Acorn Archimedes

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Re: Acorn Archimedes

Postby desUBIKado » Sun Feb 17, 2019 8:30 pm

This superb core has the problem that it must be alone inside SD card without other cores, and renamed to core.rbf. It doesn't work if it is launched from the menu core. Could this problem be solved so that it could be launched from the menu core and could share the SD with other cores?

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Re: Acorn Archimedes

Postby Higgy » Sun Feb 17, 2019 10:20 pm

Ah, is that the issue. I have been trying slingshot's tweaked Cores with allsorts of riscos.rom files and just got black screens.
I have run out of time now, but I will try tomorrow with a blank 2gb SDcard and just this Core.

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Re: Acorn Archimedes

Postby slingshot » Mon Feb 18, 2019 7:58 am

It's BS, the problem is that the CPU cannot resetted after RISCOS loaded into memory, or other initialization problem, doesn't matter what's on the SD-Card. Try this:
- Load the core (fail to start)
- DON'T TURN OFF MIST, just press the left button, and load the core again

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Re: Acorn Archimedes

Postby slingshot » Mon Feb 18, 2019 4:22 pm

slingshot wrote:It's BS, the problem is that the CPU cannot resetted after RISCOS loaded into memory, or other initialization problem, doesn't matter what's on the SD-Card. Try this:
- Load the core (fail to start)
- DON'T TURN OFF MIST, just press the left button, and load the core again


Upd.: Please test the attached core, works for me 5 out of 5 times.
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Re: Acorn Archimedes

Postby desUBIKado » Mon Feb 18, 2019 8:23 pm

slingshot wrote:
slingshot wrote:It's BS, the problem is that the CPU cannot resetted after RISCOS loaded into memory, or other initialization problem, doesn't matter what's on the SD-Card. Try this:
- Load the core (fail to start)
- DON'T TURN OFF MIST, just press the left button, and load the core again


Upd.: Please test the attached core, works for me 5 out of 5 times.


Slingshot, thank you very much :cheers: . Start up with other cores in the same SD card and works for me all of times. Great update!

Only a little thing, when I try to load a floppy from OSD, "Archie" isn't default folder. Which is it?

Well, only one more thing. A reset option would be welcome.
Last edited by desUBIKado on Mon Feb 18, 2019 10:22 pm, edited 1 time in total.

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Re: Acorn Archimedes

Postby Higgy » Mon Feb 18, 2019 9:55 pm

slingshot - your a machine 8) Thanks. Boot well, and my MiST is one that originally had problems with this and the old old MSX Core.

I think there might be some joystick issues. Only using USB, but I loaded 'SWIV' and it seemed to go straight into the game in 2-player and both characters move straight to the left and keep shooting all the time.
Being an Acorn computer I am sure there is some strange thing done with the joystick in real hardware.

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Re: Acorn Archimedes

Postby Chris23235 » Mon Feb 18, 2019 10:58 pm

slingshot wrote:
slingshot wrote:It's BS, the problem is that the CPU cannot resetted after RISCOS loaded into memory, or other initialization problem, doesn't matter what's on the SD-Card. Try this:
- Load the core (fail to start)
- DON'T TURN OFF MIST, just press the left button, and load the core again


Upd.: Please test the attached core, works for me 5 out of 5 times.


Is there a way to make the core boot in a RGB resolution, so far it only syncs on a VGA monitor?

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Re: Acorn Archimedes

Postby DrOG » Tue Feb 19, 2019 5:15 am

Chris23235 wrote:Is there a way to make the core boot in a RGB resolution, so far it only syncs on a VGA monitor?

The Archie was a computer with dedicated monitor, and not a console. I'm not sure if it's doable or not. As I remember desktop has a VGA/NTSC compatible 640x480@60Hz resolution, but most games use non-TV standard video modes, i.e. 720x400...

Wiki says:
A300 series, A400 series, R140 and A3000 machines had the VIDC1a video chip, which provided a wide variety of screen resolutions, such as those provided officially by the operating system:
-160 × 256 with 4, 16 or 256 possible colours
-320 × 256 with 2, 4, 16 or 256 possible colours
-640 × 256 with 2, 4, 16 or 256 possible colours
-640 × 512 with 2, 4, 16 or 256 possible colours
-800 × 600 with 2, 4 or 16 possible colours
while the chip could be made to run others, such as:
-1152 × 896 with 2 possible colours

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Re: Acorn Archimedes

Postby teofernandez » Tue Feb 19, 2019 9:39 am

Now that we have managed to make this Core work by sharing SD with others, I wonder if it would be possible to get a signal by Rgb Scart 15hz, since I mainly use the Mist with a monitor Rgb Commodore 1084, Thanks

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Re: Acorn Archimedes

Postby DrOG » Tue Feb 19, 2019 11:40 am

teofernandez wrote:Now that we have managed to make this Core work by sharing SD with others, I wonder if it would be possible to get a signal by Rgb Scart 15hz, since I mainly use the Mist with a monitor Rgb Commodore 1084, Thanks

See my previous post...

