OSI CD-23 Hard Disk System Work

[glitch]

A bunch of us got together at System Source last weekend, and worked on the CD-23 hard disk system I've got:

https://users.glitchwrks.com/~glitch/20 ... -23-part-1

This one uses a Shugart SA-4008 drive. We think we've got the drive in pretty good shape, it had a bad motor start relay and CD40103 counter. The OSI 590 interface is not activating the read gate, which is internally generated, so I'm pretty sure the next fault to find is in the OSI 590 board.

Grounding the read gate with Mark's experimental CD-23 C3DUMP running does produce clock and stuff on the read data line that looks like it's probably data, though!

[CrawfordG]

Hey Glitch,

Was going to check if this was posted yet - you beat me to it. It was a fun time, and System Source again did a stellar job of hosting the workshop!

I’ve been trying to read up on anything about OS-65U, and the hard disks in general. The OS-65U manual mentions a CD-23 and a CD-28 drive, but in different places. I wonder if they are one and the same. Perhaps marketing got involved and wanted to use the bigger (unformatted) number and engineering insisted on the actual (formatted) 23MB?

Let us know if you locate any of the original documentation for that system.

Thanks for coming to the workshop and bringing the CD-23!

-Crawford

[bxdanny]

No, the CD-28 was a much later drive. It was the last hard drive introduced for OS-65U, in what was called the "Worksystem", that was introduced in 1984. I think the company was already Isotron at that time. The Worksystem was similar to other "Keysystem 200 series" computers, a sealed white box with one 8" floppy and one hard drive. The CD-28 drive was very similar to the CD-7, as I remember, but with four times the capacity. The Worksystem computer that it was part of (I don't think it had any other designation) came with a reasonably decent word processor that ran under OS-65U.

The CD-23 had been discontinued several years before the CD-28 was introduced. The CD-23 was replaced in later C3-C computers by the CD-36, which had exactly half the capacity of the CD-74. (Funny math there with those CD numbers.)

[CrawfordG]

Bxdanny,

Thanks for the history on the disk systems! OSI certainly went through a lot of iterations on the hardware side.

-Crawford