3 Dec
2008
3 Dec
'08
2 a.m.
On Tue, 2 Dec 2008, Fred Cisin wrote:
Oh, I forgot:
ftp.informatik.uni-stuttgart.de/pub/cm/ibm5110
You can't
just connect a 5.25"
drive to it. You may have a look at the 5114 MIM or the 5120 MIM (which
partially contains the 5114 MIM), the latter is online on my site.
URL handy? I never said that it would be EASY, . . .(although I
did erroneously imply
practical)
Although it would be nice, it really isn't practical. One problem is that
the diskette controller is external, i.e. within the 5114 case, and quite
discrete (TTL and IBM sugar cubes). This controller does FM and MFM (i.e.
3740 and System/34 format) and is attached to the 5110 I/O bus. The 5110
"firmware" (the Executable ROS) talks in a very basic manner to the
controller, like "turn the erase head on *now*" or "I'm writing address
mark bytes now, so please modify the clock pattern accordingly". Timing is
*very* critical, there are timing loops e.g. to delay turning the erase
head off after the last byte has been written to disk.
And the stepper control lines are controlled by software.
Attaching a 5.25" drive to this controller would be practically
impossible, alone because of the different erase gate delays or write
currents.
So without a 5114 (or a 5120 with internal drives) you need to make a
controller that emulates the Diskette Interface Adapter Card accurately.
The ROS I/O Supervisor routines are very unforgiving (I know that...)
I've put 5.25" drives in a few machines that
ran SA801 interface (with
mixed results). I've never done it for a drive where I would have to
build a logic board or interface.
Practically, you would need to create your own disk interface and I/O
Supervisor routines (which you can load into RWS).
Christian