H-17 dual floppy and controller board?

[cole erskine]

Hi guys,

I picked up a complete H8/H9 system at an estate sale last year. Works perfectly,
I demo'ed it at VCF West last August running a chess program (thanks Joe Travis!)

It included this dual-floppy drive which I think may be an H-17. I have not tested it yet.
It has a generic housing so it doesn't have any of the standard Heathkit badging on it.

Any idea what I have here? Any ideas on bringing it up and testing it?
Or does anyone want to take it off my hands??   ;-)

-Cole

[cole erskine]

FWIW, here's the controller board:

[Mark Garlanger]

For the demo were you using cassette tape?

The housing for these drives is the original Heath H-17 case. Originally it supported 2 drives, but Heath offered an upgrade for 3 drives and that is what you have here.The original 2 drive case had the drives mounted horizontally.

The controller board is the H-17 controller for the H8.

Mark

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[cole erskine]

Thanks, Mark!  Yes, for the demo I was loading a WAV file of the KCS cassette image.

-Cole

[Glenn Roberts]

Quite the lucky estate find! Congrats. The triple disk drive unit seems to be rather in demand. I think the last one on eBay went for well over $200, maybe more.

The drives appear to be the original Siemens FDD-100. These are single sided single density drives, essentially 100K capacity.

The controller card is the standard Heath controller board for those drives and is supported in all the H8 configurations. It can only do single density recording but it can be modified to work with double sided drives (doubling capacity to 200k) and 96TPI drives (400k). The card and associate software use index holes on the diskette to de mark the sectors, so you must use “hard sectored” disks (10 sectors)

There are devices like VSD and HSFE that emulate the index hole signals and we can help you with that if you want. These let you use PC-style “soft sectored” floppies which are quite abundant, or even swap in a 3.5” drive

Sent from my iPad

On Mar 21, 2023, at 7:33 PM, Mark Garlanger <garl...@gmail.com> wrote:



For the demo were you using cassette tape?

The housing for these drives is the original Heath H-17 case. Originally it supported 2 drives, but Heath offered an upgrade for 3 drives and that is what you have here.The original 2 drive case had the drives mounted horizontally.

The controller board is the H-17 controller for the H8.

Mark

On Tue, Mar 21, 2023 at 6:24 PM cole erskine <cers...@gmail.com> wrote:

Hi guys,

I picked up a complete H8/H9 system at an estate sale last year. Works perfectly,
I demo'ed it at VCF West last August running a chess program (thanks Joe Travis!)

It included this dual-floppy drive which I think may be an H-17. I have not tested it yet.
It has a generic housing so it doesn't have any of the standard Heathkit badging on it.

Any idea what I have here? Any ideas on bringing it up and testing it?
Or does anyone want to take it off my hands??   ;-)

-Cole

<IMG_1076.jpg>

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[Joseph Travis]

Congrats Cole,

Nice acquisition.  As Mark pointed out, the H17 cabinet has been upgraded to accommodate 3 drives.  The badging for that case is correct.

The H17 Controller board has been modified for Org 0 (CP/M or HDOS3) operation.  If you're using the 8080 CPU, you'll also need the HA-8-8

Extended Configuration board.  If using the HA-8-6 Z80 CPU board, the HA-8-8 isn't needed.

Personally, I would clean up the wiring to the two regulators mounted on the bracket and slip some heatshrink over the connections.

Regards,

Joe

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[smb...@gmail.com]

That's interesting, I had seen the occasional 3-drive H17 but had no idea this is a modification. Did Heathkit sell these upgrade kits or were they aftermarket?

3 drives is something I haven't seen a lot of in my vintage experience. Usually either 2 or 4. Do they address the third drive by asserting both drive select lines?

Scott

[Douglas Miller]

The H17 controller supports three distinct drive select signals. But I don't think all 5" drives had three DSx signals? I know that 4 came later, and there was some inconsistency about which wire on the cable was DS4. But don't recall about DS3. I know that at MMS one of the first things we did was add a third drive to the H17.

The problem was that the Heath H17 Floppy ROM, which was normally used by even HDOS, only supported 2 drives in the select routine. There is a common "hack" used to leverage most of the select routine but handle 3 drives. MMS used that hack in their Monitor ROMs for the H89 in order to allow booting off any of the three drives.

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[Mark Garlanger]

It was a Heath modification - check out the catalog on my site: https://heathkit.garlanger.com/catalogs/1982/Heathkit_Catalog_857.pdf

It's on page 33. The H-17-3.

