Do I have to open up my new 800 to see if I have GTIA or CTIA?

[JamesD]

Do I have to open up my new (to me) 800 to see if I have GTIA or CTIA?

I don't see any kind of sticker with a manufacture date (check that first) but the serial number is readable.

If I have to type in a program to see if the new graphics modes work that would be fine, just wondering if there was a easy way.

[Fox-1 / mnx]

from: http://www.computers-n-robots.de/atari_8bit_revisions.html

 

 

 

 

 

GTIA or CTIA?

 

In early 1982, Atari began upgrading ist computer models 400 and 800 by using the newer GTIA graphics chip instead of the older CTIA. Execute the following BASIC program:

 

10 GRAPHICS 9

20 GOTO 10

 

If the screen turns blue, your computer has an CTIA chip. If it turns black, that you have an GTIA.

[sloopy]

One way to give a good indication but not 100% answer is to look at the RAM modules. If its two screws holding it in and not thumb latches, then almost for sure not CTIA, if the memory modules are not encased, and have a small plastic 'stabilizer' across the top about .5" wide, then its unlikely you have a CTIA machine... but if you have thumb latches and encased RAM/Personality Modules, then there is a greater chance of CTIA being installed...

 

sloopy.

[Bryan]

Also, if you have the factory RAM size printed on the bottom label, then you have an early machine.

[+Stephen]

From BASIC, you can also do POKE 623,64. If the screen turns black you have GTIA, if no change, CTIA.

[JamesD]

And black it is! YES!

 

Thanks for your help!

[sloopy]

And black it is! YES!

 

Thanks for your help!

 

If you were 'worried' about getting a CTIA machine, then dont... I am sure you would have gotten offers 9 wide of people who would trade a GTIA for a CTIA ;')

 

sloopy.

[Rybags]

Yep - CTIA chip only is probably worth $60 + just for collector value.

[JamesD]

Crap, that would have paid for the machine.

[+Stephen]

I'd sure like to have a CTIA (useless as it is).

[+Ransom]

I feel the pull of useless obscure computer stuff, too. If I had enough space and money, I'd have a complete set of hardware from each iteration set up on its own desk. Then I'd have to open Ransom's Museum of Computer Crap: "And here we have a CTIA-era 800, with its four-board 810 and the other peripherals that were available by the time they discontinued it. Over here, we have the GTIA 800...."

 

Of course, I'd have to do the same thing for the Apple ][ line.

[+poobah]

I feel the pull of useless obscure computer stuff, too. If I had enough space and money, I'd have a complete set of hardware from each iteration set up on its own desk.

 

Don't feel bad, I still have 2 new in the box SyQuest SQ312 10MB MFM removable cart drives (haven't seen an SQ200 cart in a good 15 years)

[heathuser]

Don't feel bad, I still have 2 new in the box SyQuest SQ312 10MB MFM removable cart drives (haven't seen an SQ200 cart in a good 15 years)

 

I know this is ancient, but so is all of our stuff. I just sent you a PM about a swap.

[scitari]

I did a blog post on GTIA where you can try some BASIC programs to demonstrate the additional graphics modes. I would be surprised if your 800 is not GTIA. Good luck!

 

[Mathy]

Hello guys

 

Would Simius' Sophia be able to turn a CTIA into a GTIA?

 

Sincerely

 

Mathy

[Rybags]

In theory a GTIA video emulator such as VBXE could be firmware modified to just ignore the top 2 bits of PRIOR which would remove the GTIA modes.

Though that alone would only be a partial solution - the PM collision stuff would be as per GTIA and in any case VBXE doesn't perform any GTIA functions that are by means of the read-only registers.

 

The other stuff though - the PMG pixel offset which I'm still dubious about would be somewhat harder.

The artifacting differences - VBXE doesn't do either type of artifacting, ie colour type where hires pixels create a colour signal or PAL colour mixing among adjacent scanlines. So this would be equally as hard on others (CTIA has different colour artifacting vs GTIA).

Edited November 4, 2018 by Rybags

[ldelsarte]

Source: Mapping the Atari (online version: https://www.atariarchives.org/mapping/memorymap.php)

See Memory Map of address 623

 

This little BASIC program will find out (CTIA vs. GTIA) and display the result on screen:

10 POKE 66,1:GRAPHICS 8:POKE 709,0:POKE 710,0:POKE 66,0:POKE 623,64:POKE 53248,42:POKE 5326l,3:PUT #6,1
20 POKE 53278,0:FOR K=1 TO 300:NEXT K :GRAPHICS 18:POKE 53248,0:POSITION 8,5:? #6;CHR$(71-PEEK(53252));"TIA"
30 POKE 708,PEEK(20):GOTO 30

You can download it here:

https://www.atariarchives.org/mapping/software/CTIAGTIA.BAS

[Rybags]

I thought it was posted earlier but the easiest way by far - black screen means you got GTIA:

 

POKE 623,64