Joe's On-line Multibus Circuit Board Guide

Created 1/16/2004

This page still under construction

Revised 1/23/2006. New items marked with *

Revised again on 1/30/2006. New items marked with **

I have created this page as an on-line reference to the Multibus circuit boards. Intel originally developed these boards in 1976 for use in the Intel MDS-800 Microcomputer Developement System (picture). However Intel quickly found that many people were buying the MDS boards in order to build these own computers and computer controlled equipment, so they started selling them as OEM boards. The demand was great enough that Intel soon developed a complete line of Multibus products. In addition, they released the Multibus specification and it was eventually standardized as IEEE-796 Bus Specification. Within a few years there were over 200 companies building over 500 different Multibus products.

In addition to the boards that fit the Multibus specification, I am also including the iSBX and iLBX boards since they are commonly found as daughterboards on the Multibus boards.

3M

*3M Breadboard (picture). (Note: the picture shows the board exactly as I found it, including the half-socketed ICs). This the only one of these that I’ve ever seen and I’m not sure if it’s intended as an iSBX breadboard or something someone made. The only markings on it are 3M and Breadboard plus some locator numbers and letters.

*Analog Devices Multibus boards

Analog Devices is a well-known manufacturer of analog ICs, digital ICs and microprocessors. It’s not commonly known that they also built test equipment and circuit cards including Multibus cards.

*Analog Devices RTI-711 Multibus card (picture). These are marked Analog Devices and RTI-711. The 11 is stamped so it appears to indicate some revision or modification of the board. It contains a large module marked “Analog Devices 949”. I haven’t been able to discover the purpose of this module or the card itself.

AMC Multibus boards

AMC (Advanced Micro Computer) was a division of Advanced Micro Devices. It appears that this entire line bought out by Zendex in 1985. I have few details on these boards. They appear to be quite rare. The ones below are the only ones that I have seen. I found these in an old AMC development system that had been gutted and some of the socketed ICs are missing from the boards. Surprisingly, there is some documentation available for these on Al Kossow's website.

AMC 95/4005 Onboard Computer (picture). These are marked Onboard Computer AMC 95/4005.

AMC 0095-0017 32k Dynamic RAM Board (picture). These are marked Dynamic RAM Board AMC and PWA 0095-0017 and have 4 x 16 AM9050EPC memory ICs.

AMC 3310 Communications Controller (picture). These are marked 3310 Communications Controller PWA 460 and PWA1427779 and have 4 x 8 2117 memory ICs.

AMC 95/6110 Floppy Drive Control Board (picture). These are marked 95/6110 FD Control Board and PWA 950(something).

*Advanced Micro Devices (AMD) Boards

*AMD Serial SBX Module. (picture) Clearly marked Advanced Micro Devices and PWA 009520028- in the center near the bottom. Also marked Serial SBX Module near the top right. I have not researched this board further.

*Applied Microsystems Corp Boards

Applied Microsystems is (was?) a major manufacturer of microcomputer test and diagnostics systems. Some of their equipment used Multibus cards. Below are boards that I found in a surplus Applied Microsystems Z-8000 Emulator that was damaged beyond economical repair.

* Applied Microsystems Break and Trace Multibus Board. (picture)

* Applied Microsystems MCB Controller Multibus Board. (picture)

* Applied Microsystems Main RAM Multibus Board. (picture)

* Applied Microsystems Z8000 Emulator Pod and Interface Board. (picture)

Augat Multibus boards

Augut Wire Wrap board (picture). These are probably outside of the scope of this page but I'll include them anyway. These are marked 8136-UG159-2. These are TOP quality boards. They use machined pins and heavy gold plating and are frequently used in military equipment and test equipment where reliability is essential. You're not like to find a WW board that's useable in it's present form but these are a good source of parts, especially since the parts are usually military grade. The boards are also useful to make your own circuits and interfaces.

*Burr-Brown

*Burr-Brown Model 830-72 72 channel TTL I/O card. (picture) This card cage was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. The Butterfly computers that these came from were a part of Simnet, a network of tank training simulators.

Cabot boards

see Intel iSBC 286-12

*Computer Machinery Corp

*Computer Machinery Corp ENP-30 Ethernet card. (picture) Marked "Computer machinery Corp" in the top LH corner and "ENP-30" on the RH edge. The most notable feature of this card is the AUI connector on the top edge and the MC6800P10 CPU. This card cage was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. The Butterfly computers that these came from were a part of Simnet, a network of tank training simulators. I'm about 99% certain that this is the same card as the Excelan EXOS201 Intelligent Ethernet controller board. I have a manual for that one and I've sent it to Al to be posted on his site at <http://www.bitsavers.org/pdf/excelan/>.

