Epson PX-16 (Gorgeous)
OK, I know it looks a bit like a cash register, especially when it’s sitting on the disk unit but I like it! I’ve removed all of the internals today and given the cases a good clean inside and out. I’ve secured the FDD and HDD in the working disk unit and made an attempt to get the FDD working.
Epson SMD-400 FDD
The FDD is an Epson SMD-400. Like the HDD it has a non-standard connection, with power being supplied via the interface cable as opposed to the usual separate cable. Unlike the HDD it doesn’t work and I’ve been unable to make it read or write to any disks. I’ve had it apart and fiddled a bit with the spin speed and head alignment but no joy. Oddly a cable to nowhere has been soldered to the board, I have no idea what it would have been connected to but hope it’s not something painfully obvious like the head.
The unit does spin up and the head moves around but it fails on every disk I’ve tried. It would of course be nice to slot another drive in there, I’ve got plenty of them but of course they all require a separate power cable.
Piggybacking the FDD
With no serial cable and no FDD I’m rather limited on what I can do with the machine as I’m unable to get any files on to it. In desperation I opened up my Windows 95 box and trailed the cable from its floppy into the PX-16 disk unit so the Windows 95 box could power it. However with it connected to the floppy interface on the PX-16 the Epson won’t start up.
PX-16 XTGold
I gave up and turned my attention to the installed modem. It has an RJ connector that I’ve not seen on a UK modem before. Usually they’re RJll’s with 4 connections. This looks more like an RJ45 and it has 8 connections, although it’s a UK specified machine and the modem is made by a UK company.
I started up Term and sent some modem commands to COM 2 and got the usual OK’s back. I tried to kludge a cable together but was unable to get a dial tone. So a slightly more frustrating day today although I did have fun playing with XTGold which was on the disk I’d salvaged from the Equity, it seems like quite an impressive file manager.
Retrocosm's Vintage Computing, Tech & Scale RC Blog 
This is really cool. I’d never heard of a PX-16 before, and it looks like a neat retro machine! Nice pictures too – thanks for the chance to see them.
Best of luck on getting it fully functional! And congratulations on the spectacular deal you got on the purchase.
LikeLike
Thanks Earl, as you can probably tell I’m a big fan of old Epson machines and I’ve been after one of these for a while, they genuinely do seem to be quite rare.
Now if I could just get my hands on a QX-10!
LikeLike
On the SMD-400 drive, pins 7,9 & 11 are +5 volts each (instead of GROUND), that’s where the drive gets its power from (it doesn’t use a +12 V line). You can run a continuity test with a multimeter across the odd-numbered pins to verify that. The remaining odd-numbered pins are all GROUNDS, as is the standard (except possibly for #3 which serves as NC key sometimes). Also the unit is set to DEVICE ID 0 (instead of 1 which is the norm on PC drives) and seems to follow the Shugart interface pinout instead of the AT pinout (this concerns pins 2 and 34 and accordingly the READY and DISKCHANGE signals).
So to use a standard PC floppy, use a cable with the usual twist (to route ID 0 to ID 1 so the floppy responds). !!! But cut-off stripes 7,9 and 11 or you’d be shorting +5V to GROUND !!! Since it’s a standard PC floppy you can separately power it e.g. from an AT or ATX power supply, so no problem by cutting-off the custom +5 V lines.
You will also likely need to swap stripes 2 and 34. Try all 4 combinations:
2 -> 34 & 34 -> 2 (Swapped with each other)
2 -> 34 & 34 -> nowhere (disconnected)
34 -> 2 & 2 -> nowhere (disconnected)
2 -> nowhere (disconnected) & 34 -> nowhere (disconnected).
And of course use DD and not HD disks! Or cover the HD hole on the disks so they’re detected as DD.
All these modifications (ID setting, AT –> shugart, HD detection disabling) can usually be performed on the PC floppy itself (some models are better suited to that than others). By isolating pins 7, 9 & 11 on the floppy drive from the GROUND plane and soldering wires from them to the +5V pin of the floppy’s power connector (and also from three GROUND pins to the matching GROUND pin of the power connector) you can even power it the way a genuine SMD-400 would be powered, so if you get lucky you could hack yourself an SMD-400 replica out of a standard PC floppy drive 🙂 only problem would be the position of the connector which is upside down on the SMD-400 and unlikely to be matched by any currently available drive (even upside down), so if the SMD-400 plugs directly into the cage without a cable, you’re a bit out of luck elegance-wise.
LikeLike
Thanks Nikos, that is invaluable information! I’d like to have a go at this mod as I have plenty of old FDD’s knocking about.
Fortunately the drive does connect by cable so I could end up with quite a neat solution.
Great stuff, thank you!
LikeLike
No prob 🙂 glad to help. If you need more specific info send an email.
LikeLike