The Parallel Bus Interface, or PBI, is a 50-pin port found on some Atari 8-bit XL computers. It provides unbuffered, direct connection to the system bus lines (address, data, control), running at the same speed as the

6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small te ...

CPU. The 600XL and 800XL computers, along with the unreleased 1400XL and 1450XLD had a PBI interface. The Enhanced Cartridge Interface, or ECI, was a modified version of the PBI designed to be smaller and less expensive to implement. Many of the pins in the PBI were duplicated in the 30-pin cartridge slot, so ECI was limited to only those 14 pins in the PBI that were not in the cartridge slot. Placed side-by-side on the back of the computer, devices plugged into both at the same time to provide the same electrical interface as the PBI. The ECI was found on the 65XE (late production units only), the 130XE and the 800XE.

Details

The PBI is implemented as a rectangular 50-pin

edge connector An edge connector is the portion of a printed circuit board (PCB) consisting of traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a sin ...

on the back of XL machines. The pins include all 16

address line In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This e ...

s (A0 through A15) and 8 data lines (D0 through D7). Other pins include various electrical supplies, clock signals, interrupts, memory strobes, and even an analog audio input. As many of these pins were already implemented as part of the already-existing 30-pin ROM cartridge slots on Atari machines, the XE series re-implemented the PBI to include only those pins that the PBI had but the cartridge slot didn't. The resulting connector contained only 14 pins, mostly the address pins A13 though A15, and the various sound and signal pins of the PBI. The ECI slot was placed beside the cartridge slot, allowing a single connector to be inserted into both connectors and re-create the functionality of the entire PBI.

Pinout

Devices

*Atari 1064 Memory Module - Designed specifically for the 600XL, it upgraded the memory of the 600XL to 64kB. Only parallel bus device released by Atari. *Atari 1090 Expansion System - Designed to give expansion slots to the XL computers. *ICD Multi I/O Board - Hooked up to either a PBI or ECI connection. Featured a RAMdisk, parallel port, serial port,

print spooler In computing, spooling is a specialized form of multi-programming for the purpose of copying data between different devices. In contemporary systems, it is usually used for mediating between a computer application and a slow peripheral, such as ...

and a hard disk interface. *Black Box - The Black Box by CSS hooks up to either PBI or ECI connection. Featured a SCSI interface, a serial port, parallel port, floppy drive interface and a built-in menu system. *SupraDrive - an early SCSI disk drive. * Karin Maxi, a parallel floppy disk drive. * KMK/JŻ IDE (aka IDEa), an ATA host adapter

. * Turbo Freezer XL/XE, a freezer with onboard ROM including a monitor/debugger and RAM expansion (re-released 2005 and 2011 by ABBUC). * IDE2ECI * RAM320XL for the PBI and RAM320XE/576 for the ECI external RAM expansions.

References

* Ian Chadwick
''Appendix 14: The XL/XE Parallel Bus''
''Mapping the Atari Revised Edition'', COMPUTE! Publications, {{ISBN, 0-87455-004-1

External links

ANTIC (magazine), Antic Magazine. Review on ICD products for the Atari. Atari 8-bit family