> No, the writer is quite technically astute and meant that the vacuum > tube circuits with their chokes, coils, etc. were ELECTRICALLY noisy. > But knowing that their audience wouldn't have a clue (as the editor > didn't either) and so cut all that out so that it just said that the > vacuum tubes were noisy (since the editor's only exposure to vacuum > tubes are at their bank's drive-in). > </extreme sarcasm>
Noticing the sarcasm, but... Tubes used in computer applications can indeed be noisy, but that is not the issue. The noise can be tolerated quite easily in those high voltage digital circuits. In fact, most computer tubes of the 1940s and 50s were more or less standard radio types, maybe souped up a little in some areas, but were tested using less stringent noise tests. Likewise, computer tubes often were tested with less stringent tests concerning balance of sections and hum. These qualities, like noise, just did not matter in a mainframe logic module. Noise was more of an issue with the early semiconductors. They were really rather poor performers, especially the British types, so noise started to become a big issue. The low voltage everything operated at in the transistor machines meant that external and internal interference could result in garbage on the signal lines that could get uncomfortably close to logic thresholds - flipped bits. The article basically gets it wrong. -- Will, wanting a 709 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
