From 9a60ca1e77bbc7dda0b315bd1c7f1733accdf4d2 Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Wed, 24 May 2023 22:12:42 +0200
Subject: [PATCH] Correctly implemented the two MM67 half-registers, closes
 #3347.

---
 src/device/isartc.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/device/isartc.c b/src/device/isartc.c
index 7c12ae032..d2127146d 100644
--- a/src/device/isartc.c
+++ b/src/device/isartc.c
@@ -401,6 +401,14 @@ mm67_read(uint16_t port, void *priv)
                 picintc(1 << dev->irq);
             break;
 
+        case MM67_AL_MSEC:
+            ret                = dev->nvr.regs[reg] & 0xf0;
+            break;
+
+        case MM67_AL_DOW:
+            ret                = dev->nvr.regs[reg] & 0x0f;
+            break;
+
         default:
             ret = dev->nvr.regs[reg];
             break;
@@ -477,6 +485,14 @@ mm67_write(uint16_t port, uint8_t val, void *priv)
             isartc_log("RTC: write test=%02x\n", val);
             break;
 
+        case MM67_AL_MSEC:
+            dev->nvr.regs[reg] = val & 0xf0;
+            break;
+
+        case MM67_AL_DOW:
+            dev->nvr.regs[reg] = val & 0x0f;
+            break;
+
         default:
             dev->nvr.regs[reg] = val;
             break;