Welcome to number 74 or about my 65th Computer Corner. One of these days I must research exactly how many of these columns I have done. It sure seems like for ever, but one loses track of time while having fun.
Their are a number of projects looking for feedback or assistance before completion. Building a PLC (Programmable Logic Controller) to use any parallel port to control industrial items is high on the list. We need some feedback about using the program INTERLNK to transfer files on non-standard PCDOS machines (see letter from Lee Hart in #73.) Need the latest status of CheapNet for ZDOS machines. The GIDE should be in use by next issue we hope. And some work on TCJ's CDROM is over due. The biggest help however will be getting some assistant editors to take over a part of the work load.
If you have been considering the idea, let me fill you in on some of the missing ideas not covered in the flyer that everyone should have gotten. For many issues we have been focusing on supporting three fronts or interrelated topics. We have always supported eight bit systems, strongly those running CP/M, but now almost any CPU type in use. Those eight bitters are now used extensively in small embedded and robotic systems, and so we spread our basic teaching skills into that area as well. After all I find the tools and needed skills are identical whether it is a CP/M program or opening and closing doors.
Since part of supporting older systems is helping out when the manufacturer forgets they ever produced the product, PC/XTs naturally dropped into our laps. You readers have always been using these systems, usually without any fun at work, and thus we hoped to bring the hobby back into dealing with those unfriendly machines. Since many of us like to tinker with operating systems just for fun (yes I know, we must be a bit brain dead to think of that as fun - but each person has their quirks), we have started playing with Linux and MINIX.
Having provided the above coverage for many issues now, but mostly in a anything-goes approach that prevented others from helping, minor changes were needed. These changes are really cosmetic and designed to make it possible for others to take on parts of the work load. As editor I will still grind out the issue and fill many pages. The difference will be having someone else provide the main focus material twice a year. That means the assistant editor has just under six months to seek out those articles, or complete that set of tests waiting to be done, and edit the results for me to include in the next issue.
Now don't get me wrong, I will have the editors ship me some of your letters to be put in reader to reader, as well as the item that just can't wait till the next focus issue. Most of our regulars have been rather busy and as you know occasionally miss an issue. This change just formalizes that happening and gives them more time to be really late than just sort of late. Overall it should still keep you well informed, educated, entertained, and wondering what will happen next.
Well I was looking for the centerfold material this issue and had trouble finding it for all the older systems and disks. I have been collecting and sorting disks for the pending TCJ CDROM and thus have piles of them all over the place. What got me thinking was how some of the items were sitting out there waiting for renewed interest, and all the history and stories that need telling, but by whom?
As I stated in the Antique article, we really have not seen much history recounted about the early days. When I gave David Jaffe his actual award at the last Forth meeting, he started talking about way back when. I could see by the glint in his eye that those times were indeed wonderful and exciting and needing to be retold. What about it David, a few stories? What about you other readers, where are those stories? I enjoyed the short comments made in Dr. S-100 by Doug Jones about his experience with those first Altair's stuck in the University. How about your stories?
I need articles on fixing and repairing these older systems as well. I get plenty of letters saying how they just started collecting and need help finding and fixing this or that system. The best call lately was from a person who had just opened the box they purchased their Kaypro in, for the first time. A real untouched Kaypro being brought to life after 12 years! What fun, but where did they put that boot disk?
At a recent SMUG meeting the topic surfaced about fixing connectors. The person said no erasers. Well now wait a minute, I have been doing that for too many years to think about, and now that's all wrong. Well...
Actually it has been an active topic for some time. The problem we are speaking about here are the gold plated edge connectors on S-100, STD bus cards, and any number of drive and system sockets. You can have a bit of flaky operation, where it works find for awhile, then stops, you tap it, it works again for awhile and so on. The usual problem is oxidation on the gold surface. This adds up to some resistance or occasionally complete loss of contact and conduction of electrons.
