From 7bf23d5b680f4cfaf2a4f1d1f03005cd1c1473a9 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Sun, 26 Apr 2026 03:14:47 -0400
Subject: Add files I forgot to add to the repo. Apparently nobody builds this
 from source but me...

---
 config/os2ram.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 config/os2ram.h |  6 ++++++
 2 files changed, 61 insertions(+)
 create mode 100644 config/os2ram.c
 create mode 100644 config/os2ram.h

(limited to 'config')

diff --git a/config/os2ram.c b/config/os2ram.c
new file mode 100644
index 0000000..587c396
--- /dev/null
+++ b/config/os2ram.c
@@ -0,0 +1,55 @@
+/* Move the XL/XE OS to RAM.
+   Based on the RAMROM code by Joe Miller, from the Mapping the
+   Atari XL appendix (see the PORTB entry). Uses $6000 to $97FF as a
+   buffer, so it won't step on the default GR.0 screen if BASIC is
+   enabled.
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <atari.h>
+#include <6502.h>
+
+#define LO_ROM_SIZE 0x1000
+#define HI_ROM_SIZE 0x2800
+
+static char *lo_buf = (char *)0x6000;
+static char *hi_buf = (char *)0x7000;
+static char *lo_rom = (char *)0xc000;
+static char *hi_rom = (char *)0xd800;
+
+static char old_nmi;
+
+static void enable_interrupts(void) {
+	ANTIC.nmien = old_nmi;
+	CLI();
+}
+
+static void disable_os_rom(void) {
+	SEI();
+	old_nmi = ANTIC.nmien;
+	ANTIC.nmien = 0;
+	PIA.portb &= 0xfe;
+}
+
+void os_to_ram(void) {
+	memcpy(lo_buf, lo_rom, LO_ROM_SIZE);
+	memcpy(hi_buf, hi_rom, HI_ROM_SIZE);
+	disable_os_rom();
+	memcpy(lo_rom, lo_buf, LO_ROM_SIZE);
+	memcpy(hi_rom, hi_buf, HI_ROM_SIZE);
+	enable_interrupts();
+}
+
+#if 0
+void main(void) {
+	if(is_xl()) {
+		puts("XL/XE, copying OS to RAM.");
+		os_to_ram();
+		*((char *)0xe003) = 0x7e;
+	} else {
+		puts("400/800, can't do.");
+	}
+hang: goto hang;
+}
+#endif
diff --git a/config/os2ram.h b/config/os2ram.h
new file mode 100644
index 0000000..46d0a0e
--- /dev/null
+++ b/config/os2ram.h
@@ -0,0 +1,6 @@
+/* cc65's libsrc/atari/ostype.s offers detailed OS type detection.
+   All we care about is "Is it an XL/XE or a 400/800?", which
+   boils down to this: */
+#define is_xl() ( *((char *)0xfcd8) != 0xa2 )
+
+void os_to_ram(void);
-- 
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