Ported the ISA RTC and Memory expansion cards from VARCem's.

Bunch of improvements in the device, memory and MMU handling.
Re-worked the NEAT 286 chipset (ported from VARCem).
Re-worked the ATI 28800 a bit, added Sierra SC1502x ramdac to VGA Wonder XL (Compaq) since it supports such.
Top 384K memory handling improvements (256K top memory too)
Added MCA version of MPU-401 (not tested much, however).
Re-worked the SCAT 286 chipset.

src/machine/m_at_compaq.c

@@ -8,7 +8,7 @@
  *
  *		Emulation of various Compaq PC's.
  *
- * Version:	@(#)m_at_compaq.c	1.0.5	2018/03/18
+ * Version:	@(#)m_at_compaq.c	1.0.6	2018/09/02
  *
  * Authors:	Sarah Walker, <http://pcem-emulator.co.uk/>
  *		Miran Grca, <mgrca8@gmail.com>
@@ -100,7 +100,10 @@ write_raml(uint32_t addr, uint32_t val, void *priv)
 void
 machine_at_compaq_init(const machine_t *model)
 {
-    machine_at_top_remap_init(model);
+    machine_at_init(model);
+
+    mem_remap_top(384);
+	
     device_add(&fdc_at_device);
 
     mem_mapping_add(&ram_mapping, 0xfa0000, 0x60000,