For many years everyone used a soft pencil eraser to burnish up the surface and renew operation. I did it many times at two in the morning so I could go back home to bed. The problem is, you are actually removing some of the gold, not just changing the chemical makeup of the surface. Gold wipes are probably the best for the newer boards. I say newer since I feel the gold surface is probably thinner than the older boards. Being thinner and maybe even different formulation will allow for the wipes to work fine.
Simply remove the boards one at a time and wipe the pins down well with the chemical saturated cloth. You should see a gray coloring in the cloth showing that it has worked. Now I have tried them on some of the very old S-100 boards with no effect. The oxidation is far too thick for these proper tools to work. So what do I do, get my eraser out and polish up, hopefully while no one is watching. Watch out for the eraser crumbs, if they fall into the fingers of the socket, they can be worse than the oxidation.
I must stress that you need also to look at the socket and attempt to clean them as well. Although I find the board edge the most likely problem, and cleaning it usually solves things, there is no reason that the socket should not be just as oxidized as the board. Also check for bent or damaged fingers, even a small piece of wire or solder that might short out the contacts. I don't know how many times I have seen other techs pull a card and never once look at the socket. I found a pin smashed against the opposite side and thus kept a PC from running.
The IBM PS2 machine is starting to appear on the used market. My advice for collectors is to stay far away from them, unless you know the technical details of them. The first problem is the need for set up disks. If any cards are removed, you must have the proper setup disk to get the system to boot. I was an un-official support person for them a few jobs back and had a full box of setup disks for each of the different systems possible.
Not only is the setup disk needed for the model number (such as 55SX) but there may be various board changes that will require a special disk ('planar' 55SX). I checked out the IBM support section on CompuServe and found many of the disks there. The sizes run from 500K to 750K in a image file. They require a special loader program available in the same directory that takes the file and formats a disk with the programs needed.
These disks have their own boot sectors and DOS, as well as files to check out the system and alter the CMOS control information. There is also an assortment of information files that go with each card you want to use. The setup program reads a serial number from the card's onboard ROM and then goes looking on the root directory for a file with that name. The file contains the addresses used by the card and how it can be changed.
The idea was to have a very simple setup system for non-literate users. The problem is that there are far too many options for the system to properly handle and thus a super user must often get in and hand edit the setup information to keep the conflicts from shutting down the machine. I also discovered that some cards had unlisted RAM or ROM portions that the setup would assign to other cards. All this equated to having a system that ended up being far from the simple concept IBM though they had designed.
I am sure there are plenty of books and manuals that will help you out, assuming you can get them when you buy one of the old machines. You will be surprised however to find that many of the units are slower than similar clone units. Besides the special boards, hard drives often had built in controllers making upgrading another problem. Oh, and don't try loading Linux or Unix as the PS2's are so non-standard you can't get them to work with anything other than a plain DOS.
Another topic surfaced at the SMUG meeting after my talk, it seems one of the engineers from Intel spoke about the 486/586 and how they worked on the various buses in use. Now since I wasn't actually there, this is pretty much second or third hand information, which I would like clarified in letters or articles if possible. The slant went something like this, the 486 is basically faster than 586 when dealing with I/O. The PCI bus is a better design, but slower than some other options. Missed cache hits are probably killing the 586, making the 486 with it's smaller cache faster. Intel knows this and is designing the 686 to solve some of the problems. The person telling us this, says the speaker had charts and graphs that clearly proved the points being made. The speaker's final words were that adding more memory, about 32 megs, basically solved all the problems.
I think the information is some what correct as I stated, however I know I missed some of what was said, and of course not being there myself, didn't see the real proof in the overheads. I did mention the topic to a fellow worker who does heavy graphics and he indicated it matched up with his experiences. His 486 graphic machine could do better in some cases than his newest 586 which he can't get to run if the cache is turned on. And yes 32 megs did make a BIG difference.
I have been reluctant, mostly due to cost, to get a 586 machine until now. Now, I add more questions about real speed and compatibility to the list of concerns, and now add buying 32 megs of RAM as well. Well that's it...Keep hacking. Bill.