Homebrew Atari ST ?

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Re: Homebrew Atari ST ?

Postby AtariZoll » Mon Mar 07, 2016 7:26 pm

There are 2 problems: thread is called homebrew Atari ST, and then OP and arf come with 68000 based computer board. None is even near ST compatible. Then, what's the point to do 68000 based computer almost 40 years after CPU release ? To run some Linux in textual mode ?
Do ST compatible project, please. This is Atari forum after all. Or rename thread.
Point of whole thing is to make something what can run existing ST SW base in big part - that's what is achieved with Milan .... Firebee , MIST.
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 Foxie » Mon Mar 07, 2016 9:31 pm

AtariZoll wrote:I would not call it homebrew, even if end user assembles it self - doing those cards in that compact format is almost impossible at home.


I think this is a common misconception. I'm really terrible at soldering, but I've seen plenty of videos on Youtube where amateurs are soldering multiple 0.5mm pitch devices to their own home-etched PCBs without any solder resist. That's much finer than anything in the ST. The secret seems to be lots and lots of liquid flux, and a big magnifier lamp. You don't actually solder each pin individually, you put a small dab of solder on the iron and "drag" it across all the pins, and the liquid flux ensures that no solder bridges are formed. Those who have done it report that surface mount is actually easier to work with than DIP.

I've also heard reports of people doing BGAs at home, using a toaster oven. That requires a commercially-made PCB, for all those through-plated vias. Stick to the QFPs I say. You can do those on a single-sided home-etched board.

I'm a bit puzzled why the OT wants to use CPLDs yet not put everything into a single FPGA? Is this so you can use older CPLDs available in PLCC packages? The big problem with CPLDs is going to be the number of registers. Something like the shifter chip with all its palette registers would consume a big CPLD all by itself. FPGAs are quite different, they have many more registers per unit of logic.

What I would like to see is an ST built entirely of TTL devices. Maybe use the floppy controller, sound chip and MFP, but absolutely none of the ST custom chips. This is totally practical - remember, the first prototype STs were done this way. Heck, even the Amiga was prototyped out of several wire-wrapped TTL boards before any of the custom chips were produced. That's even more impressive when you consider that the Amiga has very few off-the-shelf chips, even the floppy controller had to be implemented with TTL logic in the prototype.

The result would be rather large - and certainly very power hungry - but that's the point. It's kind of disappointing that an ST or Amiga can be powered with a measly 10 watts. You get a much better "feel" of the hardware when it consists of hundreds of chips drawing thousands of watts.

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Re: Homebrew Atari ST ?

Postby exxos » Mon Mar 07, 2016 9:55 pm

deja-vu....If only the MMU, shifter, glue logic was published, it would make so many hardware mods so much easier and quicker to develop.....
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Re: Homebrew Atari ST ?

Postby AtariZoll » Tue Mar 08, 2016 7:43 am

Foxie wrote:I think this is a common misconception. I'm really terrible at soldering, but I've seen plenty of videos on Youtube where amateurs are soldering multiple 0.5mm pitch devices to their own home-etched PCBs without any solder resist. That's much finer than anything in the ST. The secret seems to be lots and lots of liquid flux, and a big magnifier lamp. You don't actually solder each pin individually, you put a small dab of solder on the iron and "drag" it across all the pins, and the liquid flux ensures that no solder bridges are formed. Those who have done it report that surface mount is actually easier to work with than DIP.

I've also heard reports of people doing BGAs at home, using a toaster oven. That requires a commercially-made PCB, for all those through-plated vias. Stick to the QFPs I say. You can do those on a single-sided home-etched board.

I'm a bit puzzled why the OT wants to use CPLDs yet not put everything into a single FPGA? Is this so you can use older CPLDs available in PLCC packages? The big problem with CPLDs is going to be the number of registers. Something like the shifter chip with all its palette registers would consume a big CPLD all by itself. FPGAs are quite different, they have many more registers per unit of logic.

What I would like to see is an ST built entirely of TTL devices. Maybe use the floppy controller, sound chip and MFP, but absolutely none of the ST custom chips. This is totally practical - remember, the first prototype STs were done this way. Heck, even the Amiga was prototyped out of several wire-wrapped TTL boards before any of the custom chips were produced. That's even more impressive when you consider that the Amiga has very few off-the-shelf chips, even the floppy controller had to be implemented with TTL logic in the prototype.

