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16

Typically a similar computer system would internally generate all system and video clocks it needs to operate from a single clock source, like a crystal oscillator on a motherboard. Thus the system would only be able to free-run asynchronously and without any possibility to be adjusted to run synchronously with another system. The Amiga simply added two ...


9

In other words, what did Amiga hardware have, which other computers lacked, for this rather specific hardware use-case? It was the ability to let its video timing be synchronized from an external source - here the A1300 Genlock. So video generated by the Amiga follows the same timing and phase as the external source, enabling both to be mixed into a new ...


8

Each moveable object on a 2600 is handled by an individual counter. Each counter has the same period as the width of the display and triggers a new output of the object when it wraps around. Horizontal placement is achieved coarsely by having the CPU hit an appropriate address that prematurely resets the counter. From then on the object is as whatever ...


5

A videoadapter can be fed with invalid data (resulting in flicker) if the memory is used by someone else. Obviously, you can't do that with the CPU: you have to stall it until the memory becomes available, otherwise the program it is running will crash. To stall/resume the CPU a bus arbiter would have to be implemented, which costs money. In addition, ...


28

Why did they instead give the CPU priority? It's the lowest effort solution. It needs no additional hardware (*1). At the same time it's a transaction safe solution. Whatever the CPU writes gets written (or read). So no data loss. Letting the CPU wait would need some logic to extend a CPU access cycle. A countable effort even if 'only' a few TTL. For a ...


19

First of all: The TRS-80 was not the only computer with this problem, but there were many computers with this problem. The effect you describe is sometimes called "CGA snow" because before the introduction of EGA cards (CGA cards were used in IBM PCs) IBM PCs were showing this effect. ... it would make the machine slightly slower ... Depending on ...


13

Most of the times when a lot of stuff was being written to the screen, people would want to wait for the display to be done updating before trying to read it. Letting the update get done faster was more useful than keeping the display clearer while it was being updated. I used a TRS-80 a little bit back in the day, and I remember the black static, but I ...


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