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Re: Acorn Archimedes

Postby Chris23235 » Tue Feb 19, 2019 9:54 pm

DrOG wrote:
Chris23235 wrote:Is there a way to make the core boot in a RGB resolution, so far it only syncs on a VGA monitor?

The Archie was a computer with dedicated monitor, and not a console. I'm not sure if it's doable or not. As I remember desktop has a VGA/NTSC compatible 640x480@60Hz resolution, but most games use non-TV standard video modes, i.e. 720x400...

Wiki says:
A300 series, A400 series, R140 and A3000 machines had the VIDC1a video chip, which provided a wide variety of screen resolutions, such as those provided officially by the operating system:
-160 × 256 with 4, 16 or 256 possible colours
-320 × 256 with 2, 4, 16 or 256 possible colours
-640 × 256 with 2, 4, 16 or 256 possible colours
-640 × 512 with 2, 4, 16 or 256 possible colours
-800 × 600 with 2, 4 or 16 possible colours
while the chip could be made to run others, such as:
-1152 × 896 with 2 possible colours


At least the A300 line had RGB and composite ports, so it should be possible to run at least these machines on a standard RGB monitor (and as far as I know these machines should be fullspeed with the core, I am not sure if this is the case with later machines).

http://www.old-computers.com/museum/computer.asp?c=75

I tried it a while ago with an older version, you have to enter the command line of the OS to switch the resolution, but there is no way to save the settings to the Archimedes CMOS (I think it's not implemented in the core), but even if you change to a low resolution that should sync, it still didn't work. The core doesn't work on a 15 KHz monitor.

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Re: Acorn Archimedes

Postby hubersn » Tue Feb 19, 2019 11:48 pm

DrOG wrote:The Archie was a computer with dedicated monitor, and not a console. I'm not sure if it's doable or not. As I remember desktop has a VGA/NTSC compatible 640x480@60Hz resolution, but most games use non-TV standard video modes, i.e. 720x400...


The Archie both had TV (15 kHz PAL) modes (MonitorType 0) and VGA-like modes (MonitorType 3 and 4 - early machines like A3xx/A4xx and A3000 could not match exact VGA timing) as well as special "Multiscan" modes (MonitorType 1).

Almost all games used TV standard modes, because most people had "normal" Amiga-like 15 kHz RGB monitors connected, since the Muliscan monitors were quite pricey - and those were capable of TV modes also, so choosing TV modes for games was a natural choice.

The Archie core does not store CMOS settings and starts up with VGA monitor type. You can reconfigure it at runtime, but I don't think I ever got a 15 kHz capable monitor to sync to the resulting signal on MIST. But I didn't try very hard.

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Re: Acorn Archimedes

Postby DrOG » Wed Feb 20, 2019 9:11 am

Well, I'm not familiar with original HW, but the core seems to be imperfect anyway...

Quote from readme ( https://github.com/mist-devel/mist-boar ... Archimedes ):
...
This page has operating instructions for the Acorn Archimedes BETA core by Stephen Leary.

CURRENTLY THIS CORE IS IN BETA STATUS

1. Basic internals are implemented.
2. Basic Floppy disk support
3. Sound support added but may not work in all situations.
4. The core emulates an A3000 type machine with 4 MiB RAM with an ARM2a with caches disabled for now (has an A3010 style joystick interface).
5. Core runs at ~91% of an ARM2 @ 8Mhz when using VGA Modes.
6. Some games now run. Expect issues.

Notes

- For best results it is recommended to use this as the startup core.
- If the core does not start, try resetting the MiST (first button next to the SD card slot)
- Compatible versions of RISC OS are RISC OS 2, RISC OS 3.10, RISC OS 3.11 and RISC OS 3.19
- Only RISC OS 3.1x supports (S)VGA compatible output for all screen modes.
- Older RISC OS 2.xx versions will need a VGA to SCART cable at present (future versions may have a scandoubler).

According to the above mentioned documentation perhaps it worths to try boot with RISC OS 2.xx, as the native video output should be the 15kHz (interlaced) mode in this case.

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Re: Acorn Archimedes

Postby DrOG » Wed Feb 20, 2019 5:15 pm

Tried some methods to obtain a 15kHz-compatible video mode, but nothing worked...

