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MOS Technology Agnus

File:Commodore Amiga 1000 - main board - MOS 8367R0-7824.jpg

The MOS Technology "Agnus", usually called Agnus, is an integrated circuit in the custom chipset of the Amiga computer. The Agnus, Denise and Paula chips collectively formed the OCS and ECS chipsets.

The Agnus is the Address Generator Chip. Its main function, in chip area, is the RAM Address Generator and Register Address Encoder which handles all DMA addresses. The 8361 Agnus is made up of approximately 21000 transistors and contains DMA Channel Controllers. The Blitter and Copper are also contained here. Originally Agnus was fabricated in 5 μm manufacturing process like all OCS chipset.

Agnus features:

  • Memory controller ("Chip" memory that can be accessed by the processor and the chipset)
  • The Blitter, a bitmap manipulator. The Blitter is capable of copying blocks of display data, or any arbitrary data in the chip memory, at high speed with various raster operations as well as drawing pixel perfect lines and filling outlined polygons, while freeing the CPU for concurrent tasks.
  • "Copper", a display synchronized co-processor
  • 25 Direct Memory Access (DMA) channels, allowing graphics, sound and I/O to be used with minimal CPU intervention
  • DRAM refresh controller
  • Generates the system clock from the 28 MHz oscillator
  • Video timing

Agnus was replaced by Alice in the Amiga 4000 and Amiga 1200 when the AGA chipset was introduced in 1992.

Chips by capability

File:CBM 8370R3 top metal.jpg

* Somewhere 8372A Agnus mentioned as simply "8372".

Chips by package

  • 48-lead DIP Agnus (aka thin Agnus): 8361; 8367
  • 84-contact PLCC Fat Agnus (named Fat Lady on most Amiga 2000 motherboards) 8370; 8371; 8372; 8372A; 8372AB; 8372B; 8375

Notes
Fat Agnus 1MB and Fat Agnus 2MB also known as Super Agnus; Super Fat Agnus; Fatter Agnus; Big Agnus; Big Fat Agnus.

DMA Channels

class="wikitable"

! Priority !! Name !! Count !! Cycles/Rasterline !! Chip !! Notes

| MPU

| 1

| varying

| CPU

|

A

| Blitter

| 4

| varying

| Agnus (internal)

| yields 1/4 cycles to CPU when BLTPRI not active

B

| Bitplane

| 6

| 80

| Denise

| impairs sprite channels on severe overscan

C

| Copper

| 1

| varying

| Agnus (internal)

|

D

| Audio

| 4

| 4

| Paula

|

E

| Sprites

| 8

| 16

| Denise

|

F

| Disk

| 1

| 3

| Paula

|

G

| Memory Refresh

| 1

| 4

| -

|

colspan="5" | Reference: Amiga 500 plus Service Manual

Pinout

= PLCC versions =

When replacing or upgrading chips, pinouts need to be taken care of. Types are just mentioned for reference; four-digit types and pinouts/usage are not consistent.{{cite newsgroup

| title = Difference of 8372A vs 8375

| author = George Robbins

| date = 14 October 1992

| newsgroup = comp.sys.amiga.hardware

| message-id = 35861@cbmvax.commodore.com

| url = http://groups.google.co.uk/group/comp.sys.amiga.hardware/msg/259d7e187bd3b044

| access-date = 1 October 2018

}}

class="wikitable"
rowspan=3 | Pin

!OCS/ECS

!colspan=2 | ECS

!AGA (Alice)

! rowspan=3 | Description

A500/2000

!A3000

!A500+/600

!A4000/1200

8370/1

|8372

|8375

|8374

1

|RD13

|DRD13

|DRD13

|DRD13

|Data Bus 16 bit, bit 13

2

|RD12

|DRD12

|DRD12

|DRD12

|rowspan=12 style="text-align: center" | .
.
.

