More CGA CRTC Glitching: HD6845(R) vs. MC6845

More CGA CRTC Glitching: HD6845(R) vs. MC6845

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We've seen how the MC6845 CRTC can produce unintended, 'phantom' vertical sync pulses if R7 is re­written during active display time.  How about the HD6845?  Well, Hitachi's 6845 variant appears to be more sensitive, and will glitch in even more cases than its Motorola counterpart.
Old Chips, New Glitches: the CGA/CRTC "Phantom" VSync

Old Chips, New Glitches: the CGA/CRTC "Phantom" VSync

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A dive into an obscure hardware glitch in the 6845 CRTC chip, which has to do with register rewriting, and only seems to really have a noticeable effect on IBM CGA boards (so far).  Let's see what it is, why it occurs, and how to avoid it.  There's bonus fractals, too!
The IBM 5153's True CGA Palette and Color Output

The IBM 5153's True CGA Palette and Color Output

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CGA can output 16 digital RGBI colors, and there's a well-known standard palette which translates them to (s)RGB values - but that palette isn't a very good approximation of the colors you actually get on IBM's original CGA monitor.  Why is that, and can we do better?
Steel Survivor: an IBM XT Tale

Steel Survivor: an IBM XT Tale

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A fully-equipped IBM 5160 braves the rigors of international shipping and gets here in one piece (just barely).  As will be pictorially demonstrated, 30+ years after leaving the factory, this steel warrior is still one tough SOB.