Frequently Asked Questions
comp.arch.bus.vmebus


This list is maintained by:

Robert J. Boys

San Jose, California

formerly of Guelph, Ontario, Canada

January 5, 1996 Version 9

Email:
r.boys@genie.geis.com
rboys@best.com


I am finally updating this FAQ !

I hope all of you reading this, your families and friends had a wonderful and peaceful Christmas and New Year holiday wherever you may happen to live in the world. I wish that all of you have a continuing prosperous and safe 1996.

As you may have noticed in my header - I have moved from the land of ice and snow (Canada) to sunny California.
I now work for Hitex Development Tools - aka HiTOOLS Inc. They sell emulators and such.
VMEbus, M68K and HC11 information may now be sent to this address:

I have a new Homepage: http://www2.best.com/~rboys (California)
The latest version of this FAQ is stored there - i.e. the "work in process" version. I will be getting it running in the next few weeks. This is also true for the FAQ for comp.sys.m68k
My backup Homepage is http://www.sentex.net/~rboys (Canada)

This FAQ is also stored on:

http://www.hitex.com/automation/FAQ/vmefaq (California)
http://www.ba-karlsruhe.de/automation/FAQ/vmefaq (Germany)

www.ee.ualberta.ca/archive/vmefaq.html (Western Canada)
ftp://nyquist.ee.ualberta.ca/pub/motorola/general/vmefaq

You can get this entire FAQ with graphics by pointing your browser at the above pages and looking for the file vmefaq.zip.


The information contained in this FAQ is believed to be correct and up to date. Every effort has been made to ensure accuracy. The maintainer cannot be responsible for errors and omissions. This article is copyright © 1996 and all rights are reserved.

This article may be reprinted provided it is intact, proper credit is given and no cost is levied. Contact the author for permissions.


What's New!


CONTENTS:

1) The USENET Newsgroup comp.arch.bus.vmebus

General Information

2) The VMEbus - Technical Information

A) The VMEbus - Introduction

B) The VMEbus - Description

C) DIN Connector Assignments

D) VME64 - a new standard

3) The VXIbus - Technical Information

A) The VXIbus - Introduction

B) The VXIbus - Description

C) DIN Connector Assignments

4) Information Sources

A) VMEbus Systems Magazine

B) VXI Journal

C) Real Time Engineering

D) Micrology pbt, Inc.

E) VITA - VMEbus International Trade Association

F) Computer Design

H) The Manufacturers

I) Unadvertised ftp and WWW Sites

5) Answers to Frequently Asked Questions

A) VMEbus Interface Components

B) Battery Clocks - MK48TO2B-xx

C) Where does the name "VME" come from?

6) Profiles

Soon - Pivotal Graphics



1) The USENET Newsgroup comp.arch.bus.vmebus

A) General Information

The questions that appear on this newsgroup generally pertain to specific technical questions that are beyond the scope of a FAQ, about where to locate information about the VMEbus, where to find boards to perform specific functions or the addresses of VMEbus manufacturers. Many manufacturers of VMEbus equipment and associated products and services monitor this newsgroup on a regular basis. They include:



       Motorola            Newbridge                EKF Elektronik


       Heurikon            VITA                     Micrology pbt


       DY 4                RadiSys                  Schroff, Inc
VMIC - VME Microsystems Intn'l Corp. Titan Electronics (San Diego, CA) Radstone Technology PLC (UK) Themis Computer

et al your firm name here (email me)

The latest version of this FAQ is archived at:

ftp://nyquist.ee.ualberta.ca/pub/motorola/general/vmefaq
or
www.ee.ualberta.ca/archive/vmefaq.html
http://www.hitex.com/automation/FAQ/vmefaq (California)
http://www.ba-karlsruhe.de/automation/FAQ/vmefaq (Germany)

The working copy is on my Homepage - http://www.oise.on.ca/~rboys which may change to http://www.sentex.net/~rboys



2) The VMEbus - Technical Information

A) The VMEbus - Introduction

VMEbus modules are state of the art products and are used to construct very powerful and rugged computer systems. The VMEbus is an industrial open standard system. VMEbus boards have data bus sizes of 16, 32 or 64 bits and are designed to be plugged into a backplane that has up to 21 slots for other boards. These other boards can be CPU boards or peripheral boards providing various functions. For a photo of a MC68060 based VMEbus board, click here.

