Toshiba Logic IC's from the 80's

[Circuitbenders]

I guess gordon might probably know the answer to this one. 

Exactly what are those Toshiba logic IC's that you seem to get in just about everything made by Roland or Korg etc from the late 80's and early 90's? By that i mean the ones labelled as stuff like TC40H074 or TC40H245
They don't seem to be 7400 or 4000 series, although i know some of them are compatible with 7400 series logic as i just fixed a poly800 by replacing a TC40H074 with a new 7474.

Are they somewhere between the 7400 and 4000 series, or are they actually 7400 series with annoying Toshiba labelling? If not, does anyone know of a list of equivalent logic anywhere that will be a drop in replacement for Toshiba logic?

[Gordonjcp]

I'm not certain, but I think they're like 74HC series.  They are CMOS but duplicate the functions of 74-series chips.

[Circuitbenders]

ahhh, cheers, i thought it must be something like that but couldn't fins any mention of Toshiba logic on the net.

74HC's being low power like 4000 series but as fast as TTL stuff? That would explain a lot.

The TC40H's i've been looking for to replace dead ones in a TR727 D/A section certainly seem to have the same pinout as the equivalent 74HC's. That should save me a few pounds.