[Coco] DriveWire issues with Coco 1 F/285 Board

[Torsten Dittel]

Gene Heskett <gheskett at ...> writes:

> The 741C is a very slow op-amp, incapable of doing more than a low 
> amplitude, slew rate limited triangular wave at 31.25 kikobaud.  Its full 
> gain bandwidth is only 10Hz!

...just enough for the max. 9.6 kBaud (POKE 150,1) the CoCo was designed 
for... ;-)

> Even if you have to re-arrenge the basing, 
> one of the op-amps in the LM35X family would be many many times more 
> capable a device.  The LM358, in an 8 pin minidip, actually contains 2 
> fully compensated devices with .1 megacycle plus abilities at greatly 
> reduced power consumption.

I would have to open this particular CoCo to figure out which replacement 
IC made it in, but it was pin-compatible (and didn't require further HW-
changes), I guess one of these proposals here:

http://www.petervis.com/Education/741_Pin_Compatible_Equivalent_Op_Amps/741_
Pin_Compatible_Equivalent_Op_Amps.html

Regards,
Torsten