This is Version 0 with modified data cable connector pinouts for an easier connection to the drives.
Schematics - v.1.0
Features of v.1.0:
There are no changes in the schematics from those in the original hardware manual.
The only change is a bigger number (4 instead of 1) of connectors to the drives, as well as the signal mapping to their pins.
Data cable connectors (on the interface) for two types of drive pinouts: original Shugart standard compliant and (the more recent) IBM standard compliant, using a twisted data cable. Yet when using recent drives the cable must have no twist and only one drive per cable will be accepted. The drive connected to the internal cable will be drive B: and the one connected to the external cable will be drive D:. This limitation is dictated by the fact that the interface is designed to use separate READY signals from each drive, while the standard data cable (recent design) has only one wire assigned for READY. Since recent drives are configured from the factory as drive B: (SELECT1 active) I have connected pin 34 in connector JFDI2 to NRDY1 and pin 34 in connector JFDE2 to NRDY3.
For each type of drive data pinout, there is an internal connector for internal drive(s) and an external connector for external drive(s). JFDI1 and JFDI2 are internal connectors, and JFDE1 and JFDE2 are external connectors.
Board layout - v.1.0
Component layer (above) is drawn in red and the opposite layer in blue. The Gerber files for this layout can be downloaded as a ZIP archive.
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