From 03fa2f38eebb96494932b5b0b2559d29481110c8 Mon Sep 17 00:00:00 2001
From: Patrick Linstruth <patrick@deltecent.com>
Date: Fri, 16 Jan 2026 05:08:38 -0500
Subject: [PATCH] AltairZ80: Corrects bug in ICOM floppy device

A hobbyist found an original FDOS for 8" drives (FD360, FD3712) that
has turned up a bug in both the FDC+ and AltairZ80 implementation of
the FD3712.

In the FDC+, the data pointer into the 128 byte write "shift register"
is reset upon receipt of a CLEAR command. The real hardware never
resets the shift register, so software should not adjust the pointer
either. AltairZ80 may need the same adjustment.
---
 AltairZ80/s100_icom.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/AltairZ80/s100_icom.c b/AltairZ80/s100_icom.c
index 6bd0f6b36..0c3aa4b65 100644
--- a/AltairZ80/s100_icom.c
+++ b/AltairZ80/s100_icom.c
@@ -1434,8 +1434,6 @@ static uint8 ICOM_Command(UNIT *uptr, ICOM_REG *pICOM, int32 Data)
             pICOM->status &= ~ICOM_STAT_DRVFAIL;
             pICOM->status &= ~ICOM_STAT_CRC;
             pICOM->status &= ~ICOM_STAT_DDM;
-            pICOM->rDataBuf = 0;
-            pICOM->wDataBuf = 0;
             break;
 
         case ICOM_CMD_LDCONF: