When is a ST not a ST anymore ?

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Re: When is a ST not a ST anymore ?

Post by exxos » Sun Apr 08, 2018 1:54 am

Maybe you can help us with adapting the code for the projects we have in mind ?
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Re: When is a ST not a ST anymore ?

Post by Darklord » Sun Apr 08, 2018 11:12 pm

Very interesting thread....

Way back when I first re-cased my Falcon into a Wizztronics case, I had several people
declare that it was no longer a Falcon. /shrugs.

I also had some people say that as long as it was originally manufactured by Atari, then
it was still an Atari. Accept no substitutes apparently. :)

I don't care for emulators, a well known fact. I'm not also a big fan of the MiST and
hardware like that.

I like Chris's idea about redoing a 1040. I'd happily call it an ST, just not an *original* ST.

Hope that makes sense.
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Re: When is a ST not a ST anymore ?

Post by exxos » Mon Apr 09, 2018 1:27 pm

Darklord wrote:
Sun Apr 08, 2018 11:12 pm
I don't care for emulators, a well known fact. I'm not also a big fan of the MiST and
hardware like that.

I like Chris's idea about redoing a 1040. I'd happily call it an ST, just not an *original* ST.

Hope that makes sense.
For me the main thing is compatibility. Basically the Falcon is a upgraded ST, obviously it is not a ST. My overall aim is to keep the ST design is close to original as possible but update the chips so we can use faster memory and CPU etc. while the chips are emulated, it is emulating the original ST architecture, so my view it is still a ST.

It can be debatable about using different silicon technology do the job some people could argue its not original anymore, which it basically isn't. But if the chips are 100% compatible then there should not really be any reason not to call it a real ST.

It is basically the same as a power supplies in the STF/E. There are several different brands of power supply or basically doing the same job. Which one is a original ST ? Of course they all are, but they all use different power supplies and slightly different technology in them.

What I see is exactly the same in replacing the MMU for example, is still hopefully does exactly the same job, slightly different technology just like the power supplies. Of course we could go deeper into brands of chips.. We can just look at the CPU, MOT or ST brands etc.

Some people prefer not to buy my power supplies as they are not original. I can perfectly understand that. The thing is, my power supplies are just another brand like the other several brands already use. The only thing is my power supplies did not come out when the machine was produced it is a replacement part and obviously not original as the ST never had my power supplies fitted from factory.

I think everyone has their own take on which is original and not. Of course however they came out of the factory is its original form. But this does not mean the parts inside the identical across the whole production runs of the machines. So if we took a factory SR98 and replaced it with a DVE power supply, is that machine still original or not.. It is different as is not how it came out of the factory, of course the different power supply also came out of the factory which is a original part, but not original to that machine.
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Re: When is a ST not a ST anymore ?

Post by Stimpy » Tue Apr 10, 2018 1:11 pm

exxos wrote:
Sun Apr 08, 2018 1:54 am
Maybe you can help us with adapting the code for the projects we have in mind ?
It would come down to spare time of which I have virtually none, but perhaps enough to help advise or point any potential pitfalls out?

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Re: When is a ST not a ST anymore ?

Post by Darklord » Fri Apr 27, 2018 12:40 am

I fully agree about compatibility. Keep up the great work Chris! :)
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Re: When is a ST not a ST anymore ?

Post by tzok » Fri Jul 13, 2018 1:07 pm

What is the difference between emulating a whole computer in one FPGA chip and emulating most of the crucial chips in a separate FPGAs... for me it is still only an emulation. So cycle accurate copies of original chips in form of ASICs is ok, FPGA emulation is only emulation.

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Re: When is a ST not a ST anymore ?

Post by tzok » Fri Jul 13, 2018 2:51 pm

In most cases reverse engineering gives more or less incomplete emulation. FPGAs run a VHDL code, potentially it could be very close to the original design, but we'd have to have original chip production documentation to fully implement it in VHDL. For example - STf and STe had a joystick port controlled by a MCU in the keyboard, connected through a serial line with a motherboard. This lead to a specific delays, which are hard to emulate in FPGA if we don't have the full documentation of the original MCU and code it originally run, but has a great impact on the gaming experience. Some games become very hard to play just by using SCART to HDMI converter, which adds some slight delay (2-3 frames). On the other hand most emulator programmers tend to take some shortcuts and/or optimizations.

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Re: When is a ST not a ST anymore ?

Post by exxos » Sat Jul 14, 2018 10:00 am

The only real problems are "undocumented features". But these can always be fixed.

For example Suska shifter core does not know about "wakeup states". So some demos will fail. But now these problems are known and better understood, these can be added into future revisions of the core.

Most instructions if running from 8MHz on real 68000 CPU, will be no problem there. MMU/GLUE will be waiting for CPU to complete cycles, so there would be no speed difference there anyway, not if using real CPU.

As for ACIA, I am not aware of any side-effects of that system running faster. The only time I ever notice a difference was when playing sampled sound and moving the mouse, this would cause the sampled sound to slow down. If the system was running faster, the side-effect would be that slowdown would be a lot less. Which I would actually see as a good thing. So as far as I'm aware 100% emulating that isn't really needed anyway.

Other side effects could be MMU may work faster with DMA transfers, and indeed DMA itself may run faster. But this would be welcome anyway. I don't know of any side-effects of running transfer rates and hard drives faster. Hard drives over past 30 years have various access speeds anyway.

Floppy drive may well be special case because of various protection techniques used the timing of floppy chip.. But in this case and still use real IC anyway. Same for MFP etc. Of course floppies are thing of past and in 30 years time likely no real floppies will work anyway, having 100% floppy emulation would actually be pointless. Will likely nobody will care by the time the 1772 vanishes of the market totally.

We can always look at it like a "cloned ST" will likely be more compatible than the Falcon. We can also look at it like we have no choice but to "emulate" the Atari chips, simply because there is no alternative. Of course once we are in FPGA, we can add more features such as higher RAM speeds, better video resolutions, more colours.. And of course my goal is always 100% backwards compatibility, but sacrificing that 1% incompatibility to gain much more is a good trade I think anyway.

I guess it depends if people think the Falcon is the next "ST" computer or not. People are happy with the Falcon I think as it is still a Atari TOS running computer. And what we are talking about will be more compatible than the Falcon but obviously not as advanced.
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Re: When is a ST not a ST anymore ?

Post by Darklord » Thu Jul 19, 2018 6:59 pm

I love these threads. I commented earlier but I find other Atari users opinions to be
intriguing.

Especially the part about if you do an upgrade is it no longer an ST?

Short answer, I'd say yes.

I have a Mega ST that runs my BBS. It was originally a 2 meg, TOS v1.02 machine.
Upgraded to 4 megs, TOS v1.04 and an AdSpeed accelerator. Is it still a Mega ST?

You bet it is.

Same goes for my STacy. It was a stock 2 meg version when I got it, with a seriously
degraded screen. Took it to 4 megs, replaced the back-light for the panel, replaced
the dead (and burnt!) 10 meg hard drive with an Ultrasatan, put in a Pak 68/3
accelerator, 1.44 floppy drive upgrade and painted it black (until something darker
comes along :) ).

Is it still a member of the ST family? Is it still a STacy?

Of course it is. :)
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Re: When is a ST not a ST anymore ?

Post by exxos » Thu Jul 19, 2018 7:09 pm

But if your whole STacy circuit was a "one chip wonder" in FPGA, is it still a STacy then ?
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