32,768 Color Video Shifter for Atari ST Computers…

[jericho_21]

Hello, everybody,

 

I was on Marcello "Vezz" Vezzelli's website recently about Atari ST Hardware Hacks. He mentions how to create a 32,768-color video shifter that is said to be available for any Atari ST-compatible computer. The documentation was written by Barry Orlando, who at the time of the text was living in Napa, California. I would have to contact him to get the schematics for the video shifter. However, he no longer lives where he stated he lived at that time. So, here is my question. Does anybody have any information on where I can get those schematics so I can eventually build my own video shifter and extend the color palette on my 1040STE? If anyone knows, and can get me that information, I would be most grateful. I have been wondering for years about it. Thank you for reading this post. Appreciated, as always.

Edited February 4, 2016 by jericho_21

[+DarkLord]

Is that the one that takes a standard ST palette of 512 and takes it to 4096? If so,

isn't it basically like installing -2- shifters and both running together? Seems like I

recall a commercial version that was released way back in the day based on this

concept too - JRI or somebody like that?

[Lynxpro]

Is that the one that takes a standard ST palette of 512 and takes it to 4096? If so,

isn't it basically like installing -2- shifters and both running together? Seems like I

recall a commercial version that was released way back in the day based on this

concept too - JRI or somebody like that?

 

JRI ST4096C Board.

 

Too bad it didn't allow for matching - or surpassing - the Amiga 32-colors per screen mode. Same goes for the STe's graphics. That was a major let-down and I still don't understand the "compatibility" argument with older STs. Games would've just had an "enhanced" or "STe version" for better support just as STe enhanced games ended up with better sound in the real world.

 

Ugh…what was Atari Corp smoking? [or snorting].

[galax]

Barry Orlando's description is fairly complete, I can work out how some of the components would be connected but not all, I'm sure someone with better knowledge of electrical components than me could work out the circuit diagram from the parts list: http://cd.textfiles.com/carousel/ATARI/STZ0915.TXT

[jericho_21]

Thanks for the information, Galax. I did download the text from that link you posted. I wonder if anyone can find Barry Orlando, if he is still alive. He would know more than anything about a complete and more detailed schematic that would be easier to understand. That would definitely help not only me, but others that seriously want to extend the capabilities of their ST computers.

[Lynxpro]

Did it have a socket for a Blitter?

 

If not, that would be a helpful addition if anyone wishes to clone these boards. It would definitely be interesting to be able to add STe'ish graphics capabilities to non-STe machines. Figure out a way to get the STe's DMA chip into an ST and add the Enhanced Joystick Ports and you're talking about some worthy upgrades.

 

Interestingly enough, I noticed one of the users at Atari Forum in their signature block state they have a Mega STE with DSP. If they figured out how to add the Falcon's DSP to their rig, that would also be an interesting topic to broach.

[galax]

Did it have a socket for a Blitter? [...] STe's DMA chip into an ST and add the Enhanced Joystick Ports

No, this modification is just about expanding the number of available colours in the palette. Some STF[M]s have solder pads for a blitter socket, but given how little it is used few people bother soldering in the socket, let alone hacking up an earlier ST to solder in a blitter. Same for the enhanced joystick ports, they're barely used so hacking them into an earlier ST is probably possible but seems like a bit of a waste of time. The STE doesn't have a separate chip for DMA sound- it's integrated into the video shifter, so you'd have to replace the ST's shifter with the STE's. How many hundreds of hours would you be willing to spend to turn a $50 ST into a less stable version of a $50 STE?

 

Mega STE with DSP

I've seen someone talk about a Mega ST with DSP. I doubt it would be compatible with software written for the Falcon's DSP though, you'd be left writing your own DSP code with one of these.

[Lynxpro]

No, this modification is just about expanding the number of available colours in the palette. Some STF[M]s have solder pads for a blitter socket, but given how little it is used few people bother soldering in the socket, let alone hacking up an earlier ST to solder in a blitter. Same for the enhanced joystick ports, they're barely used so hacking them into an earlier ST is probably possible but seems like a bit of a waste of time. The STE doesn't have a separate chip for DMA sound- it's integrated into the video shifter, so you'd have to replace the ST's shifter with the STE's. How many hundreds of hours would you be willing to spend to turn a $50 ST into a less stable version of a $50 STE?

 

I've seen someone talk about a Mega ST with DSP. I doubt it would be compatible with software written for the Falcon's DSP though, you'd be left writing your own DSP code with one of these.