*Data Translation

*Data Translation DT 5712-E High Resolution Analog Interface card. (picture) This card is clearly marked on the white area of the large hybrid module on it. This card cage was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. The Butterfly computers that these came from were a part of Simnet, a network of tank training simulators. I've sent my copy of the manual for this card to Al and he should have it up on his website soon.

*Excelan

*Excelan EXOS201 Intelligent Ethernet controller board. See Computer Machinery Corp. ENP-30 Ethernet card.

Harris Corporation Multibus boards

Based on the number of Harris Multibus boards that I have found in my searching, Harris appears to have been a major producer and user of Multibus boards. However I was never able to find ANY documentation or specifications for any of the Harris boards so I disposed of the ones that I had and never bothered to pick up any more of them. Unfortunately I never made any pictures of the ones that I did had.

*Heurikon Multibus boards

Made by Heurikon Corporation of Madison, Wisconsin. I believe Heurikon is now out of business or has changed their name since I can’t find any current information about them. I have no other details about them except that I did once find a Heurikon Multibus computer. It appeared to be made to project weather maps such as those you see on the evening news.

*Heurikon HK-68-5 (picture). (Note that the board in the picture is missing several ICs including the CPU!) I’ve found several of these. They appear to be 68000 Sacs but I’ve never been able to find any documentation on any of the Heuikon cards. They contain a Hitachi HD68450 and a Motorola MC68451 and are clearly marked with the manufacturer’s name and model number.

*Hybricon

*Hybricon Wirewrap Multibus Board. (picture) This card is clearly deified by Hybricon’s name and copyright notice in the center along the bottom edge. This is another good quality wirewrap board. it uses a lot of gold plating and good machined IC socket pins. The board shown in the photo is used of course. I have no idea what it was made for but note the use of the sheet capacitors (the brown rectangles) under the ICs.

*IKON Corp

*IKON Corp Hardware/Software Manual Multibus DR11-W Emulator. I've sent my copy of the manual for this card to Al and he should have it posted on his site soon.

Intel Multibus boards

OK you've hit the mother load! As you would expect, Intel appears to have been the major producer of Multibus boards. I have far more of these than any other brand. Intel used these boards in all of their MDS-800 and MDS-2xx series Microcomputer Developement Systems as well as many other computers. The MDS-800s and MDS-2xx systems seem to have been the mostly widely used MDS systems by far. I personally have around fifteen of them. See my homepage for links to webpages describing several of them.) They're what kicked off my interest in the Multibus boards and lead to the creation of this webpage.

Intel Prototyping board (picture). These are marked Intel 1974 and PWA 1000402. These are perf boards and do not have any sockets installed. This one is used and has some circuits installed.

ROM-SIM board (picture). These are marked ROM-SIM Board and PWA 1000406. I don't know much about these except that they're some kind of ROM simulator. I found them in some old Intel 86/330 computers. They are not listed in my Intel catalog. They have 4 x 8 Intel P3106A ICs.

16k x 8 RAM board (picture). These are marked 16k x 8/450 RAM Module. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog. These seem to be the only type RAM used in the Intel MDS-800s. There's usually only two per machine but it can hold up to four of them (they can be addressed for any of the four 16k memory blocks).

16k PROM/ROM board (picture). These are marked 16k PROM/ROM Memory. These can be used with EPROM or factory masked ROM. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog. I believe were originally used in the Intel MDS-210 machines that had the editor in ROM and did not use any disk drives.

32k RAM board (picture). These are marked PWA 460 or PWA1427779 and have 4 x 8 2117 memory ICs. I believe these were originally used in the MDS-2xx machines. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog.

iSBC-056 128k RAM board See Intel iSBC-056 RAM board.

iSBC-056 256k RAM board (picture). These are marked PWA 460 or PWA144170-003 and have 4 x 8 4164 D RAM memory ICs. These feature on-board parity generator and checker and an error status register and require only a 5VDC power supply. I pulled these from some Intel 86/330 computers. Note that both of these that I have had the PWA number written on them in ink. One had the number PWA 143156-042 crossed out. The -056 board is very similar to the iSBC-028 128k RAM board and the one was probably upgraded from a -028 board.

iSBC 80/10 Single Board Computer (picture). These are marked Single Board Computer 80/10 and PWA 1000618-01M. It is a complete SBC with an 8080 CPU, 1K of SRAM and sockets for an additional 4k of RAM and sockets for 16k of ROM or EPROM. It also has 48 parallel I/O lines and a RS-232 port, a 1.04 mSec timer and a single interrupt level.

iSBC 80/20-4 Single Board Computer (picture). These are marked Single Board Computer 80 20-4 and PWA 1001320-04. It is a complete SBC with an 8080 CPU, 4K of SRAM and sockets for 8k of ROM or EPROM as well as 48 parallel I/O lines and a RS-232 port and more. The 80/20-4 is a improved version of the older iSBC 80/20 SBC.

