Logic & Memory Circuits

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Burroughs 724xx Series
 Burroughs 724xx Series

Devices included in this entry:

Burroughs 72477 diode card
Burroughs 72480 logic module (pictured in thumbnail)


Burroughs 724xx series circuit modules are the building blocks of the Burroughs B5000 mainframe, an incredibly advanced system introduced in 1961 which pioneered many features of modern computing. 724xx series pluggable modules come in two primary forms: cubical cordwood-style transistorized logic blocks, and small cards containing eight diodes suspended in a diallyl pthalate frame.

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Columbia Scientific Industries 901-6062
 Columbia Scientific Industries 901-6062

The 901-6042 is a CPU card salvaged from the corpse of a CSI Accelerating Rate Calorimeter (ARC), a computer-controlled system used in the study of exothermic reactions. The heart of the CSI ARC is a National Semiconductor IPC-16A/520D Processing & Control Element (PACE) 16-bit PMOS microprocessor, first introduced in 1974. PACE is noteworthy as being the first commercially available 16-bit microprocessor which could be purchased as a stand-alone product. Like a number of other early 16-bit microprocessors, PACE is a single-chip implementation of a preexisting board-level architecture.

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D-G Electronic Developments Super 89
 D-G Electronic Developments Super 89

Devices included in this entry:

D-G Electronic Developments Super 89 CPU card (pictured in thumbnail)
Heath/Zenith Z-89-37 Double Density Disk Controller (pictured in thumbnail)
Heath/Zenith Z-89-67 Interface Board (pictured in thumbnail)


The D-G Electronic Developments Super 89 is an aftermarket replacement CPU upgrade for the Heath/Zenith H-88/H-89/Z-89/Z-90 series of Z80-based all-in-one personal computers. The Super 89 substantially outperforms the standard H-89 CPU, as it operates at double the original 2MHz clock rate, has a built-in real-time clock, optional AM9511A arithmetic processor and up to 256K of bank-selectable RAM. The example in our collection has two official Heath/Zenith interface cards installed: the Z-89-37 Double Density Disk Controller, and Z-89-67 Interface Board, designed for use with the Z-67 Winchester drive. The Z-89-37 is noteworthy as being the differentiating component between the H-89/Z-89 and the Z-90. While the H-89/Z-89 uses an older hard-sectored floppy disk controller, the Z-90 is equipped with the Z-89-37, which controls the H-37/Z-37 soft-sectored DSDD floppy drive.

D-G also manufactured the Heartbeat, a Heath/Zenith compatible system that was little more than a Super 89 in a box. Unlike the Heath/Zenith machines, the Heartbeat requires a separate terminal to provide the user interface.

Special thanks to Victor Rizzardi for donating this hardware.

D-G Heartbeat / Super 89 Operation Manual (PDF)

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Digital Equipment Corporation R107D
 Digital Equipment Corporation R107D

DEC's 'flip chip' is an iconic example of the discrete transistor logic module. Such modules were used in DEC's computers through the 1960s, the large arrays of color-coded pull tabs a signature characteristic of DEC hardware. The module pictured here is a R107D Inverter.

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General Electric B162149-A
 General Electric B162149-A

The B162149-A is a logic card from a GE-645 mainframe, the first system designed to run MIT's Multics operating system. The GE-645 was a variant of the GE-635, specially modified to run Multics by increasing the address space to allow for virtual memory. Unlike many systems developed in the late 1960s, the GE-645 was constructed almost entirely from discrete components.

The uncharacterized circuit card pictured here was originally part of a GE-645 installed at Bell Labs. Special thanks to Bill Eaton for donating this rare piece of computing history.

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Honeywell Information Systems Level 6 Memory Subsystem
 Honeywell Information Systems Level 6 Memory Subsystem

Devices included in this entry:

Honeywell BMMU031A-001 memory controller (pictured in thumbnail)
Honeywell BCMM044A-001 64KB Memory-Pac (pictured in thumbnail)


The BMMU031A-001 is the memory controller from a Honeywell Level 6 (DPS 6) series minicomputer. The BMMU031A-001, primarily built from 7400 series TTL logic, controls four BCMM044A-001 64KB Memory-Pac cards which socket directly into the controller.

