Gotek and HP 1650a logic analyzer

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allhall
Posts: 2
Joined: Sat May 06, 2017 7:19 am

Gotek and HP 1650a logic analyzer

Post by allhall » Sat May 06, 2017 7:31 am

Reprogrammed a Gotek, installed in the logic analyzer, set it for indexed operation, and successfully booted the analyzer. Wrote a file and formatted a disk successfully. Don't have the disk change working. Gotek is replacing a Sony MP-F52W-30. Original drive is dead, so can't pull waveforms. Indexing worked once when I held down the index button, but most of the time it ends up reporting no disk inserted. Analyzer ignores the standard index step.

Does anybody have this working?

Are the extra SD card version emulations for pin2 and pin34 supported via the HXCSDFE.CFG file?

allhall
Posts: 2
Joined: Sat May 06, 2017 7:19 am

Re: Gotek and HP 1650a logic analyzer

Post by allhall » Fri May 12, 2017 4:46 am

Almost got everything working, so I'll document in case a) it helps someone else, or b) somone knows of a better way.

Analyzer always drives DrvSel0 low. Unfortunately, having the Gotek always Ready sometimes trips up the analyzer, causing drive not inserted or drive read errors.

Changing Gotek to use MotorOn works much better. Gotek access works well, but index mode still doesn't work.

Using Shugart mode causes DskChg to pulse low for 4sec and Ready to pulse high for 200msec, but only when the Gotek is Ready. The analyzer doesn't react to transitions, so it never rescans the Gotek. When the Gotek is not Ready, DksChg doesn't toggle at all. The analyzer relies on the DskChg latching in the Sony drive. Ejecting the drive drives DskChg low until a pulse on Step sets it high.

So, unless somebody has a better idea, i plan to add a HCT74 flip-flop to generate the DskChg signal. I'll run a wire fron the index pusbutton to async set the flop. Step will be routed to the clock input to clear on pulse. May need an inverter or two to get the polarities correct.

Looks like the Gotek supports reading the floppy type from the HXCSDFE.CFG file, but the advanced modes for pin2 and pin34 don't seem to work.

Engineer Paul
Posts: 1
Joined: Sun Apr 01, 2018 6:25 pm

Re: Gotek and HP 1650a logic analyzer

Post by Engineer Paul » Sun Apr 01, 2018 6:46 pm

Gearing up to continue this effort for my 1651a. Thanks for your pioneering effort. Will report back...

Jeff
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Re: Gotek and HP 1650a logic analyzer

Post by Jeff » Sat Sep 01, 2018 12:05 pm

allhall wrote:
Fri May 12, 2017 4:46 am
Looks like the Gotek supports reading the floppy type from the HXCSDFE.CFG file, but the advanced modes for pin2 and pin34 don't seem to work.
It does (nDiskChange 1 should be used here), but i think that the main issue here is the usage of the motor on as drive selection. This broke for sure the disk change detection.
What need to be "fixed" is the first issue. (Btw this is maybe already fixed with the new hxc firmware versions).

You can try to use the "Not Gated" firmware version available into the archive :
(With this firmware the drive is always "selected" and the drive selection line is ignored)

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