H89-47 ROM

[Frank_M]

In an effort to understand the operation of the H47 8" fdd interface for the H89 (Z89-47 Accessory), I am studying the schematic.  Everything is straightforward until I get to U11.  It is a 74LS188 32x8 ROM.  Evidently, 3 of the 32 available bytes are addressed at 0x00, 0x08, and 0x10.  The remaining memory is unused.  I do not have the board; so, I can't extract the contents from the memory chip itself.  I have not been able to find the ROM contents online yet.  Is anyone in the group aware of a listing for the ROM contents?

Thanks,

Frank

[norberto.collado koyado.com]

It is a 74LS188 32x8 ROM. 

 

Never used on either board (H8/H89). Based on pictures is always empty. As you can see U11 is empty. Perhaps a future expansion.

 

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[Frank Madison]

Norberto,

 

That makes sense.  The interface with that ROM is to the RDx bus.  It is seen only by the H89 and not by the Remex fdd.  I can see no mention of the interface in either HDOS or C/PM system drivers.

 

Thanks for the help,

 

Frank

 

 

Sent: Wednesday, May 31, 2023 at 6:36 AM
From: "norberto.collado koyado.com" <norberto...@koyado.com>
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: RE: [sebhc] H89-47 ROM

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[Mark Garlanger]

Frank,

Do you know if a ROM was installed in the socket, how would the H89 be able to access it?

The board also has a 4 slot dipswitch, that is also not used by the drivers. 

All the interesting stuff for the H47 drive system is on the Master Remex drive. It has a 6800 cpu, WD controller, and a ROM that controls all of it. The interface cards are just a glorified parallel port.

Mark

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[norberto.collado koyado.com]

It could be an option on boot to pass parameters to only boot from certain floppy drives. They do this on the H67 hard drive interface. HDOS will test if you have an H67 hard drive installed, or it will not boot. 

It will be nice to find out what was Heath-Kit  plan. 

On the new H47 board, I removed such circuit. 

Get Outlook for iOS

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From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Frank Madison <fjm...@mail.com>
Sent: Wednesday, May 31, 2023 5:25:12 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: RE: [sebhc] H89-47 ROM

 

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[Frank Madison]

Mark,

 

I'm still deciphering the operation of the H47 interface.  I will give you the details on how to read the U11 ROM contents when I've completed that work.  There is a state machine involved; so, it will be more involved than just inputting from an I/O address.  It appears that a certain sequence of a write and then a read in I/O address space is used.

 

I did suspect that the DIP switches are not used by the H89.  The DIP switch state is placed on the I/O bus by U5.  Though the DIP switch state is not used, other signals at U5 may be used by the system drivers.  Once again, I'll let you know.

 

Yes, the H47 interface is just an application specific parallel port.  The state machines are rudimentary, but they need to be understood to determine the sequences needed to interface with the Remex fdd.

 

I will report further progress in a day or two.

 

Regards,

 

Frank

 

 

Sent: Wednesday, May 31, 2023 at 6:01 PM
From: "Mark Garlanger" <garl...@gmail.com>
To: se...@googlegroups.com

Subject: Re: RE: [sebhc] H89-47 ROM

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[Mark Garlanger]

Hey Frank,

   I wrote a javascript implementation of the interface card and the Remex drives almost ready to be add to my H89 emulator - https://heathkit.garlanger.com/emulator/jsH89/

I'm not sure if the logic between the virtual interface card and the virtual remex drives may not be totally accurate, but from H89 viewpoint it is working good.

Mark

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[norberto.collado koyado.com]

On the H8 it states “Not Used” on the schematics.

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[Frank Madison]

Norberto,

 

That additional information seems to indicate that the feature was never implemented.  I won't need to chase down the operation details of that sub-circuit.

 

Thanks for the input,

 

Frank

 

 

Sent: Wednesday, May 31, 2023 at 11:18 PM

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[norberto.collado koyado.com]

Hello Frank,

 

It will be nice if you can document on how the H47 state machine works as I’m expecting the new H47 board hopefully soon. It will allow me to debug the board easier if needed. Hopefully I did connect everything properly.

