H8-Z5-4 CASSETTE BOARD is up and runnng!
norberto.collado koyado.com
Glenn,
Finally the H8-Z5-4 is up and running.
Tested:
- H8Tupload/download to H8.
- H8T upload/download from cassette player/recorder
- H8T baud rate at 1200bps and 9600bps in H8T mode
- Console 16C550 up and running with /INT3
- Console 82C51 up and running with /INT3
- INS82C51 or P8251 working fine with cassette workaround circuit
- Loaded original H8 cassettes. I’m impressed that such cassettes are still working after so many years.
- Loaded cassettes created with Glenn’s boards to check that is backwards compatible with original H8-5 board
- LED’s
- Added power LED
- Added H8T mode LED
- Added Player Relay LED
- Added Recorder Relay LED
- Added bit data (I/O) LED
- Added original calibration LED
- Serial Ports
- DB9 to H8T male connector worked fine
- DB9 to 16C550 console worked fine
- DB9 to 82C51 console worked fine
- Motor-On circuitry worked fine
- Added H8T switch to remotely switch between H8T mode and Cassette mode. No need to open the H8 chassis to change any jumper.
- Jumpers
- Added jumpers that matches Heathkit cables for baud rate selection
- Added jumpers to calibrate board per Heath documentation.
- The board layout is based on the H8-5 “85-2110-2” schematics with improvements for a better board.
I will clean-up the final board and will submit the files for Todd to add to his website if anyone interested on such board.
I will return your H8-5 boards this week and I thank you as both boards helped me during the debugging process. Without them, it will be hard to debug the new board. Thank you a lot!
Attached is a picture of final board and I need to work on the BOM, and calibration procedure using Heath process and a scope.
Thanks,
Norberto
norberto.collado koyado.com
Glenn,
Trionyx had the same idea of using the H8-5 tape as a backup. They were planning to build a big mass memory board bootable and using the H8-5 as a backup device. I think we need to think on how to jump start an old H8 system by just using the H8-5 and the H17 controller back to life.
Thanks,
Norberto
glenn.f...@gmail.com
So this is an intriguing tidbit but leaves many questions unanswered. Not sure what they meant by “bootable” memory? And what OS they were referring to? we already can load programs in and our of mass memory via H8-5 but they are not “floppy disk” programs (though I have a program to convert .ABS to .H8T).
I like the idea of loading disk images via H8-5 and writing to disk. this would be similar to the H89LDR technique but could theoretically load everything from a physical cassette drive (though I suspect most would still use a PC or iPhone to emulate the tape). I don’t think this is too hard. Let me think about it.
Meanwhile if you have more information on what the Trionyx folks were picturing can you share that? tx.
- Glenn
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Joseph Travis
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Douglas Miller
I took it to mean "mass memory" was something > 64K, and booting from memory was something akin to what MMS did with their 77318 memory expansion for H89: define part of the "ramdisk" to be boot tracks, and a modified ROM could then boot from that memory region. If the boot image was for floppy, then as soon as it was "started" it would switch to floppy to complete the boot. If the boot image had a ramdisk driver, it could boot entirely from RAM and run without floppy.
But, perhaps I was just projecting past experience and reading something else into the Trionyx vague description.
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glenn.f...@gmail.com
So you have a boot program (in H8T format?) that you load via the H8-5 and that bootstrap knows how to talk to the CF board to load the OS? Is this HDOS only or do you have a CP/M boot as well? of course with the Z67-IDE CF board this isn’t necessary because the Heath ROM (PAM-37) knows how to boot directly from the device, but for a custom device you’d need something like this… who wrote the bootstrap program?
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Joseph Travis
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norberto.collado koyado.com
Sent: Thursday, August 18, 2022 8:08 AM
To: se...@googlegroups.com <se...@googlegroups.com>
Glenn Roberts
Ah. Got it.
Nice use of the H8 front panel Rick!
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glenn.f...@gmail.com
Interesting. As Douglas suspected this is a primarily a RAM disk solution. They say it will work with “a variety of controller boards” but from the description it sounds like the memory board connects to the controller via a proprietary connector on the left side of the board. They were certainly thinking big. An external expansion chassis, 5 Meg of RAM, and a 16 bit CPU board for the H8! Wonder how much of this ever got off the drawing board? Much of this is written in future tense 😊
It says “the mass memory is fully bootable and may actually be used in place of any floppy disk drives at all!”. can’t understand what they’re saying. Surely this isn’t battery-backed RAM (presumably these were DRAM boards so they’d need constant refresh). Maybe you would load the OS initially via the H8-5 and subsequently could reboot from the RAM-based image?
Anyway the idea of creating disk images via the H8-5/front panel LOAD function is intriguing. Also the ability to load HDOS that way could be worth thinking about. I’ll ponder it a bit…
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Douglas Miller
I was suspecting that they had to provide some way to load from cassette (or other media) into the full, banked, RAM. So, I'm guessing there was something other than the default Heath ROM cassette routines - which could only load into the first 64K.
The MMS H89 solution was not battery backed-up RAM (which would
have been hard given H89 dynamic RAM that was refreshed by the
CPU), but once you had loaded and initialized the ramdisk you
could RESET and reboot as much as you wanted. In that case, you
booted off disk after a power-on, initialized the ramdisk (copied
files from disk to ramdisk and sysgen'ed it), and from then on you
could RESET and cold boot from ramdisk (until the next power-off).
Also, (CP/M) warm boot was pretty fast, too.
So, it's not entirely clear what Trionyx was saying. Would be helpful to see the user's manual. I'm guessing there was considerable setup required after a power-on, but subsequent RESETs could leverage existing content in the extended RAM area. But, I guess their DRAM board had refresh built-in since it had to work with an 8080 - but still that would suck a lot of power from a battery.
With the WizNET and VDIP1 add-ons, and the V4 Z80 CPU board (new monitor ROM), you can boot off the network or USB drive, which also provides alternate methods of getting an OS running. The network allows booting CP/NOS which is diskless. Theoretically, one could also "mount" a file as a disk image on the VDIP1, with some (significant) limitations.
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