 

All good points. I thought I'd just ask since some upgrade boards offer multiple upgrading options in order to save space. Like some CPU upgrade boards will include an FPU socket and a Blitter socket. It would seem to me a graphics upgrade board from that era would've thrown in a Blitter socket since so many ST owners did want a Blitter upgrade available then.

 

Thanks for the clarification on DMA support. I'd imagine swapping out an ST Shifter for an STE Shifter wouldn't be possible since the STE's version probably has different lines on the motherboard.

 

As for an Enhanced Joystick Port option, if more people had them, then it might compel the software patchers to add support for them. You do make a point about just buying an STE but they are far more limited in numbers than STm/STf/STFM/Mega models out there.

[galax]

The circuit diagrams are all available, so with enough wire and a few components anything is possible! I'd be impressed and amazed if someone completed something like this, but it's a huge amount an most people want to spend their effort making something new. It'd probably involve killing a few STs though as the modifications would be extensive, and may involve some expensive components or recycled STEs (which would be a bit counter-productive, just fix the STE instead!)

 

Yeah they are very different- the ST's shifter is an oblong 40 pin DIP but the STE's shifter is in an 84 pin square PLCC package, using the STE's shifter in an older ST would involve quite a bit of work.

 

 

The Enhanced joystick ports have quite a few extra components (shown below), but the real stumbling block is that they feed into the STE's custom 144 pin GST MCU (GLUE MMU) chip, which is also involved in the DMA stereo sound and decoding an optical pen (what were they thinking?!) - so at this point for these modifications it looks like the ST's GLUE logic, MMU and shifter would have to be replaced with the STE's - getting to the point where we may as well just manufacture an STE circuit board and bring a few components over from the old ST.

 

Edited February 12, 2016 by galax

[Lynxpro]

The circuit diagrams are all available, so with enough wire and a few components anything is possible! I'd be impressed and amazed if someone completed something like this, but it's a huge amount an most people want to spend their effort making something new. It'd probably involve killing a few STs though as the modifications would be extensive, and may involve some expensive components or recycled STEs (which would be a bit counter-productive, just fix the STE instead!)

 

Yeah they are very different- the ST's shifter is an oblong 40 pin DIP but the STE's shifter is in an 84 pin square PLCC package, using the STE's shifter in an older ST would involve quite a bit of work.

 

ST shifter.pnggst-shifter1.jpg

 

The Enhanced joystick ports have quite a few extra components (shown below), but the real stumbling block is that they feed into the STE's custom 144 pin GST MCU (GLUE MMU) chip, which is also involved in the DMA stereo sound and decoding an optical pen (what were they thinking?!) - so at this point for these modifications it looks like the ST's GLUE logic, MMU and shifter would have to be replaced with the STE's - getting to the point where we may as well just manufacture an STE circuit board and bring a few components over from the old ST.

 

Enhanced Joysticks Ports.png

 

Without having seen the other diagrams, I'd have to speculate Atari Corp did something else with the Enhanced Joystick Ports on the Falcon. That's disappointing and explains why nobody tried adding the Enhanced Joystick Ports through a cartridge port device plug-in.

 

I'd say the optical pen option would be for light gun support as was done with the Atari 8-bit computers.

[galax]

Without having seen the other diagrams, I'd have to speculate Atari Corp did something else with the Enhanced Joystick Ports on the Falcon. That's disappointing and explains why nobody tried adding the Enhanced Joystick Ports through a cartridge port device plug-in.

The Falcon EJP schematic is very similar to the STE, except it feeds into the Falcon's COMBEL instead of the STE's GST MCU: http://dev-docs.atariforge.org/files/Falcon030_Schematic.pdf (COMBEL on page 3, EJP on page 4)

Edited February 12, 2016 by galax

[Lynxpro]

 

I've seen someone talk about a Mega ST with DSP. I doubt it would be compatible with software written for the Falcon's DSP though, you'd be left writing your own DSP code with one of these.

 

Mystery solved.

 

Digidesign made a board for the Mega ST Megabus so it could be plugged into the SoundTools Sound Accelerator which had a Motorola 56K DSP inside it.

 

http://www.atarimania.com/utility-atari-st-sound-tools_s17566.html

 

http://duc.avid.com/showthread.php?t=293936

 

http://www.verycomputer.com/10_87d269d84dd19ffa_1.htm

 

http://atari-forum.com/viewtopic.php?t=6308