Replacing Tandon TM-100-2A in HP 9130 disk drive for HP 86A

HxC Floppy emulator support for all others computers...
Martin Hepperle
Posts: 23
Joined: Fri Sep 09, 2016 11:20 am
Location: Germany

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP

Post by Martin Hepperle » Tue Oct 18, 2016 2:47 pm

Thank you, Jeff.

It is not becoming better. Both images seem to behave the same.
I can read up to sector 44 (which is on cylinder 1) and then the first error occurs when seeking back to sector 0.

In order to investigate more, I have modified my BASIC program further to retry reading using the ON ERROR statement.
This allows me to continue after an error for testing purposes.

Unfortunately I cannot change the error handling of the operating system. The System surely has its own retry mechanism as I can see that it recalibrates and retries on bad floppy disks (usually there are up to 10 retries). But I do not have the ROM code of the HP-86A to investigate.

Algorithm:

Code: Select all

FOR N=0 TO 2*16*35-1
{
   display "target sector N"
	
   try
   {
      read sector 0
   }
   catch ERROR
   {
      display "Error on seek to 0"
      retry read sector 0 up to 5 times
   }
	
   try
   {
      read sector N
   }
   catch ERROR
   {
      display"Error on seek to N"
      retry read sector N up to 5 times
   }
}
Now:
All errors occur when trying to read sector 0, i.e. in the first error clause of the loop.
Due to my error handling, the sector can always be read on the second try.

The corresponding sector numbers are irregular, no clear pattern.
Interestingly the distance between the errors after the previous one is always a multiple of 8.

Table with 3 columns:
N = sector when read sector 0 error occurs
DIFF = difference in sectors between previous error and this one

Code: Select all

N	DIFF	How many multiples of 8
44	-	-
52	8	1
60	8	1
76	16	2
108	32	4
124	16	2
132	8	1
156	24	3
164	8	1
172	8	1
180	8	1
212	32	4
220	8	1
228	8	1
260	32	4
268	8	1
276	8	1
284	8	1
308	24	3
316	8	1
332	16	2
340	8	1
348	8	1
356	8	1
364	8	1
372	8	1
396	24	3
420	24	3
436	16	2
444	8	1
452	8	1
460	8	1
484	24	3
508	24	3
516	8	1
548	32	4
556	8	1
580	24	3
588	8	1
620	32	4
636	16	2
676	40	5
692	16	2
748	56	7
756	8	1
780	24	3
788	8	1
804	16	2
and	so	on
Notes:
sectors are numbered from 0
each cylinder has 2x16=32 sectors
there are 35 cylinders

Jeff
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Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP

Post by Jeff » Wed Oct 19, 2016 7:49 am

Any possibility to get the source of the error ? (Sector not found ? DATA CRC error ?...)
Which firmware version is present into the emulator ?
What about the bus termination ?
Martin Hepperle wrote: It is not becoming better. Both images seem to behave the same.
I can read up to sector 44 (which is on cylinder 1) and then the first error occurs when seeking back to sector 0.
Not sure to understand: "back to sector" of the cylinder 1 or 0 ?

EDIT : Please retry with this firmware version :
http://hxc2001.com/download/floppy_driv ... rmware.zip

Martin Hepperle
Posts: 23
Joined: Fri Sep 09, 2016 11:20 am
Location: Germany

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP

Post by Martin Hepperle » Wed Oct 19, 2016 1:44 pm

Jeff wrote:Any possibility to get the source of the error ? (Sector not found ? DATA CRC error ?...)
Which firmware version is present into the emulator ?
What about the bus termination ?
Martin Hepperle wrote: It is not becoming better. Both images seem to behave the same.
I can read up to sector 44 (which is on cylinder 1) and then the first error occurs when seeking back to sector 0.
Not sure to understand: "back to sector" of the cylinder 1 or 0 ?

