| Re: [hatari-devel] defaulting to SMALL_MEM |
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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] defaulting to SMALL_MEM
- From: Christian Zietz <czietz@xxxxxxx>
- Date: Sun, 13 Feb 2022 17:14:34 +0100
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Eero Tamminen schrieb:
There was recent discussion on EmuTOS devel list that non-existent RAM
can be *read* without exception on *Atari* machines in certain cases. [1]
Christian Zietz:
Yes, the STE has some additional unused ROM decodes, that allow reads
from 0xD0xxxx.
I would call it "non-existent *RAM*", though. The STE simply has some
ROM select lines that are unused (i.e. not connected to anything).
Reading from these addresses does not cause a bus error but returns
"garbage", i.e., often something similar to the last instruction due to
the data bus capacitance.
Of course, Hatari should not crash when something reads any memory;
regardless of whether there is a bus error or not.
But I think my remark (as quoted by Eero above) w.r.t. STE ROM select
lines is not connected with the Hatari crashes that we discussed.
Regards
Christian
--
Christian Zietz - CHZ-Soft - czietz@xxxxxxx
WWW: https://www.chzsoft.de/
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