Honeywell Memory-Pacs seem to have been built with whatever 16384-bit dynamic RAM was handy at any given moment. The BCMM044A-001 was manufactured with multiple bins of National Semiconductor MM5290J, Texas Instruments TMS4116 and Toshiba TMM416D.

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IBM TH-537
 IBM TH-537

IBM's early computers and electronic accounting machines used large arrays of 'finger' modules, most of which have one tube and some amount of passive support circuitry. This is an extremely rare TH-537 two-tube module from an IBM 604 Electronic Calculating Punch or similar. The module has two examples of the IBM/Tung-Sol 5696, a xenon-filled thyratron tetrode used as a high speed switch in early IBM computers.

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IBM SLT Modules
 IBM SLT Modules

Devices included in this entry:

IBM 6332YB SLT module
IBM 7448YB SLT module
IBM 7480YB SLT module
IBM 7528YB SLT module
IBM 8267DO SLT module
IBM 8268YE SLT module
IBM 8279DO SLT module
IBM 8926YH SLT module (pictured in thumbnail)
IBM 831290 SLT module


First developed for the System/360 in 1964, IBM's proprietary Solid Logic Technology (SLT) hybrid integrated circuits were used to build both their mainframes and smaller computers like the IBM 5100. Earlier SLT ICs are built from glass-encapsulated transistors and diodes mounted on a ceramic substrate, while later devices feature a monolithic construction. SLT circuit cards have an unusual multi-layer design with a grid of solder pads covering the entire board. IBM SLT modules are believed to be the first implementation of BGA interconnection, now a prevailing standard in the electronics industry.

In the not-so-distant past, SLT modules would occasionally flood the surplus collectors' market, usually with no accompanying pedigree. If you can identify any of the boards we have pictured here, please contact us.

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Smith-Corona Marchant 10095-F
 Smith-Corona Marchant 10095-F

The Smith-Corona Marchant 10095-F is a memory PCA from an as-yet unidentified model of large desktop calculator. The 10095-F features a TDK EM-2985 432-bit magnetic core memory plane, capable of storing the equivalent of 108 BCD digits. While this is a small fraction of the core memory typically used in computers from the era, it's a substantial amount for an early electronic calculator. For comparison, the impressive NCR 18 desktop calculator has only 256 bits of core memory. The remainder of the card is occupied by sense amplifier hardware, primarily built from uncharacterized CDC10107C and CDC10157F transistors.

Special thanks to Victor Rizzardi for donating this rare memory device.

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Sperry Rand UNIVAC 7052282-00
 Sperry Rand UNIVAC 7052282-00

This ruggedized circuit card is a six-transistor control line driver from the UNIVAC CP-667 36-bit military computer. The CP-667 was intended for the US Navy's ill-fated Mobile OPCON program, and only three of these systems were ever built. The CP-667 logic was built from hybrid integrated circuits, similar to the Western Electric GF401xx devices used in the SAGE program.

Circuit cards of this type, salvaged from dismantled CP-667 systems, were reused in the Ground I/O and Control Console segments of the Univac 1830 (CP-823/U) Anti-Submarine Warfare Digital Computing System engineering prototype.

UNIVAC 7052282-00 Specifications (PDF)

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Victor Comptometer Calculator Logic
 Victor Comptometer Calculator Logic

Devices included in this entry:

Victor Comptometer 59138B logic PCA
Victor Comptometer 63175B logic PCA (pictured in thumbnail)


Like many me-too calculator manufacturers in the 1970s, Victor Comptometer chose to base their electronic adding machines on a rapidly evolving series of Rockwell calculator chipsets. Early machines using large chipsets were quickly supplanted by newer models built on increasingly smaller chipsets. The logic PCAs of the Victor 1800 and Victor 1900 are ideal examples of this phenomenon. The Victor 1800, introduced in 1971, makes use of a 7-chip Rockwell LSI chipset. The functionally equivalent Victor 1900, introduced two years later, has a similarly sized logic PCA as the Victor 1800, but the size of the chipset has been reduced to five ICs, allowing the thermal printer drive hardware to fit on the same PCA.

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