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Re: Follow-up: 6502 deaths?

Subject: Re: Follow-up: 6502 deaths?
From: Patrick Schaefer <patrick.schaefer@topmail.de>
Date: 2000/10/05
Newsgroups: comp.sys.apple2
Organization: Forschungszentrum Juelich GmbH
References: <39B100A7.2E2D94B7@ien.it> <39DB9622.8AB09376@ien.it> <39DBB31A.B2E4271F@swbell.net> <39DBE679.F4967E31@wanadoo.nl> <39DC4B35.759CEF9@ien.it>

Sabino Maggi schrieb:

> What is strange to me now is that the screen shown by second A2, that
> now houses the dead 6502, is quite different (many different characters
> in random positions) from what I previously observed on the original
> machine, where I had alternate rows "@"s and "!"s.
> Any idea?
> The only thing that comes to my mind is related to different
> initialization of the video RAM.

The RAM chips on your second board came from a different manufacturer.
After power-up, the state of the RAM cells is undefined. It depends on
the chip layout which of them are "1" or "0".

Swapping the RAM chips you should be able to create different startup
patterns.


Patrick

Follow-Ups:
- Re: Follow-up: 6502 deaths?
  - From: Sabino Maggi <maggi@ien.it>

References:
- Apple IIe dead?
  - From: Sabino Maggi <maggi@ien.it>
- Follow-up: Apple IIe dead?... Repaired!
  - From: Sabino Maggi <maggi@ien.it>
- Re: Follow-up: Apple IIe dead?... Repaired!
  - From: Rubywand <rubywand@swbell.net>
- Re: Follow-up: 6502 deaths?
  - From: "ruud.dingemans" <ruud.dingemans@wanadoo.nl>
- Re: Follow-up: 6502 deaths?
  - From: Sabino Maggi <maggi@ien.it>

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