3

|RD11

|DRD11

|DRD11

|DRD11

4

|RD10

|DRD10

|DRD10

|DRD10

5

|RD9

|DRD9

|DRD9

|DRD9

6

|RD8

|DRD8

|DRD8

|DRD8

7

|RD7

|DRD7

|DRD7

|DRD7

8

|RD6

|DRD6

|DRD6

|DRD6

9

|RD5

|DRD5

|DRD5

|DRD5

10

|RD4

|DRD4

|DRD4

|DRD4

11

|RD3

|DRD3

|DRD3

|DRD3

12

|RD2

|DRD2

|DRD2

|DRD2

13

|RD1

|DRD1

|DRD1

|DRD1

14

|RD0

|DRD0

|DRD0

|DRD0

|Data Bus 16 bit, bit 0

15

|Vcc

|Vcc

|Vcc

|Vcc1

| +5V ±5%

16

|RST*

|_RESET

|_RESET

|/RESET

|Global RESETn, low active

17

|INT3

|_INTR

|_INTR

|/INTR

18

|DMAL

|DMAL

|DMAL

|DMAL

19

|BLS*

|_BLISS

|_BLISS

|/BLS

20

|DBR*

|_BLIT

|_BLIT

|/DBR

21

|RRW

|_WE

|_WE

|/WE

22

|PRW

|R/W

|R/W

|R/W

23

|RGEN*

|_REGEN

|_REGEN

|_REGEN

24

|AS*

|_AS

|_AS

|NC2

25

|RAMEN*

|_RAMEN

|_RAMEN

|/RAMEN

26

|RGA8

|RGA8

|RGA8

|RGA8

27

|RGA7

|RGA7

|RGA7

|RGA7

28

|RGA6

|RGA6

|RGA6

|RGA6

29

|RGA5

|RGA5

|RGA5

|RGA5

30

|RGA4

|RGA4

|RGA4

|RGA4

31

|RGA3

|RGA3

|RGA3

|RGA3

32

|RGA2

|RGA2

|RGA2

|RGA2

33

|RGA1

|RGA1

|RGA1

|RGA1

34

|28 MHz

|28 MHz

|28 MHz

|SCLK

35

|XCLK

|A20

|A20

|A20

36

|XCLKEN*

|_XCLKEN

|_CDAC

|14 MHz

37

|CDAC*

|_CDAC

|7 MHz

|/CDAC

38

|7 MHz

|7 MHz

|CCKQ

|7 MHz

39

|CCKQ

|CCKQ

|CCK

|CCKQ

40

|CCK

|CCK

|14M

|CCK

41

|TEST

|TEST

|GND

|/NTSC

42

|Vss

|Vss1

|DRA0

|GND2

43

|MA0

|DRA0

|DRA1

|DRA0

|Memory address bus 9 bit, bit 0 (except 8375 which is bit 1)

44

|MA1

|DRA1

|DRA2

|DRA1

|rowspan=7 style="text-align: center" | .
.
.

45

|MA2

|DRA2

|DRA3

|DRA2

46

|MA3

|DRA3

|DRA4

|DRA3

47

|MA4

|DRA4

|DRA5

|DRA4

48

|MA5

|DRA5

|DRA6

|DRA5

49

|MA6

|DRA6

|DRA7

|DRA6

50

|MA7

|DRA7

|DRA8

|DRA7

51

|MA8

|DRA8

|_LDS

|DRA8

|Memory address bus 9 bit, bit 8 (except 8375 which is bit _LDS)

