Intersil 6100
Encyclopedia
The Intersil 6100 family consisted of a 12-bit
microprocessor
(the 6100) and a range of peripheral support and memory ICs developed in the mid-1970s.
The microprocessor
recognised the PDP-8
instruction set.
As such it was sometimes referred to as the CMOS-PDP8.
Since it was also produced by Harris Corporation, it was also known as the Harris HM-6100. The Intersil 6100 was introduced in the second quarter of 1975,
and the Harris version in 1976.
By virtue of its CMOS technology and associated benefits, the 6100 was being incorporated into some military designs until the early 1980s.
The 6100 family was produced using CMOS rather than the bipolar and NMOS
technologies used by its contemporaries (Z80, 8080, 6800, 9900, etc.).
As a result of its CMOS technology and low clock speeds (8 MHz max. for the Harris HM-6100A), it had relatively low power consumption (less than 100 mW at 10V/2 MHz) and could be operated from a single supply over the wide range of 4-11V.
Thus, it could be used in high reliability embedded system
s without the need for any significant thermal management, if the rest of the system was also CMOS.
The 6100 family was used in a number of products, including the DECmate
line, DEC
's first attempt to produce a personal computer
.
The 6100 was available to military specification and since it was dual sourced by Intersil and Harris, it was used in some military products as a low power alternative to the 8080, 6800 etc.
Although it had a very simple instruction set and architecture, it was eminently suitable for use in systems that had previously used discrete logic circuits and even relay based controllers.
Intersil
sold the integrated circuits commercially through 1982 as the IM6100 family. It was not priced competitively, and the offering failed. The IBM PC
s in 1981 cemented the doom of the CMOS-8s by making a legitimate, well-supported small microprocessor computer.
Although this family of ICs had less logic than many competitors, and could have had smaller silicon and therefore undersold competitors, it used CMOS, then a larger technology, and failed.
(See PDP-8
for a more complete discussion). It had three primary registers: PC (program counter
), 12-bit AC (accumulator
), and MQ. All 2-operand instructions read AC and MQ and wrote back to AC. There was no stack pointer; subroutines were returned by jumping back into the main code, typically by storing the return address in the first word of the subroutine itself.
Conditionals in the 6100 only allowed the next instruction to be skipped. Branches were constructed with a conditional and a following jump. There is only one maskable interrupt. When the interrupt is tripped, the CPU stores the current PC in 0000h, and then jumps to the location stored in 0001h. The interrupt can be disabled or enabled using IOF and ION (or SKON) instructions.
The 6100 had a 12-bit data/address bus, limiting RAM to only 4K words (6 kB). Memory references were 7-bit, offset either from address 0, or from the PC page base address (obtained by setting the seven least significant bits of PC to zero). Memory could be expanded using the optional 6102 support chip, which added three address lines and thus expanded memory to 32K words (48 kB) in the same way that the PDP-8/E expanded the PDP-8. The 6102 had two internal registers, IFR (instruction frame) and DFR (data) that offset the 4K page when the CPU accessed memory.
The IM6100 CPU was a straight-8 (basic PDP-8 without memory mapping hardware).
The IM6101 PIE (Programmable/Parallel/Peripheral Interface Element was a basic PDP-8 I/O port.
The IM6103 memory extension, DMA and interval timer converted an IM6100 into something resembling a PDP-8/E's CPU.
The IM6103 parallel I/O, and IM6402 UART were basic PDP-8 I/O devices on ICs.
Intersil also offered compatible sizes of RAM
and ROM
: the 6561 1 kB (256x4) SRAM, and the 6312 12kB (1kx12) mask programmable PROM
.
The basic 6100 was later upgraded to the 6120, which had the 6102 memory controller built-in.
A selection of these components were offered as the Intersil 6960 "IM6100 CMOS Family Sampler", a single-board system.
12-bit
Possibly the best-known 12-bit CPU is the PDP-8 and its relatives, produced in various incarnations from August 1963 to mid-1990. Many ADCs have a 12-bit resolution. Some PIC microcontrollers use a 12-bit word size....
microprocessor
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...
(the 6100) and a range of peripheral support and memory ICs developed in the mid-1970s.
The microprocessor
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...
recognised the PDP-8
PDP-8
The 12-bit PDP-8 was the first successful commercial minicomputer, produced by Digital Equipment Corporation in the 1960s. DEC introduced it on 22 March 1965, and sold more than 50,000 systems, the most of any computer up to that date. It was the first widely sold computer in the DEC PDP series of...
instruction set.
As such it was sometimes referred to as the CMOS-PDP8.
Since it was also produced by Harris Corporation, it was also known as the Harris HM-6100. The Intersil 6100 was introduced in the second quarter of 1975,
and the Harris version in 1976.
By virtue of its CMOS technology and associated benefits, the 6100 was being incorporated into some military designs until the early 1980s.
The 6100 family was produced using CMOS rather than the bipolar and 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...
technologies used by its contemporaries (Z80, 8080, 6800, 9900, etc.).
