Patches for A2024 monitor driver to force NTSC or PAL operation
2012-03-28 0.1 First release. Please report any problems!
About the A2024
The Commodore A2024 is a high-reolution 15" grey-scale monitor which contains
a special scan converter board. The same circuitry was also available on a
card for the A2000/3000/4000 video slot, for connection to a Moniterm high-res
You can see pictures of the A2024 at
The Moniterm scan converter card can be seen at
The scan converter builds a high resolution image from four or six Amiga
fields. When connected to an NTSC Amiga, the A2024 can display a 1024×800
pixel screen in 2 or 4 colours (black and white, or black, white and two
shades of grey). Connected to a PAL Amiga, the A2024 display is 1024×1024
pixels. The A2024 driver code limits the display width to 1008 pixels on
machines with the original (non-ECS) Agnus chip.
The A2024 is compatible with any Amiga which has a 23-pin video port, even the
Amiga 1000 and CDTV. It does not require a particular CPU or chipset. A2024
support is built into version 2.0 and later of the Amiga OS. The A2024 came
with a special "Jumpstart" disk to enable A2024 modes under Kickstart 1.2/1.3.
The ability to use A2024 modes is not limited to OS-legal software. Some
software which does not run under the Amiga OS also supports A2024 modes, for
· Amiga UNIX
· The A-Max Macintosh emulator (ReadySoft)
While only a few people today have a working actual A2024 monitor, the WinUAE
Amiga emulator includes emulation of A2024 modes from version 2.4.0. That
allows a nice high resolution Workbench without needing RTG software or a
faster emulated CPU (the Picasso96 RTG software requires at least a 68020). It
also allows a high-res desktop with the A-Max Macintosh emulator.
About the patches
The patches are only of use on machines with the ECS Agnus or AGA chipset.
The original A2024 driver uses a 1024×800 display on NTSC machines, and
1024×1024 on PAL machines. The patches allow you to create modified versions
of the A2024 driver, which always use 1024×800, or always use 1024×1024,
regardless of whether your Amiga is PAL or NTSC.
There are several reasons why you might want to force the A2024 driver to work
in a particular mode:
· The pixels of the "NTSC" 1024×800 mode are almost square on a 4:3 monitor,
whereas the pixels of the "PAL" 1024×1024 mode are wider than they are
tall. If you have a PAL Amiga, you might prefer the almost-square pixels in
· The A2024 monitor screen has a 4:3 aspect ratio. When using the 1024×1024
mode, the mouse pointer is more sensitive in the vertical direction. (For a
given distance of mouse movement, the pointer moves by more pixels
vertically to move the same physical distance, compared to horizontal
movement.) When using 1024×1024 mode with an emulator which displays the
pixels 1:1, the mouse pointer moves faster vertically than it does
horizontally. With the 1024×800 mode, the difference in vertical pointer
speed is lower.
· If using an emulator on a computer whose monitor resolution is 1280×800,
1440×900 or 1600×900, the full PAL 1024×1024 display will not fit on the
screen. Even with a 1680×1050 monitor, showing a full 1024×1024 A2024
screen might not be possible due to the taskbar and window borders.
· If your emulated Amiga is NTSC and you use a 1280×1024 or larger monitor,
you might want the A2024 display to be 1024×1024 instead of 1024×800.
· If you have an NTSC Amiga and a PAL-model A2024 monitor, or vice versa, you
might need to force the A2024 driver to work in the correct mode for the
monitor. (Can someone with a real A2024 confirm whether or not that is
How to apply the patches
These patches apply to version 43.9 of the A2024 monitor driver, as included
in the AmigaOS 3.5 Boing Bag 1 update. It is probably also on the AmigaOS 3.9
CD. That version remains compatible with Workbench 3.1. As far as I know,
version 43.9 was the final version of the A2024 driver.
Included in this archive is copy of GPatch 3.0, which is copyright © 1997-
2002 Ralf Gruner. You can get the full GPatch distribution from Aminet,
To apply the patch, in a CLI/Shell window use a command like this:
GPatch A2024 A2024_43.9_force_NTSC.gpch RAM:A2024_NTSC
GPatch A2024 A2024_43.9_force_PAL.gpch RAM:A2024_PAL
To revert the patched file to its original state, use a similar command:
GPatch RAM:A2024_NTSC A2024_43.9_force_NTSC.gpch A2024_original
GPatch RAM:A2024_PAL A2024_43.9_force_PAL.gpch A2024_original
Once you have your patched monitor driver, move the original A2024 driver out
of DEVS:Monitors (e.g. to SYS:Storage/Monitors), and copy the patched driver
to DEVS:Monitors. Remember to create an icon for it, e.g. copy A2024.info to
Since the patched drivers act exactly like the original, you can only have one
active each session. So if you first run the PAL-patched A2024 driver, in
order to use either the NTSC-patched or original driver you need to reboot and
run that driver.