 

Attached is my new H47 controller schematics version along with test LED’s and jumpers, based on Heathkit documentation.

 

Thanks,

Norberto

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[Douglas Miller]

It may be that the H47 interface is overly complicated. In contrast, the MMS interface to Remex drives (not software compatible with H47, but plugs in to the H47/Remex drives and works) is fairly simple, much more like the SASI interface. The code seems simple in both cases, so I'd have to wonder what all this state machine stuff really does to help. I don't seem to have an H89-47 (or H8-47) schematic, so can't see what we're talking about here.

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[norberto.collado koyado.com]

Both schematics are here:

 

http://koyado.com/Heathkit/H-47_Schematics_files/WH8-47%20Schematics.zip For H8

 

http://koyado.com/Heathkit/H-47_Schematics_files/Z89-47%20Accessory%20Manual.pdf  - For H89 - it is on last page.

 

Norberto

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[Douglas Miller]

Looking at the schematics, it appears that only two locations in the ROM can be accesses, since the two connected address inputs come from a 74'155 and only one of those outputs can be active at a time. The two bytes from the PROM can be read at I/O addresses port+2 (0x10) and port+3 (0x08).

I find no code in the HDOS driver (that I have available) that even pretends to know about those two ports. The MMS boot ROM does not access them, nor does the PAM37 as best as I can tell.

My guess wold be it was either an attempt to assign a serial number to the product, or else an attempt to make it "plug-n-play" - i.e. a way to identify what type of board was inserted.

[Mark Garlanger]

Interesting. My emulator doesn't implement anything for those two ports and everything seems to be working fine. My virtualization

of the interface card is also very simple, no state machine. The actual implementation of the Remex drives is where the there is

a state machine and logic is more complicated to support all the commands and the data transfers.

Can you tell from the circuit, what would be returned from those two addresses when the ROM chip is missing? 

Mark

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[Douglas Miller]

I'll also concur that the H47 interface board is very simple. I'm not sure what all the logic on the Heath board is intended to do, but the MMS Remex interface is very simple and only has one flipflop that it uses to "echo back" the ACK after servicing the DTR. Judging from the H47 software, there really is nothing special about all that extra logic. You basically just watch the signals from the Remex, and when you get DTR you transfer data. There are some semantics for starting a command, and detecting the data direction (DDOUT), but it seems to be very simple and not really dependent on timing at all (except maybe for recovery from RESET).

Regarding what would be read with the PROM missing, I would say "FF" since there are pullups on the data bus. But, that's not to say what would happen if the entire H47 I/F PCB was missing. Given there doesn't appear to be any software to support the PROM, I'm guessing it was an idea that got dismissed before any product shipped.

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[Mark Garlanger]

The status/control port had two bits which don't seem to be used by the software drivers - "U137B Set", and interrupt enable. My emulator doesn't do anything with either of those bits.

Mark

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[Frank Madison]

Douglas,

 

You caught a mistake in my earlier finding that 3 ROM locations can be addressed.  Indeed, only 2 can be addressed.  And, the addresses you give are correct.

 

I am designing a virtual floppy drive that connects directly to the H89 P504 and P510 and uses the H47 drivers.  I have not yet decided whether to duplicate the operation of the H47 interface board circuitry (in a CPLD e.g.) or emulate it in software in the mcu that I am using (STM32Fxxx).  The design uses serial flash memory.  I am also examining whether of not to also use serial PSRAM to reduce reduce write cycles to the flash.

 

I have found quite a bit of "dead" circuitry.  I intend to use only what is needed to interface to the H89 and its existing drivers.

 

Thanks to everyone who has chimed in with useful information.

