Hi all, I hope someone can help me for my problem. Several months ago, i decided to upgrade my Apple //c rom 255 to 4x. Everything was great and i bougth a Floppy Emu which work fine too. After one month, I decided to buy a Fujinet Apple also to make tests. After several days, my Apple stopped to recognize the Fujinet Apple and the Floppy Emu with a "No bootable device" error. I tried to exchange the ROM 4X, nothing happened. The strange thing is that if I connect an external drive as a second unit, it works like a charm. All is working except the smartport !!!
Thanks for your hints.
Can a 5.25" drive (being it internal or external) write on a physical diskette?
It's seems you are right it's "Write protected" :-(
I am usually right and heavily censored here on this forum. Now if you disconnect/replace the internal drive do you still get the false write protect status?
Do you mean, the smartport problem is due to the internal drive outage ? So I dont have a drive replacement except the external one, but I have disconnected the internal drive and tried to plug my Floppy Emu in the internal port. The answer is always "No Bootable device" !!
The /WPROT is directly connected to the internal drive, and to the external drive connector, and to the IWM ASIC chip. There had been a small chance of internal drive pulling the line due to its burned WRPROT output, but alas, it seems you burned the IWM chip of your //c. That's why it is good to experiment and play with more conventional apple2s that use easily repairible or obtainable DISK II controllers.
If you have fried your IWM chip you might search for the thread about the IWMless replacement which is currently entering beta test phase. Other than that there aren't many options for replacing an IWM since they haven't been made since the early 1990s and have been essentially "unobtanium" for years other than salvages from dead motherboards.
You should be able to verify if the issue is inside the IWM chip by disconnecting all drives (internal and external), and testing the resistance between pins 10 and 1 on the external disk connector with a digital multimeter. Normally the resistance should be high, but if a short exists in the IWM it would be lower (not sure of the exact value).
Mother board
What's wrong with analogue multimeter? Don't torture the guy, I already made the diagnostic remotely.
Dont worry, it's not a torture :-) I am not a experienced electronics engineer but i can test if someone explain me.
You have already done sufficient tests.
While working on the 'IWMless' it came to my attention that the SENSE (aka WRITE PROTECT) input of the IWM is located on the opposite of a +12V power pin when these signals are on the usual 20 pin header as seen on the original DISK II.
The original 'Liron' card from Apple stamped with "IF-98 1-616-130-11 LIRON" on the solder side has much the same pin layout on its CN101 connector and connects pin #19 and #20 there which in the DISK II context would mean that WRITE PROTECT is connected to +12V, but this does not happen, ever, on this version of the 'Liron' card as the rainbow flat band cable has the black wire (of pin #19) snipped away so they could attach the DB-19 connector at the other end, where further pin permutations occur.
I also had a 'Liron' clone card donated by Brad for testing the 'IWMless' in a 'Liron' environment and discovered that he had connected pin #19 and #20 in his layout (same as on the original 'Liron' card) and then had scratched away the trace doing this to disconnect them again. I was wondering for a while for his reason to do this (the original 'Liron' version mentioned above has the connection) but then it occured to me that if you plug in a DISK II floppy disk drive into that 20 pin connector of the 'Liron' clone, the floppy disk drive shorts pins #13, #15, #17, #19 and this means #19 now is on +12V. If the trace connection #19 and #20 is there, SENSE of the IWM gets +12V and the IWM dies. Hence, the trace must be cut to play it safe.
The suspected silent IWM 'killers'
Now, having the facts on hand, I think it's quite possible that there may be all sorts of Floppy Emus and associated cables and adapters around which, if plugged into such a dangerous 20 pin socket, will put +12V on the SENSE input of the IWM, which kills it.
On my own Apple IIc, the internal 20 pin floppy disk connector has no such dangerous connection but there have been several PCB revisions of the Apple IIc, so we can't rule out that the dangerous connection never was there, in any variant.
What I know for certain is that about 20 years ago, I experimented with plugging an original DISK II floppy disk drive into the internal 20 pin connector of one of my Apple IIc, and after this the IWM was dead. Alas, having no IWM replacement, I stripped this motherboard of all socketed ICs and sold the sad remains on Ebay for parts, so somebody else could cannibalize it to fix his own Apple IIc. Now I regret this because I can't inspect it anymore whether there was a #19 #20 connection in that version of the PCB.
Conclusion
Be careful what you plug into these innocent looking 20 pin and DB-19 floppy disk drive connectors. Use a connectivity beeper first to make sure whatever contraption you have at hand, it does not connect +12V to the SENSE pin.
- Uncle Bernie