When a bad sector error is not a drive problem

When I was working on my book for NRI Schools I was having a lot of bad sector errors and cross linked sector errors on my computer.  Stuff like that.  Every day.

I even continued to get these after I upgraded my hard drive so I began to smell a rat.  My 32MB of RAM tested good so it wasn't that.  If the processor cache RAM was bad this should also cause the main RAM test to fail, unless the algorithm for the memory test is too naive.  I decided to replace the cache RAM chips on my motherboard anyways.  I think this was 128K of chips in eight sockets on my motherboard.  I don't remember how much this was, but I don't think it was very expensive.

I'm sure I got the RAM chips from Metrowest Computers in Framingham, Massachusetts because that's where I bought the computer from.  I tore the machine down.  I was very careful not to static out anything.  Inserting those little DIP chips with their little legs requires some care or they get bent!

Got it all back together and crossed my fingers as I booted it up successfully.  :-)

I never got another sector error.  Mission accomplished.

I do own a leather jacket!

Sometimes when a computer breaks the cure can be surprising. We purchased a very expensive software solution for one our engineering tasks. It came with an HP Unix workstation. I never really used this machine. It was a single task appliance and I'm not even sure precisely what it was for. One day however it refused to boot, and I guess we must have stopped paying for support because they called me over to have a look.

Turning the machine on yielded the usual power supply fan noise and nothing else. None of the expected hard drive spinning or seeking was heard. This could be a bad power supply, or it could be a failed hard drive controller, or it could be... sticktion! That is pronounced stick-shun. Yes, really. Look it up. This happens on some hard drives when the hard drive sits powered down for hours or days, and the mirror smooth surface of the hard disk platters get stuck to the magnetic heads which have come to rest on the surface. The coating is just soft enough to stick.

The only way to find out if the problem is sticktion is to open the machine and bang on the hard drive casing to see if the heads can be freed. An ideal tool for this is the plastic handle of a screwdriver.

We opened the computer and I rapped on the hard drive a few times with the butt end of a screwdriver. We turned on the computer and waited... success! I felt just like the Fonz! :-)

All Night Long

About this time I got a phone call from the video rental store in Somerville which was using the software that I wrote when working for Patrick Alessi. They were having a problem with their hard drive. They were using an IBM PC/XT with a 10MB hard drive. They were backing up their hard drive onto about 30 floppy disks but for some reason their restore wasn't working correctly. They asked if I could help.

I drove to Somerville and took their computer home with me. I used a disk editor application to examine the disk. I needed to look at each sector on the disk and manually reconstruct their database. I was up all night long working on this. Thankfully I did manage to make their system work again. I took their computer back to the store and gave them the bill. $115. I was surprised to see the owner thought this was too much, but I thought it was actually a good deal given the heroic effort I put in. I didn't lower my price.

I was really, really tired and when I got home there was a church meeting going in our living room, so I sat down. My eyelids were very heavy, and I could barely stay awake. When the meeting was over I'll never forget that Joe Silipo, the one doing most of the speaking, came up to me. I thought he was going to scold me but he just smiled and said, "Brother, get some sleep."

CNC Machine Simulator

The two Osborne 1 computers we were using in engineering were getting a bit worn, so Bob sprung for some Kaypro computers. I don't think they appeared all at once but soon enough we had two Kaypro II machines and one Kaypro 10. The Kaypro II's were similar to the Osbornes but with bigger screens. Now we had 80 columns of bright green text. The Kaypro 10 also had a built in 10MB hard drive.

One really important difference with these new machines is that they had block graphics characters, and you could plot lines and points. This wasn't high resolution but it was good enough to inspire me to write a simple interpreter for the CNC programming language. Remember how I tried to write a programmable calculator program for my VIC-20 but never finished it? This interpreter was the realization of ideas that I'd been kicking around for a while. I wrote this as an extension of the machining text editor in MBASIC.

Now we could run a rough simulation of how a routing or drilling program would work and see the result on the screen. There was no fine detail, but it was easy to see if we accidentally drilled outside the board, or if a panel would be ruined by an accidentally placed cut. This certainly saved time and money because we were able now to make fewer first pieces so the single head Excellon machine and it's operator were more efficient.

Enter IBM

After I had worked on a couple of projects on the Apple II+, Mr. Alessi decided it was time to develop software for the IBM PC. I think he bought his at the Sears Business Systems Center in Natick, Massachusetts. He purchased one with two floppy drives, an expansion unit housing a 10MB hard drive (the first one I had ever used), and a green phosphor monitor. He also bought a daisy wheel printer so we could produce letter-quality documentation for our software.

I enjoy discovering a new computer, but my initial impression was not all positive. The machine was big and expensive. It felt slow. This didn't make sense to me because even though the PC's 4.77MHz Intel 8088 processor was clocked at nearly 5 times higher than the 1MHz 6502 processor in the Apple II+, the Apple felt much, much faster. Steve Wozniak's hard work on the Apple II+ was clearly more efficient in many ways.

In addition, the computer came with PC-DOS 1.10. I was expecting something more advanced than CP/M from IBM but was disappointed. In fact PC-DOS seemed to me to be nothing but a ripoff of CP/M.

Overall, this computer was underwhelming. With IBM behind it this design would be copied widely. The variety and innovation in the microcomputer market was slowly wiped out by this computer and its imitators.

Early networks

When I started in high school at Xavarian Brothers High School in Westwood, Mass. they had an early example of a network. It amounted to a shared hard drive between four TRS-80 Model 3 computers (or maybe they were Model 4s). There were also Epson MX-70 printers.

I didn't actually take the programming class, which was only available for juniors and seniors, but my math class was in the classroom where the computers were, and I would sometimes write little programs for them in the minutes before or after class.

I'm not sure if the hard drive was manually or automatically switched, or if these computers ran a real disk operating system. I don't remember the computers having floppy drives, and it seems unlikely that they had networking code built into the power-up ROMs; just BASIC.

Perhaps someone else would be eager to comment on this?