The VMEbus standard originated with the Motorola VERSAbus in 1979 which was designed using the then new MC68000 microprocessor. The VMEbus signals are patterned after the M68000 bus signals and timing. VMEbus boards now contain processors such as DEC Alpha, MIPS, i960, various DSP chips, AM29000 (RISC chip), PowerPC and 80486 in addition to the Motorola 680x0 line. Many peripheral boards exist including VGA, telecommunication, analyzers, data acquisition, video processors and memory (1 gigabyte!). The VMEbus originated in 1981.

The VXIbus is an instrumentation bus compatible (sort-of) with the VMEbus. The VMEbus specification specifies the physical dimensions of the boards, backplane and the chassis as well as the electrical specifications of the bus and various communication protocols.

In addition to the VMEbus, the VXIbus and Futurebus+ will be covered in this document in the future.

A PMC (PCI Mezzanine Card) is a proposed IEEE specification for a low profile mezzanine expansion bus for VMEbus, Multibus II and Futurebus+ systems. It has a 32 or 64 bit bus and has the same electrical specifications as the PCI bus (Peripheral Interconnect Bus).

There are over 200 vendors supplying products to the VMEbus community. VMEbus suppliers are most active in the USA, Germany and Canada and range from large corporations to small custom shops. Specifying a VMEbus system releases the user from the expensive, time consuming and sometimes (often) risky business of in-house hardware design.

Information resources for the VMEbus come mainly from three sources: VITA, the VMEbus Systems Magazines (edited by John Black) and the manufacturers. All prices quoted are in US dollars.


B) The VMEbus - Description

A VMEbus board can be either single or double height. A single height board is 100mm x 160mm with one 96 pin DIN 41612 connector called P1 on the rear that plugs into the backplane. A double height board is 233mm x 160mm and may have a second 96 pin DIN connector named P2. A single height board is also known as a 3U and a double height a 6U. There are 9U boards in existence but they are not part of the VMEbus specification. The front edge or face of a typical board is 20mm wide and may incorporate RS-232 connectors, indicator lights and switches.

The backplane can have up to 21 slots providing the J1 connectors for the boards to plug into. The J2 connectors (if required) can be supplied with a second backplane board or in one piece with both J1 and J2 connectors. A J1 (on the backplane) matches to a P1 (on the board) and a J2 to a P2. The spacing between slots is 20.32 mm (0.8 inches).

Power is supplied to the VMEbus board through P1 and P2 (if used). The DIN plugs used are arranged in three rows (A, B, C) of 32 pins on 0.1 inch centres. These plugs are approximately 0.85 mm wide and 84 mm long.

P1 supports 16 and 24 bit addressing and 8 and 16 bit data paths. P2 uses the centre 32 pins to support full 32 bit data and addressing paths. The two outer rows of P2 are user defined and are used for i/o ports, disk drives and other external peripherals.


C) DIN Connector Assignments

J1/P1 Pin Assignments J2/P2 Pin Assignments

================================ ===== Pin # Row A Row B Row C Row B
1 D00 BBSY* D08 +5v 2 D01 BCLR* D09 GROUND 3 D02 ACFAIL* D10 RESERVED 4 D03 BG0IN* D11 A24 5 D04 BG0OUT* D12 A25 6 D05 BG1IN* D13 A26 7 D06 BG1OUT* D14 A27 8 D07 BG2IN* D15 A28 9 GROUND BG2OUT* GROUND A29 10 SYSCLK BG3IN* SYSFAIL* A30 11 GROUND BG3OUT* BERR* A31 12 DS1* BR0* SYSRESET* GROUND 13 DS0* BR1* LWORD* +5V 14 WRITE* BR2* AM5 D16 15 GROUND BR3* A23 D17 16 DTACK* AM0 A22 D18 17 GROUND AM1 A21 D19 18 AS* AM2 A20 D20 19 GROUND AM3 A19 D21 20 IACK* GROUND A18 D22 21 IACKIN* SERCLK* A17 D23 22 IACKOUT* SERDAT* A16 GROUND 23 AM4 GROUND A15 D24 24 A07 IRQ7* A14 D25 25 A06 IRQ6* A13 D26 26 A05 IRQ5* A12 D27 27 A04 IRQ4* A11 D28 28 A03 IRQ3* A10 D29 29 A02 IRQ2* A09 D30 30 A01 IRQ1* A08 D31 31 -12V +5V STDBY +12V GROUND 32 +5V +5V +5V +5V ===================================================================

Notes:

  1. J2/P2 Rows A and C are user defined. They are specified in the VXIbus which is one reason why the VXIbus and VMEbus are not totally compatible.

