Standard Disk And Midi Interface For Atari St

EE 20 February 1987 Fig. 1. Two open- collector drivers need to be fitted into the Atari 1040ST micro to enable it to handle the load presented by a second disk drive to the Shugart standard. STANDARD DISK AND MIDI INTERFACE FOR ATARI ST As a follow-up to last month"s article on a video interface for the Atari ST series of microcomputers, this article explains how to upgrade the machine with a Shugart- compatible second disk drive outlet and a more practical MIDI interface. Microcomputers in the Atari ST series generally incorporate the Type AY-3-8910 or second source equivalent Type YM2149 CSG (com- plex sound generator) chip, fea- turing two bi-directional 8-bit ports equipped with internal pull-up resistors and TTL-compatible output drivers. Albeit that the drive capacity of these outputs is just about sufficient to handle the load presented by a Centronics printer or an Atari 31/2 inch floppy disk drive, it would ap- pear recommendable to provide the computer with real buffers...