iSBC 80/24 Single Board Computer (picture). These are marked 80/24 and PWA 1003137-07. This one has a ROM in it with a label that says EDUGOOOO. I wonder if it might be some kind of educational system? These are replacements for the Intel iSBC 80/20-4. It is a complete SBC with an 8080 CPU running at 4.8 or 2.4 MHz, 8K of SRAM and sockets for 32k of ROM or EPROM as well as 48 parallel I/O lines and a RS-232 port, 2 programmable 16 bit timer/counters, 12 levels of programmable interrupts and more.

iSBC 86/30 CPU board (picture). These are marked 145066-01 and have an Intel 8086-2 CPU just to the left of the center of the board. However the one in the picture has an Intel iSBC 337 Numeric Data Processor installed in the CPU socket. To install the NDP board, you first remove the CPU, then plug the 337 board into the CPU socket and then plug the CPU into the vacant socket on the 337 board. Modified 86/30 CPUs boards in the Intel MDS-2xx machines as RPB-86 and RPC-86 8086 CPU boards. I found these 86/30 boards in some old Intel 86/330 computers.

* iSBC 86/35 Single Board Computer (picture). These are replacements for the iSBC 86/30 and are marked 86/35 and PBA 146071-007 and have an Intel 8086-2 CPU just to the left of the center of the board. The CPU can run at 5 or 8MHz. They also have 24 programmable IO lines, 9 levels of interrupts, three 16 bit times, a programmable serial interface, sockets for up to 128k or 24 or 28 pin PROMs or ROMs. They also have 512k of dual port read/write memory that can be expanded to 1mb on-board. I believe that these boards came from some old Intel 86/330 computers. I have also found them in SMS 8000 40 computers. The SMS 8000 40 manual on Al's site has some details about this card.

*iSBC 88/25 Single Board Computer (picture). These are marked PWA 145904-001 on a paper tag on the bottom right and 88/25 on a paper tag on the LH edge. These are 8MHz 8088 SBCs with a 1Mb address range. They come with 4k of static RAM installed but it can be expanded up to 16k. They don’t have a socket for an 8087 NDP but one can be added by using an iSBC 337 Multimode board. These have four JEDEC 24/28 pin sockets for up to 128k of local EPROM memory. They have two on-board programmable 16-bit times/counters. They handle 9 levels of vectored interrupts and have a Centronics compatible printer port and a programmable synchronious/ansynchrous serial interface as well as 24 programmable parallel IO lines.

*iSBC 286/10 CPU board (picture). (Note: the board shown in the picture is missing the major ICs) These are marked AA 174080-002 on a paper tag on the LH edge and 286/10 (and other things) on a paper tag on the RH edge. Note that the board shown in the picture as an add-on Intel 82289 Emulator board near the bottom LH corner. These are 8MHz 286 SBCs with 0-wait state interface for EX expansion boards and up to 384k of on-board memory, a socket for the 80287 NDP. They handle 16 levels of vectored interrupts and have a Centronics compatible printer port and two programmable synchronious/ansynchrous serial interfaces.

*iSBC 286/12 CPU board (picture). These are marked PBA 147522-01 on a paper tag on the LH edge. I’ve been told that they’re also marked PSBC286/12 but I haven’t found that on the ones that I have. These have an Intel 80286-8 CPU just above the P1 connector and a 80287 under the metal cover just above it. These have 8MHz 286 CPUs, a socket for the 80287 NDP, a 0-wait state interface for EX expansion boards, 1Mb of 0 wait state dual port parity memory of on-board and two JEDEC 28 pin sockets for up to 128k of local EPROM memory They handle 16 levels of vectored interrupts and have a Centronics compatible printer port and two programmable synchronious/ansynchrous serial interfaces.

This one has an Orbot I/O Channel iSBX board installed on the top left and an Intel 1 Mb iLBX RAM board installed at the lower right.

iSBC 214 Peripheral Controller Subsystem Board picture It has an 80186 CPU and can control two ST-506 type hard drives, four floppy drives and up to four QIC-02 tape drive.

iSBC 215 Winchester Disk Controller Board. There is something odd about these. I have two of these that are both marked 215 but they're entirely different styles. The first one (picture) doesn't match the picture in the catalog. It has two top edge connectors instead of three and also has DIP switches. It is marked Winchester Disk Controller 215 and PWA 162037-041. The second board (picture) looks like the picture in the Intel catalog and is marked Winchester Disk Controller and PBR 146484-002. Note that the one in this picture has an iSBX 217C 1/4" Tape Interface board on the top LH side and an iSBX 218A Flexible Disk Controller on the top RH side. I believe that one of these two boards came out of an Intel MDS-2xx machine that had a hard drive on it but I don't know which one.

