Copyright 1984 by ABComputing ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» º Memory - More for Less º º º º by º º º º Ken Holcombe º ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ EDITOR'S NOTE: When I first read this article I was so impressed with its humor and homespun flavor that I opted not to edit it. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Old Motherboards ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ For those of you who purchased your IBM-PC long ago and can only expand to 64K of RAM on the motherboard, did you really think you would be satisfied with that? Are you? With PC/MS DOS getting increasingly sophisticated and larger, and with the abundance of RAM DISK, print spooling and partitioning programs, 64K on a PC can really make you feel left out. There are hundreds of thousands of IBM PCs with the "old" motherboard that uses 16K bit chips for RAM memory. The newer PCs use the 64K chips. Though the PC uses a 16 bit microprocessor, fortunately for us thrifty folks it has an 8 bit bus; therefore each bank of memory has a chip for each bit (8) and a chip for parity for a total of 9 chips per bank. (A sixteen bit bus requires 16 chips plus one for parity for each bank, therefore almost twice as expensive! Come on, you purists; the 8088 isn't that much slower than the 8086 - the 8087 takes out most of the real sluggishness, number crunching). With 9 chips per bank and 4 banks on the motherboard, the old PC's come to the grand total of 64K without using a memory expansion card. A fully populated "new" motherboard has 256K. I built a memory expansion card by buying a TK Engineering bareboard that added 256K more for a total of 320K. (With a bareboard, you buy the parts and install them yourself.) As most of you have discovered, memory is like money; the more you have, the more ways you find to use more. Besides, I just love it when people with TRS-80s and Apples ask me how much RAM I have. I started considering the options for going beyond 320K, keeping in mind that I eventually want to wind up with at least 640K, the DOS BIOS "ceiling." ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Heartburn ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ However I did it, it had to be cheap; that's just a basic part of my personality (and my budget, which some say has a lot to do with determining your personality). The AST megaplus card was almost within reach, but I don't like the idea of piggybacking RAM banks; I would still wind up with only 576K and I worried about the heat build-up with 4 banks of RAM sitting directly on top of another 4 banks of heat producing RAM. Use another slot to get the last 64K, you say? Forget the last 64K, you say and be content with 576K? Well, there is a board on the market now that allows you to install 576K on it for a total of 640K without piggybacking and using only one slot, but it doesn't have all the other functions that the Megaplus does. Any way you cut it, I'm being penalized for buying an early PC. It really burns me up that my reward for being one of the first to recognize the advantages of an IBM was being stuck with those rinky-dink 4116 16K chips on the motherboard. Oh yea, they're cheap - I can get 'em for $1 apiece but they use almost the same amount of power as the 64K chips with 1/4 the density. I want to save that power supply for bigger and better things. (Worst of all, the 4116 is the same RAM chip that the TRS-80 and other 8-biters use. I do have some pride, you know. Incidentally, there are those who say that the 8088 is really an 8-bit microprocessor. I don't care what they call it, it can directly address a megabyte. Try that on your 6502 or Z-80; you'll be selecting banks more than you'll be computing.) The more I thought about it, the more I knew that I would have to get rid of those 4116s and get some 4164s - somehow, someway cheap. The 64K chips themselves aren't expensive- about $5 apiece from the right places - but one can't just take out the 4116 and install the 4164: the 4116 requires +12,-12, and +5 volts. The 4164 needs only +5 and some of the pin connections are different from the 4116. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Bareboards at Bare-bottom Prices ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ There are several companies making bareboards for the motherboard that use the 64K chips. The cheapest is from Netronics at $89.95 with $140 more for a complete kit. Super Computer has either a PC or an XT bareboard for $95. Both of these companies have many other bareboards, kits, and assembled units for the PC covering all functions and combinations, e.g., 4 drive disk controllers with parallel printer port, clock/calendar,and hard disk SASI interface, etc. Display Telecommunications Corporation has a bareboard/motherboard that can accept the 64K chip or the 256K chip for $99.95. Others are more expensive, like the Colorado Computer Peripherals bare motherboard (sounds kind of kinky to me) for $175. The most expensive is the bare motherboard from Micromint, Inc., at $300, although it does have more functions built on the board. You pay a mint (some pun intended) since these are designed by Mr. Hardware himself, Steve Ciarcia of Byte fame. Micromint offers the motherboard completely assembled, as does Edge Micro Systems. I decided against all of these because the assembled ones cost more than I wanted to spend and the bareboards would take too long to finish. I didn't want my computer out of commission for more than a couple of hours. Another viable option was a kit from Add-MEM that sells for $69.95. Ah, the price was right and I was able to talk my wife into giving it to me for Xmas. Well, it's in and it works. The three banks on the motherboard that are socketed are emptied of the 16K chips; the chips in bank 0 are soldered in by IBM and are left in though electrically disconnected. Assembling the Add-MEM kit consists of soldering 29 tiny pins, one resistor, 35 bypass capacitors (they leave one off because of space constraints ) and 36 sockets to a small printed circuit board. With sixteen pins on each socket, that's a lot of soldering and it might be worth it to pay $30 more for an assembled board if soldering isn't therapeutic for you. