Re: Apple II Minus Question

[mjmahon@aol.com (Michael J. Mahon)]

Bill Garber wrote:

>"Wayne Stewart" <waynes@telus.dotnet> wrote in message
>news:MPV%b.23987$A12.3961@edtnps84...
>: Bill Garber wrote:
>:
>: > I already told him that if he is seeing the checkerboard
>: > pattern that the cpu is not getting power. It is the same
>: > on all Apple IIs. Take out your cpu and turn it on. You'll
>: > see what he is getting.
>:
>: It isn't the same on all Apple IIs. You're describing what
>happens
>: in an autostart machine. With my non autostart machines the
>only
>: difference between what I get on screen is that when the
>processor
>: is present I get a the monitor prompt at the bottom of that
>: checkerboard pattern
>
>Well, I can't really check what the non-autostart
>ROM does, I only have autostart machines, and a ROM
>card. Would it do that with the ROM card and no CPU?

The Autostart ROM, and all subsequent Apple II ROMs,
clear the text screen before "signing on" for a power-on or
cold reset.

The non-Autostart ROM does not initialize the text screen,
but simply enters the monitor upon RESET.  Before a RESET,
the state of the text screen is however the DRAMs powered
up.  After a RESET, the screen is changed only by the
writing of the monitor prompt.

If, for some reason, the CPU does not reset, or does not
run the ROM code, then all Apple II's will display the power-up
state of the text screen DRAMs.

So, an original Apple II's screen after power up looks pretty
much the way _any_ Apple's screen will look if the processor
does not run the ROM cold reset code.

-michael

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