iSBX 217 1/4" Tape Drive Interface Board See this picture, the 217 is shown on the top LH side. These are marked PSBX 217C and PBA 146050-004.

iSBX 218 Flexible Disk Controller Board See this picture, the 218 are shown on the top RH side. These are marked PSBX 218A and PBA 145591-002. Here is a picture of another 218 on the other style iSBC 215 board.

iSBC 300 board This is an iLBX board with 32K of RAM. See RPB-86 for more info and a picture.

iSBC 304 board (picture). This appears to be an iLBX board with 128K of RAM. *******Get photo of 304 on RPC-86. These are marked SBC 304 and PWA 143561. It has 2 x 8 4164 64k x 1 DRAMs and an Intel 8203 on it.

*iSBX 311 Analog Input Board Multimode Board. (picture) This board is marked 311 along the bottom edge and is easily identified by the vertically mounted Analog Devices ADDAC80 and the three potentiometers in the top LH corner. It is also marked PBA 142757-005 on a paper tag on the back. This board has 8 differential or 16 single ended analog inputs. It operates in either Unipolar (0 to 5VDC) or Bipolar (-5 to +5VDC) mode and its gain is resistor programmable from 20mV to 50mV full scale input. It features 12 bit resolution and sample rates up to 18KHz.

*iSBX 328 Analog Output Multimode Board. (picture)This board is marked 328 in a square box just above the crystal located at the bottom LH corner. It is also marked 143425-001 on a paper sticker on top of the large Intel D8741 Micro-controller. It is also marked PBA 142759-004 on a paper sticker on the back. It is similar to the iSBX 311 in that it has an Analog Devices ADDAC80 and the three potentiometers in the top LH corner but this time the DAC is mounted horizontally instead of vertically. This board has 8 analog outputs that can individually be configured as voltage or current loop outputs. Each output can configured as 4 to 20 mA current loop or 5VDC Unipolar or Bipolar output. It features 12-bit resolution and output is up to 5kHz for single channel or 1kHz for all eight channels.

* iSBX 331 Fixed/Floating Point Math Multimode Board.(picture) This board is marked iSBX 331 on a paper sticker near the bottom LH corner. It is also marked PBA 145174-001 on a paper sticker on the RH edge. It can also be identified by the Intel C8231A IC at the bottom left. This board is a Fixed/Floating Point Math board but it doesn’t use the 8087! It operates at 4 MHz and can perform fixed single (16-bit) or double precision (32-bit) math or double precision (32 bit) floating point math. It performs addition, subtraction, division, multiplication trig metric and inverse trigometric functions as well as square roots, logs and exponential functions and floating point to fixed conversions and vice versa.

*iSBX 350 Parallel I/O Multimode Board. (picture) (work in progress). This board is marked PBA 100367- in the top left corner. The board features 24 programmable parallel I/O lines with sockets for interchangeable line drivers/receivers. It has three selectable interrupt request sources and is addressed as a I/O port.

*iSBX 351 Serial I/O Multimode Board. (picture) This board is marked 351 near the center along the bottom. It is also marked PWA 156040-001 on a paper sticker on the back. It has an Intel 8251 and an Intel 8253 near the bottom. This board has a programmable synchronous / asynchronous communications channel. It features software programmable BAUD rate, two programmable 16 bit timer/counters, four selectable interrupt sources and is addressed as an I/O port.

*iSBX 354 Dual Channel Serial I/O Multimode Board. (picture) This board is marked 354 near the bottom left corner. It is also marked 146512-001 on a paper sticker on top of an IC near the bottom right corner. (this is probably a part number of a PAL used on the board.) The board is also readily identified by the 9.830 MHz crystal near the center of the board. This board is usually in that it uses a Zilog SCC LSIC instead of an Intel part. This board has two programmable synchronous/asynchronous communications channels. It features software programmable BAUD rate or each channel, full duplex operation, and three selectable interrupt sources for each channel. It supports HDLC/SDLC, NRZ, NRZI or FM encoding/decoding.

*iSBX 488 GPIB Interface Multimode board. (picture) This board is marked 488 Intel near the bottom center. It is also etched PWB 142828-001 on the back along the top edge. It is also marked PWA 142827- near the top left corner but most of that marking is ground away on several of the boards that I have. The board is also readily identified by the Intel 8292 and 8291 on the left side and the two Intel 8293 ICs along the right side. As you probably guessed by now, this as a GPIB (aka HP-IB, aka IEEE-488) interface board. It is a complete IEEE-488 Talker/Listener and a complete IEEE-488 controller.

iSBC 517 Combination I/O Expansion Board (picture). These are marked Intel SBC 517 Combination I/O Expansion and PWA 1001052-012. These have 48 programmable IO lines with 8 14-pin sockets along the top edge for different types of line drive ICs. They also have a programmable serial port and 8 mask able interrupt lines with a pending interrupt register and a 1mSec timer. I found this one inside of an Intel MDS-800. It was definitely not standard.

