Hard Disk Controller; Port Decoding - Tandy 6000 Service Manual

Service Manual
7.10

Hard Disk Controller

7.10.1 System Overview
The Tandy 6000 with built in hard disk is identical to the
standard 6000, except for the additional 15-meg HD drive,
identical to the standard 16B (Cat. No. 26-6004), except for
the addition of a 15-megabyte (formatted) hard disk drive,
controller PC board, drive power supply, and associated
cables. The drive is mounted next to the existing floppy
drive in place of a second internal floppy.
supply for the hard disk is mounted to the outside of the
drive mounting tower.
the bottom slot of the card cage.
connecting the controller and the internal hard drive.
There are also connectors on the controller for adding a
secondary, external hard drive.
used to power the internal hard drive and a small cooling
fan located under the drive tower.
is powered from the main card cage.
7.10.2 Hard Drive Controller Board
The hard drive controller (HDC) board is a two sided PC
board with the same form and size as those used in the Model
II and Model 16.
control and data signals for connecting one internal and one
external 5.25" Winchester technology drives.
1. Host System Interface
The HDC is connected to the 6000 motherboard via an
80-position card edge connector,
through an AMD 8303 inverting transceiver, U39.
address lines are buffered by a 741S240, U 4 0 .
signals are buffered by another 741S240, U41.
uses the Z80 interrupt priority daisy chain, so the board
must be placed in either the bottom card slot, or the next
one up, if the system also has an Arcnet board installed.
2.

Port Decoding

The HDC uses a range of 16 consecutive eight bit port
locations with the standard range being CO to CF.
of the correct range is done by U33, a 74S138 using the
upper 4 address lines and Ml and IORQ*.
enables changing of the range to be recognized. For
use, the jumper should be installed between El and E 2 .
the following table for other configurations.
TANDY COMPUTER PRODUCTS
The controller PC board is located in
The extra power supply is
This board is designed to provide all
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TANDY 6000/6000-HD
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The power
There are two cables
The controller PC board
Jl. Data lines are passed
Eight
Most control
This board
A 4 position jumper
Decoding
normal
See