Homebrew Atari ST ?

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Re: Homebrew Atari ST ?

Postby Cyprian » Wed Mar 16, 2016 5:47 pm

AtariZoll wrote:That's completely wrong. EMUTOS is for ST HW, with it's custom chips, it's FDC, MFP ....
No, you need to make pretty much work on I/O to make it work. Complete BIOS and XBIOS ++ some other things.


nope.
Maybe you are not aware but EmuTOS doesn't need any part of ST hardware.
As I mentioned, there is only needed a small startup code. There you can find amiga's one:
https://sourceforge.net/p/emutos/code/c ... os/amiga.c

And there you can find a binary file emutos-amiga: https://sourceforge.net/projects/emutos ... tos/0.9.5/
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Re: Homebrew Atari ST ?

Postby AtariZoll » Wed Mar 16, 2016 7:06 pm

Cyprian wrote:
AtariZoll wrote:That's completely wrong. EMUTOS is for ST HW, with it's custom chips, it's FDC, MFP ....
No, you need to make pretty much work on I/O to make it work. Complete BIOS and XBIOS ++ some other things.


nope.
Maybe you are not aware but EmuTOS doesn't need any part of ST hardware.
As I mentioned, there is only needed a small startup code. There you can find amiga's one:
https://sourceforge.net/p/emutos/code/c ... os/amiga.c

And there you can find a binary file emutos-amiga: https://sourceforge.net/projects/emutos ... tos/0.9.5/
Works fine under WinUAE


Hey, we talking about Atari ST compatibility here. EmuTOS for Amiga is extension, and must using Amiga OS HW access system calls.
EmuTOS for Atari must have what I said in previous post. How you think that EmuTOS can work without HW access code ? For instance there is floppy access via XBIOS and GEMDOS - what calls XBIOS - there is plenty of code communicating with DNA and FDC chip.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Homebrew Atari ST ?

Postby stimpy » Thu Mar 17, 2016 10:14 am

joska wrote:
stimpy wrote:Yet again more mis-information about FPGAs :shrug:


What are you referring to?


...that supporting tricks used by demos isn't neccesary if the FPGA is configured to be the same as the ST at a logic level. Which the Suska project strives to be.
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Re: Homebrew Atari ST ?

Postby joska » Thu Mar 17, 2016 10:41 am

stimpy wrote:...that supporting tricks used by demos isn't neccesary if the FPGA is configured to be the same as the ST at a logic level. Which the Suska project strives to be.


I would assume that is exactly what "supporting tricks" means. To get overscan/colour changing techniques to work with the ST MIST core two things has to be done (like Troed says):

1. CPU implementation must be cycle exact.
2. The Shifter state machine must be implemented. Currently the Shifter implementation is rather simplified.

Especially (1) is a *lot* of work. I would imagine that the Shifter state machine wouldn't be that much work compared to (1), but pointless without (1).

If the MIST had a real 8MHz 68000 it would be a lot easier to implement the ST core. But then the MIST would be a lot less flexible too.
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Re: Homebrew Atari ST ?

Postby joska » Thu Mar 17, 2016 11:09 am

Cyprian wrote:[Maybe you are not aware but EmuTOS doesn't need any part of ST hardware.
As I mentioned, there is only needed a small startup code. There you can find amiga's one:
https://sourceforge.net/p/emutos/code/c ... os/amiga.c


That's only a small part of it. In order to work on the Amiga EmuTOS has hardware-drivers for the following Amiga Hardware:

- RAM setup, both chip-RAM and fast-RAM.
- Video. Mono only, as the Amiga colour modes has a different layout than the ST. To get colour modes working you'll need a new VDI as well.
- Keyboard.
- Mouse.
- IDE.
- RTC.
- Floppy drives.

The very definition of an OS is to act as a layer between the hardware and the user application. So naturally EmuTOS needs drivers for all supported hardware on all machines it's supposed to work on.
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Re: Homebrew Atari ST ?

Postby simongarstin » Thu Mar 17, 2016 12:25 pm

I missed out Sound and FDC (and probably other things...)

A 1772 FDC IC would be designed...straight from the original schematics probably to allow a floppy drive to be attached, though many people may argue this is not necessary ??

Sound...YM2149 & MIDI (Musical Instrument Digital Interface)

I haven't really put much thought into the Sound part, except for using a YM2149. MIDI should really be included, but as I don't know much about this topic I might miss it out ! Though Many ST user will say it was the MIDI part of the ST that was used the most, especially in the Music industry !


simongarstin wrote:Further Musings about by 6800 design :

CPU
68HC000FN20 safely overclocked to 24MHz to make it approximately 3 times faster than the original ST.

