27 Jul
2013
27 Jul
'13
12:52 p.m.
On 2013 Jul 26, at 3:21 PM, Tony Duell wrote:
I have never seen it used previously.
That's a lot of ambiguity and non-obvious rules for a de-facto or
unwritten standard.
I understand that, it can be nice to see the logic without the
clutter of pin numbers. It means, however, you end up with
unnecessary line crossings as the input order on the page is
determined by the physical implementation of the IC.
I take the position that the primary point of a schematic is to
elucidate the functional, electronic organisation of the device. The
physical implementation is important, but a secondary consideration.
For somebody repairing a unit, which they are probably doing on a one-
off instance for an RE'd item, the first priority is still that
functional understanding.
So the schematic gets organised with signal flow left to right and
electron flow up the page (for +V systems) as much as possible, and
functional associations as close together as possible, even if that
means bits of one board end up on multiple pages. All within reason
as there are always exceptions.
The physical implementation is still present and recorded in full in
the form of IC pin numbers and connector pins along signal lines, and
there are pages with all the connectors pins laid out if one wants to
go from the physical to the functional.
If you want all the physical associations as close together as
possible, prioritised over the functional, it becomes a wiring diagram.
(The pages you are looking at are old, it has since been encapsulated
in a single PDF, updated now.)
While one may want to communicate with an author
about more subtle
aspects of their work, this is such a basic thing I see no need for
asking, and waiting, for an answer about it. I can't say it would
even occur to me to ask, as if you have a convention about it, it
I have sene this convention used so many times that it never
occured to
me to describe it. could simply
be noted at the beginning or end of the work, along with
such things as source material identification, dates, table of
contents, etc.
As a matter of preference, when working on something, I don't want to
have to go from the schematic, then to a pinout to interpret what pin
is being ref'd, and then to the device.
And I have the opposite preference I am afraid. I find pin numbers on
scheamtisc to be irritating. In most cases I know the common TTL
pinouts
anyway. For anything else I don't mind having the data book open.
You have your preferences and conventions, I have mine, some may
prefer yours, some may prefer mine.
I think that;'s right. I took a look at your AL1000 schematics (BTW
there
are a couple of broekn links there). In the form you have presented
them
they are very useful for understnading how the machine works, I think,
but not so useful for actually repairing one. Wpoorkign out what is on
each board, what components comprise each gate and flip-flop (and
yes, I
ahve read your conventions, etc) is too much to have to deal with if I
had the machine in bits in front of me. This
wasn't really about your schematic, it was whether it is
acceptable for anyone else to RE something Tony already has.
Yo uare reading far too much into this I will just point out that _you_ raised the issue of
my schematics. I
did not mention them at first.
Yes, you did. You first raised the issue of your "reverse
engineering" in relation to my efforts.
If you hadn't, I wouldn't have said anything about your RE/schematic.
Ingenuousness, Tony.