Intel 8237 and Related Topics

Motherboard of a NeXTcube computer (1990). The two large integrated circuits below the middle of the image are the DMA controller (l.) and - unusual - an extra dedicated DMA controller (r.) for the magneto-optical disc used instead of a hard disk drive in the first series of this computer model.

Direct memory access

Feature of computer systems and allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU).

In the original IBM PC (and the follow-up PC/XT), there was only one Intel 8237 DMA controller capable of providing four DMA channels (numbered 0–3).

IBM Personal Computer

First microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard.

Internal view of a PC compatible computer, showing components and layout.

Original IBM Personal Computer motherboard

IBM Personal Computer with IBM CGA monitor (model 5153), IBM PC keyboard, IBM 5152 printer and paper stand. (1988)

The back of a PC, showing the five expansion slots

Digital Research CP/M-86 Version 1.0 for the IBM PC

The peripheral chips included an Intel 8259 PIC, an Intel 8237 DMA controller, and an Intel 8253 PIT.

One 8-bit and five 16-bit ISA slots on a motherboard

Industry Standard Architecture

16-bit internal bus of IBM PC/AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s.

8-bit XT, 16-bit ISA, EISA (top to bottom)

16-bit ISA: Madge 4/16 Mbps Token Ring NIC

It has four DMA channels originally provided by the Intel 8237.

IBM Personal Computer/AT

Released in 1984 as the fourth model in the IBM Personal Computer line, following the IBM PC/XT and its IBM Portable PC variant.

The bus also offered fifteen IRQs and seven DMA channels, expanded from eight IRQs and four DMA channels for the PC, achieved by adding another 8259A IRQ controller and another 8237A DMA controller.

A rare Intel C8086 processor in purple ceramic DIP package with side-brazed pins

Intel 8086

16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released.

The 8086 pin assignments in min and max mode

Simplified block diagram over Intel 8088 (a variant of 8086); 1=main & index registers; 2=segment registers and IP; 3=address adder; 4=internal address bus; 5=instruction queue; 6=control unit (very simplified!); 7=bus interface; 8=internal databus; 9=ALU; 10/11/12=external address/data/control bus.

Intel 8237: direct memory access (DMA) controller

An Intel P8085AH-2 processor variant with black plastic and silver pins

Intel 8085

8-bit microprocessor produced by Intel and introduced in March 1976.

NZPP Novosibirsk IM1821VM85 (Soviet Union)

8237 – DMA Controller

PCI IDE ISA Xcelerator

Family of Intel southbridge microchips employed in some Intel chipsets.

The PIIX integrated an IDE controller with two 8237 DMA controllers, the 8254 PIT, and two 8259 PICs and a PCI to ISA bus bridge.

DOSBox emulates the command-line interface of DOS.

JPC (emulator)

X86 emulator written in pure Java.

Direct Memory Access Controller (DMA): Intel 8237

Two ATA motherboard sockets on the left, with an ATA connector on the right.

WDMA (computer)

The fastest method used to transfer data between the computer (through the ATA controller) and an ATA device until UDMA.

The explanation for the difference between single and multiword DMA can be found in how the Intel 8237 DMA chip works.

NEAT chipset

4 chip VLSI implementation (including the 82C206 IPC) of the control logic used in the IBM PC compatible PC/AT computers.

8237 DMA controller