  2. A01 to A31 is the address bus. Notice it is similar to the MC68000 scheme ie without A0. DS0* and DS1* (DS = Data Strobe) specify the upper or lower portion of the data bus. (rather than having a A0) See the FAQ for comp.sys.m68k for a discussion of this issue.

  3. * means an active low signal.


D) VME64 - a new standard

The regular VMEbus standard accommodates 32 bit address and data buses. Data transfers are 32, 16 and 8 bytes wide. One type of data transfer, called a Block Transfer, allow up to 256 bytes to be transferred with only the start address placed on the address bus once. For the rest of the transfer, the address bus is idle. The VME64 standard utilizes this unused bandwidth to enable 64 bit block transfers. The lower 32 bits are placed on the regular D0 to D31 and the upper 32 bits placed on the idle address bus A01 to A31.

The VME64 standard adds many other advanced features. VME64 is a VITA Standard. This standard, which has recently gained ANSI approval, is backwards compatible with existing VMEbus boards.

For more information: http://www.vita.com/jvita.html

There is a VME64 Reflector (mailing list). To subscribe, Email to majordomo@syspac.com leaving the subject line blank with the following command in the body: of the message: subscribe vita
You will receive confirmation of your subscription and to send a message to others send your Email message to vita@syspac.com.

Back to What's New!



3) The VXIbus - Technical Information

A) The VXIbus - Introduction

The VXIbus is an instrumentation bus based on the VMEbus, the Eurocard and standards such as IEEE 488.2 and the HP GPIB (General Purpose Instrumentation Bus). It is an open architecture and is useful for automated test systems and data collection. The issue of electromagnetic radiation is part of the VXIbus specification. VXIbus is an acronym for "VMEbus eXtensions for Instrumentation". The VXIbus was announced in 1987.

The VXIbus expands on the VMEbus so the two bus specifications are very similar. TTL and ECL trigger lines, a local bus and an analogue summing bus are among the added features. The December 1988 issue of "VMEbus Systems" contains a good outline of the VXIbus. The Spring 1995 issue of "VXIjournal" is a VXIbus Buyer's Guide.


B) The VXIbus - Description

There are two more board sizes in addition to the VMEbus single and double sizes:



       Size      Height    Dimensions (mm)     Connectors        Slot Spacing


       ----------------------------------------------------------------------


       A         Single    100 x 160           P1                  0.8 inch


       B         Double    233 x 160           P1 & opt P2         0.8 inch


       C         Double    233 x 340           P1 & opt P2         1.2 inch


       D         Triple    366 x 340           P1, opt P2,P3       1.2 inch

======================================================================

Notes:

  1. opt = optional

  2. P1, P2 & P3 are the same 96 pin DIN connector as in the VMEbus.

  3. The increased width of the C and D sizes are to accommodate thick analogue modules and EMI shielding.
The VXIbus uses the same pin assignments on P1 and the centre P2 pins as the VMEbus. The two rows (A & C) on P2 that were user defined on the VMEbus are assigned on the VXIbus. Features added include ECL (emitter coupled logic) and TTL trigger signals, a 10 Mhz ECL clock, more supply sources (+-24, -2 and -5.2 volts), an analogue summing bus, local bus lines and a module identification line. The optional P3 available on the D size board offers the same type of resources as P2 but at a speed of 100 Mhz (P2 is only 10 Mhz).

Reasons why the VMEbus and the VXIbus specifications are not totally compatible include:

  1. conflicts may arise depending on the use of the A & C rows on P2.

