V-11
Encyclopedia
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
chip set implementation of the VAX
VAX
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
instruction set architecture (ISA) developed and fabricated by Digital Equipment Corporation
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
(DEC).
History
The V-11 was Digital's first VAX microprocessor design, but was the second to ship, after the MicroVAX 78032MicroVAX 78032
The MicroVAX 78032 is a microprocessor developed and fabricated by Digital Equipment Corporation that implemented a subset of the VAX instruction set architecture . The 78032 was used exclusively in DEC's VAX-based systems, starting with the MicroVAX II in 1985...
. It was presented at the 39th International Solid State Circuits Conference held in 1984 alongside the MicroVAX 78032 and was introduced in early 1986 in systems, operating at 5 MHz (200 ns cycle time) and in 1987 at 6.25 MHz (160 ns cycle time). The V-11 was proprietary to DEC and was only used in their VAX 8200, VAX 8250, VAX 8300 and VAX 8350 minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s; and the VAXstation 8000 workstation
Workstation
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...
.
At 5 MHz, the V-11 performed approximately the same as the VAX-11/780 superminicomputer. At 6.25 MHz, it performed approximately 1.2 times faster than the VAX-11/780.
The V-11 was part of the Scorpio program, which aimed at providing DEC with the ability to develop and fabricate very-large-scale integration
Very-large-scale integration
Very-large-scale integration is the process of creating integrated circuits by combining thousands of transistors into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed. The microprocessor is a VLSI device.The first semiconductor...
(VLSI) integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s (ICs). Other aspects of the program were the development of a new computer-aided design
Computer-aided design
Computer-aided design , also known as computer-aided design and drafting , is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer...
(CAD) suite and semiconductor process, the results of which are CHAS and ZMOS, respectively. ZMOS was the first semiconductor process to be developed entirely by DEC.
Description
The V-11 was a multichip design, consisting of an I/E chip, a M chip, a F chip and five ROM/RAM chips. Unlike the MicroVAX 78032, which implemented a subset of VAX ISA, the V-11 was a complete VAX implementation, supporting all of the 304 instructions and 17 data typeData type
In computer programming, a data type is a classification identifying one of various types of data, such as floating-point, integer, or Boolean, that determines the possible values for that type; the operations that can be done on values of that type; the meaning of the data; and the way values of...
s (byte, word, longword, quadword, octaword, F-floating, D-floating, G-floating, H-floating, bit, variable-length bit field, character string, trailing numeric string, leading separate numeric string, packed decimal string, absolute queue, and self-relative queue).
The chips in the chip set were connected with four buses: the MIB, DAL, PAL and CAL. The MIB (microinstruction bus) carried microinstructions control signals and addresses from the control store to the I/E and F chips. The MIB is 40 bits wide, the same width as a microword and is parity
Parity bit
A parity bit is a bit that is added to ensure that the number of bits with the value one in a set of bits is even or odd. Parity bits are used as the simplest form of error detecting code....
protected. The DAL is a 32-bit parity-protected bus that carries data addresses to and from the I/E, M and F chips, cache, backup translation buffer RAMs and the port interface.
ROM/RAM chip
The ROM/RAM chip (DC327) implemented one-fifth of the patchable control storeControl store
A control store is the part of a CPU's control unit that stores the CPU's microprogram. It is usually accessed by a microsequencer. Early control stores were implemented as a diode-array accessed via address decoders, a form of read-only memory. This tradition dates back to the program timing...
. It contained a 16,384 by 8-bit (16 KB) read-only memory
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
(ROM), a 1,024 by 8-bit (1 KB) random-access memory
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...
RAM and a 32 by 14-bit content-addressable memory
Content-addressable memory
Content-addressable memory is a special type of computer memory used in certain very high speed searching applications. It is also known as associative memory, associative storage, or associative array, although the last term is more often used for a programming data structure...
(CAM). The ROM contained the control store, with the RAM used to hold control store patches. The ROM/RAM consisted of 208,000 transistors on a die measuring 344 mils by 285 mils (8.74 mm by 7.24 mm) for an area of 98,040 mil2 (63.25 mm2). It dissipated 1 W.
I/E chip
The I/E chip (DC328) contained an instruction buffer, a microsequencerMicrosequencer
In computer architecture and engineering, a sequencer or microsequencer is a part of the control unit of a CPU. It generates the addresses used to step through the microprogram of a control store....
, an execution unit
Execution unit
In computer engineering, an execution unit is a part of a CPU that performs the operations and calculations called for by the Branch Unit, which receives data from the CPU...
and a mini-translation buffer (MTB). The instruction buffer is a two-entry 32-bit buffer that held prefetch
Instruction prefetch
In computer architecture, instruction prefetch is a technique used in microprocessors to speed up the execution of a program by reducing wait states....
ed instructions. It improved performance by maintaining a number of instructions ready for execution. The hardware attempted to keep the instruction buffer full at all times. The execution unit consisted of sixteen 32-bit general purpose register
Processor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...
s defined by the VAX ISA, an arithmetic logic unit
Arithmetic logic unit
In computing, an arithmetic logic unit is a digital circuit that performs arithmetic and logical operations.The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers...
