Multifunction Modules
Overview
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.
Summary
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.
References
- LSI-11 Systems Service Manual, 5th Edition, January 1985 (EK-LSIFS-SV-005)
- PDP-11 Microcomputer Interfaces Handbook 1983-84 (EB-23144-18)
- Microcomputer Products Handbook, 1985 (EB-26078-41)
Additional Resources
- MicroNote 5 - Q22 Compatible Options
- MicroNote 10 - Differences between the MXV11-A and MXV11-B
