Drive :2on a Model 4P

[BillB3857]

I have a model 4P and found a hardware mod to bring the control line out from the Floppy circuitry to allow use of a third drive. So far, I have had response from the drive (motor starts) whenever I type in a command such as DIR :2. This is followed by a message that says "Illegal drive number." I have entered the command SYSTEM (DRIVE=2, ENABLE) and the system goes off into never-never land. I'm using LS-DOS 06.03.01.

I also tried the ZAP/Patch listed on Ira's site and get the message that I am trying to access a protected file.

Any suggestions?

 

[Agent Orange]

I'm thinking that the BIOS only supports two floppies at any one time. You might however, get away with one internal and one external.

 

[leeb]

Which CP/M are you running?

Montezuma has a CONFIG that has to be set to the # of physical drives available...
Then you can manipulate them into whatever order you want them...

Are you attaching thru the external connection? I dont believe it is normally active w/o a hard drive system onboard.
It may not be sending the rest of the lines out since it is not enabled.

Im only running a single floppy since the other bay is full of an IDE-hd... :D

edit: I see you're NOT running CP/M... but trsdos (LDOS) ... Other than the part about the external connection I cant help... dont use it.
But DO suspect the external port may be the issue unless you're tapping EVERYTHING of the internal connection... in which case it may just not be quite 'right'... How are you connecting to the 3rd drive?

 

[BillB3857]

But DO suspect the external port may be the issue unless you're tapping EVERYTHING of the internal connection... in which case it may just not be quite 'right'... How are you connecting to the 3rd drive?

I am extending the cable that connects the internal drives with a "Tap" IDC connector. If I disconnect the internal drive :1 and set jumpers on external drive to :1, it works. Somehow, LSDOS is not allowing me to set up anything beyond :1. Strange thing is that the hardware seems to recognize the drive since the motor starts only when trying to access drive :2, but LSDOS thinks it is illegal.

 

[leeb]

I am extending the cable that connects the internal drives with a "Tap" IDC connector. If I disconnect the internal drive :1 and set jumpers on external drive to :1, it works. Somehow, LSDOS is not allowing me to set up anything beyond :1. Strange thing is that the hardware seems to recognize the drive since the motor starts only when trying to access drive :2, but LSDOS thinks it is illegal.

This is not really any help, as the MOTOR ON signal is handled by a different part of the controller and is applicable to ALL drives connected.

... a 'tap' idc connector....

Where EXACTLY are you tapping this cable? Im sure you're aware that the connectors on the ORIGINAL drive cable have ALL BUT THE desired drive connector REMOVED... and the drives are normally active for ANY DRIVE so that placement on the cable determines 0 or 1...

edit: Did some more looking... THERE ARE NO LINES connected for the :2 and :3 drives...

U32 (74ls174) is responsible for the :0 and :1 signal on pins 2 and 5...
pins 7 and 10 WOULD (I believe) be correct for :2 and :3 but are NOT connected to the INTERNAL FDC header and are NOT routed to the external bus...

LDOS may be claiming it is illegal bcause it expects only 2 drives to be available...

I fear you may be SOL on this one! :

(Im getting good at this... !)

Another thought...
IF you can find room on the U20 (7416 hex inverter)... possibly pins 7-8 and 9-10 ? you could feed the U32 lines thru them and to the FDC header... but I cannot confirm that pins 7 and 10 ARE :2 and :3...

Ya know... Im getting tired of editing this!
Please provide some details of the 'hardware mod' you mentioned in your FIRST POST... it may not be quite right, or not working as expected...

 

[BillB3857]

This is not really any help, as the MOTOR ON signal is handled by a different part of the controller and is applicable to ALL drives connected.

I didn't realize there was only one Motor ON signal. Thanks for the clarification!

... a 'tap' idc connector....

Where EXACTLY are you tapping this cable? Im sure you're aware that the connectors on the ORIGINAL drive cable have ALL BUT THE desired drive connector REMOVED... and the drives are normally active for ANY DRIVE so that placement on the cable determines 0 or 1...

The "tap" IDC connector is a Male Pin smash on for flat cable. I 'smashed it on' close to the motherboard.

edit: Did some more looking... THERE ARE NO LINES connected for the :2 and :3 drives...

U32 (74ls174) is responsible for the :0 and :1 signal on pins 2 and 5...
pins 7 and 10 WOULD (I believe) be correct for :2 and :3 but are NOT connected to the INTERNAL FDC header and are NOT routed to the external bus...

I found directions somewhere (can't locate it now) that extends the unused pins on the bus driver to make the connector look like the connector on a Model 4 desk type. There was a clarification about the schematic having the IC marked with the wrong number on the schematic. (See your last edit

LDOS may be claiming it is illegal bcause it expects only 2 drives to be available...

I fear you may be SOL on this one! :

(Im getting good at this... !)

Another thought...
IF you can find room on the U20 (7416 hex inverter)... possibly pins 7-8 and 9-10 ? you could feed the U32 lines thru them and to the FDC header... but I cannot confirm that pins 7 and 10 ARE :2 and :3...

Ya know... Im getting tired of editing this!
Please provide some details of the 'hardware mod' you mentioned in your FIRST POST... it may not be quite right, or not working as expected...

Thanks for all the help and suggestions from everybody. I'm sure this will work but I must have a gremlin in there somewhere.

 

[BillB3857]

Back Again

Back Again

Sorry for the delay in responding to the replies. Been on vacation to see the grandsons. Anyway, I pulled the motherboard and double checked the mod that I had done after finding the instructions again. My Motherboard has a part number of 1700284. The instructions I used are:

For the Gate Array's with the green screen.
# Don't rely on page 132 of the 4P Service Manual #26-1080 for the correct IC labels because there are a few typo errors. Change these labels on page 132 before doing the work: U54 to U34
# U35 to U16
# U34 to U14
# Make Jumper: U34 pin 7 to U14 pin 9
# Make Jumper: U34 pin 10 to U14 pin 13
# Make Jumper: U14 pin 8 to J5 14
# Make Jumper: U14 pin 12 to J5 6
# Make a cable with *ALL* of the pins in it and select the drives as 0 & 1 inside the 4P (#10 is for 0 and #12 is for 1) Numbers 14 is for drive 2 and #6 is for drive 3. If you are going to use double sided drives, be sure that #32 is connected because it's used for side select.

These instructions are from Ira's site.

Again, does anybody know of a patch for LSDOS to allow extending the drive count above two drives?

 

[BillB3857]

Sorry for the long delay in getting back. Had to shelve my project for a while. Latest update....

I re-checked all my wiring changes, etc. Connected my Techtronics data analyzer to the floppy Drive select FF. If the individual outputs are cycled by means of the Basic command "OUT &F4,X" where X is either 1, 2, 4, or 8, the responses are as expected. When attempting a system generated function, such as DIR :2, the response is "Illegal drive number".

If I'm right, the problem is within LS-DOS. I have found listings of some of Frank Dura's updates that clearly check for valid drive numbers. Not being a machine language programmer, I'm lost.

Any idea where the magic number is stored within LS-DOS 6.03.01?