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TI-99/4A MYARC HFDC Hard Floppy Disk Drive Expansion Card (Winchester)


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Between a rock and a hard place - not enough information to list in AA Market Place and certainly not enough to list on that other E-unnamed selling site.

As this isn't the appropriate forum, I'll keep entry short (photos attached).

Pricing? Looking to give this Myarc HFDC Hard + Floppy Disk Drive Expansion Card a good home.

I purchased it from Tim Tesch the summer of 2019 repaired, but never got around to putting in a PEB and testing it let alone using it.

Other than what's available on Ninerpedia, Mainbyte, WHT documentation-wise, I don't know more history about it but I know it's aging away in my '99 part drawers.

It didn't come with clamshell or cables, but I'll include a 20-pin + two dual 34-pin cables I purchased new shortly after I got the card.

Serious inquiries, I guess PM me as I can monitor AA for a couple days though I don't regularly get around these parts much any more.

Doug

Myarc HFDC V11.zip

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  • 1 year later...

I have a question, and maybe there is no good answer. I know that the datasheet calls out specs for the 40 pin Dip version of the HDC9234  and the PLCC 44 pin version. What other systems used these chips? Id like to be on the lookout for a PLCC version as well as anymore of the 40 pin version that may pop up. I can't believe that Myarc was the only one using these chips. @Ksarul @InsaneMultitasker, someone?

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51 minutes ago, RickyDean said:

I have a question, and maybe there is no good answer. I know that the datasheet calls out specs for the 40 pin Dip version of the HDC9234  and the PLCC 44 pin version. What other systems used these chips? Id like to be on the lookout for a PLCC version as well as anymore of the 40 pin version that may pop up. I can't believe that Myarc was the only one using these chips. @Ksarul @InsaneMultitasker, someone?

Rochester has them, with a minimum order of 19 chips. . .with over 6,000 in stock.

 

 

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16 hours ago, RickyDean said:

Looks like I'll have to wait a bit to buy the minimum of 19 though. I'll be patient, don't really need them yet.

May also be a candidate for a group buy, as there are a number of the HFDCs out there. The "A" variant of the data separator would also be extremely useful, as it is a lot more stable than the one in most of the cards.

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It's good to have replacements, especially for cards that were never fully populated.  Based on my not-infallible recollection of repair work, the hard-to-find chips that failed were typically the 9216B, 9223, 9226, DS1000 and 9234 in order from most often to least often replaced. I may have 1-2 spares of a few of these chips having exhausted most of my stock over time.  The logic chips, particularly those connected to the edge connectors like the LS240 and LS374 and especially the LS31/LS32, were always prime suspects for a failed card.  These are still available though not always the brands, like National parts, that were best suited for the circuit.

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@InsaneMultitasker, I've just removed the jumpers off my HFDC that I used with my Geneve, but it's been awhile, then installed DC-Dc converters.  I've tested it in the TI and it didn't operate, found it had a bad 74ls374. Replaced that and tested again and the system operates, but it takes it about 30 seconds to start access a program, then it loads it fast. Is it looking at the non-existent hard drive for an emulated drive one first? I've not used one on a ti for many years. I just did the same for that working Geneve, and will be trying it out in the same PEB box another day.

My other HFDC had at least a bad 74ls245 buffer chip, I installed converters on it to, but it is working yet either, I'm going to buy a few of the easier to find chips. Hoping it's not a gate array.

Edited by RickyDean
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38 minutes ago, RickyDean said:

Replaced that and tested again and the system operates, but it takes it about 30 seconds to start access a program, then it loads it fast. Is it looking at the non-existent hard drive for an emulated drive one first?

The HFDC checks for a hard drive the first time you attempt to access DSK1 or a WDSx device name.  For the former, it is looking for the DSK1 subfolder or an emulated drive, as you surmise.  the timeout seems about right if you do not have a MFM drive connected.  You can bypass the delay if you plan to use the card for floppy devices only, otherwise I would advise against the mod unless you install a jumper to enable/disable.  Be sure you connect the floppy cable to the right connector, i.e., do NOT connect it to the edge connector at the back end of the card.

