Scott Holder wrote: > The Mac Plus/etc mouse is a pretty dumb device generally speaking - the > sensors are wired straight into a 6522 which generated an interrupt > whenever the mouse moved a notch any direction and a line to sense the > button. Pretty simple design, but not very flexible. It worked for the > one design of mouse, and not much else.
It would work fine for any mouse. But ADB is just much more versatile. It can support multiple keyboards and mouse through a single ADB port. At the same time ADB was introduced IBM introduced the PS/2 interfaces which are basic, one keyboard or one mouse. And it wasn't stable. I worked on a project using it with a bar code scanner plugged inline with the keyboard. One day it stopped working on new machines. It turned out IBM changed how the protocol worked. Frustrating. If it had been ADB it wouldn't have been a problem as the bus works with multiple devices. > > Functionally speaking, ADB is somewhat similar to USB from a logical > perspective (Greatly simplifying - this is not to say there's any chance > of adapting between the two without significant work, just that when > thinking about them they're similarly set up). Each device is assigned > an address, which is used by the hardware and OS to address it > specifically and tell it apart on the line and read registers from it. > It could, theoretically, have been used for a lot more than it was - > networking, storage, etc. It just ended up not being practical with the > other options available. Speed is a big limitation, it ran in the 1-2KBps range. There was a modem from Global Village that worked on just the ADB port (power and data). But that was pushing the limit on speed. IIRC the bus was impacted by it. -- Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
