Which ROMS are needed in the Apple II / II+ for machine to function

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Can someone tell me what is the bare minimum ROMS to install to have a usable Apple II?

There are ROM D0, D8, E0, E8, F0, F8 sockets

Which ones are dedicated to basic, and which ones are for disk and other purpose? How did the configuration change when apple switched from Integer basic to Applesoft.

In person an in pictures I have seen different combinations and empty sockets.

I have a II+ where the pins rusted off two of the ROM chips, but it has other issues and I wasn't sure if its all ROM related.

Thanks!

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tokabln's picture
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Re: Which ROMS are needed in the Apple II / II+ for machine ...
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Re: Which ROMS are needed in the Apple II / II+ for machine ...

That helps tremendously but not sure if it answers my question. What happens when you don't have the last rom plugged in. Does the computer scan for all roms at boot or does it just error when trying to access it.

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Re: Which ROMS are needed in the Apple II / II+ for machine ...

Hunter012 wrote:

What happens when you don't have the last rom plugged in. Does the computer scan for all roms at boot

No.

Quote:

or does it just error when trying to access it.

Yes.

The code and data in the ROMs appear at locations $D0xx, $D8xx, and so on in the 6502's address space. Each ROM chip holds 2048 bytes. If there's no ROM chip plugged into a particular socket, then the 6502 will read garbage data when it accesses that location.

Hunter012 wrote:

Can someone tell me what is the bare minimum ROMS to install to have a usable Apple II?

There are ROM D0, D8, E0, E8, F0, F8 sockets

Absolute bare minimum is the F8 ROM, because the 6502 starts executing instructions from the location indicated at the top of the address space, and in the Apple II ROM, that will be in the F8 ROM. You'll crash as soon as the Apple tries to jump to BASIC, but you'd be able to use the Monitor to program in assembly language and run machine language programs elsewhere in RAM.

Quote:

Which ones are dedicated to basic, and which ones are for disk and other purpose? How did the configuration change when apple switched from Integer basic to Applesoft.

Integer BASIC used only E0, E8, and F0. That left D0 and D8 empty in a stock Apple II configuration. The Programmer's Aid #1 was commonly installed in socket D8 with Integer BASIC, leaving D0 empty.

For Applesoft, that uses all the sockets (except for F8). So an Applesoft Apple II has no empty ROM sockets on the motherboard.

The disk controller card has its own firmware. There's no disk ROM on the Apple motherboard.

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Re: Which ROMS are needed in the Apple II / II+ for machine ...

Thank you Dog! Exactly what I was looking for. Wow each rom is only 2048 bytes? That explains why they needed so many in those early computing years

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Re: Which ROMS are needed in the Apple II / II+ for machine ...

Looks like you need to go here:

https://www.1000bit.it/support/manuali/manuali.asp

On the pull down menu, click Apple.

Steven Smile

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