(ALU) and a shifter. The MTB is a translation lookaside buffer
Translation Lookaside Buffer
A translation lookaside buffer is a CPU cache that memory management hardware uses to improve virtual address translation speed. All current desktop and server processors use a TLB to map virtual and physical address spaces, and it is ubiquitous in any hardware which utilizes virtual memory.The...
(TLB). It contained five page table entries (PTEs), one for instruction and four for data. In the event of a miss, the backup translation buffer (BTB) in the M chip is used. The I/E chip consisted of 60,000 transistors on a die
Die (integrated circuit)
A die in the context of integrated circuits is a small block of semiconducting material, on which a given functional circuit is fabricated.Typically, integrated circuits are produced in large batches on a single wafer of electronic-grade silicon or other semiconductor through processes such as...
measuring 354 mils by 358 mils (8.99 mm by 9.09 mm) for an area of 126,732 mil2 (81.76 mm2). It dissipated 5 W.
M chip
The M chip (DC329) was responsible for memory managementMemory management
Memory management is the act of managing computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. This is critical to the computer system.Several...
and interrupt handling. It contained the backup translation buffer (BTB) tags, cache tags and internal processor registers. The M chip also contained the I/O functionality defined by the VAX architecture and generated the clock signal
Clock signal
In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is utilized like a metronome to coordinate actions of circuits...
for the chip set.
The backup translation buffer was essentially a translation lookaside buffer
Translation Lookaside Buffer
A translation lookaside buffer is a CPU cache that memory management hardware uses to improve virtual address translation speed. All current desktop and server processors use a TLB to map virtual and physical address spaces, and it is ubiquitous in any hardware which utilizes virtual memory.The...
(TLB) which handled a miss in the MTB. The BTB contained 512 page table entries
Page table
A page table is the data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses. Virtual addresses are those unique to the accessing process...
(PTEs), of which 256 were for system-space pages and 256 were for process-space pages. There are 128 BTB tags, one for every four PTEs, located in the M chip. The BTB was implemented with external RAMs.
There are 26 internal processor registers, which are used by the microcode for temporary storage when executing complex instructions requiring multiple cycles.
The M chip consisted of 54,000 transistors on a die measuring 339 mil by 332 mil (8.61 mm by 8.43 mm) for an area of 112,548 mil2 (72.61 mm2). It dissipated 3 W.
F chip
The F chip (DC330) contained a floating-point unit (FPU). It supported most VAX floating-point instructions and the f_floating, d_floating and g_floating data types defined in the VAX architecture and was also responsible for executing integer divide and multiply instructions. The F chip received opcodeOpcode
In computer science engineering, an opcode is the portion of a machine language instruction that specifies the operation to be performed. Their specification and format are laid out in the instruction set architecture of the processor in question...
s from the I/E chip and microinstructions from the control store over the MIB bus. Operand
Operand
In mathematics, an operand is the object of a mathematical operation, a quantity on which an operation is performed.-Example :The following arithmetic expression shows an example of operators and operands:3 + 6 = 9\;...
s were received from the memory or the general purpose registers over the DAL bus, which is also used to write back results. It consisted of 29,600 transistors on a 341 mil by 288 mil die (8.66 mm by 7.32 mm) for an area of 98,208 mil2 (63.36 mm2). It dissipated 2.5 W.
The F chip was a derivative of the FPA, which belonged to the J-11
DEC J-11
The J-11 is a microprocessor chip set that implements the PDP-11 instruction set architecture jointly developed by Digital Equipment Corporation and Harris Semiconductor. It was a high-end chip set designed to integrate the performance and features of the PDP-11/70 onto a handful of chips...
microprocessor chip set, an implementation of the PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
. The F chip was supposed to be a completely new design developed for the V-11, but was cancelled in favor of a derivative as part of an effort to simplify the V-11 so it could be completed quicker as development of the MicroVAX 78032
MicroVAX 78032
The MicroVAX 78032 is a microprocessor developed and fabricated by Digital Equipment Corporation that implemented a subset of the VAX instruction set architecture . The 78032 was used exclusively in DEC's VAX-based systems, starting with the MicroVAX II in 1985...
had begun.
Cache
The V-11 has an external 8 KB primary cacheCPU cache
A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations...
. The cache was physically addressed and has a 64-byte cache block.
Physical
The V-11 chip set contained a total of 1,183,600 transistors spread over nine dieDie (integrated circuit)
A die in the context of integrated circuits is a small block of semiconducting material, on which a given functional circuit is fabricated.Typically, integrated circuits are produced in large batches on a single wafer of electronic-grade silicon or other semiconductor through processes such as...
s fabricated in Digital's ZMOS process, a 3.0 µm NMOS
NMOS logic
N-type metal-oxide-semiconductor logic uses n-type metal-oxide-semiconductor field effect transistors to implement logic gates and other digital circuits...
process with two levels of interconnect.
Further reading
- Johnson, W.N.; Herrick, W.V.; Grundmann, W.J. (October 1984). "A VLSI VAX chip set". IEEE Journal of Solid-State Circuits 19 (5): 663–674.
- Johnson, W. (February 1984). "A VLSI superminicomputer CPU". ISSCC Digest of Technical Papers: 174–175.