ZX Spectrm Emulation on Atari 1200 XL

[Shawn Jefferson]

Now you are really talking about a program with only two users...

 

Nice work on the zx emulation, makes me wish I had to rapidus.

[JamesD]

Now you are really talking about a program with only two users...

 

Nice work on the zx emulation, makes me wish I had to rapidus.

LOL! There are two?

 

They have already done most of the work between existing projects, it just makes sense to implement it.

To get the command prompt up and running should only require a handful of bios routines.

 

Imagine if this had been available back in the day!

The Apple required a Z80 card to run CP/M. It's obvious the IIgs could do it with emulation as well though.

Now the CoCo 3 can run CP/M emulation under OS-9, but that's recent, and it's slow unless you are running a CoCo 3 FPGA system. You can run multiple instances concurrently though which is pretty neat.

 

 

[drac030]

It's obvious the IIgs could do it with emulation as well though.

I am no expert on the Apple IIgs, but 2.8 MHz seems a bit too slow. The ZX Spectrum emulator does not really require Rapidus or VBXE, it can be run on Antonia too (or on Altirra, for that matter), just 1.77 MHz makes it slow below any point of usability. Even if Apple's 2.8 MHz is twice as fast, it does not help much. Maybe some simple experiments in Sinclair BASIC could be done, but probably nothing beyond that. I guess the same applies to CP/M software possibly running under emulation.

[Mclaneinc]

LOL! There are two?

 

 

 

 

Yeah, the guy who made it treated himself to a spare

[Matej]

This is nice! I wish that Lotharek or anyone else will make new XE motherboard with Rapidus, Ultimate 1m, stereofinal, vbxe2.1 - all upgrades onboard...

Simply I will screw my old motherboard send it to manufacturer of new. And I will pay money for new one. And postman will bring me new motherboard.

I will screw back new motherboard and play or watch new demos, games, gui... Thats my dream... Like Atari 260XE motherboard.

Edited August 17, 2016 by Matej

[JamesD]

I am no expert on the Apple IIgs, but 2.8 MHz seems a bit too slow. The ZX Spectrum emulator does not really require Rapidus or VBXE, it can be run on Antonia too (or on Altirra, for that matter), just 1.77 MHz makes it slow below any point of usability. Even if Apple's 2.8 MHz is twice as fast, it does not help much. Maybe some simple experiments in Sinclair BASIC could be done, but probably nothing beyond that. I guess the same applies to CP/M software possibly running under emulation.

Keep in mind that CP/M has no speed requirement like the Speccy. (I wasn't referring to the Spectrum emulation)

You could run CP/M on a TRS-80 Model I at 1.77 MHz with the aid of a plug in board and I'm not even sure it's the slowest system.

On the high end, there were 6 MHz HD64180 based systems (roughly equivalent to an 8 MHz Z80) in the mid 80s and I'm sure even faster systems have been built.

The software is text based and running slow isn't the end of the world. (Whether it's usable from a sanity standpoint is another matter.)

The main thing is that you aren't trying to push a lot of graphics and sound in real time, so the CPU load is relatively low for the most part.

 

Also remember that the IIgs has had accelerator boards like ZipGS since the 80s.

People have been overclocking those to 16MHz or more long before the Rapidus existed.

I think they have been doing that since at least the 90s.

 

Edited August 17, 2016 by JamesD

[JamesD]

...

Also remember that the IIgs has had accelerator boards like ZipGS since the 80s.

People have been overclocking those to 16MHz or more long before the Rapidus existed.

I think they have been doing that since at least the 90s.

 

After a quick search, running the ZipGS at 20 MHz seems to be common.

It requires swapping RAM, overclocking the 16 MHz CPU, etc... but it sounds reliable. And that was posts from 2003.

[Irgendwer]

It is the stock FX core. The display itself is generated by ANTIC, the VBXE is used to add colors by means of the color map. The conversion of the color attributes from the ZX Spectrum format to the VBXE format is being done by the blitter, so it practically does not engage the CPU.

 

Very nice! Next stage is Amstrad emulation? (Or Game-Boy ?)

Edited August 17, 2016 by Irgendwer

[drac030]

Keep in mind that CP/M has no speed requirement like the Speccy. (I wasn't referring to the Spectrum emulation)

I was however, because it is a good reference point: if we are still talking about turning the ZX Spectrum emulator into a CP/M emulator, it will basically be the same program, and the performance (in terms of raw processing power) will be nearly the same, as the ZX Spectrum part does not cost much there.

