RE: Overclocked Deluxe - limited success

I know the vector ram cycles between the CPU bus and the VG bus, I don't
know if this is from the PH 2 clock from the microprocessor or from
somewhere else. Either way, you would have to speed up the VG section to
match the speed of the processor so the memory can be accessed properly and
I don't know what effect that would have on the vector section. (I'm
guessing the display will be dimmer and/or smaller)

-jeff

-----Original Message-----
From: Neil Bradley [mailto:neil@synthcom.com]
Sent: Thursday, April 26, 2001 2:24 PM
To: vectorlist@synthcom.com
Subject: VECTOR: Overclocked Deluxe - limited success

Well, I tried overclocking the Asteroids Deluxe board and here's what I've
found. I cut the trace between the CPU and the solder points so I'm not
increasing the clock to any other circuitry - only the processor. Then I
jumpered pin 37 of the CPU (clock) to pin 14 (6Mhz), pin 13 (3Mhz) and
eventually back to its original home at pin 12 (1.5Mhz) on chip C3.

@ 3Mhz - I get 5 high tones then 1 low tone, and this cycle completes. I
don't have a diag manual for Asteroids Deluxe. Anyone know what this
means? RAM Error perhaps?

@ 6Mhz - Nothing happens.

I'm not sure what the problem is, but I have a few hunches:

* How fast can the 2114s on this board actually run? Is 6Mhz too fast for
them to keep up? Hm.... 6Mhz=166ns if it can do a SRAM every clock. Is
this possible? I've found some 2114s that are rated to 200ns. Is it
worthwhile to swap them out?

* Are there any other circuits that are connected to the data/address bus
that might also be speed sensitive? The vector SRAM?

* Maybe the CPU can't keep up?

Any help would be greatly appreciated...

-->Neil

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---
Neil Bradley            Play a song wrong once and it's a mistake.
Synthcom Systems, Inc.  Play a song wrong twice and it's Jazz. 
ICQ #29402898	       
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