RiscOS 3 boots into 640x480@60Hz, which is VGA compatible. Tried hold down the numeric pad 0, as this should force 50Hz TV-standard colour monitor, without luck. Pressing numpad 2 during boot resulted an 1600x900@65Hz image, which corresponds to 64Hz high-resolution monochrome monitor. Tried RISC OS 2, this boots to a 720x400@70Hz command line. The games I started from desktop (Dune II, Zarch) ran in 720x400@70Hz as well. I found one exception: Xenon II uses 640x480@60Hz, this works well with my homemade RGB->YUV converter, the result is a nice 720x480@60Hz progressive component video.

Some screenshots:
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Re: Acorn Archimedes

Postby slingshot » Wed Feb 20, 2019 7:51 pm

DrOG wrote:Tried some methods to obtain a 15kHz-compatible video mode, but nothing worked...

But built-in component output should work on all modes.

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Re: Acorn Archimedes

Postby Chris23235 » Wed Feb 20, 2019 9:24 pm

slingshot wrote:
DrOG wrote:Tried some methods to obtain a 15kHz-compatible video mode, but nothing worked...

But built-in component output should work on all modes.


The core changes the resoultion, this can be seen, when you type in blind on the command line to change the resolution, but even the RGB compatible resolution don't sync.

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Re: Acorn Archimedes

Postby DrOG » Thu Feb 21, 2019 5:22 am

slingshot wrote:
DrOG wrote:Tried some methods to obtain a 15kHz-compatible video mode, but nothing worked...

But built-in component output should work on all modes.

Didn't try it, but I'm not sure that 400 lines @ 70Hz would work, as most games use this video mode, and it's non-TV standard...

EDIT:
Just as I expected: desktop and Xenon II works well without external converter in component mode, but Dune II results an 'unsupported format' error message over YPpPr...
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Re: Acorn Archimedes

Postby hubersn » Thu Feb 21, 2019 11:16 am

DrOG wrote:Didn't try it, but I'm not sure that 400 lines @ 70Hz would work, as most games use this video mode, and it's non-TV standard...


Those 400 lines@70 Hz is just what your monitor reports, it is not the truth about the real video mode, which is almost certainly 320x256 or 640x256.

You are using MonitorType 4, which implements an automatic Letterboxing of those TV modes to fake the timing to be compatible with most (S)VGA monitors.

The problem is that the modes generated by Archie core when the MonitorTypes 0 and 1 are active (which are the only ones with unmodified TV modes) are not (timing?) compatible with all the 15 kHz-capable monitors I tried - and those monitors work just fine with original Archie hardware (tested with A310, A3000, A5000).

Unfortunately I only know a lot about RISC OS and Archimedes hardware, but nothing about FPGA programming, so I can only help testing, not doing.

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Re: Acorn Archimedes

Postby slingshot » Thu Feb 21, 2019 11:32 am

hubersn wrote:
Unfortunately I only know a lot about RISC OS and Archimedes hardware, but nothing about FPGA programming, so I can only help testing, not doing.


I'm somewhere at the other side. But what I discovered while hacking on the core, that the original pixel clock is adjusted to make it even more VGA compatible, e.g. its base is 25MHz, not 24, as the original docs says. When I switched back to 24, compatibility was even worse, so I left it.

Btw, is there an SD-Card interface present for Archie?

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Re: Acorn Archimedes

Postby hubersn » Thu Feb 21, 2019 1:39 pm

slingshot wrote:
hubersn wrote:
Unfortunately I only know a lot about RISC OS and Archimedes hardware, but nothing about FPGA programming, so I can only help testing, not doing.


I'm somewhere at the other side. But what I discovered while hacking on the core, that the original pixel clock is adjusted to make it even more VGA compatible, e.g. its base is 25MHz, not 24, as the original docs says. When I switched back to 24, compatibility was even worse, so I left it.


"Compatibilty" wrt video output, or general?

On original Archie hardware (A3xx/A4xx/A3000), there was a single oscillator providing 24 MHz which drives VIDC pixel clock. On later hardware (A540/A5000/A3010/A3020/A4000/A4), there are three oscillators: 24 MHz, 25.175 MHz (for precise VGA timing) and 36 MHz.

For original hardware, there were add-ons called "VIDC enhancer" which provided additional oscillators. See here for a modern implementation:
https://www.retro-kit.co.uk/Ultra-VIDC-Enhancer/

Btw, is there an SD-Card interface present for Archie?


I don't even understand the question, I'm afraid...SD-card interface on the MIST side?

If you are interested in improving the core, I can provide links to nearly every bit of Archie hardware. There are detailed data sheets for VIDC/MEMC/IOC by VLSI available, as well as circuit diagrams for all Archie models. Always happy to help.

