User Port Floppy Parallel Cable - Hardware



	Home Search Games Tapes Covers Cheats Maps Software New Stuff Hall Of Fame HVTC Game Endings Solutions Remakes Publications Magazines Effects Top List Members Groups Features Plus/4 Encyclopedia Hardware Tools Options Forum Home Search Games Tapes Covers Cheats Maps Software New Stuff Hall Of Fame HVTC Game Endings Solutions Remakes Publications Magazines Effects Top List Members Groups Features Plus/4 Encyclopedia Hardware Tools Options Forum	Login

Hardware - User Port Floppy Parallel Cable
Name:	User Port Floppy Parallel Cable
Category:	Cable
Introduced:	Unknown

Introduction
These kind of cables are intended to reduce disk loading times. The principle is to modify a floppy disk drive (generally the Commodore 1541) and install a parallel port that can be used to transfer data to the computer at a faster speed than what is allowed by the standard IEC protocol, which is a serial protocol and therefore only transfers one bit at a time. This technique is used, for instance, by DolphinDOS on the C64 or by the various cables that are used to connect the 1541 to a PC (i.e.: X1541, XA1541, ZoomFloppy, etc...). While on the drive side there is usually a DB15 connector, wired according to these instructions (note that the connector might be something else, depending what the creator had available), there is no "official/standard" about how to connect that to the Plus/4. On the Plus/4 side some software used the 8-bit parallel interface of the user port while other used custom 8255 boards (mainly on the C16, see 8255 Interface). Essentially every file and disk copy programs had both versions. The two versions really differ only in a few bytes, the port is mapped at a different location, and maybe the chip intialization byte differs, but it is very simple to adapt the code from one version to the other. In all cases, only the 8 data lines are used. The additional CB1 and CA2 (1-based notation, pins 18 and 39 of the CIA chip inside the drive) handshake lines are not used as it is difficult to do so without hardware support.