  2. VMEbus Double height boards are not as deep as VXIbus size C.

  3. The VMEbus has no configuration registers while the VXIbus does.

A VXIbus system can have up to 13 modules consisting of a central timing module in Slot 0 and a maximum of 12 additional instrumentation modules.


C) DIN Connector Assignments

P1 and P2-B (the centre row) have the same pin assignments as the VMEbus and are listed above. The outside 2 rows of P2 are specified in the VXIbus. In the VMEbus specification, these two rows are user defined. Since Slot 0 on the backplane is reserved for a system timing module, P2-A has slightly different assignments than for Slots 1 to 12. P2-C has essentially the same assignments for all slots.

to be continued.....



4) Information Sources

A) VMEbus Systems Magazine



       25875 Jefferson                  (Advertising and Business Offices)


       St. Clair Shores                  The Editorial Offices are at Micrology


       Michigan, 48081                   listed below.
(313) 774-8180 (313) 774-8182 (FAX)

This magazine is free to qualified VMEbus systems users and specifiers in the United States and Canada. There is a subscription fee applicable for other countries. This magazine contains industry news, informative articles and useful advertisements. Back issues are available from Micrology. See http://www.primenet.com/~magpub for more information.
The December 1994 issue is a useful Buyer's Guide.


B) VXI Journal



       Business Offices              Editorial Offices
25875 Jefferson 11051 Pinto Drive St. Clair Shores Fountain Hills Michigan, 48081 Arizona, 85268

(313) 774-8180 (602) 837-3756 (313) 774-8182 (FAX) (602) 837-3768 (FAX)

Email address: vxijournal@aol.com

VXIJournal is published by the people at the VMEbus Magazine at the same addresses as listed above. Subscriptions are free to qualified users of the VXIbus or GPIB in Canada or the USA.


C) Real Time Engineering

A new magazine, Real Time Engineering, is also published by Micrology in Arizona. The Spring 1995 edition is a Buyer's Guide.

To get a subscription request form for any of these three magazines, send Email to John Black, Editor (micrology@aol.com) or contact the offices in Michigan.

The Web site for these three magazines is : http://www.primenet.com/~magpub


D) Micrology pbt, Inc.

2618 S. Shannon Drive
Tempe, Arizona 85282

(602) 967-5581
(602) 968-3446 (FAX)
(602) 968-9265 (Real Time Engineering Magazine)
micrology@aol.comJohn Black

A VXIbus Buyer's Guide - $33

Back issues of VMEbus Systems Magazine are available for $4 each.
Email micrology@aol.com and request a listing.

The Systems Engineer's Handbook:
A guide to building VMEbus and VXIbus systems:

John Black has edited this hard cover text that covers the VMEbus and VXIbus thoroughly. This is an easy to read book that contains the complete VMEbus and VXIbus specifications and information on graphics, disk interfaces, Ethernet, image processing and interfacing to external devices such as stepping motors...and much more.

It is now available directly from Micrology for US$59.95 + $7 shipping.
excellent. - even better at this lower price !

(602) 966-5936 or FAX (608) 968-3446

Back to What's New!


E) VITA - VMEbus International Trade Association

       VITA                                         VITA Europe


       10229 North Scottsdale Rd                    P.O. Box 192


       Suite B                                      5300 AD Zaltbommel


       Scottsdale, Arizona 85253                    The Netherlands


       (602)  951-8866                              31.4180.14661 (or .16593)

(602) 951-0720 (FAX) 31.4180.15115 (FAX)

John Rynearson Zoltan Hunor Technical Director Director VITA VITA USA Europe techdir@vita.com hunor@knoware.nl

World Wide Web site: http://www.vita.com

VITA is the world-wide association of VMEbus users and manufacturers and as such organizes global promotion of the VMEbus including exhibitions, seminars and courses. Vita does not test and approve components but is a full member of ANSI and promotes standards of interest to the community. VITA publishes various magazines and manuals about the VMEbus.
In Europe, VITA has a mailing list of 100,000 engineers.

VMEbus Handbook $53 VMEbus Specification $32

The Handbook provides information for programmers, system integrators, engineers. It is written by Wade Peterson in an easy-to-read style. It contains information on the VMEbus from a general outline to hardware specifics. There are schematic diagrams and many photographs of representative VMEbus components. This book also addresses the VME64 specification and the Futurebus+ bridge and is recommended.

