Module Comparisons Third-Party Products Functional Information

Multifunction Modules


Multifunction modules can contain a combination of RAM, ROM sockets, serial line units and line time clock sources and controls. The table below contains a comparison of the different multifunction modules available for Q-bus machines.

Module Number M8012 M8047-AA M8047-CA M8047-HA M7195-FA
Model Number BDV11 MXV11-AA MXV11-AC MXV11-HA MXV11-BF
Introduced 1977 1980 1980 1981 1983
Discontinued 1984
Board Size Quad Dual Dual Dual Dual
Q-bus Address Size 18-bits 18-bits 18-bits 18-bits 22-bits
Onboard RAM no 8 KB 32 KB 32 KB 128 KB
Parity RAM N/A no no yes no
Onboard ROM yes1 2 KB2 2 KB2 2 KB2 4 KB3
Onboard LTC no yes4 yes4 yes4 yes5
Onboard LTC Register yes no no no yes
Onboard Serial Ports no 2 2 2 2
Memory Refresh no yes yes yes yes
Termination 120 ohms no no no no
AC Bus Load 2 2 2 2 2.3
DC Bus Load 1 2 2 2 0.5
+5V Load 1.6 A 1.2 A 1.2 A 1.2 A 3.5 A
+12V Load 0.07 A 0.01 A 0.01 A 0.01 A 0.06 A

1 Module is equipped with 24 sockets supporting 1 KB and 2 KB ROMs.
2 Two sockets supporting 1 KB ROMs. Generally populated with MXV11-A2 bootstrap ROMs.
3 Two sockets supporting 2 KB ROMs. Generally populated with MXV11-B2 bootstrap ROMs.
4 60 Hz clock derived from a crystal oscillator.
5 50 Hz, 60 Hz and 800 Hz clock derived from the SLU1 DLART.


Out of the above modules, probably the most desirable is the M7195-FA, which includes 128 KB of non-parity RAM, a line time clock generator and control register, two serial ports and boot ROMs. This module is perfect for an LSI-11, or M8186-based system, but it has its drawbacks. Its memory does not have parity support and it will not support block mode DMA transfers, which makes it incompatible with some operating systems and disk controllers. See MicroNote 2.

MicroNote 19 discusses how to disable the onboard memory (and void the warranty), but it solves the DMA and parity issue. It also attempts to compare the M7195-FA with the MRV11-D and DLV11-J combination, but overlooks the Line-Time Clock generator and LTC register features, not to mention the form factor.

The next more desirable module would be the M8012, as it includes lots of ROM sockets, a line time clock register and bus termination. This module can be modified for 22-bit use and fitted with the MXV11-B2, or MicroPDP-11 boot code in a set of 8 ROMs.


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