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Tomswork · Post by **Tomswork** » Mon Dec 20, 2021 8:24 pm

I want chips to global shortage good news about the resistor

Tom

stephen_usher · Post by **stephen_usher** » Mon Dec 20, 2021 8:34 pm

Bingo!

: IMG_2510.jpg (48.16 KiB) Viewed 2301 times

Don't you just love variations in chips? Apparently needing the trigger voltage ~ 1/4 rather than a 1/3rd of Vcc is still just about in spec.

Post by **exxos** » Mon Dec 20, 2021 8:47 pm

stephen_usher wrote: Mon Dec 20, 2021 8:34 pm Bingo!

stephen_usher wrote: Mon Dec 20, 2021 8:34 pm Don't you just love variations in chips?

I think I wrote the book on that quite literally

stephen_usher · Post by **stephen_usher** » Mon Dec 20, 2021 9:01 pm

Well, assuming that it passes the full floppy diagnostic tests I think that I can declare the machine fully fixed (until something else breaks), excepting the small number of lines on the LCD which have stopped working. These aren't really fixable.

: IMG_2511.jpg (58.27 KiB) Viewed 2292 times

The only enhancement I've made is to change the internal floppy cable, extending it and adding an extra plug on the end. This allows me to hook up an external Gotek drive (or 600RPM floppy). This is accessible from the expansion hatch, along with the serial and parallel printer and RGB ports.

P.S. The floppy motor on that old drive is LOUD!

stephen_usher · Post by **stephen_usher** » Mon Dec 20, 2021 9:03 pm

exxos wrote: Mon Dec 20, 2021 8:47 pm
stephen_usher wrote: Mon Dec 20, 2021 8:34 pm Don't you just love variations in chips?
I think I wrote the book on that quite literally

stephen_usher · Post by **stephen_usher** » Mon Dec 20, 2021 9:24 pm

Hmm... How can I describe the sound of the floppy drive?

You know the loud drone of really early MFM/RLL hard drives? Well, take that down an octave and you've got something similar.

Anyway, having the original drive has been very useful. In future, if I make another adapter for Shugart drives I'll use the "Head Load" signal to control the "Motor On" instead of the one being generated by the system, as this is permanently on. On newer drives the heads rest on the platter continuously, unlike this drive, which lowers the heads in response to the "Head Load" signal. This means that although the disk is spinning continuously it's not having the head wear it out. For later drives it needs the motor to be stopped to prevent the disk being worn out.

Tomswork · Post by **Tomswork** » Mon Dec 20, 2021 9:34 pm

The floppy motor just want you to know its there for you

Tom

stephen_usher · Post by **stephen_usher** » Mon Dec 20, 2021 9:42 pm

Tomswork wrote: Mon Dec 20, 2021 9:34 pm The floppy motor just want you to know its there for you

Tom

Eh? What? Can't hear you! I'm deaf! Hehe

stephen_usher · Post by **stephen_usher** » Mon Dec 20, 2021 10:44 pm

OK, here's it booting from floppy but somehow the iPhone has removed the floppy motor sound!!!

Post by **rubber_jonnie** » Mon Dec 20, 2021 11:10 pm

Good job sir it's nice to see it's up and running, but that 555, nice find and very annoying!

exxos's Atari, Amiga & retro forum

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