Memory
SRAM
1 Meg as Standard (2pcs 512Kx8bit SRAM 55ns or 70ns 1 WAIT state) with expansion to 8Meg +. Memory map will be similar if not identical to ST. Memory Mapper will be in one of the EPM7128SLC84s Glue logic.

ROM/EPROM
1 Meg ROM (2pcs 29C040 or similar 55ns or 70ns 1 WAIT state) running at the same speed as the SRAM :
1/2 Meg ROM (2pcs 27C020 or similar 55ns or 70ns)

Glue Logic / video etc will be done using Two or three low cost EPM7128SLC84 CPLD. One being used solely as a video Generator (Video Shifter) to give Bitmapped video Modes.

I/O Mapping
as Many peripheral chips , video registers etc will be memory Mapped as original ST again this logic will be in one of the EPM7128SLC84s used. Necessary WAIT states done using the Glue logic.

Video Generation:
One CPLD wil be used to generate bitmapped ST compatible video modes (plus enhanced modes) GENLOCKED, synchronized with the second VDP V9938. I'm using the V9938 simply because they are readily available (plentiful & Cheap) , plus allow themselves for Superimpose function and have sprites etc. The CPLD (EPM7128SLC84) will give digital RBG output which will be fed to DACs to give analogue RBG. This will then go to a CXA1645 to give buffered RGB and composite outputs. The YS signal on the V9938 will switch between video outputs (via analogue switches) to give Superimpose. This should give graphics that can compete with practically any AMIGA !

Blitter: No Blitter functionality has been thought of. But I suppose the functions of the BLITTER could be emulated by using a powerful low cost micro-controller.

68901 MFP
Two 68901 will be implemented as in the TT ?

6850
Two used as in original ST memory mapped as ST

8255 CF/IDE interface For CF Card or IDE hard Drive. Using spare (Free) Memory I/O

68882 FPU ?? Probably not implemented

Atmega88 for redading SD Card and could be used as a BLITTER chip to do block moves of video RAM.

AT89C2051 PS/2 keyboard and Mouse trying to maintain compatibility with original keyboard and mouse though this may be tricky. May just copy original circuit from schematics to maintain 100%c keyboard compatibility.

Operating System :
Writing an Operating System or modifying an existing one would be a project in itself, so I'd probably just write a simple test/demo program to test the hardware to show the system works before worrying about this.

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Re: Homebrew Atari ST ?

Postby ryan » Thu Mar 17, 2016 12:27 pm

The combination of the 68k and the V99xx series sounds a lot like the Kiwi machine, though that used the 68008 (which is easier to interface on account of lower pin count). That at least shows it is possible for a 'regular person' to design and build such a system, and his plans could be a starting point.

Kiwi: https://www.ist-schlau.de/

We have in EmuTOS a compact and easy to understand open source single-tasking operating system for 68k & ColdFire architecture computers. That's a pretty great achievement. I think it's a worthy goal to pursue porting it to other, non-Atari 68k machines. And building a homebrew 68k workstation is also a great idea.The Kiwi is a great example of that, and I believe the author of that machine had emutos booting, though he didn't finish (didn't get graphics output done I think).

With the right drivers written it should be possible to run the (very few) programs that are written as well-behaving GEM/TOS applications not depending on specific hardware, resolutions etc. I wouldn't discourage anybody from doing that, or writing new such programs. It can only benefit the community.

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Re: Homebrew Atari ST ?

Postby AtariZoll » Thu Mar 17, 2016 12:50 pm

simongarstin wrote:I missed out Sound and FDC (and probably other things...)
...
A 1772 FDC IC would be designed...straight from the original schematics probably to allow a floppy drive to be attached, though many people may argue this is not necessary ??
...

Well, you did not miss to quote that long list - don't know why was that necessary ?
Here is what I think, and call me negative or whatever: only designing 1772 clone chip - I guess that it is the goal instead using that chip, what is still available, or acquirable will be extremely hard. To make it 100% like original is almost impossible - it's pretty much complex chip, in fact some microcontroller.
Myself is in this years about to stop using floppies at all even on old Ataris - on PC I did not use it over decade, except for retro computer data transfer, and writing retro SW on floppies. So, maybe better would be to forget floppy controller, and going on floppy emulation. You plan some mass storage for it, so that's possible. Support for ST format is really not hard - I did it already.

What I wrote to Cyprian was just example, first thing what came to mind. Since it will be not low level ST compatible, really don't see need support for floppy in 2016 .
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Homebrew Atari ST ?

