#anchientelectonics

[woofinstepper]

While digging around looking for some letter sized file folders, I came across this ancient gem. An HP 11C scientific calculator. I remember getting this and thinking I finally had a calculator that could help me do engineering calculations. Look at all the multifunction buttons. What more could anyone want? RPN (Reverse Polish Notation). That means to add say the numbers 3 and 5, you didn’t key in the 3, hit the plus sign and enter the 5 followed by an equils sign. You entered the 3 entered the 5 and then pushed the + key. I know it seems silly, but you didn’t need parentheses this way. This was hot stuff at the time. It used an LCD display. No power hungry LEDs requiews. I was really surprised that after all these years, it still had power to work. You will notice that at some time I had lost the little door that covered the batteries and used my engineering skills to design a masking tape replacement. You know what was really special about this calculator, it was programable!d Wow... something that would fit in your pocket that was programmable. Imagine that. It was almost like a computer.

[woofinstepper]

I tried a few things. I tried using the SD card and adapter instead of the real HD and was able to get DOS to see it, but I wasn’t able to boot from it. So put back in the hard drive I have successfully gotten working, not the one that was in it when I first turned it on in the beginning of this adventure. The reason I did this was that the latest one was recognized as a 500 MB and the first one was only recognized as about 37 MB. While that was plenty for its day, 500 MB is better.

I mounted the drives on the plastic click in bracket and put the front panels in place, so it looks more like it did in its youth. I may play with it a little more, but the fun part is over. The net gain at this time is the improved size of the hard disk and the drive cables that were added. I may see if I can understand what memory model I am working with. Is the memory above 1 MB being used as expanded or extended memory. These names confuse me because they are so similar. I seem to recall that early PCs swapped out pages in order to use the higher memory, but later versions on computers that had 80286 processors in them would switch into protected model, making the memory continuous.

I am sure that people look at this old machine and wonder how they were able to get a CPU not overheat when it has no heatsink. But then the 286 processor was only running at 10 MHz. Where as my newer machines are running at 4 GHz. So the clock rate is 400 times as high and there are multiple 64 bit processor cores. That is why processors require large heatsinks or water cooling now.

[woofinstepper]

I couldn’t get the full sized ISA card to operate the hard disk nor the floppy disk. I had located the manual for the card, but the options availabe were to enable the embeded harddrive or not, use a single or dual speed floppy, change the precompensation to something ... I think there was a 4th option as well, but these did not work. The machine came up in IBM cassette BASIC. So I switched back to the 8 bit card pictured, used the original floppy drive connected to the motherboard and the newly installed 4 pin Molex power cable to powerf the HD. From the screen shown above, you can see that the hard disk is working, being recognized as a 500 MB drive. I am not positive that the computer is seeing all the memory, the the startup disk seems to be seeing all 4 MB or RAM. This could be an issue with expanded vs extended memory. I don’t know how to tell which is being used. I think I have another ISA floppy/Hard disk adapter card. I may try that one. I think that card however also has a serial and parallel port, so those would need to be set to LPT2 and COM2 or something. More fun going back in time and relearning what I have forgotten.

[woofinstepper]

The blob or how to screw up your motherboard.

In my adventure to add standard power connectors to my old IBM PS/2 model 30 286, I skinned the wire on the power supply wires and added connectors from a spare PC power supply I had. I was reluctant to do the modification, but I did go do it. Unfortunately I did something stupid. I soldered on the new wires with nothing between where I was soldering and the motherboard. I could kick my self. A bit of paper towl or even a kleenex tissue would have stopped what happened. A solder splash hit the motherboard and as luck would have it, it hit the pins on a surface mounted TTL module and bridged them. It took me several attempts to clear all the shorts using a solder sucker and solder wick. It was very frustrating. In the end, I had to actually add solder back before the wick would absorb it and finally clear the shorts. I was happy when I finally got the machine to display memory being checked after power it on.

