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Re: Schematics of Dragon Cartridges?
Posted: Fri Apr 05, 2013 11:15 pm
by Rolo
Thank you Rink!
I made a little drawing of the 7400, just for me to make it easier to see, what's going on. I know, those symbols are old, but I always liked them better (an it's an old computer
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Code: Select all
!CTS A12 | CE1 CE2
-------------------
0 0 | 0 1
0 1 | 1 0
1 0 | 1 1
1 1 | 1 1
(CTS = Cartridge Select Signal)
- cart.jpeg (35.39 KiB) Viewed 2794 times
Re: Schematics of Dragon Cartridges?
Posted: Mon Apr 08, 2013 8:27 am
by Rink
Cool. I like the old symbols - but can never remember them. I'm not too hot with the the newer ones either mind.
Just noticed a mistake in my note about the chip selection:
Low on A12 creates a low on CE1 and a high on
CE2
I should amend the graphic really... but I think most people will realise the typo.
Re: Schematics of Dragon Cartridges?
Posted: Mon Apr 08, 2013 8:56 am
by sixxie
I think I need educating here - what are the new symbols? I thought those *were* the new symbols (well, the US standard, which we tend to use now instead of confusing boxes-with-a-symbol-inside British Standard ones)!
Re: Schematics of Dragon Cartridges?
Posted: Mon Apr 08, 2013 8:06 pm
by Rolo
Probably depends on which part of the world you live in. There are a few interesting wikipedia articles about that.
Until the late seventies, there where those German kind of flat (semicircular) symbols I tend to use. The British and the Americans used symbols, which had fancy corners and were a bit "bulky". Those a very popular in the old handdrawn schematics of "ancient" devices. Then the IEC came up with the boxes, which could be plotted faster, than circular shapes, and had a myriad of possibilities for every kind of circuit you ever could imagine. Those symbols are really complex.
Obviously the English speaking world mainly ignores them and goes on to use the old symbols, where as the Germans more or less use the IEC-boxes. And the other European countries or Asia? Well, I don't know, never saw another kind of symbols. Probably they all use one of the three systems.
I hope, that's not totally wrong
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Maybe somebody in the forum knows more about the topic? Tell us...