Posts Tagged ‘Floppy Drive

12
Aug
14

Hardware Donation

It’s not everyday that someone moves house, and when someone I know moved house recently they found a pile of old computer gear they didn’t want anymore. They asked me if I wanted any of it and of course I said yes! So last weekend I got this rather large box of old computer gear. I just had enough time this weekend to unpack it and take some photos.

Continue reading ‘Hardware Donation’

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25
Mar
14

Fixing a NEC FD1157C floppy drive

NEC FD1157C

NEC FD1157C

Last time I went to see my family out in the bush I had a look at some of the hardware I had in storage there. I found I had a NEC FD1157C 5.25″ floppy disk drive made in 1989 that had come from an Epson machine one of my uncles had given my father. The drive, whilst badly yellowed looked like it was in good shape mechanically, but upon testing with hardware I had on hand at my parents place it didn’t work. It didn’t even seem to seek properly.

This drive has a number of jumpers on the main circuit board, so I checked online to find out the settings. After trying for a while I still couldn’t get it to work. I decided I’d bring it back with me to try to work out what was wrong. I have better diagnostic equipment here.

The head rails

The head rails

Having been doing other things I hadn’t had a chance to look at it until just this weekend gone. I rechecked the mechanism to see that it moved freely. This type of head travel mechanism is nice in the sense that it doesn’t have a screw to lubricate, so it’s a bit cleaner, easier to adjust, and reliable.  Fortunately it didn’t require service as the heads moved backwards and forwards freely. The spindle motor similarly was in good condition.

It seemed likely a problem on the circuit board, perhaps a bad jumper setting. So I rigged the drive up in my MS-DOS machine and in the process of setting up the BIOS for testing the drive it performed the drive seek test and seemed to work. I was quite surprised by this as I couldn’t get it to do that at all at my folks place. I found the website with jumper settings for some NEC drives.

Circuit board

Circuit board

After setting the jumpers the drive appeared to work but the drive light didn’t ignite when the drive was in use. I tried a few things and found that the LM1 setting on the drive needs to be 1 rather than 0 for the light to work. I was a little disappointed to not get to use my oscilloscope to check the test points.

I’ve done some minimal testing and everything appears fine, but I will test it against my reference working drive to make sure the alignment is right. I want to make sure it reads and writes to disks reliably without damaging them. I might even probe some of the test points just for fun! This drive is a good one to have as it appears more serviceable than others I have. Although I have to wonder why it didn’t work when I tested it at my folks place. Perhaps a bad cable?

06
Jan
14

Floppy backup and some GwBasic programs

This week my brother brought back all the remaining floppies we had at home for the purposes of backing them up. So I’ve been quite busy this weekend imaging disks and copying data. I have in the process discovered some interesting software that I forgot we had, and some I didn’t know we had. I found quite a bit of GwBasic software created by myself and my older brother. I had something like 200 odd disks to copy so it will take some time to sort the data out.

That’s not all I did fortunately, otherwise this would have been quite the short post! Before the disks came I had time to re-write a few GWBasic games that I remembered from books I read in the school library as a child. BASIC used to be a very prolific language with a interpreter on pretty much every platform, quite often in ROM. Much software was written with it including a lot of commercial software and corporate databases. There were also books and magazines abound filled with source code for various platforms.

It was a common thing for people to acquire BASIC programs from magazines or books during the 80’s. The only way to get these programs into your machine was commonly typing them in, which could end up error prone and was time consuming. Still it was quite enjoyable once you got your program running. My problem was that there was little to no source code available specifically for GwBasic where I lived.

Fortunately there were a couple of programs generic enough that did work. The ones I re-made recently were called Ghost Guzzler and Down-hill Skiing.

Ghost Guzzler

Ghost Guzzler

Ghost Guzzler is a simple game in which you have a number (a ghost) travelling across the screen towards your number. Your job is to “guzzle” the ghost before it reaches you by changing your number to match the ghost and pressing the guzzle key. I made some changes to the original. I added some proper timing code so the game is not too fast, and speed up the game as you play.

Down-hill Skiing

Down-hill Skiing

Down-hill Skiing is another pretty simple game. You’re simply skiing down a slope and need to stay on the ski run. The run will skift left and right randomly as in the original, but I added varying width to it as well. Like Ghost Guzzler it needed to have proper timing code added. This program is interesting as it uses the text scrolling features of the machine to give the illusion of movement down the hill.

