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Amiga 1200: Indivision AGA MK2cr

After toying with video output on the Amiga 1200, I'd come to the realisation that old technology just wont display well on brand new TVs. Due to this I therefore researched what everyone else on the interwebs did to get a better resolution from these old beasts.

Results came up quickly and all signs pointed to this device, the Indivision AGA MK2cr by Individual Computers (buy it here.)

This device piggy-backs onto the Lisa chip (the Amiga's Video processing chip), taking the output and then using it's own CPU to convert this to a more recent standard that newer TVs and Monitors can reproduce. It has upgradeable firmware and configurable options. It's stated that, out-of-the-box, you won't need to configure a single boolean value to get it running.

The price isn't low.. but all the reviews I'd read indicated that the value for money ratio was high. I therefore set out in pursuit to find one and came across some hits on Amibay, but watched as faster hawks snapped the prey up VERY quickly.

eBay showed some results also; and then it happened... the exact seller of whom I bought the 1200 from provided the device up for sale. I couldn't resist... Steve understands eBay and had treated me perfectly on the previous sale and so I grabbed this item. Turns out I got a few extra bits too, of which I'll report about later.


The item arrived in record time and it felt like Christmas had come early once again. I knew I had to take my time with this though... opening a ~30 year old piece of equipment (although you could tell it had previously already been modified) required patience and a steady hand.

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The box came with all the required components. No software is provided as the device works primarily via its own firmware to detect the video signals being produced by the Lisa chip and convert them out to DVI-capable resolutions.

Installing it

All in all, this was a piece of cake. As mentioned, this Amiga 1200 had been toyed with before and so there was no hassle of breaking warranty seals and the like. Case screws were undone and then the top plate was removed.

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I'd previously wondered what the extra DB-25 port was on the left-hand-side (as you look at the back of the machine) and this became clear on opening the case. It's a SCSI port for an accelerator that contains a SCSI interface. As you can see, no such accelerator is in the slot, so the internal end of the cable was sitting loose.

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Over near the Lisa chip, I found the CF card to be sitting directly above it. Turns out that there's enough clearance above the MK2cr to have the CF sitting on top, so I unstuck it, flipped it over and stuck the new hardware in place. This went on with a nice click. Even pressure was applied to the center area, where the 4 holes are. Once in place, the cable was run (very tightly, it's the perfect length!) to the location where I'd removed the SCSI plug. Fortunately, I received a 3D printed plate to hold the DVI connector in place. I did need aftermarket screws to secure the plug in the housing; the nuts that were removed from the end of the DVI plug weren't long enough to go through the plastic plate.

First Impression

This always counts... this device was marketed as 'no configuration' ... reminds me of the old 'plug-n-pray' days. Sometimes I miss ISA/EISA cards and their jumpers of which I had supreme control over. Anyway, I hooked up a cheap VGA cable via a DVI-to-VGA adapter and plugged it into the TV. Powering it up... I nearly cried.

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The ghosting was immense ... and I truly wasn't expecting this from a Digital product. A quick google lead me to believe that the DVI-to-VGA and then the VGA cable were trashing the signal. I also noted that the resolution being output was 1280x1024. That's a great resolution; but a shitty VGA cable might have issues. I quickly tested the shit VGA cable and adapter on a VGA monitor... it looked better, but still not up to the standard I was expecting.

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So, I opened the warchest and found a chunkier cable that had a DVI on one end and a VGA on the other... on the LCD Monitor still showed minor ghosting, as follows...

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But on the TV, the ghosting was hardly noticable... Score! This is the pixel-for-pixel that I was looking for.

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At this stage I was content with the output... It has since occurred to me that I could convert the DVI to HDMI and keep the signal totally digital. I'll try that and report back soon.

Configuration Options

The 'overscan' area can be customised. On bigger screens, it will default to the background colour of Workbench. You can confgure this using BorderBlank.

Next, resolutions. The MK2cr supports the 'HighRes' driver. Download it here. To install it, move the HighGFX file from the archive to your "sys:devs/monitors" directory and reboot. Higher resolutions should now be visible in the ScreenMode prefs.

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If you want to toy with the devices configuration itself, then firstly grab the Flashing tool and v2.6 firmware to see if you have the latest installed. Once you're up to date, you can use the v1.5 Config Tool to configure the device.

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From what I understand, you choose the mode on the left and then re-map it to a resolution from the VGA column. Then hit Test/Use/Save. Will update when I tinker further...

The resolutions are awesome. You can find the HD720 driver in the HIGHGFX package, drag that to your dev/monitors folder also. I switched my TV to 16:9 scaling and the resolution looked great!

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Time for model train controller programming and games!


Quadra 950: Apple Multiple Scan 720

I'd purchased an Apple Multiple Sync 720 (17") CRT along with the PowerPC 7200 and they worked fine together. I've since gotten rid of the PPC and have tried to get this monitor to work on the Quadra 950. On first plugging in, Mac OS 8 reported that only 640x480 was available. I know it can do up to 1280x1024, so I dug deeper.

