Differences

This shows you the differences between two versions of the page.

--- blog:286_shootout_vlsi_vl82c311l [2021/03/13 21:24] – [Repairs] john
+++ blog:286_shootout_vlsi_vl82c311l [2021/04/23 14:09] (current) – [Further Testing] john
@@ Line 118: / Line 118: @@
 {{:blog:286:img20210313125205.jpg?500|}}
-{{:blog:286:img20210313203159.jpg?200|}}{{:blog:286:img20210313212205.jpg?200|}}
+//Below:// DIL-14 sockets fitted in place of the original oscillator solder pads and 40MHz and 32MHz cans pushed in:
+{{:blog:286:img20210313203159.jpg?500|}} {{:blog:286:img20210313212205.jpg?500|}}
+So, did it work?
+Well.....
+{{:blog:286:img20210313211347.jpg?500|}}
+The POST diagnostic card indicates reset held high and no CLK signal :-(
+**[Update 14/03/2021]** - I swapped the processor on a chance it was faulty...
+{{:blog:286:img20210314123150.jpg?500|}}
+The held reset light now goes out, and the CLK light stays lit. So that's an improvement. Still no error codes though.
+==== Further Testing ====
+=== Clock Signals ===
+The 14MHz oscillator which was still fitted to the board on receiving it is working; the clock is present on the output pin from the can as well as on ISA socket pin B30 (//OSC//):
+{{:blog:286:20210423_133918.png?600|}}
+There is an 8MHz clock present on ISA socket pin B20 (//CLK//):
+{{:blog:286:20210423_134011.png?600|}}
+Processor pin 31 (//CLK//) has a 9.996MHz clock:
+{{:blog:286:20210423_135456.png?600|}}
+//This doesn't seem correct//. The processor is a 20MHz unit, and is being driven, as is normal on a 286, by a standard DIL can oscillator of 2x the processor frequency (i.e. 40MHz). The definition for pin 31 is that it //"is divided by 2 internally within the processor to generate the processor clock"// (from the {{ :blog:286:amd_80286_datasheet_june_1989_.pdf|AMD 80286 datasheet}})... that would mean the processor is only at 5MHz. Unless I misunderstand the datasheet, something is drastically wrong here.
 ===== Configuration =====