HP 1662A Logic Analyser - High Density (Pin 2?)

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PMK145
Posts: 10
Joined: Tue Feb 23, 2016 1:44 pm

HP 1662A Logic Analyser - High Density (Pin 2?)

Post by PMK145 »

I've followed and distilled the excellent information on these forum pages and now have a slim HxC drive working with my HP 1662A Logic Analyzer. Interfacing the HP ribbon cable to the HxC was achieved pretty easily using an excellent PCB design I downloaded from one of this forum's contributors.

I modified the HxC board by adding 1k resistors to the R4, R8 & R9 pads. These appear to be 0805 pads not 0603 as discussed in various places, but the 0603s I had to-hand are fine, but fiddly for my XL hands.

Using the Shugart interface setting in the configuration file the 1662A is happy to read 720k files, but not 1.44MB. The original drive will handle both DD and HD. I've done a lot of experimentation but the 1662A reports 'No Disk' when I try a 1.44MB size and format file. Looking at information regarding the drive interface I see that Pin 2 might tell the system if it has a 1.44MB disk.

In the HxC configuration utility for the configuration file, there is a 'Custom' option that allows Pin 2 to be configured. I've tried setting these to High, Low and with Pin 2 to detect bot HD and *HD but according to my DMM the pin is permanently held high.

Am I missing a setting option somewhere or have I misinterpreted the functionality of Pin 2? The high/low option also appears to be present for Pin 34 in the configuration settings, but that too appears to be held high. I've tried both Generic Shugart and IBM PC 1.44MB HFE file settings.

PMK145
Posts: 10
Joined: Tue Feb 23, 2016 1:44 pm

Re: HP 1662A Logic Analyser - High Density (Pin 2?)

Post by PMK145 »

The PCB design was courtesy of SKOT9000 from 2013 - developed for his HP4145B and made available in the form of Gerber files. JLC did a nice job of producing them

PMK145
Posts: 10
Joined: Tue Feb 23, 2016 1:44 pm

Re: HP 1662A Logic Analyser - High Density (Pin 2?)

Post by PMK145 »

A few images of the project.

The floppy image shows my oscilloscope probe which I used to confirm that the drive spins at 300RPM not 600RPM.
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Floppy 04.jpg
Floppy 04.jpg (114.72 KiB) Viewed 466 times
Floppy 03.jpg
Floppy 03.jpg (117.17 KiB) Viewed 466 times
Floppy 02.jpg
Floppy 02.jpg (105.44 KiB) Viewed 466 times
Last edited by PMK145 on Sun Jul 18, 2021 5:02 pm, edited 1 time in total.

PMK145
Posts: 10
Joined: Tue Feb 23, 2016 1:44 pm

Re: HP 1662A Logic Analyser - High Density (Pin 2?)

Post by PMK145 »

Last three
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Floppy 07.jpg
Floppy 07.jpg (112.25 KiB) Viewed 466 times
Floppy 06.jpg
Floppy 06.jpg (76.31 KiB) Viewed 466 times
Floppy 01.jpg
Floppy 01.jpg (143.41 KiB) Viewed 466 times

PMK145
Posts: 10
Joined: Tue Feb 23, 2016 1:44 pm

Re: HP 1662A Logic Analyser - High Density (Pin 2?)

Post by PMK145 »

Just to finish off the hardware side of fitting an HxC Slim emulator into my HP 1662A Logic Analyzer - here are a few images of the drive fitted in the instrument. I decided to fit a 16x2 ('1602') LCD so I can keep track of which disk image I'm using. I'm going to use the 1662A to diagnose and track any problems I have with a 6502 processor circuit board that I've designed, so I will probably need to transfer listings to a PC to analyse memory and I/O read and write operations.

I needed to cut away some of the bracket that held the original floppy disk drive in place. Because the HxC slim is narrower than the original drive one of the M3 supporting screws has to be quite long with nuts to provide rigidity.

The HxC and 1662A work well together for DD (720k) images but not HD (1.44MB) size images. That's the next thing I need to look into.
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HP 03.jpg
HP 03.jpg (146.78 KiB) Viewed 250 times
HP 02.jpg
HP 02.jpg (123.96 KiB) Viewed 250 times
HP 01.jpg
HP 01.jpg (153.1 KiB) Viewed 250 times

PMK145
Posts: 10
Joined: Tue Feb 23, 2016 1:44 pm

Re: HP 1662A Logic Analyser - High Density (Pin 2?)

Post by PMK145 »

Last two
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HP 05.jpg
HP 05.jpg (141.97 KiB) Viewed 250 times
HP 04.jpg
HP 04.jpg (109.23 KiB) Viewed 250 times

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