NorthStar HORIZON Random Access Memory Manuale utente
North Star Computers, Inc.
14440 Catalina St., San Leandro, CA 94577 USA
(415) 357-8500 TWX/Telex (910) 366-7001
HRAM
HORIZON Random Access Memory
USER/ TECHNICAL MANUAL
HORIZON is a registered trademark of North Star Computers, Inc.
Copyright © 1981, by North Star Computers, Inc. All
Rights Reserved
004068
HRAM USER/TECHNICAL MANUAL
This manual was digitally remastered by Howard M. Harte, June 2003.
http://www.hartetec.com
If you find any errors, please email hharte@hartetec.com.
HRAM USER/TECHNICAL MANUAL
CONTENTS
Section Page___
1 INTRODUCTION
1.1 General Description 1-1
1.2 Warranty Information 1-1
1.3 Specifications 1-3
2 INSTALLING AND REMOVING THE HRAM
2.1 Installation 2-2
2.2 Removal 2-3
3 IMPLEMENTING HRAM OPTIONS
3.1 Example Memory Configurations 3-3
3.1.1 Example 1: Three Banks 3-3
3.1.2 Example 2: Three Banks 3-5
3.1.3 Example 3: Four Banks 3-6
3.2 Bank Switching 3-7
3.2.1 Designating Switched Areas 3-7
3.2.2 Designating I/O Port Control Bit 3-9
3.2.3 Software Instructions 3-10
3.2.4 Bank Status on Reset 3-11
3.3 Memory Address Switches 3-13
3.3.1 Revision B Board 3-13
3.3.2 Revision E Board 3-14
3.3.3 32K Board 3-18
3.4 First Quadrant Option (Revision E Board only) 3-19
3.5 Parity Checking 3-20
HRAM USER/TECHNICAL MANUAL
Section Page___
3.5.1 Designating I/O Port Control Bits 3-20
3.5.2 Designating Parity Error Response 3-21
3.5.3 Software Instructions 3-22
3.6 Board and Schematic Revision Levels 3-22
4 TESTING THE HRAM
5 THEORY OF OPERATION
5.1 Overview 5-1
5.2 Address Multiplexer 5-2
5.3 Refresh Logic 5-3
5.4 Port CO Detector 5-4
5.5 Address Latch 5-4
5.6 Address Decoder 5-4
5.7 Jumper Area JP1 5-5
5.8 Bank and Parity Logic 5-5
5.9 Strobe Generator 5-6
5.10 Voltage Regulators 5-9
6 TROUBLESHOOTING
6.1 Check HRAM Seating 6-1
6.2 Change Board Slots 6-2
6.3 Check HRAM Configuration 6-2
6.4 Run Diagnostic Programs 6-2
6.5 Replace HRAM 6-3
6.6 Repair Procedures 6-3
HRAM USER/TECHNICAL MANUAL
APPENDICES
A RAM Chip Location Chart A-1
B Bus Signals Used by HRAM B-1
C HRAM 64K - Parts List C-1
D HRAM 64K – Schematics D-1
E Reader Response Form E-1
HRAM USER/TECHNICAL MANUAL
HRAM USER/TECHNICAL MANUAL
INTRODUCTION 1
This manual supplies the user of the HORIZON Random
Access Memory (HRAM) board with information he or she
needs to install the board and put it into operation.
This includes information on selecting the various
memory options, testing the board and resolving any
difficulties associated with system integration.
The manual also provides information for service
technicians and engineers who may wish to evaluate the
technical aspects of the board or to undertake its
repair.
1.1.1 GENERAL DESCRIPTION
The HRAM board is a random access memory board
designed for use in the HORIZON computer system.
There are three versions of the HRAM board: HRAM-64
with 64K bytes, HRAM-48 with 48K bytes; and HRAM-32
with 32K bytes. The only significant difference
between these boards is the amount of memory they
contain. All three versions incorporate parity error
checking and bank switching capabilities.
1.2 WARRANTY
North Star Computers, Inc., warrants the electrical
and mechanical parts and workmanship of this product
to be free of defects for a period of 90 days from
date of purchase. If such defects occur, North Star
Computers, Inc. will repair the defect at no cost to
the purchaser. This warranty does not extend to
defects resulting from improper use or assembly by
purchaser, nor does it cover transportation to the
factory. Also, the warranty is invalid if all
instructions included in the accompanying
documentation are not carefully followed.
HRAM USER/TECHNICAL MANUAL
Should a unit returned for warranty repair be deemed
by North Star Computers, Inc. to be defective die to
purchaser's action, then a repair charge (not to
exceed $50 without purchaser's consent) will be
assessed. ANY UNITS) OR PART(S) RETURNED FOR WARRANTY
REPAIR MUST BE ACCOMPANIED BY A DATED COPY OF THE
ORIGINAL SALES RECEIPT. The item should be returned to
the dealer from whom the product was purchased, for
implementation of the warranty. When sending the item
to the factory for repair, the dealer must call the
North Star Technical Hotline to receive a Return
Material Authorization (RMA) number to accompany the
item to the factory.
The following warranty limitation applies to units
located outside the United States of America: All
costs and arrangements for transportation of the
product to and from the factory are borne entirely by
the customer.
No warranty, expressed or implied, is extended
concerning completeness, correctness, or suitability
of the North Star equipment for any particular
application. There are no warranties which extend
beyond those expressly stated herein. This limited
warranty is made in lieu of all other warranties,
expressed or implied, and is limited to repair or
replacement of the product.
HRAM USER/TECHNICAL MANUAL
1.3 SPECIFICATIONS
The HRAM specifications are given in Table 1-1.
Table 1-1
HRAM Specifications
Storage
Capacity
32K bytes for the HRAM-32
48K bytes for the HRAM-48
64K bytes for the HRAM-64
Bits per Byte Eight data bits and one parity
bit.
Access Time 300 ns typical
HRAM USER/TECHNICAL MANUAL
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