Computer Numerical Control machining is very close to running a robotic machine . Both require programming, electronics for operations and mechanisms for movement. I have specialized in the mechanical and electronic side of CNC/Robotics . Last week I was trying to get a Pic Servo system up and operating. Unfotuneately ,the program rquired Windows to run the setup for the PID (Proportional, Intgregal, Dirivitive) which downloads the gain to the servo. Now for those that dont know me, Im a Type A+++ personality. While checking the serial connect to clear a malfunction I pressed on the serial connector while the Packard Bell 486-66 computer was running. I hear a slight pop and new that something went bad and sure enough I found that I had blew the on board I/O port. I tried using a new I/O card in one of the ISA slots and even after configuring the jumpers to disable the onboard I/O I found that I had a bad motherboard.
I called some places like RePC and Computer Concepts but found that a replacement computer was going to be expensive. So I trundled down to Boeing Surplus where I knew they had some 486-66 CPUs with 250 MB hard drives and a 1.4 meg floppy. No monitor, no keyboard, no mouse but I didnt need them because I had them. I remember that the price for the whole CPU was $175. Far cheaper than computer concepts. When I got to BS (Boeing Surplus) I found several racks full of computers and video monitors. I looked at the Dell Optplex 433/ Le and noticed that the prices varied from $135 for a 486-80 down to $25 for a 486-25SX. I also noticed that they were equipped identically except for the CPU. The greater the speed , the greater the price. I decided to buy the 486-80 for $135 and a 486-33SX for $35 rationalising that I was beating the price that I thought it would be. While I was at it I thought it would be nice to have another SVGA monitor and saw the SONY 14" color monitors for prices ranging from $50 to $175. There was a sign that said there were no video cables and one was required. I bought the $75 Sony. I hurried home and spirted all my new found treasures into my work shop. I started with the 4886-80. I plugged a PS2 keyboard , a mouse and then my old SVGA monitor, turned everything on and found everything worked perfect. I shut it down and tried the 486-33SX . It too worked perfect. I was impressed, very impressed . I then shut it down took the CPU from my fried 486-66DX2 and placed that in the Dell. Even the high speed jumper was configured correctly. All I had to do was install the chip properly. I test ran it and was amazed. It too was perfect.
I started to quiver with excitement. My hands twitched as I realized that this was a really cheap way to put together a computer for other purposes. I decide to buy another CPU. I went down to Boeing on Saturday and bought another of the 487-33. I noticed several other guys milling around the computers. I said in a quiet voice " Sure is going to be fun to hack this computer. Two guys walked off, I guy broke wind and three guys turned and looked at me as they started towards me. I noticed one of the guys had a shopping cart with 5 of the 486-33SXs. I said "are you thinking what I am?". This bearded guy said "yes". He intuitively knew that I had discovered that by replacing the CPU with a faster chip you had a faster computer at a low cost. He said that he has put Pentium chips and other 100 MHZ chips in the box and they all ran fine.
I talked to him about the monitors. He told me that they were a great deal if you can find the video cables. Not many computer stores carry them. They are special and sell for about $20. I thanked him and drove off with my newest acquisition. I stopped by Vetco to buy a new Dell PS2 type windows keyboard for $12.95 and a PS2 mouse for $14.95. I asked for a monitor cable but they didnt carry them. I asked where I could find one and they said that Advanced Cable System at 1807 132th Avenue NE in Bellevue ( right around the corner from the Harley Davidson store in Bellevue had them. I walked in and asked if the had a monitor cable for a Sony CPD1304. Two guys answered, "BOEING SURPLUS!". Wow! They had the cables and they were only$6.84. Great deal.
I returned home and plugged in the newest 486-33sx with the new keyboard, PS2 mouse and the Sony monitor and turned them on. Everything work great and the picture was terrific on the Sony after I adjusted the brightness and color. What a deal $75 for the monitor and $7 for the cable.
Considering that one can buy 486-66 or better Intel chips for $30-$40 and the low price for the Dell case, power supply, 250MB hard drive and 1.44 meg floppy with 4 megs of RAM in a 72 pin Simm socket and that there were three open ISA slots with the onboard video, 2 serial ports and 1 parallel port. I think that a roboteer could easily afford a second computer for their shops or work bench.