From a9f3371772484784d2d026ad1f4f4fc77901f915 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Sat, 30 Jan 2021 17:25:35 +0100
Subject: [PATCH] safer loading code

---
 src/zvm_m65/zvm_cputest.s | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/zvm_m65/zvm_cputest.s b/src/zvm_m65/zvm_cputest.s
index 157e507c..416aba27 100644
--- a/src/zvm_m65/zvm_cputest.s
+++ b/src/zvm_m65/zvm_cputest.s
@@ -77,6 +77,8 @@ ZVM_cputest:
 	lda #$02                                     ; value means - 2*256 bytes read
 	pha
 
+	ldz #$00                                     ; in case hypervisor modified it
+ 
 @loop2:
 
 	pla
@@ -142,18 +144,20 @@ ZVM_cputest:
 	sta BIOS_LOADPTR+1
 	lda #$05
 	sta BIOS_LOADPTR+0
-	lda #$76                           ; HALT
+	lda #$76                                     ; HALT
 	sta [BIOS_LOADPTR],z
 	inc BIOS_LOADPTR
 	lda #$FF
-	sta [BIOS_LOADPTR],z               ; $FF = CP/M simulation for CPU test
+	sta [BIOS_LOADPTR],z                         ; $FF = CP/M simulation for CPU test
 
 	; Run the software
 
+	ldz #$00                                     ; in case hypervisor modified it
 	jmp ZVM_next
 
 @end:
 
+	ldz #$00                                     ; in case hypervisor modified it
 	rts
 
 ZVM_filename_Z80TEST: