VAX-11/750
| VAX-11/750 | |
 VAX-11/750 (CPU cabinet on the left) | |
| Summary | |
|---|---|
| Announcement date: | 1980 |
| FRS date: | October 1980 |
| Codename: | Comet |
| OS support (VMS): | VMS V2.0 |
| CPU Details | |
| CPU name (VMS): | KA750 |
| CPU name (console): | None [1] |
| Number of processors: | 1 |
| VMS DCL CPU: | 2 |
| VMS DCL XCPU: | 0 |
| SID: | 0200xxyy xx = microcode revision yy = hardware revision |
| XSID: | 0 |
| CPU cycle time: | 320ns |
| Instruction-buffer: | 8 bytes [2] |
| Translation-buffer: | 512 entries [2] |
| Control store: | 6K 80-bit words [2] |
| Writable Control Store: | 1K 80-bit words [2] |
| Cache: | 4KB [2] |
| Compatibility mode: | Yes [2] |
| Console processor: | CPU |
| Console device: | TU58 [2] |
| Memory | |
| Minimum memory: | 1MB [2] |
| Maximum memory: | 14MB |
| Physical address lines: | 24 |
| Memory checking: | 7-bit ECC/longword [2] |
| I/O | |
| Max I/O throughput: | 5.0MB/s |
| MASSBUS: | 3@ 2.0MB/s |
| UNIBUS: | 1 @ 1.5MB/s |
| LAN support: | optional |
| Performance | |
| VUPs: | 0.65 |
The VAX-11/750 (also known as the VAX/750) is a slower, more compact, but less expensive successor to the initial VAX-11/780. It was primarily implemented in gate array chips holding 400 NAND gates; they were configured at manufacture time into the 39 different types used in the /750.
It is built around the KA750 CPU. It supported several pre-existing DEC I/O buses (UNIBUS and MASSBUS), so there are almost no VAX-11/750-specific peripherals.
One of the first OS's available for the 750 was 4.1 BSD. According to 'Quarter Century of UNIX', the DoD could purchase 6 750's for about $150,000 USD.
Contents
Internal structure
The /750 has a plethora of internal data paths; many of them are contained entirely within the KA750 CPU, and will not be detailed here. The one significant one which connected all the major functional units, including the CPU, main memory, and I/O bus adapters, was the CPU/Memory Interconnect bus (CMI). The mandatory major CMI sub-systems (and components thereof) were:
- KA750 CPU
- MS750 Memory System
Optional sub-systems included:
- FP750 Floating-Point Accelerator
- KU750 Writetable Control Store - used to support extended range G and H floating-point
CMI Options
A variety of optional bus adapters and device controllers were available for the CMI:
- RH750 Massbus Adapter
- DW750 Second Unibus Interface
- CI750 Computer Interconnect Interface
- DR750 General Purpose Interface
Physical structure
The VAX-11/750 comes in an H9645 cabinet and has one large backplane (DEC part number 50-13821/70-16486/54-13822), into which plug:
- KA750 boards
- CMI option boards (RH750, etc)
- memory array boards
Although it is one physical unit, the backplane can be seen as divided into several logical sections; indeed, the connectors used in the memory array board section are different from those used in the 'main' section of the backplane (where all the other boards plug in).
However, the biggest difference the sections has to do with which buses are connected to each slot; many slots are thereby customized to a particular board, which has to go in that slot - and that slot can't hold anything else.
The 'main' (i.e. non-memory) section of the backplane can be logically further divided into two sub-sections: one holding optional CMI cards, and another (specifically, slots 1-6 and 10) holding the main memory controller, and the CPU (and optional ancillaries thereof). (Those latter slots have internal buses, such as the MBus and WBus, running between them.)
The CMI appears on the backplane (and nowhere else), and goes to some (but not all) slots/cards. (E.g. the FPA is not a 'CMI' card; it's part of the KA750, and plugs into the /750 backplane which carries the CMI to other slots, but that's all.)
So, one shouldn't put much weight on whether boards plug into the 'main' slots (1-10) on the /750 backplane, because that section holds a mix of special-purpose slots, and 'CMI option' slots (7-9). Although cards that the CMI goes to (MIC, UBI, RDM, WCS) are in some sense 'CMI' cards... because they have dedicated, customized, slots, one should reserve the term 'CMI card' for the cards that can go in the CMI option slots: RH780, etc.
