HxC and HP1650A

[synthprof]

Hi HxC’ers,

I have been trying follow the various threads on this forum on how to get the HP1650A logic analyser to boot using either an SD or USB HxC device. There are many threads, some dead ends, many are just notional with scraps of information. Is there a definitive guide to getting this to work? What we know so far:

1. The original Sony MP-F52W diskette drive is about as non-standard as they come. The usually grounded portion of the 34 way provides power, the drive motor operates at a non-standard speed and the track layout isn’t 0-79 as normal. So at least an adapter cable would be required to attach the drive to the analyser (without shorting the PSU!)

2. The files system on the HP boot disks is LIF format and sector copy protected. I have all the HP utils and a stone age laptop with the ‘real’ diskette drive for creating replacement boot disks so I know the original drive is faulty.

Has anyone got this to work, what is the recommended wiring for the drive, what settings need to be changed in the config file as regards speed, pin out functions, etc. Does anyone have a working HFE file which I can use which is know to work?

If anyone can help let me know. I have a lovely 1650A sitting here with all the accessories and I can’t use it after a good number of hours trying to do so.

Many thanks in advance to anyone who has this working!

[Jeff]

Have you currently a floppy emulator ?

[synthprof]

Hi Jeff,

Thanks for writing back. I had parked this project as I thought that no one had any ideas on it. However, I did make a bit of progress which I will share with you. Yes, I do have an SD card based HxC device, a classic Lotharek enclosed one. This has been updated with the latest firmware from the HxC site (v1.8.8.1). I have wired this to the disk controller of the 1650A in the following manner:

34 /READY
32 /SIDE1
30 /RDATA
28 /WPT
26 /TRK0
24
22
20 /STEP
18 /DIR
16 /MTRON
14 /DS2
12 /DS1
10 /DS0
8 /INDEX
6
4
2 /DCD

The +5V and GND has been split out of the ribbon cable and feeds the power connector (remember the original diskette drive has an interface which caries the supply voltages on what would normally be ground on a standard floppy cable). The target ID of the SD drive is 0, disk A.

I managed to find an HFE image which is supposed to work posted on the forum. I have the contents of this copied as the only files on the SD card.

https://hxc2001.com/download/floppy_dri ... A_BOOT.zip

OK. So we start up the analyser and the following happen. The drive ticks once and switches from side 0 to side 1. The track number then seeks at very high speed to 82 and stops. The analyser reports that the system disk isn’t loaded and can’t proceed.

That’s as far as I have got. I dare say the either the wiring to the disk controller is wrong or I have a config mistake. But I still can’t figure it out in the limited time I have away from my repairs business.

Any input would be gratefully received and thanks!

Andy

[Jeff]

OK. So we start up the analyser and the following happen. The drive ticks once and switches from side 0 to side 1. The track number then seeks at very high speed to 82 and stops. The analyser reports that the system disk isn’t loaded and can’t proceed.

Can you check that the "DIR" signal is working properly ? (it should go to track 0...)

[synthprof]

Hi Jeff,

I think the /DIR line is OK. What I have done is a Sigrok trace for you to look at. This trace describes the main signal lines to the floppy emulator at switch on to the point where the analyser reports 'no boot disk'. If you have PulseView I can send you the original trace file rather than the image for closer examination.

Thanks as ever,
Andy

[synthprof]

Just a quick update. I have just replaced the attachment as it was incorrectly labelled. I have now sorted this out and the data lines should make more sense. Also, just FYI, the display says T:079/085 when it gets to the end of the read. I think this might be relevant as an HP LIF disk has more than 80 tracks on it. Config problems?

Thanks!

[Jeff]

Just a quick update. I have just replaced the attachment as it was incorrectly labelled. I have now sorted this out and the data lines should make more sense. Also, just FYI, the display says T:079/085 when it gets to the end of the read. I think this might be relevant as an HP LIF disk has more than 80 tracks on it. Config problems?

Thanks!

I have just added a search engine on the hxc2001.com and then you enter "1650" you can find this in the compatibility list :

Agilent / HP 1650B, "Shugart","Note : Original disk copy protected : Can be dumped with the hxc software", "Drive always selected. Disk change detection cleared on track step."

So first question : Is the HP 1650A and HP 1650B revisions are close enough to be considered the same about the floppy interface ?
If so, it seems that the emulator drive select line should be connected the the vss/gnd. Can you try this ?

EDIT : unfortunately HP 1650A and HP 1650B appears to be different.

I managed to find an HFE image which is supposed to work posted on the forum. I have the contents of this copied as the only files on the SD card.

https://hxc2001.com/download/floppy_dri ... A_BOOT.zip

unfortunately if i read this : viewtopic.php?p=12503#p12503, i see no evidence that the image is working.

but i got a positive report some years ago by email, so with some settings we should be able to make this working...

