sec of bandwidth. Just like ISA, the bus design was used for interfacing various motherboard components - IDE, SCSI, USB, on board video for example. Even the ancient ISA bus was to become a component along the PCI bus on motherboards. PCI has evolved over time to keep up with the demand of high speed peripherals. Their are two easy ways to gain bandwidth, one by increasing the clock speed and another by increasing the bus width and the industry went both ways to increase speed. 64 bit PCI slots are backwards compatible with 32 bit cards and run at the same voltage. For 66 Mhz slots, the voltage had to be dropped from 5 volts to 3.3 volt and has a slightly different slot key. Cards can be made to run at either 33 Mhz or 66 Mhz, allowing card makers to take advantage of the extra speed with compatibility in mind. For the ultra high end motherboards, manufacturers can use 64 bit and 66 Mhz techniques for 533 MB/sec of bandwidth. The B&W G3 is the only Apple machine to have a 66 Mhz PCI slot. The B&W G3 and all G4's to date have 64 bit PCI slots. The new Xserve is uber cool with its 64 bit/66 Mhz PCI slots. [b]AGP - Accelerated Graphics Port[/b] The industry was content with PCI except for one segment - the video card market. The high demands of video received its own dedicated bus - AGP. Video cards quickly migrated over to the new bus given its dedicated, high bandwidth design. Even PCI cards are happy since they didn't have to compete with a video card for shared bandwidth. Another advantage of the AGP bus is direct access to main memory for storage of information. It can buffer information to system memory that a card cannot store on its own dedicated memory. In fact, an AGP video card does not have to have any memory of its own as it can use system memory for everything. Bandwidth on the AGP bus can be multiplied from its base 264 MB/sec of bandwidth. For example AGP 4X has just over 1 GB/sec bandwidth. [b]PDS - Processor Direct Slot[/b] This slot is generally unique in design to a machine (SE or LC) or generation of machines (Quarda, 1st gen PowerMac). The design philosophy is similar in nature to AGP as it provides a relatively fast dedicated bus to the processor/memory. However, a PDS is not limited to graphics functions as SCSI, Ethernet and other devices. The physical connector for a PDS card is just as varied as what can go into them. PDS cards are often unique and expensive due to the small market and proprietary design associated to the PDS slot.