MVME135/136 is a high-performance MC68020 microprocessor module based on the VME double-height, single-width form factor. MVME135/136 contains MC6802032 address and data microprocessor advanced multiprocessor CSR and fast DRAM of IMB or 4MB. Other key features provided include Demand Paged Memory Management Unit (PMMU), FioatingPoint Coprocessor (FPCP), and interfaces to VMEbus and VSBbus.
The MVME135/136 is specially designed for those applications that require fast on-board RAM and secondary bus (VSBbus). The features of the MVME135/136 include high performance and elegant architecture. The MVME135/136 are especially suitable for applications requiring multiple processors, where efficient inter-processor communication is important.
The 135bug resident debug package (see MVME135BUG released by Motorola) is a firmware package designed for MVME135/136 modules. 135bug provides a powerful system debugging tool for the VME module system. This firmware features a line assembler/disassembler, upload/download provisions, and disk boot commands. The 135bug is provided as a PROM-based resident package that plugs into IC sockets U54 and U56 on the MVME135/136.

The MVME135/136“S on-board memory is designed to operate without wait states when the speed of the memory is sufficient or when parity operation is not required. Jumper block J6 allows for a wait state to be inserted. Parity operation requires between J6 pins 2 and 3. For best performance, care should be taken to ensure that jumper J6 pins 1 and 2 are installed when parity is not required.
Another case where jumper caps must be installed on pins 2 and 3 is to accommodate low DRAM devices. Note that the MVME135A and MVME136Aversfons utilize the slower IM bit DRAM, therefore jumper J6 is configured for I wait state operation. For wait-state-free operation at 16.67MHz, a 78ns memory mezzanine module is required. Wait state operation at 20MHz does not require 60 nanoseconds. memory mezzanine module. Upgrading a 16.67MHz MVME135/136 multiprocessor to a 20MHz unit requires a 20MHz oscillator (Y2) and a 10-tap delay Tine (DL4) of 80ns.
The MVME135-1 multiprocessor is pre-configured to 20MHz at the factory. It is not recommended for users to upgrade MVME135 multiprocessor to MVME135-1 configuration.