EDIT : Please retry with this firmware version :
http://hxc2001.com/download/floppy_driv ... rmware.zip
Sector 0 is on the first cylinder/track. The sector 44 is on the second cylinder (2*16 per cylinder/track.
Sorry, maybe I confused track/cylinder numbers, so instead of cylinder "0"= I now say "first" in the following.
  • The error occurs like that
    - read sector 0 (on first cylinder side 0) OK
    - read sector 43 (on second cylinder side 0) OK
    then trying to read sectors 0, 44
    - read sector 0 (on first cylinder side 0) ERROR
    when I retry to read inside the ON ERROR trap works
    and I can then continue to read sector 44.
  • Unfortunately the system just gives me DISC ERROR, no more information.
  • I use the latest firmware that you posted with the display activated. The display is useful for debugging, so I would like to keep it. But I also thought maybe to try a version without the display if this output is time consuming?
  • Will try with the 1.8.6.14a firmware this evening.
  • About the bus termination I am not sure. From the schematics I see that the Tandon comes with pull-up resistors of 150-680 Ohms (depending on which manual I check) on several lines (unfortunately I am no expert here). I also see that the HxC has some pull-ups, but of much higher resistance. The HP-86A has two separate drive cables coming from the CPU box, so there is no chain. So probably each drive is the "last" drive in the chain?
The Tandon/HP schematics shows pull-ups (The HP schematic has 150, the Tandon schematics has 680 Ohms to 5V) on the 7 input lines:
STEP
DIRECTION
MOTOR ON
WRITE GATE
WRITE DATA
HEAD SELECT
DS0...DS3 (only for the selected one)

From your experience: should I try to add such pull-ups in addition to the ones already on the HxC? Sorry for my ignorance, I am not an expert with these terminating things.

Martin

Martin Hepperle
Posts: 23
Joined: Fri Sep 09, 2016 11:20 am
Location: Germany

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP

Post by Martin Hepperle » Tue Oct 25, 2016 2:33 pm

Jeff wrote:Any possibility to get the source of the error ? (Sector not found ? DATA CRC error ?...)
EDIT : Please retry with this firmware version :
http://hxc2001.com/download/floppy_driv ... rmware.zip
This update file gives me
Error 5 : (blink 5 time and 2 seconds pause cycle) Bad UPD File header! (bad file)
I tried on a "quick formatted" as well as a completely new formatted FAT 32 SD card.

Previous updates worked fine, so I think I performed the update process properly.

Martin

Martin Hepperle
Posts: 23
Joined: Fri Sep 09, 2016 11:20 am
Location: Germany

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP

Post by Martin Hepperle » Thu Nov 03, 2016 6:54 pm

Additional information:

the attached image shows in graphical form, when the errors occur.
There seems to be some loose pattern and beyond a certain distance (track 28 ff.) errors occur each time sector 0 is to be read.
I also played a bit with additional 1K terminator resistors but could not produce any change.

Also found some additional information about a similar disk format in another HP system.
This gives some details about gaps and marks etc.
While I do not have the same document for the HP-.86 I guess that it uses almost or exactly the same format. Maybe this helps.

Code: Select all

FLEXIBLE DISC DRIVE REFERENCE MANUAL
MODEL 64000

Table A-1. Minifloppy Physical Track Format
There are 70 physical tracks on an HP 5-1/4 inch disc. 

Item	Number of Bytes	Hex Value	Description
1	85	4E	Postindex gap
-	-	-	- repeat items 2 - 17, 16 times per track ------
2	16	4E	Sector preamble
3	12	00	ID address mark
4	3	A1	Note: missing clock transitions between bits 4 and 5.
5	1	FE	ID address mark
6	1	xx	Cylinder number (see note 1)
7	1	xx	Head number (see note 2)
8	1	xx	Sector number (see note 3)
9	1	01	Sector length (01 implies 256 bytes)
10	2	xx	CRC (see note 4)
11	22	4E	ID gap
12	12	00	Date address mark synchronization
13 3	A1	Note: missing clock transitions between bits 4 and 5.
14	1	FB	Data address mark
15	256	xx	Data
16	2	xx	CRC (see note 4)
17	28	4E	Sector postamble
18	approx. 600	4E	Preindex gap.
			The number of characters in this gap is approximate.
			Bytes with value 4E should be written until the index pulse occurs.