 

You could run CP/M on a TRS-80 Model I at 1.77 MHz with the aid of a plug in board and I'm not even sure it's the slowest system.

Certainly, but in my "1.77 MHz" I was referring to the host system speed, not to the Z80 speed. The divisor here is about 6, to achieve the performance of a 1.77 MHz Z80 you'd need about 10 MHz host CPU. Likewise, a 1.77 MHz host provides a Z80 emulation being an equivalent of a 0.3 MHZ Z80 and 2.8 MHz host (assuming that there is no additional cost of DMA and such) - 0,45 MHz Z80. That is the speed of a calculator, I would assume.

 

The software is text based and running slow isn't the end of the world.

Sure, but for "slow" I mean really very, very slow. Like ZX Spectrum at 1/12 of its normal performance. Even the system startup takes half a minute.

 

People have been overclocking those to 16MHz or more long before the Rapidus existed.

I think they have been doing that since at least the 90s.

Now, or in 90s for sure. I just had an impression that you were talking about the times "back in the day". When IIgs came out, a 14 MHz 65C816 did not even exist, I think, and a 4 MHz could not be overclocked much (at 7 MHz it already stopped working).

 

Very nice! Next stage is Amstrad emulation? (Or Game-Boy ?)

Amstrad, I am afraid not. Maybe someone else The result with the ZX Spectrum emulator is so good because the machine being emulated is very simple. I would call it "only-one computer": only one display mode, only one memory space (no banking), only one interrupt, only one ASIC with only one hardware register etc. Amstrads, as far as I know, are much more complex, and besides, I have no acquaintance with them whatsoever.

 

As for Game-Boy, people already have suggested that to me in various conversations, but for now I feel that CP/M emulator is much more appealing (although probably really it will be for 2 people). Later, we will see.

[JamesD]

The overhead should be slightly less for CP/M since the video emulation is simpler and there is no sound.
But yeah, we may be talking about a .5 MHz or less Z80 on a stock IIgs machine, and it would be worse on a standard Atari.

I knew several people that had Commodore 128s and they would brag it could run CP/M.
When I asked them what CP/M software they ran, the response was always that they didn't but they could.
Maybe more appropriately, it's like the Amiga Transformer software. You could run MS-DOS on the Amiga. It wasn't fast, but you could.
It sold some machines.

The ZipGS supposedly came with a 7 MHz CPU. It overclocked up to 10 MHz without swapping the CPU.
At least that's all I could find on it.

[pseudografx]

I knew several people that had Commodore 128s and they would brag it could run CP/M.

The C128 had a Z80 built-in. Not sure about the frequency though.

[JamesD]

The C128 had a Z80 built-in. Not sure about the frequency though.

I didn't say it was software, I was just pointing out that part of the reason people bought the C128 was because it could run CP/M... and then they rarely used that feature.

I'm sure some people did use it, just not any of the people I knew.

Bottom line... it's more of a bragging rights thing than something people had to have which is what I see this being.

 

On a 20 MHz 65816 the CP/M emulation should be quite usable and it would be even faster than many actual CP/M systems. The Altair was only 2MHz after all.

At a slower MHz this is more of a "look what the Atari can do" or an "I can use it if I had to" sort of thing.

"If I had to" meaning that back in the day you could type something up in Wordstar, transfer the file to someone with a CP/M system and they could load it, or you could use Turbo Pascal to complete an assignment for a programming class. We clearly wouldn't bother now other than just to demonstrate the possibility.

I would think you'd want an Atari that ran at least double speed in order for this to be really usable though, and you are still talking about a 1 MHz or less Z80.

 

For those that think it's doubtful this would have been possible back in the day, there was an 8080 simulator released for the KIM-1 in 1978, and then the Apple II months later.

It was really designed for cross development or learning the 8080, but the potential was there. Sadly the author let the wrong people market it and it didn't really sell, so development stopped there. If there had been sufficient sales, he might have ported it to the Atari simply due to the faster CPU. I don't think you would have seen CP/M emulation until the IIc+ or IIgs, but the potential was there.

 

It will be interesting to see how this turns out and how fast it will run.

 

 

[+mytek]

I didn't say it was software, I was just pointing out that part of the reason people bought the C128 was because it could run CP/M... and then they rarely used that feature.