The result would be rather large - and certainly very power hungry - but that's the point. It's kind of disappointing that an ST or Amiga can be powered with a measly 10 watts. You get a much better "feel" of the hardware when it consists of hundreds of chips drawing thousands of watts.


I did not mean soldering - you are right about people very skilled in it. Making quality, high density board is what is hard without special equipment.

Considering building ST entirely, or mostly of TTL (well, I guess that you will allow some HC(T) chips too :mrgreen: ) - that's almost insane idea. Of course that in development of ST something like that was used - I seen those photos with Shiraz Shivjy too. You must test whole logic before doing expensive production of custom chips. I will not comment your fascination with power hunger and feel of hardware - maybe your heating in room is just broken ? :D That would be really lot of work, in often dark areas. Certainly could help in reverse engineering of ST custom chips, but never enough accurate - just because you will never achieve close enough timings, gate delays.

So, just another "I would like to see" idea. Go on and do it self. I think that all it can be done, and actually is done in big part with FPGA - that's what is practical.
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 Mark123 » Tue Mar 08, 2016 4:46 pm

Maybe a little bit off topic but for example here in Finland working real Atari St/STE s are becoming more and more hard to find. So if there is not going to be any re-production on St like for example c64 has had, in the future most workin st-compatible machines are probably some kind of fpga clones :D
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Re: Homebrew Atari ST ?

Postby simonsunnyboy » Tue Mar 08, 2016 4:53 pm

Mark123 wrote:Maybe a little bit off topic but for example here in Finland working real Atari St/STE s are becoming more and more hard to find. So if there is not going to be any re-production on St like for example c64 has had, in the future most workin st-compatible machines are probably some kind of fpga clones :D



IMHO this is the exact use case of the MiST.
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Re: Homebrew Atari ST ?

Postby penguin » Tue Mar 08, 2016 9:09 pm

arf wrote:There were homebrewed STs in the beginning, e.g. the IPB 190ST or a commercial version, the Rhothron ST - both in a 19" rack case, built from Europa-card-modules, with several extensions. The building of the IPB has been described in a magazine. A later version of it, run by a 68020 cpu, is described in the German http://stcarchiv.de/stm1991/06/190st-020 ST-Magazin 1991/06.

This article mentions two other clones, the ESTE 1 from Musik Konkret and the Mega Station from Hybrid Arts: http://stcarchiv.de/stm1989/08/datenaustausch

See also
https://randoc.wordpress.com/2015/05/17/ibp-190st/
http://wiki.newtosworld.de/IBP_190_ST
http://dieter.lerntux.de/index.php/computer/hardware/9-ibp190-st


No, these weren't homebrew STs, they were professional modifications of the 1040ST and Mega ST for the industry and musicians. All the original ST chips were used with Atari's blessing. The closest thing to a 80's/early 90's homebrew ST was the Elrad ST, which is similar to the IBP ST. but could be built at home.
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Re: Homebrew Atari ST ?

Postby simongarstin » Tue Mar 15, 2016 9:53 am

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:

Best Prices I've sourced so far :

MC68HC000FN20 PLCC $2.0/ea
MC68000P10 or HD68000P10 DIP $2.0/ea
512Kx8 bit SRAM (AS6C4008,HM628512,KM684000 etc) DIP $3.5/ea
512kx8bit EEPROM (SST39LF040,27C040,MX29C040 etc) DIP $1.7/ea
512kx8bit EEPROM (SST39LF040,27C040,MX29C040 etc) PLCC $1.7/ea
256K EPROM/EEPROM 27C020 DIP/PLCC $1.0 each
EPM7128SLC84 $2.0 each PLCC84
6850 ACIA DIP $1.7/ea
6850 PLCC $1.7/ea
MC68901 DIP $2.5/ea
MC68901 PLCC $2.5/EA
AtMega88 DIP/PLCC $2.5/EA ATMEGA88V-10PU
DS12C887 DIP $2.5/ea
8255 DIP $1.7/ea
8255 PLCC $1.7/ea
V9938 DIP64 $5.5/ea
CXA1645 PAL/NTSC Encoder DIP $1.0 each
YM2149 DIP $2.0/ea or less
1772 / WD1772 FDC DIP/PLCC $5.5/ea

Based on these prices my specification :