Both of these programs were quite enjoyable to code, and only took about an hour to code each. It was quite a nostalgic process for me as I often spent many afternoons experimenting and coding. Now having a backup of all my old floppies in a new and better form I will revisit a few more programs.

Space Escape

Space Escape

I did this in part because of finding a website dedicated to GwBasic. The author had similarily looked on the net as I have in the past and not found much in the way of programs or information specific to this interpreter. He has posted some nifty information about his history with GwBasic, but most notably has written a new game for it called Space Escape. It shows what could be accomplished with the interpreter with relatively simple code. You can find his site here.

05
Aug
13

Low Level Formatting Floppy Disks

QuickBASIC Manual and disks

QuickBASIC Manual and disks

Yesterday I re-aligned my old 5.25″ floppy disk drive from our old computer. In the process I was formatting and checking the alignment of the disk using software called ImageDisk by David Dunfield. My drive was behaving badly at one point and thought there were bad sectors at random points, due to the heads not being clean and connectors to the drive control board being dirty.

Normally with software provided in DOS (or windows for that matter) even re-formatting the disk would not fix this issue with the disk even if the magnetic media is in good shape. I found with ImageDisk I was able to redo the low level format of the disks.

There are a few different ways to go about doing this. ImageDisk has the function to format disks directly, but you have to know all the parameters for the disk format you’re using (or planning to). This is useful in the case that you have to format a disk for a system that uses an exotic system, like C/PM systems for instance. Unfortunately this doesn’t write a file system.

The second method you can use is to completely erase the disk using ImageDisks erase function then format the disk normally on the system you wish to use it for. I had mixed success with this as sometimes the format program didn’t always do a good job. It does work most of the time however and performs the operation in the fewest steps.

Finally the method I prefer is to create an image of an empty disk in the format you desire, and then writing that image to as many disks as you desire. In the process of writing the image the software also formats the disk. It may be prudent to erase the disk before hand if the new format is different to the original on disk. The downside is ImageDisk doesn’t check for bad sectors during the format and is not filesystem aware so you should run Scandisk or the equivalent for the system used.

These techniques have all worked for me, but they only really fix bad formatting on an otherwise good disk. So when a sector of a disks surface is genuinely bad this won’t magically fix the disk for you. It did surprise me however how many of my disks I thought were bad, are in fact actually sound media wise but just needed to be low-level formatted. It also pretty much only works on disks that are compatible with the IBM PC drives. Fortunately ImageDisk will handle many different formatting types and even 8″ drives, so most disk formats can be done with the software with the exception of a few like that used on C64 disks.

04
Aug
13

Aligning a Canon MD 5501 5.25″ FDD

Floppy drive minus shield

Floppy drive minus shield

A couple of weeks ago I mechanically serviced an old Canon 5.25″ floppy disk drive that came out of our old computer. As I mentioned here, the drive was in desperate need of repair and restoration. I decided to repair this particular drive mostly for sentimental reasons as it was the first floppy disk drive I used and learned programming with.

Firstly I had to make sure I had everything I’d need to make sure the drive was completely functional. It’s important to have some blank disks so you can test your new drives alignment without risking something with data on it. Another working floppy drive is a must as you’ll need to check that disks work in both drives correctly. Finally some software that tells you what track is under the head and how good the signal is. I found David Dunfields ImageDisk is perfect for that task as it gives a beep to tell you how good the signal is. This means you can hear the signal change as you manually move and adjust the head.

I ran the software with a good drive and a newly formatted good 1.2M disk, just so I could get a baseline and an idea of what I should get when the drive is repaired. Next I transferred the drive to be repaired into the machine so I could see what the current situation is. I used to software to move the heads back and forth to check that the mechanism was indeed completely functional with good results. The drive was however out of alignment as it was reading track 2 instead of track 0 where it thought it should be.

Every floppy disk drive has it’s own different mechanism for aligning the disks. Some of the older drives have a screw that you can adjust, others will be different. The Canon drive that I have is a one quarter sized drive, so it doesn’t have room for the older style of mechanism. In fact the stepper motor arrangement is pretty much the same as those of the newer 3.5″ floppy drives. My drive has two main ways of aligning the heads. It has a zero track sensor that can be moved after loosening a screw. It is basically and optical interrupter type sensor and is easy to adjust. The other way is to loosen some screws and move the whole head assembly. Fortunately I didn’t have to do that.

