VGA ISA on ST

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artik-wroc
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VGA ISA on ST

Postby artik-wroc » Wed Jun 13, 2018 3:29 pm

VAR Reg : BYTE;
BEGIN
Reg := Port[$3CC];
Reg := Reg OR 1;
Port[$3C2] := Reg;
END

VGA graphics card mono/color emulation on PC. And what will be the equivalent for Atari, if I know that:
Membase: $FEC0.0000
I/O Base: $FED0.0000
ET4000

czietz
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Re: VGA ISA on ST

Postby czietz » Wed Jun 13, 2018 4:25 pm

As you already wrote yourself, the IO ports will appear in the address space at a certain offset, $FED0.0000 in your case. So for example IO port $3CC would be at $FED0.03CC -- and $D0.03CC as well in case of an ST because the upper 8 address bits do not matter there. However, note that many 68000 <-> ISA adapters (such as the Nova) will not allow you to read odd numbered IO ports unless you have previously switched the ET4000 into 16 bit IO mode.

EmuTOS has support for ET4000 built in, you can see there how I access the ET4000: https://github.com/emutos/emutos/blob/m ... ios/nova.c
Last edited by czietz on Sat Jun 16, 2018 5:41 pm, edited 1 time in total.

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frank.lukas
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Re: VGA ISA on ST

Postby frank.lukas » Wed Jun 13, 2018 6:38 pm

VOFA, Multiboard and Panther, Panther/2 Adapter has 8-bit IO mode at the ET4000. Nova has 16-bit
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artik-wroc
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Re: VGA ISA on ST

Postby artik-wroc » Sat Jun 16, 2018 5:04 pm

How can you bypass the VGA BIOS interrupt call (INT10H) from the Atari level? I'm too weak :(

czietz
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Re: VGA ISA on ST

Postby czietz » Sat Jun 16, 2018 5:40 pm

artik-wroc wrote:How can you bypass the VGA BIOS interrupt call (INT10H) from the Atari level? I'm too weak :(


By doing all the hard stuff yourself: Program all the ET4000 registers like the VGA BIOS would do. The ET4000 data book is required: https://archive.org/details/bitsavers_t ... 0_11230195

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Re: VGA ISA on ST

Postby ctirad » Sun Jun 17, 2018 1:57 pm

Cziets, you are awesome. I have to check it on my Mulltiboard and Panther2.
Is there a way to enable some debug info? I'm going to start emutos from the floppy (image).

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Re: VGA ISA on ST

Postby czietz » Sun Jun 17, 2018 4:47 pm

ctirad wrote:Cziets, you are awesome. I have to check it on my Mulltiboard and Panther2.
Is there a way to enable some debug info? I'm going to start emutos from the floppy (image).


You can uncomment the line...

Code: Select all

/* #define ENABLE_KDEBUG */
...to get some basic debug output. As usual with EmuTOS, you also have to change the include/config.h file to define where you want the debug output to be. I normally enable RS232_DEBUG_PRINT to get the output on the serial port.

To use a different adapter, you might have to modify detect_nova() to check the respective addresses.


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