Software 80 Columns

[Mark2008]

On 9/17/2022 at 10:33 PM, scottinNH said:

Oh. I infer this sounds doable from CC65 then, that's good to know.

 

Unfortunately I don't know enough about the Atari platform (or C) to work out how, exactly. I don't even know all the things I don't know, lol/

 

I'll get there eventually, but right now I'm only competent enough to take the simple happy-path to something (like a library).

----

I'm starting to port some of David Ahl's Basic Computer Games into CC65-friendly (but not Atari-specific) code. See other thread.

 

 

 

I don't really understand what you are asking, but I'm not sure if anyone else jumped in to answer.

 

I used to program in CC65, and even wrote in 80 column support into a couple games - none are released - I just mean I have demos of writing partial games, and engines that draw characters to the screen.

 

As far as I know, if you are doing a plain text game - which I never did, I was always in a graphics mode of some kind - but in that case you can use the E: device - and just ask the user if they are using 80 columns or 40 columns.

 

Or, you can program for an 80 column device like a VBXE - which is one of the methods I used.

Or you just write your own software driver, which is the other method.

 

Othe people here are more experienced than me, but a pattern I do repeatedly in my programs, is I just have an area of memory that holds - a pattern for say a player, or a pattern that represents a character to be drawn on the screen, or a software sprite to be drawn on the screen.  Then I just use lookup tables, and copy the pattern to the screen video memory.

 

It's that simple - not really anything else to it.   Now, if you need to implement a driver with scrolling and other stuff - more complex, but I just always wrote to specific areas, cleared the screen, if needed, and so on.  

 

ah - maybe I'm starting a controversy...I don't know...but as far as I know - it isn't built into CC65 as a library - I mean, maybe it is, and I never heard about it - so don't take my word for it.

 

But what I found is over and over again - examples abound for how you write to the screen, so I just used those examples and incorporated them into my programs.

 

 

[Mark2008]

On 9/17/2022 at 10:33 PM, scottinNH said:

Oh. I infer this sounds doable from CC65 then, that's good to know.

 

Unfortunately I don't know enough about the Atari platform (or C) to work out how, exactly. I don't even know all the things I don't know, lol/

 

I'll get there eventually, but right now I'm only competent enough to take the simple happy-path to something (like a library).

----

I'm starting to port some of David Ahl's Basic Computer Games into CC65-friendly (but not Atari-specific) code. See other thread.

 

 

To expand on my earlier answer, even though I switched from CC65 to kickC, and even though this is some other graphics mode - the same principle applies.

 

export char letterA[8]= kickasm {{

.byte $AA, $9A, $66, $66, $56, $66, $66, $66 //A

}};

export char letterB[8]= kickasm {{

.byte $AA, $5A, $66, $66, $5A, $66, $66, $5A //B

}};

export char letterC[8]= kickasm {{

.byte $AA, $9A, $66, $6A, $6A, $6A, $66, $9A //C

}};

 

First I am defining the characterset.

 

Then I am making up a table for it.

 

char letterTblL[91] = kickasm {{

.byte <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank

.byte <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank

.byte <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank

.byte <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank

.byte <blank

.byte <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank, <blank

.byte <neg

.byte <blank, <blank

.byte <number0, <number1, <number2, <number3, <number4, <number5, <number6, <number7, <number8,<number9

.byte <blank, <blank, <blank, <blank, <blank, <blank, <blank

.byte <letterA

.byte <letterB

.byte <letterC

 

etc. and so on

 

And then I use the characterset, and lookup table, to copy to the screen area:

 

void gprint(char charL, char charH, const char *msg) {

int i;

charX = charL; //0x53;

//charH #$88

 

for (char character = *msg; character != 0; character = *++msg)

{

 

asm {

 

ldx character

lda letterTblL, x

sta MSGL

lda letterTblH, x

sta MSGH

 

lda charX

inc charX

sta SHPMOL

lda charH

sta SHPMOH

 

ldy #$00 // COUNTER

NUM0: lda (MSGL),y

sta (SHPMOL),y

 

clc

lda SHPMOL

adc #39

sta SHPMOL

bcc ok

inc SHPMOH

ok:

iny

cpy #$8

bcc NUM0

}

}

 

}

 

Now - if I have completely misunderstood the question - my apologies.  I don't know what people are asking half the time around here.

 

But - anyway, I got a sense you were trying to write out 80 characters.  The Atari only has 40 characters.  The software mode is just to use half a character - or in bitmap mode 3pixels and a space pixel - to fit 80 characters within 320 pixels.

 

 

[Eric Rousseau]

Ouf ! Many messages since my last visit !

 

Here is one option that I wish I had used in 1985 with my 800XL: A real 80 columns televideo terminal connected in RS-232 to the Atari !

I remember the 300 Bauds MPP Modem that connected to the joystick port supported real RS-232 protocol if I remember correctly.

Except in was TTL Level (0v-5v) not real RS-232 (+25v -25v).

But with a converter, it would allow the 800XL to connect to the terminal via the joystick port at 300 bauds using software encoding... up to 450 baud I think.

But now that I know that the Pokey chip uses 19,200 bauds or higher (38,400) with it's peripherals and SpartaDos, I would be curious to connect the 800XL serial port to the terminal.

With a little modification to Synassembler wich use GETCH and OUTCH we could user Synassembler with a real 80 columns terminal at 19,200 bauds.

Yes I know, the full screen editor won't work unless modified to work in VT-100.

 

It would be like the XEP-80 but with a clean sharp terminal screen.

 

Now that I have money to buy everything I wish i had when I was young, unfortunately it's too late !

The need is gone, the curiosity is gone, the thrill is gone, and even if I have a big windows 10 computer with terabytes of storage, speed and GPU power, 

it's still not the same....

 

Ok, enough crying...