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ 512K is Nice as Rice ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ I prefer the kit because I like to solder in the chips directly and not use the sockets. I know that makes them harder to replace, but I think that most RAM chip malfunctions are actually bad socket connections. Sure it works when you put in a new chip; in essence you fixed the bad connection. In any event, you wind up with a small PC board that plugs into the banks 1,2, and 3 sockets with these 29 little pins sticking out on the bottom of the Add-MEM PC board. (PC stood for printed circuit long before it meant personal computer; you know, back in those old days when we thought it was really amazing that PC boards had foil on both sides.) You cut through the foil in a few places on the motherboard, solder a few wires from the Add-MEM board to the motherboard, and voila- 256K without using any slots. I put back my TK board, set the dip switches, and decided that 512K is nice as rice. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Doing the Dirty Work ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ It takes a certain personality type to purchase this kit. I have some friends who think that the motherboard was built in the Holy of Holies, and the thought of taking a knife and cutting though some foil on the motherboard is like a thousand fingernails on a chalkboard to them. To them I recommend Sorbus Service: they will install a 256K motherboard for $208 in Phoenix. That is labor included; they don't sell parts. The price may not be that low at the Sorbus service center nearest you. The Sorbus center in San Antonio first quoted me a price of $354 and then decided that they didn't want to do it at all. Oh well, I am very happy with my Add MEM modification. I have my sights set on 640K now. Netronics has a bareboard with 256K memory and serial port for $39.95 Let's see; that would take me to 640K and even beyond. Maybe I'll wait to see how cheap the 256K chips get - the cheapest I can locate now are $42 bucks apiece; they need to be about half that before I'm interested. But just imagine that Mega-board from Display Telecommunications with only 4 banks on the motherboard and one megabyte staring you in the face. Isn't it fun to dream? Incidentally, Add-MEM has as much as promised a modification to use the 256K chips that should be inexpensive. The 256K chip has one additional address pin connection that the 64K chip doesn't; other than that, they are identical. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Objectivity ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ Do I have anything bad to say about Add-MEM to prove that I'm really being objective? Well, Add-MEM says you can eliminate the lengthly power-on diagnostics if you set the DIP switches on the motherboard to 0K of RAM. That didn't work for me at all. Also, they say that if you use the sockets on the little PC board, you can use only two low-slung boards. (Compare the disk controller board and the color graphics board - the color graphics is low-slung as well as being longer. Low-slung boards provide a little more room to install parts.) They say if you leave the sockets off and solder the RAM chips in directly, all five slots can use low-slung cards. I say baloney; if you use the sockets or not, you can only squeeze in two low slungs. And if you do use the sockets, even the regular boards are going to be a tight fit, like resting right on the socketed chips. I just installed a Quadcolor I board and now I'm wondering if there is going to be room for the Quadcolor II board to piggyback on it. Oh well, I can always get one of those bareboard motherboards. I need something to do on these cold winter nights. Or maybe I can remove the soldered-in 16K chips left on the motherboard and the sockets under the Add-MEM board and solder in the Add-MEM board directly to lower it a little. The Add-MEM board is going to take some whittling for clearance to do that. But that would solve the only other problem I had with the Add-MEM modification. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Trouble at OK Corral ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ While pressing down on the Add-MEM board to seat the 29 pins in the sockets on the motherboard, I unknowingly cracked a socket. IBM uses double side-wipe DIP sockets for the RAM and a cracked socket means that the pins don't get wiped too well. Well, a few days later my computer became very sensitive; I mean like going bananas if you tapped it with your finger. I finally located the problem to the cracked socket and ran a jumper to fix it (my answer for most of life's problems). I was so happy when my PC started purring again and could take smacks on the side undaunted; I was sweating jalapenos there for awhile. