MFM emulator to STDC controller no joy.

[Jay Cotton]

Hi:

I am trying to get the STDC controller working with an  mfm emulator. 

https://www.pdp8online.com/mfm/

I have been following the instructions at 

https://smpl.fyi/2016/09/testing-cromemco-mfm-st506-hard-disk/

This all seems very strait forward.  But I am hitting a wall.

The primary bug seems to be that the controller simply does not see what it wants

to from the emulator.   The emulator also does not seem to see the controller.

When I get to the initstdc command

# initstdc
STDC Hard Disk Initialization Program Version 30.00
Press:  RETURN to supply default answers
        CONTROL-C to abort program
        To only do Alternate tracks and Partitions answer "x"
                to "first cylinder" question.
Warning: INIT can destroy all disk data

Disk to initialize (devname)? std31

Testing:
Initializing disk controller - OK
Testing dma - OK
Rotational speed - FAILED

[ I would expect the emulator s/w to print some kind of trace here.  But nothing]

Now I have been able to get the same output with or without the control/data cables

connected. 

After that fail, a rerun generally produces 

# initstdc
STDC Hard Disk Initialization Program Version 30.00
Press:  RETURN to supply default answers
        CONTROL-C to abort program
        To only do Alternate tracks and Partitions answer "x"
                to "first cylinder" question.
Warning: INIT can destroy all disk data

Disk to initialize (devname)? std31

Testing:
Initializing disk controller - FAILED

The disk cables I got from  iec

https://iec.net/product/mfm-hard-drive-cable-set-20in/

These seem to buzz out correctly.

I am also getting a verity of time out messages and errors.  

jc

[Jay Cotton]

More observations.

The STDC can tell if the emulator is not supplying the correct drive number.

i.e.  drive = 0 does not work, but drive = 1 does.

The error status bit says that the ready is not asserted, and yes that line is

a 1 state.

Also, I see that the STDC has a 150ohm pull up on many control lines, there is also

a 150ohm pull up on the emulator.  Should I remove one of these ?

jc

[damian]

Hello Jay

In the Cromix Plus systems that I have looked at that used STD disks, there was a command in /etc/iostartup.cmd to download firmware to the STD controller.  Does your system have this?

% Download new Std controller firmware (required)
  /etc/stdload /etc/stdcfirm std0

% Remove comment signs, "%", in order to load IO processors
% with quadart driver
% /etc/iopload /etc/quadart.iop io1

...

Damian

[Jay Cotton]

Ah yes, lets try that.

jc

[damian]

Have you checked that the STDC is correctly jumpered for a DPU?

Do you have the Priority Interrupt Cable installed?

[Jay Cotton]

STDC is factory strapped for DPU.  Yes the daisy chain is installed.

I ran the 
# ./iostartup
STDC Open Error: Unit 0, Block 0, Head 0, Cyl 0, Stat e1,Error 7ff
Disk I/O error

I can't tell if the firmware load was performed or skipped....

the 7ff is saying that the drive ready is not set.  I have found that to be true by looking at pine 22

of the cable with a scope.  It is high.

So, that issue is over in the emulator board.  But, I don't see how to make a change to it.

jc

[Jay Cotton]

Does this look correct for the mfm_emu log ?

root@beaglebone:~/emu# ./mfm_emu --initialize --file /disk/D41.C4096.H16.hdd --cylinders 4096 --heads 16 --drive 1
Board revision C detected
Emulated drive RPM 3600

<< very long wait here >>
Drive 0 num cyl 4096 num head 16 track len 20836
PRU clock 200000000
  Waiting, seek time 0.0 ms max 0.0 min free buffers 75
bad pattern count 0
Read queue underrun 0
Write queue overrun 0
Ecapture overrun 0
glitch count 0
glitch value 0
0:test 0 0
0:test 1 0
0:test 2 0
0:test 3 0
0:test 4 0
1:test 0 0
1:test 1 0
1:test 2 0
1:test 3 0
1:test 4 0
select 3 head 0

[Damian Wildie]

The STDC supports a maximum of 1024 cylinders.

---- On Tue, 28 Jun 2022 07:30:26 +1000 Jay Cotton <lbmg...@gmail.com> wrote ---

[Jay Cotton]

o.k.  tried that, still no joy.

jc

[MikeS]

Hello again, Jay,

 

Well, since you didn't buy it from me we can't be sure that the STDC is actually working properly... ;-)

 

But it does sound as though maybe the 'drive' is just not being selected, especially that 'no index' error; that should be pretty fundamental and not really dependent on the firmware version, interrupt priority cable, etc.

 

Pin 1 of the data cable should indicate when the drive is selected; does it? Maybe also check the select signal on pin 26 of the command cable.

 

And sorry if I'm stating the obvious, but the data cable is plugged into the left header (J5), correct?

