Hewlett-Packard 5061-30xx Series [Detail]  
Written by Accutron on 2007-06-02  

The first completed BPC masks taped out on April 8, 1973, and HP had a fully functional microprocessor before the end of the year. The BPC was birthed just ahead of National Semiconductor's laughably slow PMOS-based PACE design, widely miscredited as the first 16-bit single-chip microprocessor. The BPC is also noted as the first NMOS microprocessor and the first microprogrammed microprocessor. Intel would not arguably surpass the HP hybrid microprocessor until the release of the 80286 in 1982.

The hybrid microprocessor package is a completely unique ceramic LCC with 82 gold pins and a metal lid. The microprocessor also has a large heatsink, affectionately referred to by HP engineers as the 'Honda cylinder head'. Even when shrunken down to pocket size, HP minicomputers still have a requisite shell of cast aluminum. As we like to say around here, HP hardware is truly designed to both execute and survive a nuclear war.

There is surprisingly little information about the HP hybrid microprocessor available on the internet. HP never licensed the device to other companies, condemning it to historical obscurity in spite of its extremely high technological significance. Most so-called CPU museums ignore its existence altogether, preferring instead to document yet another Intel chip. Even the Smithsonian fails to document the BPC, alternately regurgitating a secondary source which erroneously credits PACE as the first 16-bit microprocessor.

The first version of the hybrid microprocessor was the 09825-67907, used in early 9825A systems and the 3585A Spectrum Analyzer. HP soon revised this original design to correct a well-documented ground bounce problem. This revised design is the 5061-3010, first used as the language processor (LPU) in the 9845A computer. Along with the -3010, HP introduced the 5061-3011, a variant of the -3010 which omits the EMC, intended for use as the I/O processor in the HP 9845A. The -3011 was later used as the CPU in the 64000 and 64100 Logic Development Systems and the 4955A Protocol Analyzer. HP then introduced the 5061-3001, a 107-pin enhancement of the -3010 which adds an Address Extension Chip (AEC). The -3001 was first used as the CPU in the 9835A and 9835B, and a dual -3001 configuration was employed in the 9845B and 9845C. Two other lesser known 82-pin variants of the hybrid microprocessor were used in the HP 250 multiuser business computer (5061-3043) and in the 8566A and 8568A Spectrum Analyzers (5061-4204).

The HP hybrid microprocessor had a number of other relatives which shared various technologies. The BPC was manufactured as a standalone product (1818-2500), packaged in a 40-pin cerDIP. The TACO tape drive controller (5061-3012), used in the 9845 and 4955A, was fabricated using a newer NMOS III process, but retained the elastomeric connector socket. HP also introduced an 8-bit 'nanoprocessor' (1820-1692), packaged in a 40-pin cerDIP. The hybrid microprocessor's packaging technology was used on the 5061-3020 20-bit shift register, the 00080-60106 hybrid ROM for the HP-80 business calculator, and the 00065-60218 hybrid calculator LSI, heart of the HP-65 programmable calculator.

There are two known lid variations seen on hybrid microprocessors. Earlier examples are equipped with a 'Type 1' lid, which has a dull finish and sharper edges, while later examples have a 'Type 2' lid, which has a more polished finish and rounded edges. The -3001 also has a third 'grey trace' variation with a Type 2 lid. Such grey trace examples are quite rare, as they were both preceded and succeeded by more typical gold trace variations. Type 1 lids are affixed to the substrate with a range of questionable substances. Type 2 lids are always affixed with an ample machine-applied strip of epoxy.


HP A5061-3010 hybrid microprocessor, Type 1 lid, removed from the dual-processor CPU of a HP 9845A computer. The second processor is a 5061-3011 no-EMC variant.


D5061-3011 no-EMC variant hybrid microprocessor, designed as the Language Processing Unit (LPU) of the HP 9845A. Instead of the standard hybrid microcode, the -3011 has an onboard BASIC interpreter. This example has a later Type 2 lid.


Located in the triangular gap along the bottom row of pins, there is a small gold HP logo inside a heart, an indicator of its origin at HP's facility in Loveland, Colorado.


The 'Honda cylinder head', as installed in a HP 4955A Protocol Analyzer.


Two halves of the HP 9845B CPU, the Peripheral Processing Unit (top) and the Language Processing Unit. Both boards are equipped with identical D5061-3001 AEC variant hybrids.


D5061-3001 AEC variant hybrid microprocessor, grey trace variation with Type 2 lid. Both earlier and later gold trace variations also exist. Note the handwritten serial number, which is present on some examples while absent on others.


Closeup of elastomeric compression connectors, which consist of flexible elastomer cylinders wrapped in numerous gold wire loops.


C5061-3012 TACO tape drive controller. Like the hybrid microprocessor, this chip is heatsink-aligned to board-mounted elastomeric connectors. There is a gold trace variation of this IC, as well as the unusual 'green trace' variation shown here.

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