I'm sure some people did use it, just not any of the people I knew.

Bottom line... it's more of a bragging rights thing than something people had to have which is what I see this being.

 

On a 20 MHz 65816 the CP/M emulation should be quite usable and it would be even faster than many actual CP/M systems. The Altair was only 2MHz after all.

At a slower MHz this is more of a "look what the Atari can do" or an "I can use it if I had to" sort of thing.

"If I had to" meaning that back in the day you could type something up in Wordstar, transfer the file to someone with a CP/M system and they could load it, or you could use Turbo Pascal to complete an assignment for a programming class. We clearly wouldn't bother now other than just to demonstrate the possibility.

I would think you'd want an Atari that ran at least double speed in order for this to be really usable though, and you are still talking about a 1 MHz or less Z80.

 

For those that think it's doubtful this would have been possible back in the day, there was an 8080 simulator released for the KIM-1 in 1978, and then the Apple II months later.

It was really designed for cross development or learning the 8080, but the potential was there. Sadly the author let the wrong people market it and it didn't really sell, so development stopped there. If there had been sufficient sales, he might have ported it to the Atari simply due to the faster CPU. I don't think you would have seen CP/M emulation until the IIc+ or IIgs, but the potential was there.

 

It will be interesting to see how this turns out and how fast it will run.

 

 

 

Yeah I remember back in the early eighties almost our entire office was using CPM, predominately for word processing with WordStar, but also for database aspects (using a combination of Osborne1's and some dedicated desktop boxes connected with terminals). I think if I had been into Commodores, the C128 would have been an excellent addition when it came out in the mid 80's. So if Atari had offered a similar dual purpose system, I'm sure I would have bought one and charged it off as a business expense. But as it was, I was still able to sneak in 3 Atari systems for the R&D lab, but that's another story which I believe I covered elsewhere.

 

- Michael

Edited August 19, 2016 by mytekcontrols

[drac030]

There is some progress in the matter:

 

 

(the film recorded on Altirra, 20 MHz on, VBXE on).

[JamesD]

Well done!
Performance seems quite good at 20 MHz.
Clearly faster than a lot of CP/M systems.

[drac030]

For comparison, here is the 1,77 MHz and no VBXE.

 

 

Note the slow Wordstar response to Ctrl/F.

[pirx]

Still WOW!!!

[w1k]

its possible download this software?

[Mclaneinc]

That is some seriously nice work there Drac (again), I was never in to CPM but as I was office based as the manager I used Wordstar etc but I just never got involved with it, too busy I guess but seeing that 20Mhz version running on the 1200 (with a little help) was incredibly impressive. Its amazing to see the old Atari do stuff people said would never happen on it.

 

:thumbsup: :thumbsup:

Edited August 27, 2016 by Mclaneinc

[Spanner]

Thanks amazing,wounder if you could run the BBC B+ on it or any other emulator.

[Beetle]

Really impressive - and only a few days after starting to talk about it...

[JamesD]

For comparison, here is the 1,77 MHz and no VBXE.

...

From the looks of that I'd say it needs to run at least twice as fast to be very usable, but you could do it if you had to.

Compiling something in Turbo Pascal might be painful. Start the compiler, have lunch....

 

With a little code profiling a person could have created some address traps specific to certain programs.

Maybe perform a checksum or CRC when a program loads or the user hits a key and then load a set of native routines that match that number.

Then it might be very usable. It would be a lot of work though.

*edit*

Thinking about back in the day there.

Edited August 27, 2016 by JamesD

[JamesD]

Ya know, you could emulate a TRS-80 model I on a narrow playfield using a custom font.
You'd have to limit it to one DOS, but you could do it.

[ricortes]

I have to add my name to the list of many WOWs!

 

Burning brain cells just trying to come up with reasons why this would have been important in the day and why it would be important today. Would'a could' should'a: I remember logging into Citidel BBS, as I recall they were rock solid and ran on Z80 systems. It would have been nice to have it as an option to AMIS. Ditto for just about everything software back in the telephone line era. Now and then, it would have been nice to have access to all the development tools like BASIC compilers, C language, and Pascal written for the Z80/CPM. I imagine even today people could use it for archival purposes for extracting old compression and storage techniques. I know when I was fooling with my ATR8000 I ended up having to do a lot of work using an emulator to extract disk images.

[w1k]

download?