From a brief google I couldn't work out if this monitor was supported officially or not. The resolution available indicated that the monitor was not correctly detected; but was this a fault of the monitor or an issue with my macintosh/rom/software/firmware? Or just the fact that the monitor was newer than the Quadra and was never going to be correctly detected?

A little digging indicated that Apple monitors used 'sense pins' to tell the Macintosh what was connected and then what resolutions should be displayed. This monitor uses 'extended sense pins' and I wasn't sure if the Quadra 950 understood these.

Sense Pins and related IDs

There are some very interesting articles online relating to Apple video hardware. I found this email to the comp.sys.mac.hardware usegroup from Dale Adams who was actually one of the engineers who created the specifications/hardware. In it he describes the technology and the 'pinouts' of the sense pins and associated monitors. I've reproduced this here for easy reference.

Monitor Sense Pin 0 (4) Sense Pin 1 (7) Sense Pin 2 (10) Resolution
Apple 21S Color 0 0 0 1152 x 870
Apple Portrait 0 0 1 640 x 870
12" Apple RGB 0 1 0 512 x 384
Apple Two-Page Mono. 0 1 1 1152 x 870
NTSC 1 0 0 underscan - 512x384
overscan - 640x480
12" AppleMonochrome 1 1 0 640 x 480
13" Apple RGB 1 1 0 640 x 480
Extended sense code monitor 1 1 1

From the table above, I can tell you that my monitor is of the 'extended' variety and provides '1' on each sense pin. When the 'extended' mode is found, the Macintosh BIOS is then meant to send voltages to each line and determine what the value of the other pins are. I couldn't actually find out when this logic was supported in what Macintosh ROM/BIOS and so I assumed that the Quadra 950 didn't know how to do this. A little bit more reading through Dale's post indicated that if I could ground the wires then I could fake a monitor code and test other variants.

Faking codes via the sense pins

I started with aluminium foil, folding it down to a thin strip and punching a hole in one end. These strips were then slid over the three pins that needed to be grounded to fake an Apple 21S Color monitor. This was fiddly work and took quite a few attempts. Foil isn't strong when punching it with a pin and isn't easy to manipulate. It also moves as you plug the monitor into the port, so it was a very one-shot affair.

After getting a successful connection, I started the mac and ... shit ... it just worked. The resolution was already set to the only fixed resolution that this monitor could handle. From the information page at everymac you can see that it can support 1152x870, but I had assumed that this was the max and that I could set any resolution up to that. Turns out that the 21S is a vintage monitor and only does one resolution; but I'm sure it does it well!

But I want to fake a multi-sync monitor!

It turns out that you can't. To do this you need 1,1,1 on the pins, of which my monitor is already outputting! Therefore I was back to zero. I kept reading posts/documents online and stumbled across the Video Compatibility reference article where I see it mentioned that, if you mate my monitor up to the Quadra 950, you can output the correct resolution. Why doesn't mine work then? Reading Monitor Adjustment Info by James Davis tells me that if the BIOS doesn't support the extended sense pins then the monitor will be seen as a 12" RGB. This seems to be the case, as I can only choose 640x480 when the monitor is plugged in as usual. But then again, that contradicts the first page.

Installing the correct drivers...

After a little more googling, it seemed that I'd needed enabling software called "Apple Multiple Scan Software". This was mentioned in this tidbit on hooking up foreign monitors and in the manual from my actual monitor. This wasn't easy to find but a lot of digging produced a copy over at

I initially tried with my PowerPC card enabled and the install software told me that my machine didn't need it. So I rebooted to 68k and it installed... but.... as it was installing it told me that the files on disk were already newer than the files being copied. Whatever... I copied them anyway. After a reboot there was no change.


I managed to find this version (and have made SwitchRes v2.1 available here) and tinkered. I had assumed it would allow magical resolutions to be set... it really did nothing but cause problems.


A fellow vintage Macintosh enthusiast in a forum post over at the 68k Macintosh Liberation Army entertained me with the following user manual for the Mutliple Scan 720. I assumed it would lead to another dead-end... but as I was reading through I noticed that it indicated that if DDC was enabled then specific machines (PPC9600, PCs, etc..) would behave differently. What if it happened to be enabled and my poor Macintosh was getting confused?

I got home and booted the machine into its glorious array of 640x480 pixels. Flicking through the onscreen display on the monitor itself, I navigated to information and then DDC. It was set to 2B. I wonder what those codes even stand for... anyway, I knew that DDC wasn't what the Quadra spoke, so I turned it off.

Low-and-behold after a reboot the standard Monitors and Sound control panel allowed me to select right up to 16-bit 1024x768. Not quite the 1280 or 1152 that I was after, but nearly twice as good as what I had before. Moral of the story? Don't use newer tech on older machinery!