diff --git a/src/mame/drivers/symbolics.cpp b/src/mame/drivers/symbolics.cpp
index d9e09490cc7..f5460953f9c 100644
--- a/src/mame/drivers/symbolics.cpp
+++ b/src/mame/drivers/symbolics.cpp
@@ -340,7 +340,7 @@ void symbolics_state::symbolics(machine_config &config)
 ******************************************************************************/
 
 ROM_START( s3670 )
-	ROM_REGION16_BE(0x40000,"maincpu", 0)
+	ROM_REGION16_BE(0x40000,"maincpu", ROMREGION_ERASEFF)
 	// the older 'FEP V24' has similar roms but a different hw layout and memory map
 	ROM_SYSTEM_BIOS( 0, "v127", "Symbolics 3600 L-Machine 'NFEP V127'")
 	ROMX_LOAD("00h.127.27c128.d13", 0x00000, 0x2000, CRC(b8d7c8da) SHA1(663a09359f5db63beeac00e5c2783ccc25b94250), ROM_SKIP(1) | ROM_BIOS(0)) // Label: "00H.127" @D13
@@ -355,7 +355,7 @@ ROM_START( s3670 )
 	ROM_CONTINUE( 0x18000, 0x2000 )
 	ROMX_LOAD("10l.127.27c128.d10", 0x08001, 0x2000, CRC(b8ddb3c8) SHA1(e6c3b96340c5c767ef18abf48b73fa8e5d7353b9), ROM_SKIP(1) | ROM_BIOS(0)) // Label: "10L.127" @D10
 	ROM_CONTINUE( 0x18001, 0x2000 )
-	// D17, D11 are empty sockets; these would map to 0x0c000-0ffff and 0x1c000-0x1ffff
+	// D17, D11 are empty sockets; these would map to 0x0c000-0ffff and 0x1c000-0x1ffff; these are verfied from real hardware to read as 0xFF so there must be pullups on the eprom bus/auto-dtack area
 	ROM_REGION16_BE( 0x20,"fep_paddle_prom", 0)
 	ROM_LOAD("fpa-458.bin", 0x0000, 0x0020, CRC(5e034b33) SHA1(fea84183825013b2adc290f71d97e5cffd0cf7fd)) // nFEP Paddle S/N 458
 	ROM_REGION16_BE( 0x20,"fep_prom", 0)