I remembered what my Dad had done to the drive. My Dad knows a bit about electronics and likes to fix things, and he did this a lot when I was a kid. I used to watch him work, and it’s part of the reason I like to fix things myself. Unfortunately Dad doesn’t know a whole bunch about fixing computer/digital electronics, including this floppy drive.

Dad was cleaning the old computer to get all the dust out. He took the drive out and cleaned the heads using metho like you do for tape recorders (which was the dominant audio medium of the time). In order to do this he had removed the upper head from the assembly to get better access. When he reassembled the drive he didn’t align the upper head with the lower one, and I found upon inspecting it they were a couple of millimetres out. Fortunately it was easy to fix, loosening a few screws, moving the heads and tightening. Appart from that he had actually done a pretty good job of cleaning it.

I finished aligning the drive by moving the optical sensor until I got the best result I could. But even though the drive was aligned it seemed to still find bad sectors randomly around the drive. I tried re-aligning it a few times to see if I could improve the situtation but couldn’t improve it. I found a few problems including the cable for the heads hitting the drives shielding. Still I couldn’t stop what seemed like random bad sectors. Each time I re-formatted the drive from scratch the bad sectors turned up in different places.

So it looked like there might be a problem with the heads themselves. I cleaned them with some metho and cotton buds much the same way as Dad did, but without removing the upper head. This seemed to yield better results, but not perfect. The heads in this drive are connected to the main controller board via some small cards in edge connectors on the board. I pulled these out and cleaned them carefully with medical wipes (they have isopropyl alcohol in them). This seemed to do the trick, floppies formatted and checked out with no bad sectors!

Finally to test the drive works with disks from other drives, I used the other drive to check the disks made by the one under repair and vice versa. They both were able to read and write to the same disks, and even both found the same bad sector on the main disk I had been using for testing. This is why I bought some “new” blanks, I was sure with all the fiddling I might damage a disk, turns out I was right to do so. The repair went so well, I’ve permanently installed the drive in my MS-DOS machine.

16
Jul
13

More Hardware Shenanigans

This weekend I was rather busy catching up on housework and replacing some parts on my motorbike after going on a short holiday. So I was unable to really find any time to play a game for writing about. I did however find some time to do a little bit of hardware tinkering with some new bit and pieces I’ve recently acquired.

Compensating the probes

Compensating the probes

Firstly I recently bought myself a decent oscilloscope for the purposes of fixing old computer hardware and to help with hardware projects. I bought a Rigol 2000 series 70Mhz scope which was about 900 Australian Dollars (inc GST). So far I’ve found it pretty easy to use and have been able to probe points all over my poor ZX Spectrum which seems to have destroyed another video chip. Using it I have located a capacitor that looks like there is no voltage reaching it so the board may have power issues or that cap may be bad. In any case the scope I got seems quite good, and even though I only ever used an old school analog scope back at Uni I’ve found this one easy to do what I want with it.

The second thing I brought back from a holiday to see my parents recently. It is the original 5 inch floppy drive from our old Twinhead 386sx computer we got when I was a kid. It is a Canon MD 5501 drive that unfortunately has seen better days, it originally had a problem when my well meaning Dad tried cleaning it. After he cleaned it reading disks became basically impossible, and the eject mechanism eventually began to stick. We thought the drive was dead, but it probably just needed proper lubrication and alignment after Dad messed with it. Not knowing this I removed the power connecter from it some years later for connecting up some fans I was wiring up for my then computer chassis.

Floppy drive minus shield

Floppy drive minus shield

So the drive requires heaps of attention to try to restore it. But so far I’ve been quite successful in freeing up and lubricating the eject and head mechanism with some simple silicon spray. It now looks pretty good mechanically! I’ve soldered on a power connecter cannibalizing a Molex to dual SATA power converter. It’s not as tidy as the original connector but it seems to work. I have yet to work out how to go about re-aligning the heads but that is the next challenge!

Because the original main board for our 386sx is still functional I am entertaining the thought of re-building our old machine. The main problem being I don’t have the original chassis as it got rusted when the external CMOS battery leaked. Fortunately the main board survived this, but being what it is, it doesn’t fit any chassis I have laying around. I guess that’s not an issue until I get to putting it in a pretty case!




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