1 May
2013
1 May
'13
1:17 p.m.
I've opened up the drive. The external interface
is to a "Data Path"
module that has a bunch of TTL and one large chip (40 -pin, probably an
8031) with a Phillips logo. I think this is confirmed to be an LMSI
rebrand.
I would not bet on it being an 8031, for several reasons.
The trivial one is that if it was from taht series, it would be more
likely to be an 8051 with an internal ROM.
But amazingly, Philips used 6805-series micrcontrollers in some CD-ROM
drives (and CD players). I have no idea why, but they did.
And the CD-ROM drive I mentioned has a 40 pin IC numbered PCF1801BP in
the data circuit. This is not a microcontroller, it's a mask-programmed
ULA which extracts the wanted data from the stram at the output of the
SAA7310 I suspect the chip in your drive is soemthing similar.
For the record, 3 of the RS422 drivers are drive by that IC. Pin 32 is
the clock output, it's inverted 3 times byy 4001 NOR gates (probably also
to delay it a bit). Pin 27 is the data output. nd pin 33 is Attention.
-tony