The next thing I am going to try is to install an 16 bit ISA adapter card that has both a 34 pin standard floppy drive connector and a 40 pin HD connector. I am hoping that this more modern adapter will allow the use of a master and a slave drive on the 40 pin interface. With the cabling fix mentioned above, I have 2 molex style 4 pin connectors and 1 floppy drive style 4 pin connector. So there are a lot of things I could do with this configuration.

[woofinstepper]

I was looking into how to conect to PATA drives since the PS/2 doesn’t have any additional conectors for powering IDE or Floppy drives. The PS/2 powers its disks using the ribbon cables for these devices. This is not industry standard. So I located and older power supply that I have kept after upgrading and cut off the power conectors that would give me two of the Molex style 4 pin connectors and one floppy drive power connector. While I was at it, I checked to see if 300 W power supply whould fit in the space of the original power supply. I found that it was mechanically smaller than the original. I don’t know if the details could be worked out, such as the power cabling, fan, power switch and mounting, but the basic volume and dimensions looked good. I also measured the voltages on the original power supply sould I could identify which wires on the original connector were needed to deliver the voltages to the drive connectors.

[woofinstepper]

Further back in time: IBM Model 30 286

Since the old floppy drive in the machine had given up the ghost, I started trying to figure out how to replace it with a standard one. My thoughts were to take out the 8 bit Hard Disk adapter and reeplace it with a 16 bit ISA adapter that had both a 34 pin floppy connector and a 40 pin Hard Disk connector, plus a whole lot of jumpers. Not exactly plug and play. I got as far as taking most everything out of the machine when I noticed that ... the other end of the power cable wasn’t connected to anything. It had plugged into the 8 bit card, so the floppy drive and the hard disk were getting their power from the ISA bus through that card. So what are my options? On the motherboard there is a 40 pin connector for the original hard disk and a 34 pin connector for the original floppy drive. Each of these should have power available if I select the right pins and make an adapter. The only other place I can see to connect is to the power supply connector and I don’t think I have connectors that will match that. I have old ribbon cables that I could make an adapter to get power for the floppy and HD. Further examination of what I thought was a 40 pin PATA connector turned out to be something else. I suspect that the connector has about 44 pins and I assume that some of those are power connections. It could be an even older disk drive interface and I don’t have a pin out for it. If I did, I could make an adapter to pull the power from there.

I was reading about the Kingston SX now upgrade that my computer has. It apparently has a 33 MHz 386 SX processor in it. The speed test that comes with it proudly declares that it is running as fast as a 47 MHz PC/AT.

[woofinstepper]

IBM Model 30 286

Someone out there aquired a Model 30 286 and was looking for help, so I gave some advice off the top of my head. It just so happened that the Apple iMac I had repaired was no longer on my bench so I had a place to set up my Model 30 286 and see if my advice was accurate. The person in question brought up their computer and it gave an error message that it didn’t have a valid system disk. I suggested that they needed a boot floppy which could be made using the format a: /s command in DOS. Of course that would require a machine running DOS to make it unless they already had one. So, I made one on my computer and was able to boot from it and look at my drive C:. When you make a boot floppy with with that command, what you find on the floppy is one visable thing on the floppy and that is comand.com. That is sufficient to boot. However, it does not have the format command. Nor does it help with partitioning or scanning the disk for errors.

The command sandsk is a separate executable and is what is needed to check the hard disk for bad sectors.

I looked in my supply of 3.5” floppies and found one in a wrapper that indiccated that it contained OpenDOS 7.1, so I booted from that to see if it would work on the IBM machine. It did come up. It was funny though, reading the text files I learned that some of the commands on it were there to help you install OpenDOS from a CD ROM. I am not sure that I have that CD and the PS/2 probably predates CD drives. There is no USB on it, so information can’t be transfered that way either. The floppy disk did have more than the command file on it, it had format and basic things one needs to get going.