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ All or Nothing ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ This brings up a good point: don't take any more of a gamble then you are willing to suffer the consequences for. Nearly all of these boards are multi-layer; if something becomes disconnected in one of the middle layers of a board because you didn't think a 25-watt soldering iron would be too hot, it can depress one for quite a while. On the other hand, do you know that nearly all repairs on PCs are done on the FRU (field replaceable unit) level ? That means if a chip is bad on the motherboard, they replace the motherboard, or at least IBM and Sorbus do. If the disk controller board malfunctions, it is replaced. It's a concept the TV manufacturers have been using for years. There's less for the technician to diagnose, but the customer pays more because he/she is buying a module. Of course, labor should be less. That's one of the reasons I do my own repairs. If I can't fix my color/graphics board, I just buy a Quadcolor; what have I got to lose? And I can keep my old board and sell it to somebody who thinks they know more than I do about fixing it. There's always somebody like that around in life. If IBM fixes your computer, they take your old board in exchange and send it to IBM heaven where angels who know everything fix it and then they sell it to someone else some day and charge him labor too. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Static Electricity ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ Care must be exercised when installing RAM chips with regard to static electricity. My favorite technique used to be sitting naked in the bathtub with the parts on a TV tray in my lap. Used to be, I say, until the vent pipe to the roof was struck by lightning. What hair I have is permanently "fro-ed." Now I just make sure I'm on a floor like wood or linoleum and discharge myself to a metallic ground before I start. It might be good to remove nylon socks and work on a cookie sheet. Someone once said that bravery is knowing all the possible consequences and being willing to accept them. Well, how much memory have you got now? What are you going to do about it? You need some kind of a comeback when those Commodore people say, "Oh yeah, you got that brand with the weird keyboard, don't cha?" Add-MEM is now marketing their products through user groups. In case your user group isn't hip to this, I'll list Add-MEM's address along with the other references. ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Conclusion ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ To wrap up a few loose ends, I know that not everyone agrees with my theory about eliminating sockets. I know a guy who is installing sockets for all the chips on his motherboard, those that IBM soldered in. Yes, I know that the best way to unsolder a chip is to cut all the pins first. No, I don't know for a fact that all the bare motherboards I mentioned are 100% IBM PC compatible, but I do know that the biggest incompatibility with "compatibles" is the ROM and you can always use your old IBM ROM chip. Yes, I know there are at least three versions of the IBM ROM including the XT's and that the old one diagnoses the first 256K of RAM no matter how much you have. Yes, I know that altering the motherboard as is done with the Add-MEM modification voids the warranty, but if it's been less than 90 days since you purchased your PC, I really hope you don't have the old motherboard anyway. And if you're the kind of guy or gal who has a service contract, you're probably kicking yourself for wasting your time reading this whole thing anyway. And finally, note the thought that IBM might change out your old motherboard for a new one just because you're like me and want nothing but 64K or larger chips. You sure ask a lot of questions! ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ Addresses and phone numbers of companies mentioned in this article ³ ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´ ³ Add-MEM ³ Colorado Computer Peripherals ³ ³ 22151 Redwood Road ³ R.R. 6, Box 7-D ³ ³ Castro Valley, CA 94546 ³ Golden, CO 80403 ³ ³ (415) 886-5443 ³ (303) 278-7172 ³ ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´ ³ Display Telecommunications Corp. ³ Edge Micro Systems, Inc. ³ ³ 4100 Spring Valley Road ³ 2350 Walsh Avenue ³ ³ Suite 400 ³ Santa Clara, CA 95051 ³ ³ Dallas, TX 75234 ³ (408) 980-9866 ³ ³ (214) 991-1644 ³ ³ ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´ ³ Micromint Inc. ³ Netronics R&D, Ltd. ³ ³ 561 Willow Avenue ³ 333 Litchfield Road ³ ³ Cedarhurst, NY 11516 ³ New Milford, CT 06776 ³ ³ Order: 1-800-645-3479 ³ 1-800-243-7428 ³ ³ Info: (516) 374-6793 ³ In CT use (203) 354-9375 ³ ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´ ³ Sorbus Service Center ³ Super Computer, Inc. ³ ³ Phoenix, AZ ³ 1710 E. Newport Circle, Suite P ³ ³ (602) 997-1064 ³ Santa Ana, CA 92705 ³ ³ Manager: Leonard Goodman ³ (714) 540-1880 ³ ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´ ³ TK Engineering ³ ³ ³ P.O. Box 1936 ³ ³ ³ Corona, CA 91720 ³ ³ ³ (714) 736-0572 ³ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ File Name: ÛÛ memory.txt ÛÛ ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ D SAVE IN ATTRIBUTE ADD AL,FOREGROUND MOV ATTRIBUTE,AL ;--SET THE