diff --git a/software/bios/Makefile b/software/bios/Makefile
index bfd0aafa5..42aa7bfe4 100644
--- a/software/bios/Makefile
+++ b/software/bios/Makefile
@@ -1,7 +1,7 @@
 M2DIR=../..
 include $(M2DIR)/software/common.mak
 
-OBJECTS=crt0.o isr.o ddrinit.o main.o microudp.o tftp.o boot-helper.o boot.o
+OBJECTS=crt0.o isr.o ddrinit.o main.o microudp.o tftp.o boot-helper.o boot.o dataflow.o
 
 all: bios.bin
 
diff --git a/software/bios/dataflow.c b/software/bios/dataflow.c
new file mode 100644
index 000000000..b3c64a2c8
--- /dev/null
+++ b/software/bios/dataflow.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+#include "dataflow.h"
+
+void print_isd_info(unsigned int baseaddr)
+{
+	volatile unsigned int *regs;
+	int neps;
+	int nbytes;
+	int i, j;
+	int offset;
+	unsigned int ack_count, nack_count, cur_status;
+	
+	regs = (unsigned int *)baseaddr;
+	if((regs[0] != 0x6a) || (regs[1] != 0xb4)) {
+		printf("Incorrect magic number\n");
+		return;
+	}
+	neps = regs[2];
+	nbytes = (regs[3] + 7)/8;
+	
+	// regs[4] is reset
+	
+	offset = 5;
+	for(i=0;i<neps;i++) {
+		ack_count = 0;
+		for(j=0;j<nbytes;j++) {
+			ack_count <<= 8;
+			ack_count |= regs[offset++];
+		}
+		nack_count = 0;
+		for(j=0;j<nbytes;j++) {
+			nack_count <<= 8;
+			nack_count |= regs[offset++];
+		}
+		cur_status = regs[offset++];
+		printf("#%d: ACK_CNT:%10u   NAK_CNT:%10u %s %s\n",
+			i, ack_count, nack_count,
+			cur_status & 1 ? "stb" : "   ",
+			cur_status & 2 ? "ack" : "   ");
+	}
+}
diff --git a/software/bios/dataflow.h b/software/bios/dataflow.h
new file mode 100644
index 000000000..965983070
--- /dev/null
+++ b/software/bios/dataflow.h
@@ -0,0 +1,7 @@
+#ifndef __DATAFLOW_H
+#define __DATAFLOW_H
+
+void print_isd_info(unsigned int baseaddr);
+
+#endif /* __DATAFLOW_H */
+
diff --git a/software/bios/main.c b/software/bios/main.c
index 8df3cab1d..30cd87187 100644
--- a/software/bios/main.c
+++ b/software/bios/main.c
@@ -14,6 +14,7 @@
 #include <hw/minimac.h>
 
 #include "ddrinit.h"
+#include "dataflow.h"
 #include "boot.h"
 
 enum {
@@ -285,6 +286,23 @@ static void wcsr(char *csr, char *value)
 	}
 }
 
+static void dfs(char *baseaddr)
+{
+	char *c;
+	unsigned int addr;
+
+	if(*baseaddr == 0) {
+		printf("dfs <address>\n");
+		return;
+	}
+	addr = strtoul(baseaddr, &c, 0);
+	if(*c != 0) {
+		printf("incorrect address\n");
+		return;
+	}
+	print_isd_info(addr);
+}
+
 /* Init + command line */
 
 static void help(void)
@@ -349,6 +367,8 @@ static void do_command(char *c)
 	else if(strcmp(token, "ddrwr") == 0) ddrwr(get_token(&c));
 	else if(strcmp(token, "memtest") == 0) memtest();
 	else if(strcmp(token, "ddrinit") == 0) ddrinit();
+	
+	else if(strcmp(token, "dfs") == 0) dfs(get_token(&c));
 
 	else if(strcmp(token, "") != 0)
 		printf("Command not found\n");