Can you tried the attached files instead ?

HP1650A.7z

(236.63 KiB) Downloaded 130 times

[synthprof]

Hi Jeff,

Thanks for your continued support. I got a chance to load the new image you provided. I have also tied the drive select line to ground as suggested. So with the new disk contents loaded and connected the following happens from switch on:

The emulator reads the SD card and prints the following on screen: RA T:000/083 S:1
The analyser runs through the boot test and then runs the diskette drive test. The emulator prints: RA T:000/083 S:0 (note the side change)
The analyser tries to boot and the track number increments at high speed until the emulator prints: RA T:079/083 S:1.

The analyser reports that the disk can't be read and to press any key to try again. If you do this the emulator prints: RA T:157/083 S:0. !!

The disk controller is clearly having problems with the geometry of the disk image. If you retry once more the emulator prints: LBA 0000 0000 08. I have never seen this before but it might give some clues.

If you have any ideas what might be happening here then please let me know.

Best wishes,
Andy

[Jeff]

The emulator reads the SD card and prints the following on screen: RA T:000/083 S:1
The analyser runs through the boot test and then runs the diskette drive test. The emulator prints: RA T:000/083 S:0 (note the side change)
The analyser tries to boot and the track number increments at high speed until the emulator prints: RA T:079/083 S:1.

The analyser reports that the disk can't be read and to press any key to try again. If you do this the emulator prints: RA T:157/083 S:0. !!

this is very odd. Are you sure the DIR signal is ok ? Maybe the track 00 too ?

Have you a working floppy disk for this machine ? If so, have some hardware (old pc ...) to dump it ?

EDIT : In fact the track 79 is the copy protection track. And the copy protection is present in both provided images. For some reasons the hp1650a can't read it. Can you check the read signal with an oscilloscope ?

[synthprof]

Hi Jeff,

I don't have the original boot disk for the analyser anymore. However, I do have a copy of the original utility which can write out a new LIF disk for the analyser and an MS-DOS based computer with a 'real' FDD controller. Are there any DOS utilities I can use to create an HFE file from the commend line? At least I could try that if possible.In the mean time I will check the two lines you mentioned. Did you manage to take a look at the logic trace for the unit booting up? It looked to be like the lines you mentioned were active. If you would like the original trace file and have a copy of PulseView (open source and free) on your computer I can send in these.

Best wishes,
Andy

[Jeff]

Did you manage to take a look at the logic trace for the unit booting up?

yes, and the rdata line is not good at all, but this may be an logic analyzer capture sampling rate issue
you should have active low pulses every 2us,3us,4us.
can you check this ?

(attached another image i found to try)

OS_V110.7z

(239.04 KiB) Downloaded 90 times

[Jeff]

Also please try these images.

[synthprof]

Hi Jeff,

I have tried all the images you provided and they all do the same thing. Whiz through the tracks from 0 to 79 in about a second and then the emulation stops and the analyser reports what it can't boot. I think to be honest it is nothing to do with the images; there is some hardware or timing fault here. I managed to get hold of another SD based HxC drive just to make sure and prepped a new SD card. Same results. I checked the /RDATA line and I am getting a pulse about every 3uS. I have even plotted a new trace for you at a higher sampling rate than before. The one thing that strikes me as odd is that the /DIR line always stays high when loading. If you ground the line manually then the HxC drive toggles S: from 0 to 1 and back again. I don't understand why the analyser would try to read the next track in any case when there is no valid data to be read.

As they say in 'Britain' I think we are 'flogging a dead horse' here. I can find evidence to support that the 1650A will or ever has worked with the HxC drive (the B model perhaps). Perhaps I'll just save up and get myself a nice new one?! Seriously, I am a bit down that I can't get this working, so if you have any good suggestions let me know and I'll try them out

Thanks for your help so far,
Andy

[Jeff]

As they say in 'Britain' I think we are 'flogging a dead horse' here. I can find evidence to support that the 1650A will or ever has worked with the HxC drive (the B model perhaps).

The B for sure and A too (got a positive feedback in 2019)

The one thing that strikes me as odd is that the /DIR line always stays high when loading. If you ground the line manually then the HxC drive toggles S: from 0 to 1 and back again.

This means that you have a wiring issue : The "S:" indicator is the SIDE signal , not the DIR one. Please check the wiring !

[synthprof]

Hi Jeff,

I think what I will do is start again with my cable adapter and double check everything. It has turned into a bit of a mess! If it has been proven to work then I'll persist with the project. I'll let your know how I get on...

Cheers,
Andy