Apple IIgs slots

[KG7PFS]

Many 8- or 8/16- bit computers have some kind of internal slots. Most don't have enough. Is the Apple IIgs the exception?

I know Apple I/O is mapped to use certain slots for certain things, but the IIgs has most of them built in. How would I avoid conflict between built in interfaces and slots? Could I (for example) plug Apple Super Serial boards into their usual slots and still use the built in ports? (no one can ever have too many serial ports.) Since it has a disk controller built in, could I put something else in one of the slots usually used for a floppy controller?

If so, the Apple IIgs may be the only home computer ever made with enough slots.

 

[george]

many 8- or 8/16- bit computers have some kind of internal slots. Most don't have enough. Is the apple iigs the exception?

I know apple i/o is mapped to use certain slots for certain things, but the iigs has most of them built in. How would i avoid conflict between built in interfaces and slots? Could i (for example) plug apple super serial boards into their usual slots and still use the built in ports? (no one can ever have too many serial ports.) since it has a disk controller built in, could i put something else in one of the slots usually used for a floppy controller?

If so, the apple iigs may be the only home computer ever made with enough slots.

rtfm.

 

[KC9UDX]

No. The built-in stuff "occupies" slots. You free up the slot by disabling the built-ins.

Certain things can be used in certain slots without disabling built-ins, but not in this case.

 

[groink]

I'm extremely over-simplifying things here, so apologies to those who want/know the details....

In short, don't think of expansion slots as "slots." Think of them as memory locations. Slot 1 occupies a certain memory location, so does slot 2, slot 3, etc.

With this in mind, there are basically two types of expansion cards: cards that utilize those memory locations, and cards that do not.

Cards that use the memory location of the slot - this is why you need to disable one of the built-in ports. Let's take slot 1 for example. The printer port on the IIGS occupies what would be the space used by slot 1. If I insert a printer card into slot 1, the card won't work because a printer card is one of those that use the memory location of the slot, as it has software built into the card used by the computer. So when the built-in printer port is disabled, it frees up that memory location for slot 1, and therefore the printer card's software will be enabled.

There are cards that sit in an expansion slot, but does not take up the memory location or the soft switches for that slot. For example, such a card can sit in slot 3, even though the IIGS has the 80-column feature built into slot 3. Even if the slot's memory location is occupied by a built-in feature of the IIGS, the slot can still be used to tap things such as the clock, power, reading the address and data buses, etc.

Therefore, it comes down to being familiar with the functionality of a given expansion card, including how it interacts with the IIGS. And knowing this will help determine when a built-in feature needs to be disabled, and which of those features need to be disabled.

 

[Anthony Adverse]

The ROM3 is better at this than the ROM1 is. But there are still limitations. If you've got a smart enough coder you can bypass some of them, although I don't have any examples to show, you need to talk directly to the hardware rather than any other part of rom or os. If you expect smart peripherals they'll need exclusive ownership of the slot they're in.