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Old_hitech
December 31st, 2017, 07:40 AM
I have been using a cassette tape recorder with my SOL-20 for years. I'd like to try interfacing a disk drive to my SOL. What is the most reliable disk interface card and drive to use with the SOL-20?

glitch
December 31st, 2017, 10:09 AM
The North Star hard sectored controller was popular, of course the Helios drives were the official Processor Tech thing to have. You can interface any S-100 disk controller, but beware that the 2 MHz 8080 will limit you on what you can do with an I/O based controller like the SD Systems VersaFloppy II. There are several good controllers with onboard CPUs, I've only personally used the Jade Double D controller (onboard Z80, supports many formats, does double density of course).

deramp5113
December 31st, 2017, 12:02 PM
I’ve run my Sol with both the single density and double density North Star controllers (North Star DOS and CP/M). The required hard sector disks (10 sectors) are very hard to find these days.

I have also run the Sol with the Micropolis floppy controller (MDOS and CP/M). The required hard sector disks (16 sector) are not easy to find either, but much easier than the 10 sector disks.

I’ve also used the Tarbell SSSD controller with 8 inch drives with my Sol running CP/M.

Using the North Star controllers with an inline virtual sector generator allows using readily available soft sector 5.25” floppies. Half-height floppy drives like Teac are very reliable with a VSG.

Mike

Old_hitech
December 31st, 2017, 12:42 PM
Thanks for replies. Mike, can you tell me more about the North Star controller witn inline virtual sector generator?

-Gil

Corey986
December 31st, 2017, 01:58 PM
I have a 16k Sol-20 with a single density hard sector Northstar 5 1/4 drive. I typically run with a single drive, but have a second that isn't hooked up right now. This is my early 1977 setup :-)

I also have a 48K Sol-20 with a completely rebuilt (including all bearings and motors) Helios II system. My 1978 setup...

The Northstar is cool, but the Helios is amazing but very complex and heavy. The only problem with a Helios is finding one that actually works (or getting it working) and is able to exchange disks with another Helios. Kinda like finding an Apple Lisa Twiggy, only a few left can share disks between each other. Besides worn bearings and eject gears, the Helios has a glass voice coil and they are typically broken from shipping if someone doesn't know exactly how to ship them. You also need to change a boatload of tantalum caps on the drive, some of which are very difficult to get to and you will need a professional desoldering station. No brad or solder sucker can get into some of these places. The tantalum caps don't always explode, but they do cause some strange behavior with these drives when they aren't replaced. Don't know if it's the brand that was used, but they are the most problematic tantalum I have ever found. FYI: It took me months to restore my Helios. It is my biggest single project to date (time-wise).

The other cool thing about the Helios is PT-DOS, it's very modern Unix like for 1977/78. I even have PT-DOS versions of Focal, Fortran and Cobol. I also have a version of lifeboat CPM 1.4 for Helios.

Old_hitech
January 1st, 2018, 07:35 AM
Corey,

Thanks for the info. I think if I get a disk drive interfaced to my SOL-20 it will be more like your 1977 setup with a Northstar drive. Helios II system with PT-DOS sounds great, but I think trying to find and the cost of an Helios II drive will me more than I can afford. On your Northstar disk system are you using an inline virtual sector generator?

-Gil

Corey986
January 1st, 2018, 08:08 AM
Nope no funny business here like a virtual sector generator, on the Northstar I’m using real hard sectored disks. I bought a bunch of NOS from Athana a few years back. When they run out, I’ll build a jig and make my own hard sector disks.

deramp5113
January 1st, 2018, 10:21 AM
Thanks for replies. Mike, can you tell me more about the North Star controller witn inline virtual sector generator?

-Gil
Gil,

In my opinion, the most practical and still authentic North Star configuration would be the double density controller with a couple of full height 5.25” drives. Shugart SA-400 drives were often used and they’re still amazingly reliable once given a little TLC.

The SA-400 is single sided and has a very slow step rate, so you might also consider full height double-sided drives like the Tandon TM100 drives. These offer twice the storage and a 10x faster step rate. Lifeboat CP/M 2.2 for the North Star supported single or double sided drives and fast or slow step rates. However, I haven’t found the Tandons to be as reliable in their old age as the Shugarts.

If you’re not able to find hard sector disks, an inline VSG lets you use all the same hardware (controller and drives) and transparently use both hard and soft sector media. However, not every full height drive will be reliable with a VSG because of the belt driven hubs found in full height drives. See this page for more information http://deramp.com/vsg.htm.

Mike

deramp5113
January 1st, 2018, 10:39 AM
The Northstar is cool, but the Helios is amazing but very complex and heavy. The only problem with a Helios is finding one that actually works (or getting it working) and is able to exchange disks with another Helios. Kinda like finding an Apple Lisa Twiggy, only a few left can share disks between each other. Besides worn bearings and eject gears, the Helios has a glass voice coil and they are typically broken from shipping if someone doesn't know exactly how to ship them. You also need to change a boatload of tantalum caps on the drive, some of which are very difficult to get to and you will need a professional desoldering station. No brad or solder sucker can get into some of these places. The tantalum caps don't always explode, but they do cause some strange behavior with these drives when they aren't replaced. Don't know if it's the brand that was used, but they are the most problematic tantalum I have ever found. FYI: It took me months to restore my Helios. It is my biggest single project to date (time-wise).


Thank goodness for Martin E. and all his Helios expertise and repair documentation!

Mike

Nama
January 1st, 2018, 11:39 AM
I use both Northstar Double density controller (with virtual sector generator and standard disk media)), and a Disk Jockey 2D disk controller connected to 8" drives (or my Gotek HxC drive emulator). I'm hoping that the Gotek will get hard sector capabilities soon so I can also use it with the Northstar controller.

Corey986
January 1st, 2018, 01:57 PM
Thank goodness for Martin E. and all his Helios expertise and repair documentation!

Mike

Yep without Martin and his documentation, procedures and unobtaniun spare parts I would have a 70lb door stop.