Atari ST Display Basics

All information relating to connecting your ST to a modern TV/monitor.
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IngoQ
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Re: Atari ST Display Basics

Post by IngoQ »

exxos wrote: Sun Mar 18, 2018 1:02 pm I just checked pin 8 on STE & STM is via 1.2K resistor. Assuming a typo Ingo ?
In only have a STE, the information about the 520ST having GND connected on Pin 8 is based on this pinout:

http://info-coach.fr/atari/hardware/int ... _connector

Since it is obviously wrong I corrected it.

I did a little research, and found that many sites show this wrong pin out. This page did a little research where this mistake actually came from, and it seems to be based on the Book "The Concise Atari ST Programmer's Reference Guide" by Katherine D. Peel, ISBN 1 85181 017 X.
Ingo :geek:

| Atari 1040STE@32MHz | Amiga 1200 (ACA1220) | Atari 800XL (U1MB, SIDE2) | Atari 130XL (Sophia DVI) | C64 (1541 Ultimate II, Rev3 RFMod Replacement) | TI 99/4A (F18A, 32k, FlashROM 99) | Sinclair ZX Spectrum 128 (Stereo, DivMMC) | Amstrad CPC664 (512k, M4 Wifi) | ... |
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Re: Atari ST Display Basics

Post by IngoQ »

Yep, here it is:
2018-03-18 14_19_32-The_Concise_ST_68k_Prog_Ref_Guide.pdf.png
2018-03-18 14_19_32-The_Concise_ST_68k_Prog_Ref_Guide.pdf.png (342.92 KiB) Viewed 9261 times
Ingo :geek:

| Atari 1040STE@32MHz | Amiga 1200 (ACA1220) | Atari 800XL (U1MB, SIDE2) | Atari 130XL (Sophia DVI) | C64 (1541 Ultimate II, Rev3 RFMod Replacement) | TI 99/4A (F18A, 32k, FlashROM 99) | Sinclair ZX Spectrum 128 (Stereo, DivMMC) | Amstrad CPC664 (512k, M4 Wifi) | ... |
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Re: Atari ST Display Basics

Post by IngoQ »

What confuses me further is, that Atari calls pin 8 in their schematics "mode switch". Since it is only connected to 12V this does not make any sense to me. One could assume that this is the signal that pin4 needs to switch to mono mode. But this would be GND, so why "mode switch"?
Ingo :geek:

| Atari 1040STE@32MHz | Amiga 1200 (ACA1220) | Atari 800XL (U1MB, SIDE2) | Atari 130XL (Sophia DVI) | C64 (1541 Ultimate II, Rev3 RFMod Replacement) | TI 99/4A (F18A, 32k, FlashROM 99) | Sinclair ZX Spectrum 128 (Stereo, DivMMC) | Amstrad CPC664 (512k, M4 Wifi) | ... |
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Re: Atari ST Display Basics

Post by exxos »

IngoQ wrote: Sun Mar 18, 2018 1:20 pm Yep, here it is:
So we have a bit of a mystery then... At this point I would assume the image has the wrong info there.. Though unless someone comes across a ST with no 12V on pin 8.. then there must be some "early early" design out there which pre-dates even the schematics..
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Re: Atari ST Display Basics

Post by IngoQ »

Found a possible explanation... SCART uses a 12V signal to differentiate between RGB and composite inputs. As you can see i.e. here, many SCART cables use pin 8 to provide these 12V. And on SCART connectors, this is actually called "mode switch".

So my theory would be, that this was actually intended by Atari. But this would leave us with absolutely no reason, why any machine would NOT have 12V on this pin.
Ingo :geek:

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Re: Atari ST Display Basics

Post by troed »

troed wrote: Sun Mar 18, 2018 1:13 pm (I've started to doubt what my 520STM does. I'm currently running it on 5V only waiting for a picoPSU to arrive, so it obviously cannot put out 12V .. )
I guess we'll need to find someone with a 260ST to see what they had on pin 8 ;) Now with the picoPSU connected to my 520STM I can verify that it has 12V, as the schematics say it should.

/Troed
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Re: Atari ST Display Basics

Post by displaced »

Hi! Just a small addendum/correction:

I have a UK 520STFM and Pin 2 definitely has a composite signal, despite this being indicated as STE-only.

I don’t have the board revision to hand, but it’s the odd one with the TOS ROMs under the PSU, with the RAM chips below (where ROMs are on most boards)
A bunch of Ataris and others:
Atari XEGS with RGB mod - STFM - Portfolio - Lynx Mk1 with McWill display - Mega STE - Falcon030 - Jaguar
Commodore VIC-20 CR with ClearVideo - CDTV (Wicher 8MB+IDE)
Acorn Electron - Archimedes A3020
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Re: Atari ST Display Basics

Post by rubber_jonnie »

displaced wrote: Thu Jan 03, 2019 9:26 am Hi! Just a small addendum/correction:

I have a UK 520STFM and Pin 2 definitely has a composite signal, despite this being indicated as STE-only.

I don’t have the board revision to hand, but it’s the odd one with the TOS ROMs under the PSU, with the RAM chips below (where ROMs are on most boards)
Is it one of these: https://www.exxosforum.co.uk/forum/viewt ... f=56&t=717
?
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: Atari ST Display Basics

Post by displaced »

rubber_jonnie wrote: Thu Jan 03, 2019 11:45 am Is it one of these: https://www.exxosforum.co.uk/forum/viewt ... f=56&t=717
?
That's the one -- a C103253. Mine's a C103253 Rev. 1
A bunch of Ataris and others:
Atari XEGS with RGB mod - STFM - Portfolio - Lynx Mk1 with McWill display - Mega STE - Falcon030 - Jaguar
Commodore VIC-20 CR with ClearVideo - CDTV (Wicher 8MB+IDE)
Acorn Electron - Archimedes A3020
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Re: Atari ST Display Basics

Post by rubber_jonnie »

displaced wrote: Thu Jan 03, 2019 11:54 pm
rubber_jonnie wrote: Thu Jan 03, 2019 11:45 am Is it one of these: https://www.exxosforum.co.uk/forum/viewt ... f=56&t=717
?
That's the one -- a C103253. Mine's a C103253 Rev. 1
Yeah, seems to be a bit of an oddity that one, I ended up using mine as a test board for my PAK 68/2 accelerator. I will say it has been very stable and reliable.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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