 

Frank

 

 

Sent: Thursday, June 01, 2023 at 6:58 PM
From: "Douglas Miller" <durga...@gmail.com>

To: se...@googlegroups.com
Subject: Re: [sebhc] H89-47 ROM

I'll also concur that the H47 interface board is very simple. I'm not sure what all the logic on the Heath board is intended to do, but the MMS Remex interface is very simple and only has one flipflop that it uses to "echo back" the ACK after servicing the DTR. Judging from the H47 software, there really is nothing special about all that extra logic. You basically just watch the signals from the Remex, and when you get DTR you transfer data. There are some semantics for starting a command, and detecting the data direction (DDOUT), but it seems to be very simple and not really dependent on timing at all (except maybe for recovery from RESET).

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[norberto.collado koyado.com]

Hopefully by next week, I shall have the new H8-H47 board. If we can use your H47 floppy design to integrate both that will be great. If I need to create a new H89-H47 board, I can do that as well.

 

Thanks,

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Frank Madison

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[Frank Madison]

Norberto,

 

When I finish my design, I will make it available to you and to everyone else in the group.  I should caution you that my design will be a "hack" compared to the work that you do.  I've been impressed by how your work maintains fidelity with the architecture and design intent of the original Heathkit engineers.  My work, on the other hand, is simply the shortest path to something that works.

 

Regards,

 

Frank

 

 

Sent: Friday, June 02, 2023 at 6:59 AM

From: "norberto.collado koyado.com" <norberto...@koyado.com>
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: RE: [sebhc] H89-47 ROM

Hopefully by next week, I shall have the new H8-H47 board. If we can use your H47 floppy design to integrate both that will be great. If I need to create a new H89-H47 board, I can do that as well.

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/SN6PR01MB3855D5FBA01E6127D908D40DF74EA%40SN6PR01MB3855.prod.exchangelabs.com.

[norberto.collado koyado.com]

Hello Frank,

 

Thank you for helping out with the storage floppy design. Eventually this design must connect to the 40 pin connector. The Floppy Microcontroller, should pulse pin 39 to indicate visually that is idle to the user.

 

On power-on the microcontroller can check if the H8/H89-H47 board is online or not by asserting/deserting “/DMA_REQ” pin 35 and checking status on “/DMA_GRP” pin 37.

 

 

 

Thanks,

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Frank Madison

Sent: Friday, June 2, 2023 7:58 PM
To: se...@googlegroups.com

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[Frank Madison]

Hello Norberto,

 

I have removed dead hardware from the H47 interface design.  I've begun schematic entry into a logic compiler that can map the design into CPLDs or GALs.  My intent is twofold.  First, a logic compiler will optimize the design which may further reduce the number of gates.  In addition, the compiler will generate end-to-end logic equations that may enable me to perform the interface logic in the mcu that will be my memory controller. 

 

The DMA_REQ! (pin 35) signal is delayed about 700nS and looped back to DMA_GRT! (pin 37).  These signals are not visible to the H89.  I am leaving them in my design at this time though.

 

I don't know how streamlined the final design may become.  You are welcome to use it.  And, if you need additional features in the configurable logic, I am happy to help.

 

Frank

 

 

Sent: Saturday, June 03, 2023 at 12:17 AM

From: "norberto.collado koyado.com" <norberto...@koyado.com>
To: "se...@googlegroups.com" <se...@googlegroups.com>

Subject: RE: RE: [sebhc] H89-47 ROM

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[norberto.collado koyado.com]

The new H8 boards came in this afternoon. It includes the H8-H47 and the H8-Wiznet-SD boards. Plus a lot of Personality Modules..

 

See attached image.

 

Thanks,

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Friday, June 2, 2023 7:00 AM
To: se...@googlegroups.com
Subject: RE: [sebhc] H89-47 ROM

 

Hopefully by next week, I shall have the new H8-H47 board. If we can use your H47 floppy design to integrate both that will be great. If I need to create a new H89-H47 board, I can do that as well.

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[norberto.collado koyado.com]

Joe, Rick,

 

Once I verify the functionality of the H8-WizNet-SD board, I will send you a board with the PM cards to enable booting Heath HDOS and CP/M. Right now I can only boot CP/M3. I will include also the WIZNET module for each one as Douglas ordered them for our group.

 

Thanks,

Norberto

[norberto.collado koyado.com]

Picture of board attached.

 

😊

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