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The Poor Man's 1400XL Part 4

flashjazzcat

Entry posted by flashjazzcat

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Centronics connector arrived from RS first thing on Monday morning, but we need to finish the VBXE installation first before figuring out a bracked for the PBI socket. Following Bob Wooley's article, we use a piggy-backed 74LS08 (although Bob recommends an HC) to create the EXTSEL line which is absent on the 1200XL. This is required not only for the PBI but for VBXE itself.

 

blogentry-21964-0-74243300-1315991753_thumb.jpg

 

I haven't lost my "spaghetti" leanings, but at least some shink-fit insulation is in evidence. :)

 

blogentry-21964-0-70796100-1315991764_thumb.jpg

 

The XL VBXE adapater (originally intended for the 800XL) needs to be raised up on an extra two stacked precision DIP sockets in order to clear GTIA and the piggy-backed LS08. Fortunately there's plenty of headroom in the 1200XL.

 

Here's the VBXE finally fitted. Thanks to Candle for patiently explaining the 3.5MHz hook-up points.

 

blogentry-21964-0-52689600-1315991760_thumb.jpg

 

After experiencing sync issues and consulting with Candle again, I eventually discovered that pin 15 of CD4050 isn't even connected to anything on the 1200XL. Pin 12 provided the necessary sync signal.

 

The NTSC display is noticeably taller than the PAL screen, but I'll get used to it. Until Ultimate 1MB arrives, I'm running the VBXE core with emulates a 256KB RAM upgrade. Here's the machine running a prototype SIDE cart:

 

blogentry-21964-0-69192700-1315991756_thumb.jpg

 

So we have extended RAM, RGB output, RTC, SpartaDOS X and IDE storage. Next time we'll tackle internal BASIC and the PBI.

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Gunstar

I find the PAL screen (with my PAL ANTIC installed) far to squished looking, I have to adjust the vertical height so it's as tall as NTSC. Of course when I use games and demos that are overscanned PAL, I have to adjust the height again to see everything on screen!

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flashjazzcat

I find the PAL screen (with my PAL ANTIC installed) far to squished looking, I have to adjust the vertical height so it's as tall as NTSC. Of course when I use games and demos that are overscanned PAL, I have to adjust the height again to see everything on screen!

 

I'm so used to PAL that I found the NTSC screen too tall, but the main motivation for going PAL was that the LCD monitor didn't handle NTSC too sharply. Not sure why, but the characters weren't very crisp, and the whole setup looks much better PAL.

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