Wednesday, October 22, 2008

The best electronics find I have ever had: Intergraph Logic Boards

I have always had my eye out for surplus electronics and one of the best finds I have ever had was this:

A local business was throwing away a very old Intergraph computer. This was a very large, old, and massive computer. It consisted of several cabinets of hardware, each containing circuit boards of standard TTL logic. The best part about these boards is the fact that every single chip on each of them is socketed.

This board in particular which is labeled as a "High Speed Concentrator" has over 550 74S, 74LS, and a few other miscellaneous chips socketed.

I really wish I had more information about this machine. This board labeled as "MPCB191 Bit Slice 2903 16 Bit Processor" has over 300 socketed TTL chips along with Motorola 68000 series processors.

If anyone has information about what machine this came from, please leave a comment. I am very curious about it. My only regret is that I didn't grab more boards out of the cabinet...

Sunday, October 12, 2008

Tektronix TDS-420 oscilloscope external video display

A nice feature of the Tektronix TDS series of digital storage oscilloscopes is their external video display capability. Most (if not all) Tektronix scopes in the TDS series have an external video output (including my TDS-420) for hooking up an external display.

The internal display is very nice:

Sometimes it would be nice to have a larger display at my bench level while working...

Unfortunately this external video output is in a 9-pin form, unlike the standard DB15-pin connector we are familiar with on our VGA monitors. Because Tektronix labeled the connector as 'VGA compatible', I assumed it held to the VGA standard, and would be compatible with most modern multisync monitors.

To hook up an external display to your TDS series oscilloscope, you must perform the following. Obtain a standard 15-pin VGA connector cable and remove one end, replacing it with a standard 9-pin connector (preferably a metal connector to help with shielding). Wire the new 9-pin connector to the VGA cable as listed here. The 15-pin connector is on the left with pin assignment to the 9 pin on the right:

VGA DB15-S Female DB9 Female
15-pin, 9-pin
1, 1 Red
2, 2 Green
3, 3 Blue
4, - Monitor ID bit 2
5, - N/C
6, 6 GND
7, 7 GND
8, 8 GND
9, - N/C
10, - GND
11, - Monitor ID bit 0
12, - Minitor ID bit 1
13, 4 Horizontal Sync
14, 5 Vertical Sync
15, - N/C

I tied pin 6 on my 15 pin connector to all three grounds (6,7,8) on the 9 pin connector. After assembly of the connector, I gave it a try with success!

One of my Samsung Syncmaster 151v lcds on my bench sync'd up perfectly along with several other lcd monitors I have around. With the output being 640x480 there is plenty of resolution on the display giving the external monitor a very nice picture.