Backplane configuration
This diagram:
| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M9313 | M9202 | MS750-C 1 MB (optional) | MS750-C 1 MB (optional) | MS750-C 1 MB (optional) | MS750-C 1 MB (optional) | MS750-C 1 MB (optional) | MS750-C 1 MB (optional) | MS750-C 1 MB (optional) | MS750-C 1 MB | Memory Control (MCM) | CMI Option (optional) | CMI Option (optional) | CMI Option (optional) | Remote Diagnostic Module (RDM) | CPU Control Store (CCS) | UNIBUS Interface (UBI) | Memory Interconnect (MIC) | Data Path Module (DPM) | FP750 Floating-Point Accelerator | ||||||||||
| M8750 | M8750 | M8750 | M8750 | M8750 | M8750 | M8750 | M8750 | L0011 | L0006 | L0005 | L0004 | L0003 | L0002 | L0001 | |||||||||||||||
| UNIBUS | Memory | CPU | |||||||||||||||||||||||||||
| UNIBUS DD11-DK | Extended Hex | CMI Backplane | |||||||||||||||||||||||||||
shows the UNIBUS, main memory, and CPU backplanes.
An L008 Patchable Control Store (PCS) may be substituted for the L0005 CPU Control Store. Similarly, the later L0016 and L0022 Memory Controllers may be substituted for the L0011 Memory Controller.
VAX-11/750 images
Left of card cage:
Inside card cage:
- Left: DD11-DK Unibus backplane (with cards)
- Center: Memory backplane section (with cards)
- Right: CPU/CMI backplane section (with cards)
Backplanes:
- Left: CPU/CMI backplane section
- Center: Memory backplane section
- Right: DD11-DK - UNIBUS backplane
- Lower left corner: 5V and 2.5V Power Supply cables (as thick as a finger!)
- Bottom: 5V and 2.5V Power Supplies
Power Supplies:
- Left: H7104-C 2.5V, 85A max.
- Right: H7104-D 5V, 135A max.
Round cables, top left:
- Console
- Remote Diagnose Modem
Cables, bottom left to top right:
- DMF32 UNIBUS Multi-Function Communications Interface (3 flat cables)
- TU80K TU80 Tape Adapter (2 flat cables, one behind the other)
- DEUNA Ethernet Adapter (round cable)
Bottom right:
- H7112 - VAX-11/780 / VAX-11/750 Battery Backup Unit
References
See also
External links
- VAX Hardware Handbook Volume 1 - the VAX-11/750 is covered in Chapter 4 (pp. 154-171 of the PDF)
- VAX/750 - documentation at Bitsavers
- 11/750 Field Maintenance Print Set (MP01377)
- VAX-11/750 Installation Manual (EK-SI75F-IN-001)
- VAX-11/750 Installation and Acceptance Manual (EK-SI750-IN-003)
- VAX Maintenance Handbook: VAX-11/750 (EK-VAXV3-HB-001)
- Vax 11/750 Frequently Asked Questions
- DEC VAX-11/750 - mostly a copy of the above
- VAX-11/750
- Makings of a Comet: The VAX 11/750
- My d|i|g|i|t|a|l VAX 11/750 - lots of good images
- VAX 11/750 Parts - lots of good images
| v • d • e VAX Computers and Operating Systems |
|---|
| VAX-11/7xx (including VAX 86x0) - VAX-11/780 • VAX-11/785 • VAX-11/750 • VAX-11/730 • VAX 8600 • VAX 8650
VAX 8000 series (excluding VAX 86x0, above) - VAX 82xx/83xx series • VAX 85xx/87xx/88xx series MicroVAXen (many types also come in VAXserver and VAXstation models) - MicroVAX I • MicroVAX II VAXstation Series - VAXstation I • VAXstation II Late Model VAXen - VAX 4000 series • VAX 6000 series • VAX 7000 series • VAX 9000 series • VAX 10000 series |
| Special Purpose VAXen - VAXft series • rtVAX series • Infoserver series
Clones - CM 1700 • TPA-11/580 |
