ECG994M VCO chip; what is it??

[Jeremy N Bradbeer]

I found this VCO chip (994M) in the ECG (Philips) replacement catalogue 
(generic equivalents for proprietory devices) but the catalogue doesn't say 
what it is a replacement for. All I can say is that it is in a standard 8 pin 
package and gives separate triangle and square wave outputs and costs about 
$2.50 through my local component store.

Anyone know anything about this chip?
Any idea what it is a replacement for?

Jeremy