MC68HC0000FN20 PLCC68 $2.0
2 pcs 512K SRAM :1 Meg RAM (Min) ideally 8 Meg $7.0
2pcs 512K EPROM/EEPROM (1 Meg) $3.4
2pcs 256K EPROM $2.0
3pcs EPM7128SLC84, Glue logic, Memory,I/O Decoder, video Shifter etc $6.0
6850 2pcs $3.4
68901 2pcs $5.0
8255 PIO (IDE interface) $1.7
DS12C887 RTC $2.50
V9938 + VRAMs $7.0
AtMega88 MCU $2.50
AT89C2051 MCU $1.0
YM2149 $2.0
SN76489 $0.50
DACs,Regulators etc $10.0

Total Cost of ICs should be around the $55.0 mark.

IC Sockets, Connectors etc should cost about $25.0

I still haven't calculated the cost of a PCB, but I'm hoping the TOTAL cost will be less than $150, all going well !

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Re: Homebrew Atari ST ?

Postby AtariZoll » Tue Mar 15, 2016 10:29 am

Simongarstin, I wish you good luck with that project. I don't think that price of components is what is most important here. But it is in range of fully assembled MIST. What self is not promising considering possible sales or people going to build it.
As is pointed by many here, ST compatibility level is the problem.
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 simongarstin » Tue Mar 15, 2016 12:06 pm

This Project is not about making a 100% compatible Atari ST , nor even making a Super 68000 System ! It's about the learning Curve of Building, Designing etc a Homebrew Computer, in this case based on the marvellous Atari ST. OK it may be Doomed to fail like a lot of homebrew computers, but if one doesn't try then one will never succeeded.

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Re: Homebrew Atari ST ?

Postby alexh » Tue Mar 15, 2016 2:39 pm

exxos wrote:deja-vu....If only the MMU, shifter, glue logic was published, it would make so many hardware mods so much easier and quicker to develop.....

It may have never been published but it has been reverse engineered at least twice for MiST and Suska and the HDL description of them is freely available.

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Re: Homebrew Atari ST ?

Postby Cyprian » Tue Mar 15, 2016 3:38 pm

simongarstin wrote:This Project is not about making a 100% compatible Atari ST , nor even making a Super 68000 System ! It's about the learning Curve of Building, Designing etc a Homebrew Computer, in this case based on the marvellous Atari ST. OK it may be Doomed to fail like a lot of homebrew computers, but if one doesn't try then one will never succeeded.



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Re: Homebrew Atari ST ?

Postby troed » Tue Mar 15, 2016 10:42 pm

alexh wrote:
exxos wrote:deja-vu....If only the MMU, shifter, glue logic was published, it would make so many hardware mods so much easier and quicker to develop.....

It may have never been published but it has been reverse engineered at least twice for MiST and Suska and the HDL description of them is freely available.


... with "zero" demo compatibility ;)

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Re: Homebrew Atari ST ?

Postby AtariZoll » Wed Mar 16, 2016 9:06 am

troed wrote:...
... with "zero" demo compatibility ;)

Doing support for all those tricks used in many demos is tremendous work. I'm sure that MIST demo compatibility is higher than compatibility of this project with ST is. MIST is just not designed with running demos in sight, but running popular ST(E) SW, mostly games in first place.
What means not that it could not improve in demo support. But that depends on how much effort and people will work on it.
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 alexh » Wed Mar 16, 2016 10:51 am

I've never used or seen feedback about Demo compatibility for MiST or Suska. But I imagine you are correct. The video output stage probably has to up-converting to 60Hz output regardless of the ST video output frequency so that it works with the majority of LCD monitors?

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Re: Homebrew Atari ST ?

Postby troed » Wed Mar 16, 2016 2:00 pm

2 cycle accurate 68000 cores followed by implementation of the state machine(s)* would go a long way in improving demo compatibility. Up-conversion comes later in the pipeline and should not be a showstopper.

It's of course a matter of prioritization. As more and more ancient hardware starts to fail I'm sure we'll see more effort going into it.

/Troed

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Re: Homebrew Atari ST ?

Postby stimpy » Wed Mar 16, 2016 2:27 pm

Yet again more mis-information about FPGAs :shrug:
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Re: Homebrew Atari ST ?

Postby simongarstin » Wed Mar 16, 2016 2:36 pm

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 Cyprian » Wed Mar 16, 2016 2:40 pm

AtariZoll wrote:I'm sure that MIST demo compatibility is higher than compatibility of this project with ST is.