 

Readall will keep accessing the 'drive' while you're probing; unfortunately STDEX, the STD diagnostic program, is configured for Cromemco terminals and the display is a little messy on others. If anyone knows of a patched or configurable version like the HDTEST IMI version (or a Cromemco emulation) that would be great.

 

Maybe Roger will join the conversation; IIRC he was one of the first Cromemco users of Dave G.'s emulator and even helped him add the unique Cromemco format.

 

m

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[MikeS]

Good point, Damian,

 

The track length also looks odd; it's normally only 10KB, not 20836

 

m

----- Original Message -----

From: Damian Wildie

To: cromemco

Cc: lbmgmusic

Sent: Monday, June 27, 2022 10:00 PM

Subject: Re: MFM emulator to STDC controller no joy.

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[Roger Hanscom]

Hi Mike,

>> Maybe Roger will join the conversation; IIRC he was one of the first Cromemco users of Dave G.'s emulator

I hope you're not talking about me!  I'm stuck in the dark ages with a 4 floppy Cromix install on a "System One".  I only wish I had a hard disk to upgrade my Cromix experience.  I've never used an emulator either!

Sorry, but I can't be any help with Jay's STDC problem.

Roger

 

[randy482]

Try asking on :

MFM Discuss - Google Groups

or

MFM announce - Google Groups

Randy

[rlm2667]

I can add that when initializing the emulator disk for the first time I had to use the -n (new disk) flag. I used inithard in 31.67 and supplied the head/cylinder information. Without doing this on a new image I got drive errors. I don't think I ever tried to initialize one using initstdc. 31.xx Cromix doesn't have initstdc.

I think David made some changes to mfm_emu to address this issue but I haven't created a new image for quite a while. I have images mounted currently with 3200 cylinders and 16 heads and 4096 cylinders and 8 heads running 31.68 on an XPU system. These configurations also work in 40.xx with the XXU.

I guess in some versions of Cromix, 1024 was the cylinder limit but in 31.67 and 31.68 as well as 40.xx series up to 4096 cylinders works.

Richard

[MikeS]

Hi Roger,

 

I'm trying to remember who was playing with 4d System's tiny little RS232<>uSD card SSD and wrote some basic drivers for CP/M & CDOS for it; was that you by any chance?

 

m

----- Original Message -----

From: Roger Hanscom

To: crom...@googlegroups.com

Sent: Tuesday, June 28, 2022 1:48 PM

Subject: Re: MFM emulator to STDC controller no joy.

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[MikeS]

Some odd things going on with my email; I sent this at the same time as the 4d Systems question but it looks like it didn't get through.

 

Of course meanwhile Richard himself answered... ;-)

 

Computers!! ;-)

 

m

 

----- Original Message -----

From: MikeS

To: crom...@googlegroups.com

Sent: Tuesday, June 28, 2022 6:54 PM

Subject: Re: MFM emulator to STDC controller no joy.

Well, I was talking about you but my memory is really getting bad. I think I was thinking of Richard RLM2667; here's an old email:

 

"After some software updates by David Gesswein for his ST506 Emulator, http://www.pdp8online.com/mfm/mfm.shtml,  I have been able to format and mount a 16 head 3200 cylinder drive. He also has fixed a problem with a newly created image that had made it very tricky to get a fresh emulation initialized.  Now it's just create the image and initialize it with inithard -n. I'm not sure when the cylinder limit went up to 4096 cylinders but I'm running 31.67 and it allows it.  31.05 limits it to 1232 or so. 

So, with 2 16 head x 4096 cylinder emulated drives you could have over 1.3 Gig of hard drive online on a Cromix system.  Not bad.

Richard"

 

Some of his systems are on line, although it looks like it's shut down at the moment:

 

http://cromix.myautosolution.com/

 

m

 

 

[Jay Cotton]

Remote access to cromix is a lot of fun.  And, I find that the iostartup command is a bit different than what I have

on my boot disk.  I will try this version.

jc

[Jay Cotton]

After hours of frustration, it dawned on me (I am slow) that I might try one of the MFM disk images instead of 

attempting to create a blank disk.

I loaded D40.C1024.H16.hdd onto a USB stick and copied it into the the BBG card.

I started the emulator, and all my problems went away.  

Some sort of RTFM here if I can figure out where the FM is located.

tnx for all the help

jc

[Roger Hanscom]

>> I'm trying to remember who was playing with 4d System's tiny little RS232<>uSD card SSD

>> and wrote some basic drivers for CP/M & CDOS for it; was that you by any chance?

