Sitenotice: 11/29/2018: The wiki is back. It turns out, some anti-virus product on my web server had an issue with the latest version of PHP. My server techs have resolved this issue, and things should be working again. During the investigation, I did restore to a backup from September. There is a chance that any changes done since then were lost, but I do not recall any edits. --OS-9 Al
8/30/2016: Massive re-work is being done on the InfoBox Templates. Read that page to keep up with the plan for that, and adding better keyword tags (categories) to all the pages. --OS-9 Al (talk) 15:28, 31 August 2016 (CDT)
|Looking for CoCo help? If you are trying to do something with your old Color Computer, read this quick reference. Want to contribute to this wiki? Be sure to read this first. This CoCo wiki project was started on October 29, 2004. --OS-9 Al|
This page was last updated on 01/15/2013. Total Pages: 544. Total Files: 907.
This is the last Tandy controller. It reverted back to mere solder-tinned edge connectors, for whatever reason (cost?!). Unlike every previous model, this one uses a 28-pin ROM rather than a 24-pin ROM for Disk BASIC. This model was introduced in the 1988 Radio Shack catalog.
All Radio Shack (and some third-party) CoCo floppy controllers use a pair of 7416 open-collector buffer chips to communicate with the floppy drive(s). These chips can fail and cause various strange symptoms. They may be replaced with 7406 chips, which are more rugged (the 7416 is rated at 15V, while the 7406 is rated at 30V). Socketing the replacement chips makes future replacement much easier, should it become necessary.
This drive unit is like the FD-501, with two notable exceptions. This is the only Tandy model ever to incorporate true double-sided drives, and its drive power connectors are like those of typical 3.5" floppy drives rather than those of normal 5.25" drives. The smaller power connectors are also reportedly wired differently than typical 3.5" drive connectors. As noted elsewhere, either a patched Disk BASIC or an alternative operating system is required to gain access to the second side of disks. A cooling fan must be installed for safe operation if a second drive is added.