New project: An ACT Apricot F1 "barn find"

[stephen_usher]

OK, I'm going to step back from this project as I'm going backwards.

A couple of days ago I had a Gotek and NEC floppy drive working together. The machine would detect two drives and I could read and write (but not reliably because of the drive) to floppies.

Today, with the same cable, the same settings on everything the machine sees one drive and it won't boot off the Gotek with the second drive powered.

So frustrating.

(Yes, the two Goteks do work together fine still.)

[Tomswork]

@stephen_usher
The old 8in shaugart i have are bad for that because of the drive terminator pack

Tom

[rubber_jonnie]

Hope you can figure it all out, but these long refurbs can be trying and taking a step back often helps. My first Mega was a bit like that, fix it, stops working, fix it, stops working and soon.

I lost count of how many times I stepped away from it and it took a long time to get it going. I'm certain you'll get there in the end.

[stephen_usher]

Yeah. Though I can do other stuff on the machine and think about a board which uses an ATTiny85 to decode the signals to/from the floppy drive as described previously.

Now, do I use a 74LS32 or two diodes as an OR gate?

[stephen_usher]

I must admit I have been tinkering a bit and discovered something interesting.

There's no connection between the signal ground and power ground on the Gotek. I think a lot of my problems may be due to the signal voltage levels being low with respect to the local ground. Time for a thick bodge wire methinks.

Forget that! I think my Shugart/Apricot cable adapter is broken, in that there's no GND on the 34 pin socket somehow! What has the routing done?!

[stephen_usher]

With the grounding problem fixed with a thick bodge wire I can at last have the disk drives external, though not with the 300rpm drive compatibility as the stack is too tall to fit under the PSU frame.

Still, this is a lot safer way of working.

IMG_2359.jpg (73.58 KiB) Viewed 2417 times

(Please excuse the reflection of my washing!)

A second drive on the floppy chain is still not being recognised, though I see it scanning the drive on power-up. This could be a clock speed issue so I'll have to worry about it later. At least the case is together.

[stephen_usher]

Picked up a proper Apricot monitor, but no external 17V AC power supply for it. Still, as the AC is immediately rectified with a set of four diodes, 17V DC from my bench PSU does just as well. I'll have to find a 17V 1.5A power supply from somewhere as it needs nearly 1.2A. I can only find cheap 1A ones on-line though.

Anyway, after a clean and some retro-brightening of parts of the case it'll look a lot better.

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[stephen_usher]

Productive morning redesigning the Shugart/Apricot cable adapter board and WD2797A daughter board and submitting them to PCBWay for manufacture. Probably at least a week an half until they arrive, which will be just before I go on holiday.

Holidays are so inconvenient.

[rubber_jonnie]

@stephen_usher I said over on FB earlier today that this was a magnificent effort, and I can only reiterate that now

[stephen_usher]

@stephen_usher I said over on FB earlier today that this was a magnificent effort, and I can only reiterate that now

It's the tinkering which is the fun bit. Once it's all working there's the, "OK, what now?" bit.

Anyway, if I get the DSKCHG to /READY conversion stuff working correctly this will be directly applicable to using PC drives with Ataris and Amigas. I can create a generic converter board which can re-route the DSKCHG to pin 2 and generate the /READY signal on pin 34 so any PC drive can be used without modification. I could even swap the drive ID lines etc. if necessary. It wouldn't be difficult.