Motorola MC68882FN16A

The MC68882 extends MC68020 and MC68030 systems with IEEE 754 binary floating-point instructions. It can also be interfaced as a peripheral processor in other M68000-family designs. It includes eight 80-bit floating-point registers, a 67-bit arithmetic unit and separate floating-point control, status and instruction-address registers. Its host processor handles effective address calculation and data transfer requests.

• Hardware arithmetic conforming to IEEE 754-1985 binary floating-point behavior.
• Eight general-purpose 80-bit floating-point registers.
• Single, double and extended precision support.
• Concurrent operation with the host processor where bus timing permits.
• Documented M68000-family coprocessor interface.

The Motorola technical summary describes 46 instructions, eight FP0-FP7 registers, a 67-bit arithmetic unit, a 67-bit barrel shifter, and hardware for binary-format conversion. FPCR controls rounding and exception behavior; FPSR records status; FPIAR tracks the instruction address relevant to exceptions. Seven integer, real and packed-decimal data types are supported.

The manufacturer orderable-part and material documents state that MC68882FN16A uses a 68-lead plastic quad J-lead package, PLCC 68. The local package registry uses 68-LCC (J-Lead) and expects the JPG below. Compare the controlled mechanical drawing with the socket, pin-one corner and lead seating before installation.

Assembly checks

• Check all J-leads for damage and oxidation.
• Confirm PLCC pin-one orientation.
• Inspect supply decoupling and board timing.

The registered local 68-LCC JPG is missing.

The original MC68882 signal summary assigns A0-A4 to address inputs and D0-D31 to the bidirectional data bus. SIZE, AS, CS, R/W and DS qualify the bus cycle; DSACK0 and DSACK1 acknowledge transfer size. RESET, CLK and SENSE provide control functions, with VCC and GND for power. One terminal is NC and reserved by Motorola. Use the manufacturer's PLCC diagram for exact terminal numbers.

Use the controlled Motorola/Freescale DC and AC tables for board-level design limits rather than a distributor summary.

No LCDChip internal alternate is approved or linked. MC68882FN16AR2 is another exact-family code, but packing, lot and board fit require independent checking. Faster MC68882 grades can differ in clock limits; MC68881 is a related earlier coprocessor with different performance. Verify electrical, software, package and sourcing conditions before substitution.

The Motorola/Freescale BR509 technical summary, hosted by NXP, documents architecture, signal groups and the 16.67 MHz electrical column. Manufacturer orderable-part and material declarations specifically list MC68882FN16A as PLCC 68; this exact package identification is stronger than a generic family package description.

• MC68020 and MC68030 boards needing floating-point acceleration.
• Legacy scientific and instrumentation controllers.
• Repair of systems designed for a 68-lead MC68882 PLCC.

Inspect full FN16A markings, date and lot codes, J-lead condition, package dimensions and provenance. The manufacturer material declaration lists the historical device as not RoHS compliant; assess process compatibility before rework. Obtain a dated authorized exact-code stock and price quote before changing catalog commercial fields.

Confirm exact FN16A lot, PLCC geometry, clock and bus timing, 5 V supply and lead finish using the manufacturer documents and actual board. Missing package artwork and unreconciled current price terms prevent publication.