52

|LDS*

|_LDS

|_UDS

|Vcc2

53

|UDS*

|_UDS

|_CASL

|NC1

54

|CASL*

|_CASL

|_CASU

|/CAS

55

|CASU*

|_CASU

|DRA9

|Vbb

56

|RAS1*

|DRA9

|_RAS1

|DRA9

57

|RAS0*

|_RAS

|_RAS0

|/RAS

58

|Vss

|Vss2

|GND

|GND3

59

|A19

|A19

|A19

|A19

60

|A1

|A1

|A1

|A1

61

|A2

|A2

|A2

|A2

62

|A3

|A3

|A3

|A3

63

|A4

|A4

|A4

|A4

64

|A5

|A5

|A5

|A5

65

|A6

|A6

|A6

|A6

66

|A7

|A7

|A7

|A7

67

|A8

|A8

|A8

|A8

68

|A9

|A9

|A9

|A9

69

|A10

|A10

|A10

|A10

70

|A11

|A11

|A11

|A11

71

|A12

|A12

|A12

|A12

72

|A13

|A13

|A13

|A13

73

|A14

|A14

|A14

|A14

74

|A15

|A15

|A15

|A15

75

|A16

|A16

|A16

|A16

76

|A17

|A17

|A17

|A17

77

|A18

|A18

|A18

|A18

78

|LP*

|_LPEN

|_LPEN

|/LPEN

79

|VSY*

|_VSYNC

|_VSYNC

|/VSYNC

80

|CSY*

|_CSYNC

|_CSYNC

|/CSYNC

81

|HSY*

|_HSYNC

|_HSYNC

|/HSYNC

82

|Vss

|Vss3

|GND

|GND1

|Ground, common on whole board

83

|RD15

|DRD15

|DRD15

|DRD15

|Data Bus 16 bit, bit 15

84

|RD14

|DRD14

|DRD14

|DRD14

|Data Bus 16 bit, bit 14

References: A500 Service Training, A3000 Service Manual, A500+ Service Manual, A1200 schematics

See also

{{Portal|Amiga}}

References

;Sources

  • AMIGA 1000 ASSEMBLY LEVEL REPAIR (Commodore-Amiga, Inc.) 1985 PN 314038-01 [https://web.archive.org/web/20060514232237/http://www.shiftreload.com.au/users/4x4/schematics/index.html Dave's Amiga Schematics and Manuals]
  • Commodore Amiga A500/A2000 Technical Reference Manual (Commodore-Amiga, Inc.) 1987 [https://web.archive.org/web/20060514232237/http://www.shiftreload.com.au/users/4x4/schematics/index.html Dave's Amiga Schematics and Manuals]
  • A500 SYSTEM SCHEMATICS COMPONENT PART LIST (Rev 6A/7) [https://web.archive.org/web/20060514232237/http://www.shiftreload.com.au/users/4x4/schematics/index.html Dave's Amiga Schematics and Manuals]
  • A3000 SYSTEM SCHEMATICS (Commodore Business Machines, Inc.) March, 1990 PN-314677-01 [https://www.1000bit.it/support/schema/commodore/a3000/A3000_schemas.pdf www.1000bit.net]
  • CDTV SERVICE MANUAL (Commodore International Spare GmbH) May, 1991 PN-400403-01 [https://web.archive.org/web/20070928222058/http://www.ianstedman.co.uk/Downloads/cdtv-schematics.zip www.ianstedman.co.uk (ZIP-file)]
  • A500 PLUS SERVICE MANUAL (Commodore International Spare GmbH) October, 1991 PN-400420-01 [https://www.1000bit.it/support/manuali/commodore/a500plus_sm/amiga500plus_sm.pdf www.1000bit.net]
  • A600 SYSTEM SCHEMATICS (Commodore International Spare GmbH) April, 1992 PN-400422-02 [http://www.1000bit.it/support/manuali/commodore/a600_sm/a600_sm.pdf www.1000bit.net]
  • [http://obligement.free.fr/articles/chipsetamiga.php OBLIGEMENT: les chipsets de l'Amiga]
  • [https://bboah.com/index.php?action=artikel&cat=51&id=2174 Big Book of Amiga Hardware]
  • alexh on [https://web.archive.org/web/20071118092300/http://eab.abime.net/archive/index.php/t-21961.html English Amiga Board] (Agnus 8372B info)
  • National Amiga Inc. [http://l8r.net/technical/t-achips.shtml mirrored on l8r.net]
  • [http://members.chello.hu/varga.gabor8/Amiga/ Marketed Commodore Amiga models]
  • [https://web.archive.org/web/20070928011404/http://www.titan.co.nz/Amigaak/AA060193.htm AMIGA Auckland Inc.]
  • [https://web.archive.org/web/20030425082107/http://amigau.com/natamiga/chipsandpartnumbers.htm Amiga University]
  • [https://web.archive.org/web/20070608013202/http://cbmmuseum.kuto.de/zusatz_8361_agnus.html Commodore Computer Online Museum]

;Notes

{{Reflist}}

{{Amiga hardware}}

{{DEFAULTSORT:Mos Technology Agnus}}

Category:MOS Technology integrated circuits

Category:Amiga