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Check that Speed!
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I wanted to test the upgrades I have been doing, and particulary wanted to see the speed difference between
the 16K of VDP (the RAM that comes in the console) and the added 32K of 16-bit RAM.
Thierry Nouspikel wrote a
little Assembly program which tests the RAM. For those of you not familiar with Thierry's website please go
here.
Below is the code that Thierry wrote:
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| | DEF START
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START | | MOV | | @INIT1,@COUNT1 | |
LP1 | | CLR | | @COUNT2 | |
LP2 | | DEC | | @COUNT2 | |
| | JNE | | LP2 | |
| | DEC | | @COUNT1 | |
| | JNE | | LP1 | |
| | B | | *11 | |
* | | | | | |
INIT1 | | DATA | | >0020 | |
COUNT1 | | DATA | | 0 | |
COUNT2 | | DATA | | 0 | |
| |
END | | | |
Below is a table which shows the above code running with different settings on my console. Keep in mind that not
all software will take advantage of the 16-bit RAM. Programs that only use the 16K VDP RAM will not, but any
program that requires the 32K expansion will.
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With standard RAM Setting (Switch in defeat postition) | | 34 seconds | |
With Fast 32K 16-bit RAM | | 20 seconds | |
With Fast 16bit RAM and 3.58MHz crystal speed | | 16 seconds | |
As you can see in the above table there is a remarkable speed difference between the different settings. With the
32K 16-bit RAM and the faster crystal you can have a console that runs at twice the speed of the original.
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