**iSBC 534 4 Channel Communications Expansion Board (picture). These are marked INTEL and Communications Expansion Board near the center of the board and PWA 142693-002 on a paper sticker. These have four programmable synchronous/asynchronous channels. Each channel’s baud rate is individually programmable through software. They also have two independent 16-bit programmable timers, 16 maskable interrupt lines, 16-bit parallel I/O interface and interface control for auto-answer and auto-originate MODEMs. I found this particular board in the board scrap at a surplus company and it is rather dirty. The white “blobs” near the top of this board are two DIP header plugs that have been covered with white RTV.

**iSBC 544A Intelligent Communications Controller Board (picture). These are marked 544A in a square box near the center along the bottom edge and PBA 134422-007. They have an onboard 8085 CPU to provide buffer management and communications control for four programmable Synchronous/asynchronous channels. They also have sockets for up to 8k of EPROM and 16k of dual port DRAM.

ICE 48 Control Board (picture). These are marked ICE-48 Control Processor and PWA 1001682-01. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog. These ICE-48 Emulator and ICE-48 Control boards must be used together and are used as an In-Circuit Emulator for the Intel 8048 and related microprocessors. In use this pair of boards is connected together by an auxiliary connector on P2.

ICE 48 Emulator Board (picture). These are marked Emulator and PWA 1001374-03. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog. These ICE-48 Emulator and ICE-48 Control boards must be used together and are used as an In-Circuit Emulator for the Intel 8048 and related microprocessors. In use this pair of boards is connected together by an auxiliary connector on P2.

ICE 80 Processor Board (picture). This board came in one of the Intel MDS-800 that I have. More detail to be added--------These are marked ????ICE-48 Control Processor and PWA 1001682-01. These ICE-80 Processor and ICE-80 Trace boards must be used together and are used as an In-Circuit Emulator for the Intel 8048 and related microprocessors. In use this pair of boards is connected together by an auxiliary connector on P2.

ICE 80 Trace Board (picture). This board came in one of the Intel MDS-800 that I have. More detail to be added--------These are marked Emulator and PWA 1001374-03. These ICE-80 Processor and ICE-80 Trace boards must be used together and are used as an In-Circuit Emulator for the Intel 8048 and related microprocessors. In use this pair of boards is connected together by an auxiliary connector on P2.

ICE 85 Control Board. (picture). These are marked ICE-48 Control Processor and PWA 1001682-01. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog. These ICE-48 Emulator and ICE-48 Control boards must be used together and are used as an In-Circuit Emulator for the Intel 8048 and related microprocessors. In use this pair of boards is connected together by an auxiliary connector on P2.

ICE 85 Trace Board (picture). These are marked Emulator and PWA 1001374-03. I don't know if they have an iSBC model number or not, I've never seen one marked that way and these are far older than my Intel catalog. These ICE-48 Emulator and ICE-48 Control boards must be used together and are used as an In-Circuit Emulator for the Intel 8048 and related microprocessors. In use this pair of boards is connected together by an auxiliary connector on P2.

ICE 86 86-Controller Board (picture). These are marked ICE-86 86-Controller and PWA 1001879-04. Unlike most (all?) other ICE board sets, this set consist of three boards. However at the moment I only have two of the three boards. The Controller, Trace board and ??? board must be used together and are used as an In-Circuit Emulator for the Intel 8086 and related microprocessors. In use, this triplet of boards is connected together by an auxiliary connector on P2.

ICE 85 Trace Board (picture). These are marked PWA 1001849-05 and hand marked in ink ICE 86 Tr. Unlike most (all?) other ICE board sets, this set consist of three boards. However at the moment I only have two of the three boards. The Controller, Trace board and ??? board must be used together and are used as an In-Circuit Emulator for the Intel 8086 and related microprocessors. In use, this triplet of boards is connected together by an auxiliary connector on P2.

Unknown ICE Controller Board (picture). These are marked Controller and PWA 1001355. They were in a pile of surplus parts that I found and I haven't researched them yet to see what processor for but it looks like it's for an 8080 since it has an 8080 on the board. However these are very different from those used in my MDS-800s.

Unknown ICE Trace Board (picture). These are marked Trace and PWA 1001191. They were in a pile of surplus parts that I found and I haven't researched them yet to see what processor for but it looks like it's for an 8080 since it has an 8080 on the board. However these are very different from those used in my MDS-800s.

