More PX-16 Adventures

Things are progressing quickly with the PX-16.  Having got the main unit working my attention was today turned to the two disk units that came with the Epson.  Designed to hold either one or two FDD’s or an FDD and an HDD the units sit under and clip onto the main machine.  The two units are then connected via a cable at the back.

JVC JD-3824

The first unit I tried seemed dead, no amount of fiddling would coax it into life.  The second unit however powered up first time, although the FDD in it won’t currently read or write to any disks.  The dead unit had a daughter card and from it a cable with a 26 pin connector which I assumed was for the HDD, although I’d not seen that sort of connector before.

Epson Equity

I enquired over at the Vintage Computer Forums as to whether anyone recognised this connector.  Mike S & Chuck G pointed me in the direction of the JVC JD-3824 drive, Chuck remembering it from a Gridlite he used to own.  I did a search for JVC JD-3824 and had a doh! moment when my own blog came up.  This is the drive in my Epson Equity.  I was considering, somewhat reluctantly, taking the Equity apart and trying the HDD in the PX-16.

26 Pin Connector

Then I remembered I had another Equity, seriously beaten up and not working, tucked away somewhere.  I dug it out, took it apart and low and behold there was a JVC JD-3824 drive in it and on the drive that familiar 26 pin connector and cable, I love moments like that!

JVC JD-3824 in the PX-16

I quickly removed the drive, cleaned it up and put it in the PX-16 drive unit into which I’d also installed the daughter card from the dead unit.  I turned it on and… nothing.  Then I noticed a jumper by the mainboard connector to the daughter card.  On checking the unit from which I’d removed the daughter card I realised the jumper was in the alternative position.

PX-16 & Disk Unit

I swapped the jumper, turned the unit on and the HDD whirred into life.  Not only that but it actually booted to the drive’s original installation of MS-DOS.  I was astonished to say the least, it’s noisy and clunky but I love it.

PX-16 Mainboard with ROM Sockets (Right) & Modem (Left)

The PX-16 is highly configurable, in fact it’s so highly configurable that it makes my head hurt.  There’s a bank of DIP switches in the unit to set depending on which configuration you require.  This includes two boot modes, one of which behaves like a regular PC but also denies access to the system’s ROM’s.  I’m still trying to fully understand the other mode.

I’d like to try and get the FDD working next and I want to build an RS232 cable at some point.  The system also came with some additional RAM which I can’t seem to access in the PC boot mode although it’s available in the standard mode so I need to look at that.

Additional RAM

There’s also a Modem in the unit which I’d like to try and I need to do some swapping around to get all the working components into the cleanest cases and secure the various drives properly.

2 thoughts on “More PX-16 Adventures

  1. Oh my… I have stumbled across your blog searching for a replacement drive for my Roland S-770 sampler. It uses a JVC JD-63848H1RA drive with a 26pin connector. I’ve been told this is a SCSI drive, probably about 40MB in size. If only I was as lucky as you to have another unit sitting around to canibalize!


    1. Hi Rikk, it certainly was a stroke of luck, these non-standard interfaces certainly make it tricky reviving old machines. Good luck with the search for a drive for your Roland, it’s worth keeping an eye on Ebay as all manner of stuff turns up on there.


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