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8 hours ago, InsaneMultitasker said:

  You can bypass the delay if you plan to use the card for floppy devices only, otherwise I would advise against the mod unless you install a jumper to enable/disable.  

Got it, that what I thought. Not really interesting in using it as floppy only. I've built those two MFM emulators and want to get ready to try them out. Finally found the PCB for the 3rd one, have to probably wait till I get my shoulder surgery over with and recover to the point I can continue.

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@InsaneMultitasker I changed out the 74ls245 buffer and the 32k sram and the card is living again, except when I go into editor assembler and try to load the IDEtest program, it doesn't do anything immediately, then it comes back with a "I/O error code 02". Where should I look next? All the logic chips that will test on my Minipro have been tested. I can't test the 74ls251's or the AM2631CN or AM2632ACN and of course I can't test the SMC chips on the board. But I can part swap and see what happens. The AM chips can still be ordered from Mouser, so I'm going to do so, as well as the other untestable chips. My Modular Technology IC tester switch is bad.

I should have included that this is the other HFDC, the one I got working last night seems to be okay.

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44 minutes ago, RickyDean said:

@InsaneMultitasker I changed out the 74ls245 buffer and the 32k sram and the card is living again, except when I go into editor assembler and try to load the IDEtest program, it doesn't do anything immediately, then it comes back with a "I/O error code 02". Where should I look next? All the logic chips that will test on my Minipro have been tested. I can't test the 74ls251's or the AM2631CN or AM2632ACN and of course I can't test the SMC chips on the board. But I can part swap and see what happens. The AM chips can still be ordered from Mouser, so I'm going to do so, as well as the other untestable chips. My Modular Technology IC tester switch is bad.

I should have included that this is the other HFDC, the one I got working last night seems to be okay.

Hard to say.  Are you loading from DSK or WDS?  How many devices are connected and which ones have resistor packs?  Have you attempted to catalog the DSK or WDS device, or format either?  Does the LED for one or more devices turn on when you try to load the program?  When you say it doesn't do anything immediately, is there any LED or drive activity? 

 

My typical approach to the repairs is to try to catalog a known-formatted disk or hard drive.  On rare occasions, the LS240 / L374 will produce effects similar to termination errors, and you may need to remove the floppy drive to access the hard drive.  Regardless, I often try to format both devices to get an idea of what is or is not working. 

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I am trying to just access the a DSSD image on my lotharek hxc floppy emulator. It works with my working Corcomp and the working HFDC, but this HFDC is not reading the program from the image, gives me the error. Switches are set the same as the working HFDC, and I'm just trying to read that program, because for the moment the IDE dsk is the one I have been testing my IDE cards with. I try running the Idetest program from the disk image, it will have the same roughly 30 second delay that the other one has, then the access light will come on the Lotharek, and but not sound, then I get the error message. I'm hoping it's one of the regular logic chips I can't test, but I'm suspecting the HDC9234, as a possibility. I have not tried any hard drives at this point, just trying to get the floppy side working. I did remove, last night one of the 374's from this board to get the other one operational, and found an old one in my stash, it checked out on the Minipro, but I will attempt to put the orignial back on and see if that makes a difference. The 240 checked out okay on my Minipro. I can try to format this image, it wouldn't hurt anything. I'll let you know.

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@InsaneMultitasker, I changed the one 374 back and swapped the HDC9234, same results. Then I went into DM3 and tried initializing the drive as a DSDD and it seemed to format, but I got a "Disk Error 41 Record not found on Print" message when it tried to go verify the drive. I then tried again as a DSSD drive with the same results. It is not the HDC9234 at least.

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Try swapping the 9216.  Also, some of the logic chips are common to the extent that if the MFM drive works, the DSK often works.  It can be difficult to troubleshoot the floppy if you don't know whether the MFM portion is working, as that can help to rule things out.  If you are going to test the 9234 and other chips, it can be beneficial to pull the core chips (9234, 9226, 9216) and place them into the working card one by one versus trying to put a known working chip into a card that may have other problems. 

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