Unknown ICE Trace Board #2 (picture). These are marked Trace Board and PWA 1001191. (I've got to figure out what these are for!)

RPB-86 (picture). These are 8086 Resident Processor Boards for use in the Intel MDS-2xx machines. Adding the RPC-86 board to a Series II MDS made it a Series III machine but it did not change the model number. They are modified iSBC 86/30 boards. They are marked RPB-86 and PWA 123329-001. The one in this picture has an iSBC 300-iLBX 32k RAM board on it in the lower RH corner.

RPC-86 (picture). These are 8086 Resident Processor Cards for use in the Intel MDS-2xx machines. Adding the RPC-86 card to a Series II MDS made it a Series III machine but it did not change the model number. These cards are modified iSBC 86/30 boards. They are marked RPC-86 and PWA 145066-002. The one in this picture has an iSBC 304 iLBX 128k RAM board on it in the lower RH corner.

Intel iLBX boards

The iLBX bus (Intel Local Bus eXtension) was developed by Intel in an effort to overcome the bandwidth limitations of the main (Multibus) bus, particularly in multi-processor systems or systems with lots of I/O. Their intention was to give each CPU it's own local bus for things like I/O and some amount of local memory. The physical characteristics, handshaking, electrical loads, etc are all specified by the Intel iLBX Bus Specification 145695 Rev A.

Intel iSBX I/O Bus boards

iSBC 337 8087 board see iSBC 86/30

1 MB memory module see iSBC 286/12

*Matrox Multibus boards

Matrox is a well known manufacturer of high end video cards located in Montreal Canada and is still in business. Few people are aware however that one of Matrox’s first products was a video frame grabber card for Multibus systems. Click on <a href=" http://www.matrox.com/imaging/about/25yrs_feature.cfm">link </a> for more information.

*Matrox OVR-640 “Overlay” Board (picture). These are marked OVR-640 along with a date and serial number on Matrox paper sticker on the back of the board. It’s also marked 210-06-02 and OVERLAY along the LH side of the board. I don’t know what the purpose of this board is but considering that it was made by Matrox and that it has a 3.579545 MHz (Color-burst frequency) crystal on it it’s almost certainly a video board of some kind.

*Matrox MSBC 24/320 Multibus Board. (picture) This board is clearly marked MATROX and MSBC 24/320 near the bottom RH corner. It has a RCA socket near the top left corner. Evidently it is a video board but I have no other information about it.

*Methode Laboratories Inc

*Methode Laboratories Inc Wirewrap Multibus Board. (picture) Readily identified by the Methode Laboratories Inc name along the LH edge and the blue color of the PCB material.

* Micro Memory Inc (MMI) Multibus Boards

These cards are made by Micro Memory Inc.

*Micro Memory Inc. MM 7250 Multibus Board. (picture) Marked "MM7250" on the back LH edge. I believe this is a 4Mb memory card. It came out of a SMS 8000 40 computer. The SMS 8000 40 manual on Al's site has some details about this card.

*Micro Memory Inc. MM 7280 Multibus board. (picture) Marked "MM7250" on the back LH edge. I believe this is a 2Mb memory card. It contains 4 banks of 9 each Intel P21010 ICs. Only half the sockets are filled so it's memory capacity could be doubled. This came out of a SMS 8000 40 computer. The SMS 8000 40 manual on Al's site has some details about this card.

*MMI MM880 PROM Multibus Board. (picture) This is a PROM/EPROM board with 48 28-pin sockets. Note the three cutouts for connectors along the top edge. Note: the board shown as two PROMS and three battery-backed RAMs installed.

**Microbar System Inc.

**Microbar System Inc DBC68K2 68000 SBC. (picture) This board is marked Mircobar System Inc on the LH side and DBC68K2 along the RH side. It appears to be a 68000 SBC even though the CPU is missing from this particular board. I found this board in a pile of board scrap at a local surplus company and it is dirty and beat up. This one has a daughterboard on it RH side that’s marked RAM Expansion Module and Microbar Systems.

*Microspec

*Microspec CPU Multibus Board. (picture) This board is well marked in several places with the Microspec name. I found several Microspec boards in one assortment of surplus material but I’ve seen of heard of them before or since. I don’t have the boards handy at the moment so I can’t give any more details.

*Microspec Interface Multibus Board. (picture) This board is well marked in several places with the Microspec name and is also marked Intrf. It appears to be an interface board but I don’t know for what. I found several Microspec boards in one assortment of surplus material but I’ve seen of heard of them before or since. I don’t have the boards handy at the moment so I can’t give any more details.

