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--- blog:286_shootout_vlsi_vl82c201 [2021/05/27 13:29] – [Differences between this Unknown VLSI VL82C2012 and others] john
+++ blog:286_shootout_vlsi_vl82c201 [2021/05/27 18:47] (current) – [Addendum - Shadow RAM / UMB Support] john
@@ Line 194: / Line 194: @@
+----
+===== Addendum - Shadow RAM / UMB Support =====
+//The Last Byte// supports the VL82C802 memory controller used in the VLSI chipset on this board. However, I had problems enabling it.
+Whichever way you set shadow RAM in the BIOS, it always ended up with an error message about 'Shadow RAM relocated':
+{{:blog:286:vl_amibios.png?400|}} {{:blog:286:lastbyte_sys.png?400|}}
+Unfortunately there's no labelled jumpers on this motherboard m(
+Through trial and error, and reading the {{:blog:286:chipset.doc|}} documentation included with //The Last Byte//, it seems that shadow RAM control is by pin #69 of the chip. Checking for continuity from that led me to a set of jumpers just above it - which were shorting to ground. Removing the jumper from J16, below:
+{{:blog:286:img20210527191631.jpg?600|}}
+//Note to self: it was in position 3-4, furthest away from the board edge//, this lead the board to start up with 3712KB of RAM, versus 4096KB. A good sign. On booting Dos and watching //The Last Byte// load, I was greeted with this more successful looking banner:
+{{:blog:286:lastbyte_vlsi_working.png?600|}}
+**However**.
+Once //The Last Byte// has loaded, the system is incredibly unstable - with the keyboard or screen locking up at frequent intervals.
 (Go back to the [[blog:286_pc|286 PC main page]])