Re: Apple II ROMs?

["RedskullDC" <RDC@oz.org>]

Hi again Ernest,
>
> I think that with a bit of training/experience, I would be very
> electronically minded but as things are, I'm left out in the cold with
this
> stuff. I'm curious to the point, though, that I'm sometimes maddened by my
> inability to get my mind around the inner workings of the old computers
> that I've collected. I would compare it to trying to understand written
> Chinese without any training. I look at all those chips on the motherboard
> and wonder, "what does it all mean?"

Perseverance is everything.

> I do have a Base 64 but the computer that I was refering to is the OS-22.
In
> fact, now that I look at it again, I don't even see a Monitor ROM on the
> motherboard. The only "ROMmy" looking ROM chip on the board is the
> Character Generator. The ROM add-on Card has two chips -C-103 and a 2732.
I
> can't remember what the C-103 chip does. Is that the Apple Monitor? The
> motherboard has both a Z80a and a um6502.

Ok, Then since you have a Z-80 on the mainboard, you won't have a slot #4.

I'm familiar with the motherboard you mean. The small ROM 'riser' board
is fairly flexible, and will take a variety of 2716,2732, or 2764 eproms.
You have a 2764 and a 2732 in the middle two sockets, no?

>
> The Base 64 is a slick little clone. It has Basic, Tiny-Assembler, and a
> menu-driven text editor called Mini-Writer -all in ROM. I haven't played
> with this system much but I've been curious to play around with the F1/F2
> keys. I really like the keyboards that have extra functions written on
> them, like the Base 64's keyboard.
>
> > Neat way of expanding some of the monitor routines, or add the
mini-assem
> > to Autostart for example.
>
> Is that what they did with the Base 64?

Yes, I had forgotten about the 'mini-writer' until you mentioned it.

>
> I just re-read what I wrote above, and I didn't explain what I meant very
> well, when I used the term "address." What I meant was does the Apple II
> (or II clone) look for certain information on a ROM that is located in a
> particular ROM socket, or does it look for things in a different way that
> has nothing to do with the particular ROM (EO for example) or physical ROM
> socket? Is it all, more or less random, in terms of ROM label or location?
>
> Could you reverse ROM F0 with EO on the motherboard?

The former is true. The ROMS themselves are electrically identical, but
carry
different information. The decoding logic which decides which ROMS are
activated at which memory addresses are external to the ROM chips, so
you can't plug any ROM into any of the rom sockets.

Red