*Microspec Motor Driver Multibus Board. (picture) This board is well marked in several places with the Microspec name and is also marked Mot Dvr. It appears to be a stepper motor driver board. From I found several Microspec boards in one assortment of surplus material but I’ve seen of heard of them before or since. I don’t have the boards handy at the moment so I can’t give any more details.

Mupac Multibus boards

Mupac Wirewrap Board (picture). These have MUPAC and 3150014 etched into the top VCC plane. These are the Crème de la Crème of prototyping boards and probable the nicest built of any Multibus boards. Due to the large amount of gold used on them and their price these are used almost exclusively for military projects. They don't use IC sockets. The sockets pins are mounted directly in the circuit board. There are also sockets for de-coupling capacitors adjacent to each IC location. The pins are all machine turned and have heavy gold plating as do the edge contacts. There is a VCC plane on the top of the board and a ground plane on the bottom.

*Mupac Multibus 6 slot Card Cage. (picture) This card cage was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. Here <http://www.classiccmp.org/hp/bbn/BBN4.jpg> is a picture of the Multibus card cage inside of the Butterfly computer. The computer is laying on its right side in a scrap yard.

*National Cash Register (NCR) Multibus Boards

*NCR HP-SIO card. (picture) Marked "NCR" and "HPSI/O" along the RH edge. This board has 8 Sync/Async serial ports and 1 parallel printer port. This card cage was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. The Butterfly computers that these came from were a part of Simnet, a network of tank training simulators.

National Semiconductor (NS) Multibus boards

National Semiconductor seems to have been a prolific producer of Multibus items. I frequently encounter them in my search for old computers and parts.

Extender board (picture). Marked National Semiconductor Microcomputer Systems Board Level Computer and Assy 980305496. NS was just one of the many people that made extender boards for the Multibus systems. Here is one of their products. Another variant of this model had several relays and a switch on it. When the switch was off it turned the relays off. Opening the relay contacts removed power from the board that was plugged into the extender. NS said that you could then safely remove and reinstall the board in the extender even with power still on the system. Not a good idea in my mind.

*NS SLC-16 RAM Multibus Board. (picture). No details at this time.

Orbot Multibus and iSBX boards

**Orbot I/O Channel CS iSBX Board. This one is marked "Orbot I/O Channel (iSBX) CS" and only has a few TTL "glue"chips. See the Intel iSBC 286/12 CPU board descriptions for information. Here is a picture of one mounted on the Intel CPU board.

*Perceptronics

*Perceptronics Simnet DMA Board. (picture) This card is clearly marked in the bottom RH corner. It was custom made by Perceptronics and was used in a SMS 8000 40 computer that was a part of Simnet, a network of tank training simulators. It contains two MC68450L8 and sixteen TRW 1030J6C ICs.

*Proconics

*Proconics I/O Multibus Board. (picture). This board is clearly marked Proconics and I/O Multibus Board near the top left corner. I don’t have the board handy at the moment so I can’t give any more details.

*Scientific Micro Systems (SMS) Multibus Boards

*SMS 8007 Floppy/Hard drive controller. (picture) Marked "SMS 8007" on a paper label on the back of the card. This card was removed from a SMS 8000 40 computer. The SMS 8000 40 manual on Al's site has some details about this card.

*Vector Electronics

*Vector Electronics is a well known manufacturer of wirewrap boards, prototyping boards and extender boards as well as many other products used in prototyping circuits.

*Vector Electronics Model 3690-18 Multibus Extender Board. (picture) This board is readily identified by the model number shown in the center of the board and Vector’s name shown on the reverse side.

*Versatec

*Versatec Dual Port Memory Board. (picture) This card is readily identified by the manufacturer’s name and item description on the RH edge of the board.

*XYlogics

*XYlogics. 431 Floppy/tape/Winchester controller card with DMA. (picture). This card is marked in the top RH corner. This particular card was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. The BBN manuals contain some detail about this card. Al is scanning my BBN manuals and should have them posted shortly. Now finished and posted at <http://www.bitsavers.org/pdf/bbn/gp1000/>. I've sent my XYLogics 43x manual to Al and he now has it scanned and posted at <http://www.bitsavers.org/pdf/xylogics/>.

*XYlogics 472 Multibus Board. (picture). This is a crummy picture and I’ve misplaced the card so I can’t give any more details at the moment.

Zendex Multibus boards

Zendex seems to be one of the larger manufacturers of Multibus boards and systems and is still in business (www.zendex.com). I believe they are manufacturing new updated Multibus boards as well as Multibus II, PC/104 and others.

**Zendex ZX-208A Diskette Controller (picture). This Board is clearly marked with the manufacturer’s name, board name and model number near the center. I found this particular board in the board scrap at a surplus company and it is rather dirty.

