Talk:ATASCII

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Untitled[edit]

The information about "inverse characters", is misleading, and the image illustrating it is plain wrong. The ATASCII character set consists of characters 0-127 "normal", and 128-255 inverse. 82.210.159.30 15:09, 9 July 2006 (UTC)

Corrected information on inverse video. PabSungenis 14:21, 21 August 2006 (UTC)

Table needed[edit]

The main article could be improved if a table of equivalencies were added, comparing the Atari, Commodore, and PC ascii sets. 216.99.219.165 (talk) 23:24, 27 December 2008 (UTC)

Yes, I agree with you. And maybe a discussion of what sets Atari graphics apart from the Apple II of the day. 198.177.27.21 (talk) 20:54, 13 March 2009 (UTC)
Well add it then. SimonTrew (talk) 22:25, 13 March 2009 (UTC)
My experience with the Atari is limited to the 520 ST, which doesn't use ATASCII. Instead, the 520 ST uses some kind of a "plain vanilla" ASCII, which is kind of disappointing since all my prior experience was with the Commodore series of computers. Now, as for the eight bit Atari, that is something that I am curious about. 198.177.27.29 (talk) 00:30, 14 March 2009 (UTC)
I've added a character chart, but I haven't been been able to find the Unicode value for RIGHT ONE QUARTER BLOCK (ATASCII 02) or UPPER ONE QUARTER BLOCK (ATASCII 0D). DanBishop (talk) 01:56, 6 June 2009 (UTC)
Can we add a key as to whate the colors mean? I presume it is something along the lines of whether it matches ASCII or something. SimonTrew (talk) 08:22, 17 August 2009 (UTC)
Yellow background is for ATASCII-specific graphics characters. White background is the same except that you have to press ESC first or they get interpreted as control characters. The rest are the same as ASCII, classified by letters, digits, and punctuation. DanBishop (talk) 05:40, 20 August 2009 (UTC)

Quote Mode for the Atari?[edit]

Did Atari ever have a "quote mode" like Commodore had with its PETASCII? 198.177.27.15 (talk) 08:57, 8 March 2009 (UTC)

Yes, it is already discussed in the article. SimonTrew (talk) 22:25, 13 March 2009 (UTC)
Where? In the Commodore quote mode, control codes become visible as "inverse" or "reverse" bytes when you type a quotation mark. (The "inverse" or "reverse" byte is only a switching of colors, so instead of black on white, the character is drawn white on black.) With the Commodore quote mode, there is no need to press the Escape key. You can actually add a long series of control bytes, one after another, until you decide to get out of quote mode. But to get the same effect on an Atari, you'd have to press an Escape key for every control code you want to make visible. Am I right? But I am not sure, as I have never had an Atari 8 bit computer. I am basically guessing, according to what I am reading in the main article. 198.177.27.29 (talk) 00:36, 14 March 2009 (UTC)
Good question. And your above discussion should maybe be a little section, as you validly point out the differences. On the Atari, you can go into Graphics mode, I forget the name of the key but essentially it lets you access all the keys including inverse video, quite similarly to the C64. I am just doing this off the top of my head so I can't quite remember either, but Ataris had one or two graphics characters on each key (as I think C64's did?) accessed by a special "shift" key (whose name I forget). So, I reckon, your comments are very useful but I dunno how we get to find the facts. Sometimes this kind of information is not easy to find. If you can do so, go for it! And actually, if not, what you already have is better than nothing at all.
Sounds like the C64 inverse video system was pretty much the same as the Atari's. I had a C16 but that, despite being superficially similar, was completely different architecturally. }}}}
I have no real experience with the Commodore PET computers, but from what I gather from talking to my friends, the Apple II treated Bit 7 a little bit differently. It had something to do with flashing the character. For instance, if you set Bit 7, the character would flash. If you cleared Bit 7, the character would stop flashing. This is what makes me raise an eyebrow about how, exactly, the Atari 8 bit flashed its cursor. Was it a graphical feature, as part of the graphics chips on the Atari 800? Was it part of the way Atascii implements its control codes? Why, it could be just about anything. (And seeing as how webbrowsers like to use "unicodes" here at Wikipedia, the question becomes that much harder to address. I remain curious about how ATASCII does its thing. It is really hard trying to find an Atari 8 bit programmer who actually knows what is going on in his machine, and why. 198.177.27.32 (talk) 02:57, 14 March 2009 (UTC)
The Atari did NOT flash its cursor. It displayed it in inverse video. (There was, however, a POKE you could do to change the display of inverse video to normal text or invisible text, so if you really wanted to, you could write a program that had a flashing cursor.) DanBishop (talk) 02:11, 6 June 2009 (UTC)

Yeah I think perhaps we are talking about different things.

