> I think the problem is that many modern motherboards don't have the pins
> of the second drive select and MotorOn signal wired up. Whether the
> signals exist on accessible pins of an I/O chip I don't know (if they do,
> it may be possible to add jumper wires, but some people are afraid of
> soldering to motherboards).
Quite likely they don't. The first time I ran into a motherboard like this,
I was fortunate enough that the manufacturer provided a schematic online. I
looked at it and at the data sheet for the SuperIO chip that the motherboard
uses, and I found out that that SuperIO chip does not have enough pins to
run two floppy drives and also drive all the fans and other stuff on that
motherboard. IIRC, the SuperIO is configurable and does have the option of
bringing the signals for the second floppy drive out to pins, but if you did
that, some other functions that the motherboard needs more could not be
brought out to pins.
Ok, apparently my PC knowledge is dated ;)
I've been working on rebuilding my Hercules setup (vm/360 with CMS and MVS/JES2). This is currently a token ring setup with a 3179 terminal going to a 3174 establishment controller. The 3174 connects to an IBM 8228 MAU. Also connected to the MAU is a token ring card in a PC running Linux/Hercules. I'm changing it to a FreeBSD PC that dualboots with FreeBSD (for hercules) and DRDOS (for PUTR which I'll use a 5.25 floppy for, and for running PromLink to attach to my Data I/O, and several other classiccmp related items that require DOS). Long story short, it will be a more "general purpose (classiccmp)" PC. I'm getting rid of the token ring card in the PC (FreeBSD dropped Olicom support, the only token ring card previously supported). So the PC running hercules will connect to an IBM 8271 ethernet switch, which connects to an IBM 2210-24M token ring/ethernet router. That will connect to the MAU and back to the 3174 and 3179.
Much to my chagrin, I've become aware when I started rebuilding that PC last night with a modern mainboard that most mainboards these days that have a FDC connector (many don't even have one) which only supports ONE floppy drive. I really need to have both 5.25 and 3.5 floppy drives, and they need to be recognized by DOS (which rules out any cards that have special drivers). I can't find a PCI floppy controller, and even if I could I'm worried DRDOS won't recognize it.
So, the only idea I can think of is would it be possible to put a small switch on the front panel that allows me to switch between 3.5 floppy and 5.25 floppy? I realize I'd have to reboot and change BIOS settings each time, but at least I would have to derack the PC and open the case and move cables. Any ideas if that is feasible or anyone have some other ideas?
I thought a video might be easier for you all to see the issue I am
having with restoring my Xerox Alto.
The issue I am having is the Diablo Disk drive does not power on fully
(I am measuring +15 and -15V on the drive, but +5V is only measuring at
around 2.5V. The lamps on the front of the drive do not light-up, and
the LOAD/RUN button does nothing, hence the door lock does not unlock.
Here is a link to the video: http://www.youtube.com/watch?v=mx80CvjuvyE
I have visually inspected all PCB boards and components, nothing seem to
be damaged. Also, the power supplies seem to be outputting power
properly (as seen via the RED voltage LEDS in the Alto card cage.
Any recommendations on how to troubleshoot the disk drive further?
Hi! I've received permission from the author of "68000 Microcomputer
Systems Designing and Troubleshooting" to include the S-100 68K CPU board as
part of the N8VEM home brew computing project for educational purposes.
This is a classic text found in many computer science and engineering
courses in the 1980's and 1990's. It is possible some here recall the book
>from their own college and/or professional experiences.
As part of that effort, I am capturing the schematic and PCB layout from the
book as closely as possible. The intent is to replicate the authors'
original board. There is a draft schematic and PCB layout on the N8VEM wiki
If anyone is interested in helping with this project please contact me. In
particular, I am looking for volunteers to review the schematic and compare
it against the schematic and PCB layout in the book. Due to the complexity
of this board quality assurance is extremely important. Actually if anyone
has one of these boards or experience with them I would be very interested
in hearing from you.
The plan is to make a limited run of manufactured prototype PCBs to do an
initial build and test of the board. If you are an experienced builder and
interested in participating in the initial build and test please contact me.
The corrections/updates from the prototype board will be incorporated into a
board to be made available for all the N8VEM builders as part of the S-100
Thanks and have a nice day!
I will in Kansas City Mo on October 22 to load up some tape drives,
CPU, large printers, and other items located there in a warehouse. If
anyone can spare some time (even 30 minutes) to come by and help load
the UHAUL rental truck on Saturday the 23rd it really needed. I hope to
start loading the smaller items on Friday after I fly in and pick up
the 26' box tuck. All the large and heavy stuff will be loaded on
Saturday. If you help load email me and I will get the address of the
warehouse and a contact phone number.
Thanks in advance,
>> hole before drilling the full size hole", or "don't tighten any of
> Use a centre punch. Or a Slocombe drill. And drill a pilot hole. And
> rememebr the drill tip angles are different for different materials.
And remember that most ordinary twist drills aren't meant for enlarging
existing holes because their centre isn't then supported, and unless
everything is held rigidly (and often not even then) will tend to produce
some sort of curve of constant width other than the desired circle.