diff --git a/core/hw/flashrom/flashrom.h b/core/hw/flashrom/flashrom.h
index 15896eed4..cfc3588d4 100644
--- a/core/hw/flashrom/flashrom.h
+++ b/core/hw/flashrom/flashrom.h
@@ -197,6 +197,9 @@ struct SRamChip : MemChip
 
 // flash logical blocks
 #define FLASH_USER_SYSCFG 0x05
+#define FLASH_USER_INET 0x80
+#define FLASH_USER_ISP1 0xC0
+#define FLASH_USER_ISP2 0xC6
 
 struct flash_syscfg_block {
   u16 block_id;
@@ -211,6 +214,25 @@ struct flash_syscfg_block {
   u8 reserved[50];
 };
 
+struct flash_isp1_block {
+	u16 block_id;
+	u8 _unknown[4];
+	char sega[4];
+	char username[28];
+	char password[16];
+	char phone[8];
+	u16 crc;
+};
+
+struct flash_isp2_block {
+	u16 block_id;
+	char sega[4];
+	char username[28];
+	char password[16];
+	char phone[12];
+	u16 crc;
+};
+
 // header block in block-allocated partition
 struct flash_header_block {
   char magic[16];
diff --git a/core/hw/holly/sb_mem.cpp b/core/hw/holly/sb_mem.cpp
index fa8151bc4..209bb312d 100644
--- a/core/hw/holly/sb_mem.cpp
+++ b/core/hw/holly/sb_mem.cpp
@@ -39,6 +39,70 @@ static std::string getRomPrefix()
 	}
 }
 
+static void add_isp_to_nvmem(DCFlashChip *flash)
+{
+	u8 block[64];
+	if (!flash->ReadBlock(FLASH_PT_USER, FLASH_USER_INET, block))
+	{
+		memset(block, 0, sizeof(block));
+		strcpy((char *)block + 2, "PWBrowser");
+		block[12] = 0x1c;
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_INET, block);
+
+		memset(block, 0, sizeof(block));
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_INET + 1, block);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_INET + 2, block);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_INET + 3, block);
+		memset(block + 27, 0xFF, sizeof(block) - 27);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_INET + 4, block);
+		memset(block, 0xFF, sizeof(block));
+		for (u32 i = FLASH_USER_INET + 5; i <= 0xbf; i++)
+			flash->WriteBlock(FLASH_PT_USER, i, block);
+
+		flash_isp1_block isp1;
+		memset(&isp1, 0, sizeof(isp1));
+		isp1._unknown[0] = 0xFF;
+		isp1._unknown[1] = 0xFE;
+		isp1._unknown[2] = 0xFF;
+		isp1._unknown[3] = 0xFF;
+		memcpy(isp1.sega, "SEGA", 4);
+		strcpy(isp1.username, "flycast1");
+		strcpy(isp1.password, "password");
+		strcpy(isp1.phone, "1234567");
+		if (flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP1, &isp1) != 1)
+			WARN_LOG(FLASHROM, "Failed to save ISP information to flash RAM");
+
+		memset(block, 0xFF, sizeof(block));
+		block[34] = 0;
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP1 + 1, block);
+		memset(block, 0xFF, sizeof(block));
+		block[9] = 0;
+		memset(block + 49, 0, 13);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP1 + 2, block);
+		memset(block, 0xFF, sizeof(block));
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP1 + 3, block);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP1 + 4, block);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP1 + 5, block);
+
+		flash_isp2_block isp2;
+		memset(&isp2, 0, sizeof(isp2));
+		memcpy(isp2.sega, "SEGA", 4);
+		strcpy(isp2.username, "flycast2");
+		strcpy(isp2.password, "password");
+		strcpy(isp2.phone, "1234567");
+		if (flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP2, &isp2) != 1)
+			WARN_LOG(FLASHROM, "Failed to save ISP information to flash RAM");
+		u8 block[64];
+		memset(block, 0xFF, sizeof(block));
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP2 + 1, block);
+		block[9] = 0;
+		memset(block + 49, 0, 13);
+		flash->WriteBlock(FLASH_PT_USER, FLASH_USER_ISP2 + 2, block);
+		for (u32 i = FLASH_USER_ISP2 + 3; i <= 0xEA; i++)
+			flash->WriteBlock(FLASH_PT_USER, i, block);
+	}
+}
+
 static bool nvmem_load(const string& root)
 {
 	bool rc;
@@ -92,6 +156,8 @@ static bool nvmem_load(const string& root)
 		
 		if (static_cast<DCFlashChip*>(sys_nvmem)->WriteBlock(FLASH_PT_USER, FLASH_USER_SYSCFG, &syscfg) != 1)
 			WARN_LOG(FLASHROM, "Failed to save time and language to flash RAM");
+
+		add_isp_to_nvmem(static_cast<DCFlashChip*>(sys_nvmem));
 	}
 	
 	if (settings.platform.system == DC_PLATFORM_ATOMISWAVE)