Differences

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

--- blog:286_shootout_vlsi_vl82c311l [2021/04/23 13:41] – [Repairs] john
+++ blog:286_shootout_vlsi_vl82c311l [2021/04/23 14:09] (current) – [Further Testing] john
@@ Line 138: / Line 138: @@
 ==== Further Testing ====
-The 14MHz oscillator is working; present on the output from the can as well as on ISA socket pin B30:
+=== Clock Signals ===
-{{:blog:286:20210423_133918.png?500|}}
+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//):
-There is an 8MHz clock present on ISA socket pin B20:
+{{:blog:286:20210423_133918.png?600|}}
-{{:blog:286:20210423_134011.png?500|}}
+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 =====