Some Altair questions, if I may..

On Mon, Aug 25, 2014 at 12:14 AM, drlegendre . <drlegendre at gmail.com> wrote: If you're going to do much hardware work, I'd strongly recommend getting an oscilliscope. You want at least three times the bandwidth of the highest frequency digital signal you are going to look at, so for old 8-bitters, I'd recommend having at least 30 MHz bandwidth, but you can probably find a used 100 MHz analog scope (e.g., Tek 465) pretty inexpensively. You don't need the scope to be well-calibrated, but it does need to work, since you don't want the scope to also be a repair project, especially for something as complicated as a Tek 465. I paid about $100 for a working Tek 465 last year. If you can afford it, a modern digital scope such as a Rigol might be a good investment. A digital scope can catch single-shot events which a normal analog scope cannot. A Rigol DS1102E two-channel 100 MHz scope costs $399 new. Note that older digital scopes are actually *less* useful than an analog scope for anything other than single-shot capture, because the older ones (up through the mid-1990s) didn't behave much like an analog scope. The newer ones are specifically design to give a similar experience to an analog scope. For really heavy-duty debugging, a logic analyzer is quite useful, but there's an intermediate step known as a "mixed signal oscilliscope", which is an oscilliscope with an extra 16 channels that are digital only, and with simple logic analyzer capabilities. For instance, a Rigol DS1102D 100 MHz 2 analaog 16 digital channel scope is $800 new. If you want test equipment suitable to work on modern computers (anything from the mid-1990s and later), you're talking Really Big Bucks (tm). IMNSHO, it's not even worth wasting time trying to do any hardware repair on newer stuff, since they aren't designed to be serviced. The manufacturer intends the whole computer to be a single FRU (Field Replaceable Unit), i.e., when it breaks, throw it away and buy a new one. :-( OK, so I exaggerate slightly. Usually the power supply, disk drive, keyboard, mouse, and monitor are still separate FRUs.