Note 1 - Cylinder numbering begins at 00. Invisible (i.e., defective) tracks have a cylinder number equal to FF.
Note 2 - Head 00 is the lower head, head 01 is the upper head. Invisible (i.e., defective) tracks have a head number equal to FF.
Note 3 - Sector numbering begins at 00. Invisible (i.e., defective) tracks have a sector number equal to FF.
Note 4 - 16-bit cyclic redundancy check (CRC). The value of the CRC is calculated according to the following formula.
        16    12    5
G(X) = X  +  X  +  X  +  1
The CRC register is initialized to 1's and includes all information starting with the address mark through the CRC characters.
Martin
Attachments
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imak
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Joined: Tue May 23, 2017 3:49 pm

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP

Post by imak » Tue May 23, 2017 4:01 pm

Hello to all in the Forum!

My name is Ian, I have recently purchased and restored a HP 86A and require the pin-outs of the Centronics jack to HP9130A cable schematic, i.e. I wish to connect a Tandon TM-100-2A drive to my computer first before trying the HxC.

Please can someone provide me with a pic of the schematic and the wire to wire connections? I have searched high and low on the net and found nothing!

Really appreciated!

Best regards,


Ian

Martin Hepperle
Posts: 23
Joined: Fri Sep 09, 2016 11:20 am
Location: Germany

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP 86A

Post by Martin Hepperle » Wed Jan 03, 2018 5:04 pm

Hi Ian,

here is some info about the Tandon TM-100-2A disk drives for the HP 86A

Useful Documentation:
- 9130K Service Manual
- HP 86A/B - Self-Paced LearningGuide 35121-90011, 108 pages Sep83

The Tandon disk drive was used at least in these HP devices
82901M, 82902M, 82901S, 82902S
9130A, 9135A, 9826, 9836
13272A
64100B, 64110A

Some details about my drive and its connection:
Model 9130A
Serial Number 2214A08244
Rating on Label
12V 1.6A
5V 0.35A

Note: My original HP 9130A drives have 680 Ohm pullups (some Tandon drives may have 150 Ohm, not sure whether this makes adifference but the load on the bus will be different).
The Service Manual shows both variants (150/680 Ohms).

Code: Select all

  Tandon Drive                                 HP 86A
    PCB edge                            36 pin "Centronics"
Circuit  Component
Side     Side
GND      Signal    Description             
 1        2        Connector Clamp         n.c.        n.c.
 3        4        (Spare)                 n.c.        n.c.
=============  slot 
 5        6         Drive Select 3         n.c.        n.c.
 7        8         Index                  27            9
 9       10         Drive Select 0         26            8
11       12         Drive Select 1         n.c.        n.c.
13       14         Drive Select 2         n.c.        n.c.
15       16         Motor On               28           10
17       18         Direction Select       29           11
19       20         Step                   30           12
21       22         Composite Write Data   31           13
23       24         Write Gate             32           14
25       26         Track 0                33           15
27       28         Write Protected        34           16
29       30         Composite Read Data    35           17
31       32         Side One Select        36           18
33       34         Connector Clamp        n.c.         n.c.

           /O|4     +5V                    1,2,3
Power      |O|3     GND                    7,25
Connector  |O|2     GND                    5,6
           \O|1     +12V                   19,20,21,22,23,24
WARNING
=======
I did my best ringing out the cable, but may have made an mistake!

So:
===
When manufacturing your own cable, please verify the power supply lines on the HP 86A before connecting them together in your cable and before connecting them to the Tandon drive!

Martin

w9gb
Posts: 1
Joined: Tue Oct 09, 2018 5:44 pm

Re: Replacing Tandon TM-100-2A in HP 9130 disk drive for HP 86A

Post by w9gb » Tue Oct 09, 2018 5:55 pm

Ian, Martin (and other readers) :

The value of the termination resistors, for EXTERNAL DISK DRIVES, varies based on the
LENGTH of the cabling from the Floppy Drive Controller.

For those still using the HP 9130 with its Tandon TM-100-2 Disk Drive,
the Sams manual is very useful for adjustments by bench tech with an oscilloscope.

Sams Fotofacts Service Manual (circa 1986)
Tandon TM100-2/2A Disk Drive.
http://chiclassiccomp.org/docs/content/ ... M100-2.pdf

Tandon TM100-1 and TM100-2 Disk Drive (circa 1983)
Operating and Service Manual (OEM models, like HP usage)
http://www.bitsavers.org/pdf/tandon/TM1 ... s_1983.pdf

greg
chicago

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