If I remember (this is all just from memory) the flashing was used on Apple II with bit 7 but not on Apple I. By "Quote mode" I had assumed was meant being able to stuff things into the program, and I've documented that at Atari BASIC. I've no knowledge of COmmodores though I owned a Commodore 16 once but they were very different from Commodore 64s and had a very different architecture, I think. It would be great to great to get this all kinda in order. The C64 used the 6502 and variants thereof, as did the Ataris, I am not sure what the C16 used, it was a bit weird as it was kinda badged like the C64 but very different.

The Atari had no quote mode in the sense I think you intended as being able to make non-printable characters printable, because all characters were printable. That is mentioned in the article but if it is not put clearly then it needs to be edited to say so.

SimonTrew (talk) 22:11, 19 May 2009 (UTC)

ATASCII did have control characters. However, these characters could be printed if they were preceded by the escape character. For example, the BASIC statement PRINT "A→B" would display "A B" on the screen, but PRINT "A␛→B" would display "A→B". And to write that last line in the BASIC editor, you had to type Esc+Esc to get the symbol for Escape, and then Esc+Right to get the right arrow. AFAICR, there was no "quote mode". DanBishop (talk) 02:25, 6 June 2009 (UTC)
But that is not to say ATASCII had escape characters in the sense that the escape sequence was stored in the string, in the way, say, we store HTML tags or & for writing literals. The E: driver had an escape toggle so that the following character entered was treated as a literal, not a control character. BUT the "escape" did not actually appear in the string as stored; it was simply a data entry meethod, and not part of the ATASCII character set. Some ATASCII characters just had one particular meaning (up, down, enter etc) for one particular editor. SimonTrew (talk) 08:15, 17 August 2009 (UTC)

How did the Atari cursor flash its characters?[edit]

The main article could be improved by explaining how characters over 128 are displayed in "inverse" colors. That is, by switching the colors so that black on white becomes white on black, presumably in a one-to-one relationship with the bits inside the character definition. Am I understanding this right? Is this related somehow to the flashing of the cursor? I assume that movement of the cursor over a particular row and column results in the flashing of the character located at that location. Is there a timer involved, so the cursor returns the character to its original state once it moves on?

The main article could be improved if it described how the Atari cursor worked. It is probably quite a bit different from that of modern Macs and PC compatibles. 198.177.27.21 (talk) 20:53, 13 March 2009 (UTC)

The curor was simply implemented by inverting the character at the character position (by XOR with $80). It didn't flash. I will add this. SimonTrew (talk) 22:25, 13 March 2009 (UTC)
Wasn't there an ATASCII code that turned the cursor off, and then later another one that turned it back on again? 198.177.27.29 (talk) 00:25, 14 March 2009 (UTC)
Strictly speaking, no. There were codes specific to the E: and S: drivers that turned the cursor on and off, but these were not ATASCII as such (they were in ATASCII but were specific to those drivers). I forget the numeric values of the codes. I wrote an 80 column driver so I used to know all this stuff, but it was 20 years ago.
Actually I think I am wrong. Turning the cursor on or off was done through a POKE. SimonTrew (talk) 06:22, 17 March 2009 (UTC)
There were no flashing cursors through interrupt or timer routines.

SimonTrew (talk) 01:29, 14 March 2009 (UTC) amended SimonTrew (talk) 02:56, 14 March 2009 (UTC)