Postby rpineau » Thu Mar 17, 2016 3:40 pm

8255 PIO (IDE interface) $1.7

I really think the IDE port(s) should be done in the CPLD, not with old crappy slow 8255.

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Re: Homebrew Atari ST ?

Postby ryan » Thu Mar 17, 2016 3:44 pm

If we're talking homebrew TOS/GEM machines, I personally would rather see another ColdFire system after the Firebee, but with the price dropped a bunch somehow, maybe by eliminating the legacy ST/TT ports. And while in there adding a larger newer FPGA. Basically a MiST with larger FPGA, DVI output, a ColdFire processor so the CPU doesn't need to be done on the FPGA, and more RAM maybe.

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Re: Homebrew Atari ST ?

Postby joska » Thu Mar 17, 2016 6:57 pm

Why ColdFire? Yes, it's fast but not if you need real 68k compatibility. The Vampire accelerator project for the Amiga has demonstrated that you can have a really fast 68k in a reasonably priced FPGA.
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Re: Homebrew Atari ST ?

Postby joska » Thu Mar 17, 2016 7:03 pm

simongarstin wrote:After Further research I've now done some costings for my 68000 System (Atari ST type Clone )


I've managed to source many of the ICs I needed either as NOS or Working pulls bypassing ebay and other sources to go direct to suppliers:


I think you have to start by deciding what you want to build. A real ST-compatible computer that runs TOS, or a 68000-based computer that somewhat resembles the ST with a port of TOS/EmuTOS?

I believe it will be a bit more work to build an actual ST, but with the advantage that TOS and ST-software runs stable without modifications. A somewhat ST-compatible computer with a TOS-compatible OS could be simpler to make, but would require a *lot* of work to get the software up and running.

Personally I would have built a real ST clone with some extended features. If you want to use a much "real" chips as possible then get yourself an ST, and start by replacing the GLUE, MMU and DMA with FPGA/CPLD replacements. When the ST runs properly with these chips you can start building the ST clone.
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Re: Homebrew Atari ST ?

Postby Cyprian » Thu Mar 17, 2016 7:05 pm

ryan wrote:I personally would rather see another ColdFire system after the Firebee

unfortunately ColdFire has problems with 68000 compatibility. You have to use 68k emu or recompile programs.
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Re: Homebrew Atari ST ?

Postby ryan » Thu Mar 17, 2016 7:52 pm

I don't actually personally care about compatibility. That's what emulators are for. For me there's a certain interest/charm in a "new" machine built by the community that continues the 68kish TOS/GEM architecture. It's why I find the Firebee interesting. It has little use as a clone or to run most existing software, but is a kind of continuation of the product line.

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Re: Homebrew Atari ST ?

Postby Cyprian » Thu Mar 17, 2016 8:11 pm

ryan wrote:I don't actually personally care about compatibility. That's what emulators are for.

you are mixing two different things - ST hardware compatibility with CPU compatibility.
You are talking about the first one, I'm talking about the second one.
ColdFire isn't compatible (or compatibility is really low) with 68000. Therefore in order have "68kish TOS/GEM architecture", ColdFire has to emulate 68000 instructions.
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Re: Homebrew Atari ST ?

Postby ryan » Thu Mar 17, 2016 8:45 pm

That's not true, as EmuTOS can be compiled native ColdFire, and it's a trivial recompilation for most TOS/GEM applications as well. Yes it's not 100% binary compatibility, but for a new machine with different specs one would probably want to recompile with modifications anyways.

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Re: Homebrew Atari ST ?

Postby joska » Thu Mar 17, 2016 8:50 pm

Sounds like you don't own a Firebee... There's only two ways to run ST software on Coldfire:

1. CPU emulation.
2. Recompiling for Coldfire.

As sources for 95% of usable ST software is lost forever (2) is not really an option. That is the main reason why my Firebee runs FireTOS (which has CPU emulation) and not EmuTOS (which doesn't).

Nobody makes software for TOS anymore, so *binary* compatibility is a must. Without that the machine is pointless.
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Re: Homebrew Atari ST ?

Postby Cyprian » Thu Mar 17, 2016 9:06 pm

ryan wrote:That's not true, as EmuTOS can be compiled native ColdFire, and it's a trivial recompilation for most TOS/GEM applications as well. Yes it's not 100% binary compatibility, but for a new machine with different specs one would probably want to recompile with modifications anyways.


I agree with you. Due to incompatibility between CF and 68k, you can't directly use Motorola 68k EmuTOS binary on CF and CF EmuTOS binary on Atari platform. You have use CF or 68k target during compiling.

