From fe06ea9b426fad19b693920ca48f131713813957 Mon Sep 17 00:00:00 2001
From: AJR <ajrhacker@users.noreply.github.com>
Date: Tue, 19 Oct 2021 11:40:07 -0400
Subject: [PATCH] express.cpp: Fix regression in interpreting db@, ib@, ob@ and
 similar memory access operators

---
 src/emu/debug/express.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/emu/debug/express.cpp b/src/emu/debug/express.cpp
index 3e15ba29a5b..8d3a15b6e95 100644
--- a/src/emu/debug/express.cpp
+++ b/src/emu/debug/express.cpp
@@ -585,6 +585,10 @@ expression_error symbol_table::expression_get_space(const char *tag, int &spacen
 		return expression_error::NO_SUCH_MEMORY_SPACE;
 	}
 
+	// allow short references to data, I/O and opcode spaces
+	if (spacename.empty() && spacenum != 0)
+		return expression_error::NONE;
+
 	// find space by name or take first populated space
 	for (int i = 0; memory->max_space_count() > i; ++i)
 	{