Okay, I think I understand what you are going at. You stored a byte in screen memory, and if bit 7 were clear, you would the get two regular colors, but if it were set, the two regular colors would be switched? —Preceding unsigned comment added by 216.99.219.23 (talk) 05:36, 17 August 2009 (UTC)
Exactly that. The text cursor location was stored in two bytes of memory (one each for X and one for Y); a vertical blank (or display list) interrupt routine could be written to flash this cursor by flipping the bit every so often at the cursor, or indeed do something else such as turn the cursor off and use a sprite instead to overlay it. However this was not part of the standard OS behavior, and as far as I know was not widely used (I think at one time I wrote a routine to do it but I didn't like it myself, preferring the steady cursor).
There were a couple of difficulties with flashing the cursor in an interrupt: first, the interrupt essentially had to track the previous cursor in case it moved (so that it could unflip the old location, not the current one), second, and related, if the Return key was hit, the character would be interpreted wrongly if it was not inverted the way the OS expected it to be. So it was easier in a sense just to turn the cursor off and use a sprite to do it, which could more easily track the cursor position independently, and also be in a different color (and shape). But setting up sprites was a bit of a faff, and it seems most people were really quite happy with the steady cursor. The only time it got at all tricky was if editing a lot of mixed inverse and normal video, but then the usual trick was simply to move the cursor around a bit to find out where it was, a bit like we do these days with the mouse when we lose the mouse cursor. Most people seemed quite happy with the steady cursor. SimonTrew (talk) 08:06, 17 August 2009 (UTC)
I think that the Commodore 64 could change the cursor color to match the character color, and have them both match the foreground (or is that the background?) screen color (mapped into memory address $D021), but that is arguably cheating as it involves a bunch of pokes and peeks. It was harder to do it when the program was actually "running" (being interpreted by the BASIC ROM). I would guess the same thing was probably done with the Atari 800. (?) So far as I can tell, it was probably impossible to do with the PC compatibles of the era. (?) 198.177.27.32 (talk) 03:03, 14 March 2009 (UTC)
The Atari 8-bits could do color using sprites, but generally did not. The flashing cursor on PCs is hardware generated and IIRC is controlled through an INT 8 call. I would not be surprised to learn it flashed a bit faster on American NTSC machines than European PAL ones, but I don;t know.
The Atari 8-bit in text mode (GRAPHICS 0) only had one colour, with two levels of luminence. So it was actually (by default) light blue on dark blue. One could POKE a location to change this color (I think 204 or 205 but I am guessing) to make it black on white, but it was basically one color with two levels of luminance. SimonTrew (talk) 03:27, 14 March 2009 (UTC)
The main article needs to be rewritten so that non-atari users don't happen across it, and go away with the wrong idea.
Nobody's stopping you rewriting it. SimonTrew (talk) 06:20, 17 March 2009 (UTC)
Did the Atari cursor flash five times a second, four times a second, or twice a second? Was this determined by the IRQ line, which pulsed periodically from a timer (so that the sytem ROM could be served regularly), as was the case with the C-64? I'm assuming there were only two states for the cursor, positive and inverse, and the flashes were sufficiently regular that they seemed to be in synch with the keyboard scan? 198.177.27.14 (talk) 06:09, 17 March 2009 (UTC)
It did not flash. I told you that. SimonTrew (talk) 06:20, 17 March 2009 (UTC)

List of Control Codes Needed[edit]

Aside from the carriage return, linefeed, and ESC characters, what other characters were considered control codes in ATASCII? 198.177.27.27 (talk) 00:11, 15 March 2009 (UTC)

None. The article says so, I think quite clearly and concisely. Some characters had special meanings to some programs, but the whole character set could be rendered graphically. Believe me I know cos I had to squeeze them in to 4x8 characters for my 80-column driver.

You could register so that I am not talking with an anonymous IP I can't reply to. It's a bit rude IMHO. SimonTrew (talk) 06:20, 17 March 2009 (UTC)

Like you, I hate anonymity. Registering with Wikipedia is simply not as good as just signing your real name, with a street address, city, and zipcode. 216.99.198.201 (talk) 09:07, 11 August 2009 (UTC)
I do use my real name. In fact, old UK atarians have found me in this way. I don't see your real name, street address, city or zipcode. SimonTrew (talk) 13:30, 12 August 2009 (UTC)
It's just the way some of us protest the theory of "anonymity" and "identity" as it relates to Internet, where authentication depends largely (but not always) on password passing (and even password sharing, when it is done by operatives of clandestine (sometimes Federal) organizations). Authentication should be guaranteed across the board, and not just dependent on agreeing as to which kind of protocol is used for passing data between Internet Points and Gateways. 216.99.201.109 (talk) 20:18, 30 October 2009 (UTC)

European (Latin-1) characters[edit]

I am trying to recall now, but somehow on Rev C. the graphics characters were replaced with accented Latin letter characters, àèìò etc. I can't remember (a) how it did this-- I think it was a completely seperate font back-- and (b) how it was accessed-- you hit the OPTION button or something to switch between them (it just changed the register that pointed to the font location). Any clues? SimonTrew (talk) 22:19, 30 April 2009 (UTC)

I remember. It was a separate font. The OPTION button must have just flipped the fonts. I am pretty sure it was OPTION. SimonTrew (talk) 08:18, 17 August 2009 (UTC)

Is metadata a better term than control code?[edit]

Would the main article be improved by changing all the references to "control codes" over to "metadata"?

It seems that someone somewhere came up with a neologism - "metadata" - and started using it instead of the historically more accurate "control code" - probably in response to the decline of proprietary ASCII sets, and the rise of some kind of universal HTML-ready "script" of commands, however misleading that might be.

How much "control" can Atari control codes actually deliver anyway? 216.99.198.201 (talk) 09:13, 11 August 2009 (UTC)

Well I suppose "control" has so many senses as a word we could argue that one till the cows come home. It would seem best to use the more contemporar names i.e. the ones Atari used.

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