*Zendex ZX-908A PROM Programmer (picture). This Board is clearly marked as you can see in the photo. This is one cool board! It programs up to eight EPROMs are one time and is a Multibus board and can be used in any Multibus system. It comes software for both CPM and ISIS. In addition, it can be used in a stand-alone mode by connecting it to a computer via a serial cable. I got this with one of the MDS-800s that I bought (Thanks Robert!).

*Unknown Manufacturers

*UNKNOWN Manufacturer (BMA?) (picture) This is another of those cards that I got and photographed but never got around to documenting until months later when I couldn’t find the card and don’t remember it’s details. BMA is probably the manufacturer’s name or abbreviation but I can’t be sure.

*DR-11W emulator card (picture). This card cage was removed from a BBN Butterfly computer. The Butterfly had a Multibus card cage in it with various Multibus cards that were used for I/O. The Butterfly computers that these came from were a part of Simnet, a network of tank training simulators. I believe the DR-11W card was used to let the various Multibus I/O cards communicate with the BBN CPU cards.

*Ink? (picture). I don’t know what this is. I found this picture in my archives but I don’t have the board handy so I can’t give any more details. Ink is the file name of the picture and SHOULD relate to the card manufacturer but I can’t be sure at the moment.

**UNKNOWN Manufacturer (Diebold?) STP Processor. (picture) These boards are marked "STP Processor" along the top edge and have the name Diebold on the paper labels covering the EPROMs. They have an 8085 CPU and a WD2001 IC made by Tundra or Western Digital along with a 62256 SRAM and a Lithium battery located near the center of the board and a SCC IC made by Zilog. I don’t know the purpose of this board but I have found a number of them (all loose) and they appear to be complete single board computers. This board also has a daughterboard on it. Note this daughterboard does not use the iSBX connectors but instead it plugs into J3 and on of the sockets previously used by one of the 62256 SRAMs. The daughterboard is marked CCA, Memory Expansion and appear to have originally contained four D27128 EPROMs and four RCA CDM6264E3 RAMs. I found these particular boards in the board scrap at a surplus company and they are rather dirty.

*UNKNOWN Manufacturer (TSP?). (picture) This card is marked "CPU" above the crystal near the top RH corner and contains a MC68000L8 CPU. I don't know who made it but it's marked TsP. I found this card and two others that appear to be part of the same set loose in a load of scrap. In fact, it hasn't been cleaned up and you can still see debris on it.

*UNKNOWN Manufacturer (TSP?). (picture) This card is marked "CPU Memory" along the top edge. It contains a six 2732 EPROMs and four 6116 Static RAMs. I don't know who made it but it's marked TsP. I found this card and two others that appear to be part of the same set loose in a load of scrap.

*UNKNOWN Manufacturer (TSP?). (picture) This card is marked "IMU" along the top edge. It contains a large Weitek WJC1010JC IC and an AMD 2910 Bit Slice Sequencer IC. I don't know who made it but it's marked TsP. I found this card and two others that appear to be part of the same set loose in a load of scrap.

**UNKNOWN Manufacturer 4 Channel Resolver/ Digital Converter. (picture) There is no name on this card so I don’t know who made it but it looks like something DDC would make. It has a couple of DDC parts along with four Multi-Speed Resolver to Digital Converters made by Computer Conversions Corporation. It is marked 4 Channel Resolver/ Digital Converter.

**UNKNOWN Manufacturer 68K with Octal I/O. (picture) There is no name on this card so I don’t know who made it but it was most likely a 68000 CPU single board computer even though the 68000 is now missing. It’s marked 68K CPU W/ OCTAL I/O and ASSY 907718 near the top LH corner. This is another card that I found in a pile of board scrap so it’s rather dirty and beat up.

**UNKNOWN Manufacturer Wirewrap Board. (picture) There is no name on this card so I don’t know who made it. The only identifying markings is a logo that looks like a SINE wave with a + symbol at it’s RH end and inside a circle. This symbol is located on the top LH corner of both the front and back. This is a nicely made board with machine turned IC sockets and long square wirewrap pins on the back side. It also features power and ground planes on the front and back and good quality gold plating on all sockets, pins and connectors.

Links of Interest

Al Kossow's list of Intel manuals by part number. (link).

List of Intel manuals that I have. (link).

Webpage with some general info about the Intel MDS systems and the ISIS operating system and Intel's connection with Gary Kidall and the development of CPM. (link).

Webpage describing my first Intel MDS-800 system. (link).

Webpage describing my third Intel MDS-800 system. (Sorry no text, just pictures) (link).

Webpage describing my fourth Intel MDS-800 system. (Sorry no text, just pictures) (link).

One of these days I'll do a webpage for my Intel MDS-235 system. (nothing).