As a result of its CMOS technology and low clock speeds (8 MHz max. for the Harris HM-6100A), it had relatively low power consumption (less than 100 mW at 10V/2 MHz) and could be operated from a single supply over the wide range of 4-11V.
Thus, it could be used in high reliability embedded system
Embedded system
An embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...
s without the need for any significant thermal management, if the rest of the system was also CMOS.
The 6100 family was used in a number of products, including the DECmate
DECmate
DECmate was the name of a series of PDP-8-compatible computers produced by the Digital Equipment Corporation in the late 1970s and early 1980s. All of the models used an Intersil 6100 or Harris 6120 microprocessor which emulated the 12-bit DEC PDP-8 CPU...
line, DEC
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...
's first attempt to produce a personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
.
The 6100 was available to military specification and since it was dual sourced by Intersil and Harris, it was used in some military products as a low power alternative to the 8080, 6800 etc.
Although it had a very simple instruction set and architecture, it was eminently suitable for use in systems that had previously used discrete logic circuits and even relay based controllers.
Intersil
Intersil
Intersil Corporation is an American company that specializes in the design, development and manufacturing of high-performance analog semiconductors for four high-growth markets — Communications, Computing, High End Consumer and Industrial.-Company history:...
sold the integrated circuits commercially through 1982 as the IM6100 family. It was not priced competitively, and the offering failed. The IBM PC
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
s in 1981 cemented the doom of the CMOS-8s by making a legitimate, well-supported small microprocessor computer.
Although this family of ICs had less logic than many competitors, and could have had smaller silicon and therefore undersold competitors, it used CMOS, then a larger technology, and failed.
Description
The 6100 had a 12 bit CPU and closely emulated the PDP-8PDP-8
The 12-bit PDP-8 was the first successful commercial minicomputer, produced by Digital Equipment Corporation in the 1960s. DEC introduced it on 22 March 1965, and sold more than 50,000 systems, the most of any computer up to that date. It was the first widely sold computer in the DEC PDP series of...
(See PDP-8
PDP-8
The 12-bit PDP-8 was the first successful commercial minicomputer, produced by Digital Equipment Corporation in the 1960s. DEC introduced it on 22 March 1965, and sold more than 50,000 systems, the most of any computer up to that date. It was the first widely sold computer in the DEC PDP series of...
for a more complete discussion). It had three primary registers: PC (program counter
Program counter
The program counter , commonly called the instruction pointer in Intel x86 microprocessors, and sometimes called the instruction address register, or just part of the instruction sequencer in some computers, is a processor register that indicates where the computer is in its instruction sequence...
), 12-bit AC (accumulator
Accumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...
), and MQ. All 2-operand instructions read AC and MQ and wrote back to AC. There was no stack pointer; subroutines were returned by jumping back into the main code, typically by storing the return address in the first word of the subroutine itself.
Conditionals in the 6100 only allowed the next instruction to be skipped. Branches were constructed with a conditional and a following jump. There is only one maskable interrupt. When the interrupt is tripped, the CPU stores the current PC in 0000h, and then jumps to the location stored in 0001h. The interrupt can be disabled or enabled using IOF and ION (or SKON) instructions.
The 6100 had a 12-bit data/address bus, limiting RAM to only 4K words (6 kB). Memory references were 7-bit, offset either from address 0, or from the PC page base address (obtained by setting the seven least significant bits of PC to zero). Memory could be expanded using the optional 6102 support chip, which added three address lines and thus expanded memory to 32K words (48 kB) in the same way that the PDP-8/E expanded the PDP-8. The 6102 had two internal registers, IFR (instruction frame) and DFR (data) that offset the 4K page when the CPU accessed memory.
Versions and supporting hardware
Intersil offered a variety of related chips to support 6100 systems.The IM6100 CPU was a straight-8 (basic PDP-8 without memory mapping hardware).
The IM6101 PIE (Programmable/Parallel/Peripheral Interface Element was a basic PDP-8 I/O port.
The IM6103 memory extension, DMA and interval timer converted an IM6100 into something resembling a PDP-8/E's CPU.
The IM6103 parallel I/O, and IM6402 UART were basic PDP-8 I/O devices on ICs.
Intersil also offered compatible sizes of RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
and ROM
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...
: the 6561 1 kB (256x4) SRAM, and the 6312 12kB (1kx12) mask programmable PROM
PROM
PROM may refer to:*Phosphate rich organic manure*Premature rupture of membranes, an obstetric term*PROM-1 land mine*Programmable read-only memory, related to electronics...
.
The basic 6100 was later upgraded to the 6120, which had the 6102 memory controller built-in.
A selection of these components were offered as the Intersil 6960 "IM6100 CMOS Family Sampler", a single-board system.
External links
- "Intersil 6100 microprocessor architecture", CPU World
- Intersil, "IM6100 CMOS Family Sampler"