The VMEbus Specification book is the complete specification list. These two books provide the information needed to understand the VMEbus system and are worth the moderate cost.

VITA also publishes a Buyer's Guide for $55 (or $110 a year).

VITA now offers a free quarterly news publication, the VITA Journal, on a complimentary subscription basis to qualified residents of the United States. It contains member and industry news and the activities of the VITA Standards Organization.


F) Computer Design

Computer Design is a magazine that contains VMEbus advertisements with articles about computer design in general. It is free to qualified readers by contacting Ron Kalusa at ronk@pennwell.com.

Back to What's New!


G) Test & Measurement World

This magazine will feature the VXIbus starting in January 1996. The February issue will feature an article on using VMEbus slave cards in a VXIbus system. It is free to qualified personnel.

275 Washington Street
Newton, Massachusets 02158
Phone (617) 558-4671
FAX (617) 558-4470
Email: tmw@cahners.com

Back to What's New!


H) The Manufacturers

There are many manufacturers of VMEbus computer modules worldwide. Refer to any of the Buyer's Guides listed above or post to comp.arch.bus.vmebus for more information. Many manufacturers are getting Internet Email addresses. They note them in their advertisements in the magazines listed above.

Many VMEbus CPU boards have a built-in monitor program similar to the TUTOR monitor and have a RS-232 port that can be hooked up to a terminal or a host computer. Programs can be entered with the provided simple assembler/disassembler and executed. Peripheral devices can be attached easily to these boards. These boards are often available used and the older ones with 68000/10 CPUs have a low cost(<$50) and is a good way to become acquainted with the VMEbus. See the FAQ for comp.sys.m68k.


I) Unadvertised ftp and WWW Sites

Motorola

There are many links between each of these sites. DR. BUB (DSP information) is not operational yet.

------------------------------------------------------------------

Other Interesting Links:

VITA - http://www.vita.com

Hitex Corporation - In-circuit Emulators http://www.hitex.com/ for California or in
Europe: http://www.ba-karlsruhe.de/automation

Heurikon - http://www.heurikon.com(nifty daily cartoons)

Dallas Semiconductor - http://www.dalsemi.com (Postscript data sheets)

Maximum Strategy Inc. - http://www.maxstrat.com (disk arrays)

Cetia Corp - http://www.cetia.com (PowerPC VME boards)

Introl Corporation: http://www.introl.com
Introl is offering a non-commercial license for their US$2,000 C compiler. This is the full version - it is not crippled. It comes with an instruction manual. It is available for MS-DOS and Windows95 for this special offer. See their homepage for more information.
Back to What's New!

FAQ - comp.sys.m68k: for information on the Motorola M680x0 and MC683xx

http://www.hitex.com/automation/FAQ/m68k California
http://www.ee.ualberta.ca/archive/m68kfaq.html Western Canada
ftp://nyquist.ee.ualberta.ca/pub/motorola/m68kfaq
http://www.ba-karlsruhe.de/automation/FAQ/m68k Germany



5) Answers to Frequently Asked Questions

A) VMEbus Interface Components

A frequently asked question is "are there any easy-to-use devices to provide a VMEbus interface to my computer design?". Two suppliers of chips to do these tasks are Cypress and Newbridge .


Newbridge Microsystems

The VME64 (SCV64) controller chip provides a 64 bit VMEbus interface from the local bus. This chip has a built-in DMA controller, VMEbus address decoder and local bus burst modes. It is a 299 pin PGA ($308CDN) or a 304 pin PQFP ($256CDN) package.

Newbridge also makes a PCI to VMEbus interface ("UNIVERSE")($US160 @ 1K) and Futurebus+ interface chips ("LIFE"). A new part, "TROOPER" is a low cost ($40 1995 @ 1K) slave-only VMEbus interface chip. Available June 1995. The SCV64 and "TROOPER" are fabricated by Motorola.

The "SPANNER" is now in production. This is a MC68040 to PCI bridge chip. This is Newbridge's introductory offering in this area.

(800) 267-7231 (North America), (613) 592-0714 in Canada
(408) 258-3600 in California.