Yep, Mike .... that was me.  I got it working with CP/M (v. 2.2), but never got around to CDOS.  I don't use CDOS enough to justify the effort (mostly just use it to INIT diskettes).  The uSD card is FAT formatted, and it is quite a simple matter to read and write files to it, and see the directory.  I believe that there are "lower level" commands to access the uSD card in a "raw" manner, but much more effort to get that to work.  Somewhat impractical anyway because the interface is only Rx, Tx, +5v, G, and reset.  Synchronization would be an issue.  FTDI used to make a device (I think they called it the "VDRIVE"?) to interface a flash stick to serial.  It had provisions for CTS/RTS so it was possible to do hardware handshake.

Roger

[MikeS]

Well, at least I got that right ;-)

 

Looks like FTDI still has a VDRIVE (v3 by now); might be fun to look at. I assume you don't have any experience with it?

 

Are your 4d drivers still on line? If so, could you share the location pls?

 

TIA,

 

m

----- Original Message -----

From: Roger Hanscom

To: crom...@googlegroups.com

Sent: Wednesday, June 29, 2022 11:10 AM

Subject: Re: MFM emulator to STDC controller no joy.

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[MikeS]

Hi Roger,

 

Tell us more; what type of floppy are you using, and which version of Cromix? How much memory have you got?

----- Original Message -----

From: Roger Hanscom

To: crom...@googlegroups.com

Sent: Tuesday, June 28, 2022 1:48 PM

Subject: Re: MFM emulator to STDC controller no joy.

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[Roger Hanscom]

Hi Mike,

>> Looks like FTDI still has a VDRIVE (v3 by now); might be fun to look at.

I begged their customer support to provide some examples (that work) to make the VDRIVE more accessible to folks like me.  They refused, and as far as I know there still are no good examples on their Web site (although I haven't checked in quite a while).  To make the device work on a Z80, I think you have to write an interrupt driven service routine with circular buffer?  Didn't sound like fun to me.  Now there is a much cheaper dongle, from China, that is supposed to provide an 8-bit parallel (or serial -- it's an option) interface to a USB device.  Of course, I was most interested in the device being a USB flash stick.  I tried to get the serial side to work, but had no luck.  A friend told me that the core of this thing is an 8051-type processor.  In any event, the protocol used on the serial interface is really strange (to me anyway).  Worse still, the "documentation" is written in very broken English, and is almost worthless.  I was going to try the parallel interface, but other things grabbed my attention.  Maybe I'll get back to it at some point?  There were at least 2 versions of the thing.  I think that they recognized that the first version had some problems (based on the CH375), so they came out with a (at least) second version that is supposed to be better.  I think that the chip in the 2nd version is the CH376(?).  If you do some on-line searches, you will probably find out a lot more.  A guy who developed a bare metal 8088/8086 (not sure which) used the newer CH376 version (in parallel) and apparently got it to work.  I only have the older (CH375) version. I think he has some YouTube videos on his project (but I don't have any specifics to search on in order to find it).  I think he was even selling PCBs for DIY builders?

>> I assume you don't have any experience with it (VDRIVE)?

I have an early version, but that's the extent of my "experience".  Oh, and another discouragement is that the connector on the back of the device is 2 mm, NOT .1" (2.54mm).  I think that FTDI could have made the VDRIVE quite popular and sold a ton of them, but seems at every turn they shot themselves in the foot.

 

>> Are your 4d drivers still on line? If so, could you share the location pls?

I don't believe they are on-line, but I'd be happy to send you copies of the code.  The directory query works very well (I have two versions).  The uDrive takes the "firehose" approach to directory queries, so I have one version that just stores what gets sent in memory (might be a problem for large directories?), and formats it to the screen later.  The other version tries to send the output directly to the screen (I think -- it's been a while since I've looked at any of this).  That might not work with slower CPU's?  The uDrive is most useful to me as a way to get files *TO* the Z80, so I've worked on the "read" utility most.  Because of the synchronization problems, it works very well for files that are multiples of 128 bytes (which is most anything that comes from a CP/M system).  It sometimes chokes on files that are not.  The UDrive lets you set up the number of bytes that get sent as a "packet".  I use 32.  If the file you are reading has anything that looks like an ACK or NACK in it, it causes confusion (packets of <32 get you in trouble!).

 

>> Tell us more; what type of floppy are you using, and which version of Cromix? How much memory have you got?

I'm using four HD (1.2 MB 5.25") drives.  It's an XPU with a 64FDC.  It works with Cromix v. 20.63, and 31.05.  As far as memory is concerned, I have a pile of 256KZ's, so the memory can be just about anything I want (and can fit).  Right now I only have 2 of them in the backplane (as you well know, the System One chassis doesn't have a whole lot of room!).  I have used the 4MB S100computers memory board with it, and it works but is unstable.  I need to get back to that to try to figure out why.  Probably have a jumper (or two *grin*) set wrong.  The S100computers PCB's typically have a forest of jumpers on them.  *frown*

Roger