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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On the H8 it states “Not Used” on the schematics.
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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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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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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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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.
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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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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).
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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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.
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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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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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
Picture of board attached.
😊
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