Email addresses:
nms-inquire@newbridge.com for general inquiries or nms-support@newbridge.com for technical support.

<prices may be inaccurate> The SCV64 (33 Mhz QFP) has been reported as costing US$ 332 (qty=5), US$ 287 (25) and US$ 248 (100).


Cypress Semiconductor

Cypress manufactures a series of useful VMEbus integrated circuits:

VIC64 - an enhanced VIC068. All the features of the VIC068 plus MBLT support. (Multiplexed Block Transfer) Provides a direct connection to the M68K family and mappable to others. VME64 compliant (64 bit block transfers - rates up to 70 mbytes/sec). 144TQFP, 144PPGA, 144CPGA, 160PQFP, 160CQFP. $US 142 (Qty 100)

VIC068 - VMEbus Interface Controller - provides VMEbus controller functions between a CPU and the external VMEbus. VMEbus SYSCON (system controller), interrupt handler, local DMA and a DRAM controller. 32/16/8 bit transfers. 144TQFP, 144PPGA, 144CPGA, 160PQFP, 160CQFP. $US 113 (Qty 100)

VAC068 - VMEbus Address Controller - forms a complete VMEbus master/slave interface when used with the VIC068.
144PPGA, 144CPGA, 160PQFP, 160CQFP. $US 91 (Qty 100)

CY7C960 - Slave VMEbus Interface Controller - VME64 (64/32/16/8 bit data transfers), auto-slot ID, DMA, DRAM controller with refresh. 80 mbyte/sec Block Transfers. CR/CSR support (used for Auto-slot identification to determine which slot a participating module is in).
64TQFP, 64CQFP, 68CPGA. $US 29

CY7C961 - based on the CY960 - includes local and remote VMEbus Master capability. on-chip DMA.
100 TQFP, 100CQFP. $US 47 (Qty 100)

CY7C964 - Bus Interface Logic Circuit - a companion part to the products listed above. This 8 bit part is used to drive the upper three bytes of the VMEbus data and address buses. Three devices are needed for VIC068 and VIC64 and four with the CY7C960/961. The VIC64 and VIC068 directly drive the lower bytes. The purpose of this part is to simplify the interfacing of the board logic by providing various counters, latches, comparators and drivers.
64TQFP, 64CQFP, 68CPGA. $US 19 (Qty 100)



        San Jose, California, U.S.A        Toronto, CANADA.
Phone (408) 943-2600 Phone (416) 620-7276 FAX (408) 943-2741 FAX (416) 620-7279 vmebus@cypress.com Ed Dupuis (ead@cypress.com) BBS: (408) 943-2954 (1200 to 19.2k, 8N1)

B) Battery Clocks - MK48TO2B-xx

Some VMEbus CPU boards contain a clock IC with an integral battery such as the MOSTEK MK48TO2B-25. The battery in this device is supposed to last for five years, then the entire chip must be replaced. It seems the manufacturers expected these boards to become obsolete when they became 5 years old.

The MK48TO2B-25 is being discontinued and has been replaced by the M48TO2-200PC1. Mauser Electronics <(800) 346-6873 or (817)483- 4422> nor Arrow have any MK48Ts and the M48Ts have a delivery time of 8 to 14 weeks. MOSTEK is apparently now owned by SGS-Thompson who will be replacing the MK48TO2B with a 2 piece part called the "SnapHat". The IC proper and the battery/crystal are replaced separately. This information is provided by Gerry Belanger and Dennis Johnson.

Dallas Semiconductor makes the Timekeeper series of clock chips. Their US phone number is (214) 450-0448 or (800) 336-6933.

The Dallas DS1642 may replace the Mostek MK48TO2B-25. The DS1642 is available in speeds of 120 or 150 nsec. It is available directly from Dallas Semiconductor for about US$17 plus shipping with a delivery time of 4 to 6 weeks. Dallas credit card orders for the USA - (800) 336-6933. Dallas suggests that Newark Electronics may have this item in stock. (800) 463-9275 CANADA number only.(?)
The postscript datasheet for this part is: ftp://ftp.dalsemi.com/pub/datasheets/1642.ps


How to add an external battery:

The MK48TO2B-25 Mostek real time clock consists of a standard 24 pin DIP with a black plastic cap attached to its top. This plastic rectangular cap contains the clock crystal and the battery.

