From: Will Sowerbutts <will@sowerbutts.com>
Date: Mon, 29 Jun 2015 20:53:01 +0000 (+0100)
Subject: zeta-v2: _trap_reboot now disables memory paging entirely
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=0dbaa32fa61812497a7b0a3af07982c8ae8317ec;p=FUZIX.git

zeta-v2: _trap_reboot now disables memory paging entirely
---

diff --git a/Kernel/platform-zeta-v2/zeta-v2.s b/Kernel/platform-zeta-v2/zeta-v2.s
index 0ace3cd9..8c7ced36 100644
--- a/Kernel/platform-zeta-v2/zeta-v2.s
+++ b/Kernel/platform-zeta-v2/zeta-v2.s
@@ -183,6 +183,21 @@ init_partial_uart:
 
 	ret
 
+;=========================================================================
+; Kernel code
+;=========================================================================
+        .area _CODE
+
+_trap_reboot:
+        ; We need to map the ROM back in -- ideally into every page.
+        ; This little trick based on a clever suggestion from John Coffman.
+        di
+        ld hl, #(MPGENA << 8) | 0xD3    ; OUT (MPGENA), A
+        ld (0xFFFE), hl                 ; put it at the very top of RAM
+        xor a                           ; A=0
+        jp 0xFFFE                       ; execute it; PC then wraps to 0
+
+
 ;=========================================================================
 ; Common Memory (0xF000 upwards)
 ;=========================================================================
@@ -280,12 +295,6 @@ _program_vectors:
 
 	jr map_kernel
 
-_trap_reboot:
-        di
-        xor a                           ; ROM starts at page 0
-        out (MPGSEL_0), a               ; map ROM to low 16K
-        jp 0                            ; jump into ROM
-
 ;=========================================================================
 ; Memory management
 ; - kernel pages:     32 - 34