Showing posts with label heathkit. Show all posts
Showing posts with label heathkit. Show all posts

Tuesday, March 2, 2010

Trouble with the Floppies

In my first years of computing my experience with floppy drives was pretty good. I had used several computers for thousands of hours total, and had seen hardly a hiccup reading and writing floppy disks.

The computers I had experience with floppies included:

Apple II+
IBM PC
Heathkit H-89

These used brands like Shugart and Tandem for their floppy drives.

Working with Patrick Alessi there was little trouble. He did smoke a pipe constantly around the equipment but this didn't seem to cause any problems.

At C.F.C. it seemed like floppy disks were more temperamental. Not that they weren't reliable enough for day to day use but they would cause problems just enough to be annoying. Maybe it was the industrial environment, or maybe the quality level for drives and floppy disks was falling. I dunno. Some of our disks came from customers and were formatted by their computers, so maybe that also had something to do with it. Floppy disks had become cheap and didn't have the same quality they did a couple of years earlier.

Some floppy drives could be calibrated using software and a screwdriver. I did try some of that, but I can't say I remember it being very successful.

Monday, June 11, 2007

Floppy disks

In the early micro days we used cassette tapes and floppy disks. Floppies were better for many reasons but they were expensive. The Apple Disk II drives were $495 including the controller. Once you had one of these babies you still needed floppy disks. I remember pretty clearly in the early 80's spending $80 for a box of 10 floppy disks. These were Dysan disks, and were of very good quality.

However these disks probably exceeded the quality required. Later on some less expensive floppy disks became available from the likes of Maxell and memorably named Elephant Memory Systems. These were $2.50 or so per disk. The disk surfaces weren't as polished, and some cheap brands didn't have a reinforced mount but no matter really. The cheap disks were pretty much as reliable as far as anybody could tell.

Disk drive systems themselves were all quite different from each other. Apple's legendary Steve Wozniak had managed to create the ultimate in economy of design for a disk controller with a small card having only 5 ICs. Most other disk controllers were long circuitboards with 2 to 3 dozen chips. Monsters. ;-)

Some of these floppy drives used hard sector disks, meaning that there was an index hole in the media for each sector on the disk. So, if the disk was meant for a 16 sector drive, the disk would have 16 timing holes cut out of it evenly around the inner part of the disk. This would be read by an LED and a sensor. The Apple II used soft sector disks where there was only one hole cut in the disk, and the drive controller itself decided how many sectors to put on the disk by doing careful timing.

I remember that my father's H-89 had hard sector disks. The drives also made a strange clunking noise as they operated. The Apple II's drives made the much more familiar brrrr, brrr, mmm, mmm sound of most floppy drives and they were faster than the H-89 drives.

Tuesday, May 8, 2007

Star Trek, BASIC and Arrays

I think most of all my early programming ideas were advanced by writing games. When I was still a beginner I decided to create my own version of the classic Super Star Trek game that I played on the Babson College minicomputer on a dialup connection from the Needham Public Library.

I grabbed a yellow lined notepad and started writing code in BASIC. After a half page of code I began to write lots of IF THEN statements, one almost exactly the same as the next. I realized after a bit of this that my program was going to be gigantic!

So while I was walking to the library with my brother Ernie I told him what I ran into while trying to write the program. He explained to me that I needed to learn to use arrays (he called them subscripted variables). I really had no idea what he meant. I can't remember clearly how I learned about arrays, except that Ernie must have shown me how to use them. Along with arrays it was great to learn about nested loops.

With his help I was able to write a version of Star Trek in BASIC for my father's Heathkit H-89. Later I wrote a version for the VIC-20 as well.

So this was a breakthrough moment for me. Arrays make many kinds of game programming practical, and I made good use of them. It was easy to for me to see that to create a game is to craft a simulation (even if for an imagined reality). This insight served me well as I wrote more and more software.

Sunday, April 29, 2007

Heathkit H-89

Finally in 1980 my father was awarded a generous bonus for his role in the creation of special radio equipment for use on aircraft carriers. He used this bonus to buy an H-89 kit for Heathkit. http://www.old-computers.com/museum/computer.asp?c=135

We finally had a real computer in the house! It ran CP/M and H-DOS (we use mostly this OS) and we had a couple of different versions of BASIC for it. We had something called Benton Harbor BASIC. The computer had no graphics modes, but it had graphics characters and I remember my brother Ernie was working on a version of Galaxians for it. We wrote a bunch of games. I remember my father also did some assembly language programming for it (or perhaps he just typed in straight machine code).

One thing I remember about the machine was that it used hard sector diskettes, and the floppy drive was loud. It would make clunking sounds. Ka-chunk, ka-chunk!

Tuesday, April 24, 2007

Heathkit

Since our father is an electrical engineer he would sometimes build electronic devices. He had built a very nice stereo receiver from a kit he bought at Heathkit. My brothers and I enjoyed reading through the Heathkit catalogs that would arrive in the mail.

There were many different kinds of computers that could be bought from Heathkit at that time including the H-8, the H-11 and the microprocessor trainer ET-3400 which had a breadboarding area, could be programmed in machine code and could also be expanded to drive a terminal and be programmed in BASIC.

We spent a lot of time fantasizing about these and other machines, but we never got to see one in person. Computers were too expensive for kids with paper routes. Of course that would all change very soon.