I'm not sure whether MIST supports code techniques like overscan or spectrum512.
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Re: Homebrew Atari ST ?

Postby simongarstin » Wed Mar 16, 2016 2:55 pm

Sourcing ICs:

I’m sure most people are aware of where to source ICs the obvious places, Mouser,Digikey, Farnell,RS etc. however for legacy stuff like this it gets more difficult if Mouser etc have these then you tend to pay quite a bit for stuff that is quite old and is now NOS. Or you have to go to China (ebay usually) and get a lucky dip! I tend to but direct and get wholesale prices usually from China, either as working pulls or NOS just to keep the price sensible. Obviously this has drawback, it can take some time for stuff to arrive and all the ICs should be tested to prove they work OK.

Building Test Rigs:

I use an Old ST to test DIP ICs especially CPUs and stuff (Fitting ZIF sockets). PLCC ICs are more difficult to test as usually you need a PLCC to DIP adaptor and then test it on a Breadboard setup. Luckily there are quite a few PCB adaptors on ebay for things like V9938s to be used more easilty on breadboard etc.

Prototyping and Breadboard:

All the smaller circuits will be first tested on Breadboard setups with the usual spaghetti of wires involved!


VHDL code:

The code for the glue logic and video display will be either written from scratch or modified from Open-Source code and tested , though this can be easier said than done. This should produce two or possible three EPM7128SLC84s in PLCC84 sockets.


It’s all looking rather complicated !!

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Re: Homebrew Atari ST ?

Postby joska » Wed Mar 16, 2016 3:04 pm

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


What are you referring to?
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Re: Homebrew Atari ST ?

Postby galax » Wed Mar 16, 2016 3:16 pm

Cyprian wrote:
AtariZoll wrote:I'm sure that MIST demo compatibility is higher than compatibility of this project with ST is.

I'm not sure whether MIST supports code techniques like overscan or spectrum512.


I think you are correct, and that's the point AtariZoll was making. MiST demo compatability is not high, but it is higher than this project's ST compatability would be.

We're all free to spend our time on whatever we want, and I'm not going to knock someone else's project, but I wouldn't want to spend thousands of hours of my time on this, to achieve the end result of a machine with zero software. If you want to do something difficult and amazing, why not implement an a cycle accurate 68000 in the MiST's FPGA. Or design a sort of Mist II with a big enough FPGA for a Jaguar, Falcon, and TT?
Last edited by galax on Wed Mar 16, 2016 3:26 pm, edited 1 time in total.

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Re: Homebrew Atari ST ?

Postby AtariZoll » Wed Mar 16, 2016 3:25 pm

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

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.


8255 for IDE IF ? I don't see that it is good idea - it is 8-bit, slow ... no way .
You can not make enough compatible keyboard, mouse, joystick IF without original IKBD chip. Lot of SW using direct access to chip. But even making that AT89... to work via TOS calls will be very hard task.
I agree with last paragraph :D
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 Cyprian » Wed Mar 16, 2016 4:12 pm

galax wrote:I think you are correct, and that's the point AtariZoll was making. MiST demo compatability is not high, but it is higher than this project's ST compatability would be.

hmm, my guess is that most demos (especially nowadays one) will not work neither on MiST nor on this project. Therefore from demoscene point of view they are in the same - incompatibility corner.

galax wrote:We're all free to spend our time on whatever we want, and I'm not going to knock someone else's project, but I wouldn't want to spend thousands of hours of my time on this, to achieve the end result of a machine with zero software.

I guess that machine will be GEM/TOS compatible, therefore you will be able to use any GEM/TOS compatible application.

galax wrote:If you want to do something difficult and amazing, why not implement an a cycle accurate 68000 in the MiST's FPGA. Or design a sort of Mist II with a big enough FPGA for a Jaguar, Falcon, and TT?

Unfortunately my skills don't allow me to support MiST. But I keep my finger crossed for MiST too.


simongarstin wrote: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.


that part is done - EmuTOS. You have to add only small startup code (like it was done for amiga's EmuTOS)
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Re: Homebrew Atari ST ?

Postby AtariZoll » Wed Mar 16, 2016 4:26 pm

Cyprian wrote:...
simongarstin wrote: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.

that part is done - EmuTOS. You have to add only small startup code (like it was done for amiga's EmuTOS)

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.
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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