the10thwiz/cc65
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Atari: fix interrupt handling if extended memory is banked in

Browse Source 
Extendend memory is mapped over the main memory in the 0x4000..0x7FFF
area. Many DOSes disable interrupts while extended memory is banked in,
but not all (e.g. SpartaDOS-X).
This change modifies the initial interrupt handler to map in main memory
before chaining to the "worker" handlers.
Since the initial interrupt handler uses a data segment to store the
trampoline to chain to the original handler, introduce a new "LOWBSS"
segment to hold this trampoline. Otherwise the trampoline may end up
inside the 0x4000..0x7FFF area.

Add a link time warning if "LOWCODE" segment lays within the extended
memory window.
This commit is contained in:
Christian Groessler
2018-09-02 23:07:03 +02:00
committed by Oliver Schmidt
parent d199ca1460
commit 1cc4fa9356
9 changed files with 47 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
cfg/atari-overlay.cfg
View File

@@ -46,6 +46,7 @@ SEGMENTS {
SYSCHKTRL: load = SYSCHKTRL, type = ro, optional = yes;
MAINHDR: load = MAINHDR, type = ro;
STARTUP: load = MAIN, type = ro, define = yes;
LOWBSS: load = MAIN, type = rw, optional = yes; # not zero-initialized
LOWCODE: load = MAIN, type = ro, define = yes, optional = yes;
ONCE: load = MAIN, type = ro, optional = yes;
CODE: load = MAIN, type = ro, define = yes;