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[smb...@gmail.com]

Ah, I didn't see the third drive select. Is it the line marked "used during test only" ?

[Douglas Miller]

On the H89 schematic, it is labeled "DRIVE 1L" on the cable connector. Data bit 3 on the output port.

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[Mark Garlanger]

All the 5.25" drives I've seen have had DS1 -> DS3. The Siemens FDD-1005B, that Heath used as the SS 48tpi drive had them, and could be even be modified to add a DS0 for 4 drives. The manual is available here: https://bitbucket.org/HeathkitGuy/heathkitinformation/src/master/Drives/Siemens%20FDD%20100-5B%20Floppy%20Disk%20Drive.pdf

The H-17 ( H-88-1 ) controller actually has the order reversed, so DS3 is SY0:, DS2 is SY1:, and DS1 is SY2:

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[glenn.f...@gmail.com]

And just a reminder, Norberto’s modern H37 and H17 interface boards provide the ability to access drives on any of the four possible drive selects.  I believe the drivers exist to support this as well, but not something I’ve tried.  See: http://koyado.com/Heathkit/H8-H17-H37-H67-USB_files/H37_67_V_1_1_Jumper_Definitions.pdf

 

 

H37 can access up to four drives, one for each DS:

 

 

H17 can access three drives but drives can have any of the 4 possible DS settings:

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mark Garlanger
Sent: Tuesday, March 21, 2023 11:27 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] H-17 dual floppy and controller board?

 

All the 5.25" drives I've seen have had DS1 -> DS3. The Siemens FDD-1005B, that Heath used as the SS 48tpi drive had them, and could be even be modified to add a DS0 for 4 drives. The manual is available here: https://bitbucket.org/HeathkitGuy/heathkitinformation/src/master/Drives/Siemens%20FDD%20100-5B%20Floppy%20Disk%20Drive.pdf

 

The H-17 ( H-88-1 ) controller actually has the order reversed, so DS3 is SY0:, DS2 is SY1:, and DS1 is SY2:

 

 

 

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[Alex - K3CIM]

although it can operate with four drives, it is my understanding that under cpm the transient program area (TPA) is reduced.

just a fyi

[Steven Hirsch]

On 3/22/23 10:14, Alex - K3CIM wrote:
> although it can operate with four drives, it is my understanding that under
> cpm the transient program area (TPA) is reduced.
> just a fyi

Yes, with each removable drive comes an additional directory check buffer.

[Douglas Miller]

And also the allocation vector buffer, both which must be big enough for
the largest possible floppy format.

But, I don't see support for 4 drives on Norberto's H17 schematic, only
the ability to use DS3 (of DS0-DS3) for one of the 3 supported drives.
So, I don't believe you can actually use 4 H17 drives.

[norberto.collado koyado.com]

Correct! Only 3-drives for the H17 and 4-drives for the H37.

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Subject: Re: [sebhc] H-17 dual floppy and controller board?

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[Mark Garlanger]

The standard hardware/software only supported 3 drives, but there was a hardware/software product that allowed more than three, I don't remember the company, I think it could support 7. By using multiple select lines, along with additional hardware at the drive which could verify the correct pattern for that drive. I remember someone on the list had one, I think Dan Emrick.

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[norberto.collado koyado.com]

Yes, you can add a 74LS138 driven by the three drive selects signals to get 7 drives (SY0_L, SY1_L, and Drive1_L). You will need a mod to the HDOS and CP/M driver. It is a simple change to the design.

 

I’m curious to see if Dan has the HDOS driver and any schematics.

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mark Garlanger

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[Dan Emrick]

Let me dig around for the driver.  I don't think I used a 74LS138 (wasn't smart enough) but whatever I used did essentially the same thing.    I used  six drives. Two of them were double sided, 96 TPI drives accessed with a Percom controller.  That mean's I modified the Percom SY.DVD.  I'll try to find that modified driver and extract the drive select decode portion.  Haven't used it for a decade or more.

Dan

[norberto.collado koyado.com]

Do you recall the schematics? I just want to see how you wired it.

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[Dan Emrick]

I found the adapter, but the chips are missing.  I'll look for the hand-drawn schematic.  My approach used pins 14, 12, and 10 of the ribbon cable (data bits D1, D2, D3) to drive the three input pins of the one-of-eight decoder.  I had wired the decoder to be permanently enabled and then ignored the Y0 output (it represented the no-drive-selected condition).  I have a write-up mostly finished and will send along soon.  First I'll look for the schematic.