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Re: Acorn Archimedes

Postby slingshot » Thu Feb 21, 2019 1:49 pm

hubersn wrote:
slingshot wrote:
hubersn wrote:
Unfortunately I only know a lot about RISC OS and Archimedes hardware, but nothing about FPGA programming, so I can only help testing, not doing.


I'm somewhere at the other side. But what I discovered while hacking on the core, that the original pixel clock is adjusted to make it even more VGA compatible, e.g. its base is 25MHz, not 24, as the original docs says. When I switched back to 24, compatibility was even worse, so I left it.


"Compatibilty" wrt video output, or general?



My VGA LCD monitors and my TV with component input definitely work better with the 25 MHz pixel clock. With 24 MHz, most modes were ended in "unsupported resolution".

On original Archie hardware (A3xx/A4xx/A3000), there was a single oscillator providing 24 MHz which drives VIDC pixel clock. On later hardware (A540/A5000/A3010/A3020/A4000/A4), there are three oscillators: 24 MHz, 25.175 MHz (for precise VGA timing) and 36 MHz.

For original hardware, there were add-ons called "VIDC enhancer" which provided additional oscillators. See here for a modern implementation:
https://www.retro-kit.co.uk/Ultra-VIDC-Enhancer/

Ah, seems it also supplies a 25MHz clock, too.
Btw, is there an SD-Card interface present for Archie?


I don't even understand the question, I'm afraid...SD-card interface on the MIST side?



A SD-Card podule (or what's those expansions called). Like the user port SD-Card interface for BBC Micro. Unable to save anything is a big lack in my point of view. I didn't even found details of the IDE interface.

If you are interested in improving the core, I can provide links to nearly every bit of Archie hardware. There are detailed data sheets for VIDC/MEMC/IOC by VLSI available, as well as circuit diagrams for all Archie models. Always happy to help.

Have fun
hubersn


Yeah, would be good for reference. I already found the VIDC datasheet. I don't say I'll work on this right now, but maybe later on.

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Re: Acorn Archimedes

Postby slingshot » Thu Feb 21, 2019 1:53 pm

Just found some IDE interface:
https://stardot.org.uk/forums/viewtopic ... 16&t=15205

SD would be easier anyway.

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Re: Acorn Archimedes

Postby hubersn » Thu Feb 21, 2019 2:36 pm

slingshot wrote:My VGA LCD monitors and my TV with component input definitely work better with the 25 MHz pixel clock. With 24 MHz, most modes were ended in "unsupported resolution".


Maybe the "not 24 MHz" is the root of the "not syncable on 15 kHz monitors"? Could you try 24 MHz, MonitorType 0 or 1, and e.g. Mode 12, if it then outputs a proper PAL TV compatible output?

A SD-Card podule (or what's those expansions called). Like the user port SD-Card interface for BBC Micro. Unable to save anything is a big lack in my point of view. I didn't even found details of the IDE interface.


No SD-card podule I would know of - usually, IDE podules are used with SD-IDE adapters.

Early Archies had no IDE. The A4xx had MFM/ST506. The A540 had a SCSI podule. Only hardware starting with the A5000 had IDE on-board. Which is the only IDE hardware directly supported by RISC OS 3.1 (ADFS module).

The IDE interface used a Chips and Technologies 82C710 on the A5000 and the virtually identical 82C711 on A4000/A3010/A3020/A4. I am not sure what is implemented in Archie core - it might use the old-style hardware of the A3xx/A4xx/A540/A3000, with a WD1772 floppy controller, 6551 for serial port etc.

The SCSI podules were usually based on the NCR 53C94/FAS216. But I'm not sure if the whole podule stuff is already there in Archie core.

To be able to save something, I think it would be a first sensible step to implement floppy writing. Although I would surely welcome a full IDE implementation!

Yeah, would be good for reference. I already found the VIDC datasheet. I don't say I'll work on this right now, but maybe later on.


Good collections of Acorn 32bit info:

For an introduction on what's inside an Archimedes, here's an emulator author's collection of notes: http://b-em.bbcmicro.com/arculator/archdocs.txt

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Re: Acorn Archimedes

Postby slingshot » Thu Feb 21, 2019 4:42 pm

hubersn wrote:
Maybe the "not 24 MHz" is the root of the "not syncable on 15 kHz monitors"? Could you try 24 MHz, MonitorType 0 or 1, and e.g. Mode 12, if it then outputs a proper PAL TV compatible output?


Maybe the bigger issue is 15 kHz needs composite sync.

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Re: Acorn Archimedes

Postby DrOG » Thu Feb 21, 2019 4:47 pm

hubersn wrote:...
Those 400 lines@70 Hz is just what your monitor reports, it is not the truth about the real video mode, which is almost certainly 320x256 or 640x256.
...

These are not TV-standard resolution either...


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