This cap is attached to the chip body at each end only with a potting material that appears to be an epoxy. If you put the MKT48 up to a light source you should be able to see a gap between the plastic cap and the DIP. Notice that the cap is glued to the DIP only at the ends and then only in the centre of the ends. ie where the half-circle is molded into a DIP to indicate where pins 1 and 24 are and at the corresponding place at the other end.

The wires for the crystal and the battery pass through this potting material on each side of the potting material. The crystal wires are at the pin # 1 and 24 end of the DIP and the battery is at the pin # 12 and 13 end. These wires do not necessarily connect to these pins.

The idea is to cut through the potting material, disconnect the positive internal battery wire and solder a new battery to the wire coming out of the DIP nearest to pin 13 and the other to pin 12 (ground) of the DIP.

The positive (+) wire is towards pin 13 (but is not connected to it). Ground is pin 12 (the external pin on the DIP).

I found a hacksaw blade the ideal tool to slowly cut through the potting material. From time to time I would probe in the cut spot with a voltmeter (gnd to pin 12) to see if I had reached the positive wire. Even though the battery is near death, mine measured 0.9 volts which is enough to detect. Then I continued cutting and scratching until the wire was exposed. The rest is easy. Cut the wire in two and solder the positive terminal of the new battery to the lower wire (ie the one that comes out of the DIP). The wire is not microscopic and relatively easy to work with once exposed.

A picture would be worth a million words, nay, a -billion- at this point. Once you have done one, it would be easy to do many. I used a small 3 volt clock battery that had two tabs spot welded on it.
Works great for me! Good Luck!

Please send suggestions for this article to r.boys@genie.geis.com
The original idea for this was provided by Michael Coughlin at MIT.


C) Where does the name "VME" come from?

In case you are new to this newsgroup..... an article written by John Black:

What meaneth VME?

In 1981, when Motorola agreed to allow Mostek and Signetics to second source the MC68000 microprocessor chip, the three companies agreed to meet and discuss the possibility of supporting a common backplane bus. At that time Motorola had already developed a 68000-based backplane bus, which they called VERSAbus. Since I had written a large portion of the VERSAbus specification, I was the Motorola technical representative at that meeting.

Motorola proposed that the three companies jointly support the VERSAbus backplane. However, both Mostek and Signetics rejected that proposal, saying that the VERSAbus board size was much too large. In response to that objection, Motorola proposed that the (much smaller) Eurocard board size be used. A backplane could then be designed with the VERSAbus electrical specifications and the Eurocard mechanical specifications. Motorola suggested that new board products (based on this new backplane) be called VERSAmodule Eurocards, which could be abbreviated "VME".

Both Mostek and Signetics were satisfied with the choice of the Eurocard mechanical standard, but they objected to the "VERSAmodule Eurocard" name, since Motorola had already trademarked the name "VERSAmodule".

Eventually this difficulty was overcome when the three companies agreed that the name VMEbus would be placed in the public domain, and that if anybody asked what VME meant; they would say....

"VME?...Oh, it doesn't stand for anything in particular".

Now you know the awful truth.

by: John Black
Editor
VMEbus Systems Magazine
Tempe, Arizona

(reprinted here with permission)



6) PROFILES:

The purpose of this section is to profile some of the products of various manufacturers to give an idea of what is available to the designer and the state of the market. This section will be rotated and previous sections will be archived.


Most Friendly Contributors:



       Andy Fraser         Ontario


       John Black          Arizona


       Michael Coughlin    Massachusets  (sold me my first VME board!)


       Gerry Belanger      Connecticut


       Dennis H. Johnson   ??


       Bosco Chan          Ontario


       Michael Bodine      Ilinois

and more to come.....

Please send all comments to:

Robert Boys
73 Knightswood Blvd.
Guelph, Ontario
CANADA
N1E 3W6


Quote of the Month:
There are no problems like computer problems.


r.boys@genie.geis.com or rboys@best.com

Back to What's New!

Hitex Development Tools
2055 Gateway Place Suite 400
San Jose, California
USA
95110

(800) 45-hitex
Phone - (408) 451-3986
FAX - (408) 441-9486