I have no problem with any non 68k platform, moreover I'd like to have full native TOS environment for Android/Windows/Ubuntu. Also I really like FireBee.
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Re: Homebrew Atari ST ?

Postby AtariZoll » Thu Mar 17, 2016 9:13 pm

I agree with Joska. Doing some enhanced ST would be the best thing. Not STE improvements, but something other, new ideas. While it would be compatible in HW level - with video, PSG chip, IKBD chip - very important. That will assure that most of SW running. Floppy is something what is now really not a must - considering all adapted SW for mass storage.
I really don't see that if you go on regular 68000 CPU, why avoid ST custom chips - at least IKBD should be used. And you will certainly not need 10000 pieces of ...
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Homebrew Atari ST ?

Postby amark » Sat Mar 19, 2016 10:09 am

Is anyone else designing/building a Homebrew Atari ST machine ? I know there's been quite a few professional Clones of the ST over the years, but are there any genuine homebrew machines, with PCB etc. to build yourself ?

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Re: Homebrew Atari ST ?

Postby exxos » Sat Mar 19, 2016 10:16 am

amark wrote:Is anyone else designing/building a Homebrew Atari ST machine ? I know there's been quite a few professional Clones of the ST over the years, but are there any genuine homebrew machines, with PCB etc. to build yourself ?


Nope. I design addons for the ST range, I have contemplated doing a new motherboard in the past and even updating the design. Though then it just gets back over to designs like MiST etc when FPGA starts getting involved. Even if a new clone was done, its a huge board, not going to be cheap to get done, small fortune for the chips and assembly. So other than the FPGA clones, or addons for real hardware, its not really viable to produce anything else, not unless you have unlimited deep pockets.
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Re: Homebrew Atari ST ?

Postby AtariZoll » Sat Mar 19, 2016 10:41 am

Yes, thing fails mostly because component prices. + large PCB price - but it is component too in fact. Same is with assembling bicycle from bought components - it will always cost more than assembled factory one, or almost anything what industry makes.
So there is good reason why it was not made. Just makes no sense. Time spent on doing it can be spent on doing expansions, mods and like - and that is what is done many-many times.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.

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Re: Homebrew Atari ST ?

Postby amark » Sun Mar 20, 2016 9:48 am

I was thinking of designing and building my own 68000 homebrew system, so just thought I'd stick my two cents in !

My Design

680000P DIP64 CPU (clocked at 12.5MHz)
Two 68901 MFP
Two 6850 ACIA
68882 FPU
Several Meg SRAM
At least 1 Meg ROM
EF4000 Video Card
YM2149 PSG
Glue logic + MMU etc on a CPLD
1772 FDC for floppies
SD interface for Storage
IDE interface
Real Time Clock (Clock/Calendar)
RS232 ports
Parallel ports
Joysticks ST compatible
Mouse ..maybe PS/2
Keyboard maybe PS/2
PSU (power supply : external switch mode)

All ICs would be in DIP , except probably the CPLD for easier breadboarding/prototyping !

Some parts of the of the design I'd plagiarize (Copy) from ST schematics.. though it wouldn't be ST compatible it would have a lot of similarities with the original ST.

Still on the drawing board...a work in progress at the moment.

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Re: Homebrew Atari ST ?

Postby simongarstin » Mon Mar 21, 2016 1:41 pm

After a lot of research here are my initial conclusions to a homebrew Atari ST (68000) system.

Can a homebrew 68000 (Atari ST)system be built by a hobbyist at a sensible price : Answer is YES ! I've proven that the components are easy to source and can be obtained quite cheaply. Making a System using DIP ICs are easier to breadboard, but PLCC stuff is more modern and usually NOS. It can be done for around $150 or less as the ICs and stuff are pretty cheap. All-in-all it should be achievable !

All I have to do now is , order the ICs start to breadboard my designs and get 'Stuck-in' ..

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Re: Homebrew Atari ST ?

Postby AtariZoll » Mon Mar 21, 2016 3:04 pm

amark wrote:I was thinking of designing and building my own 68000 homebrew system, so just thought I'd stick my two cents in !

My Design

680000P DIP64 CPU (clocked at 12.5MHz)
Two 68901 MFP
Two 6850 ACIA
68882 FPU
Several Meg SRAM
At least 1 Meg ROM
EF4000 Video Card
YM2149 PSG
Glue logic + MMU etc on a CPLD
1772 FDC for floppies
.....


In my opinion far better concept. It will be pretty much ST compatible. Even if price will be much higher than the price of other project here, that's worth.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.


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