Jump to content

Apple Display Card 4•8

From RetroTechCollection
Apple Macintosh Display Card 4•8
Apple Macintosh Display Card 4-8 Rev B (Apple Module Identification 1994)
The Rev. B card (661-0677) in Apple's 1994 module identification manual; the lines mark the two VRAM SIMM sockets
Manufacturer Apple Computer
Type 8-bit NuBus display card
Release date March 1990
Interface NuBus, DB-15 video connector
Compatible Macintosh II family and Quadra computers with a NuBus slot
Power 7 W
Part number 661-0607 (Rev. A), 661-0677 (Rev. B)

The Apple Macintosh Display Card 4•8 is an 8-bit NuBus display card for the Macintosh II family with 512K of video RAM. It gives 256 colours on the AppleColor High-Resolution RGB Monitor, 256 grey levels on the High-Resolution Monochrome Monitor and 16 greys on the Portrait and Two-Page displays.[1][2] Apple introduced it in March 1990 with the Display Card 8•24, and the two cards share their specification sheet, frame buffer controller and connector.[3][4][5] Adding two VRAM SIMMs brings a 4•8 up to 8•24 performance: 1 MB of VRAM, 24-bit colour and 256 greys on every Apple display.[1][6]

The Apple Display Card 8•24 page carries the material common to both cards: the hardware description, interlaced video and NTSC use, monitor sense codes and the DB-15 pinout.

Specifications

[edit | edit source]
Macintosh Display Card 4•8
Item Specification
Interface NuBus, slave block transfers supported
Video RAM 512K; two sockets for 256K VRAM SIMMs
Pixel depths 1, 2, 4 or 8 bits per pixel (24 after the VRAM upgrade)
Maximum resolution 1152 × 870
Convolution None
Vertical refresh 66.7 or 75 Hz, depending on display
Power consumption 7 W
System software System 6.0.5 or later; 32-bit QuickDraw on the Macintosh II, IIx and IIcx

Figures from Apple's specification sheet and technical procedures.[4][5][1]

Display modes

[edit | edit source]
4•8 display modes as shipped (Apple data sheet)
Display Resolution Colours or greys
Apple High-Resolution Monochrome Monitor 640 × 480 2, 4, 16 or 256 greys
AppleColor High-Resolution RGB Monitor 640 × 480 2, 4, 16 or 256 colours
Apple Portrait Display 640 × 870 2, 4 or 16 greys
Apple Two-Page Monochrome Monitor 1152 × 870 2, 4 or 16 greys
Interlaced video devices 640 × 480 2, 4, 16 or 256 colours

The table is from Apple's specification sheet.[4] Apple's 1996 service guide adds the later displays for the 4•8: 256 colours on the Basic Color Monitor, Color Plus 14", Performa displays and multiple scan displays at 640 × 480; 256 colours on the 16-inch Color Display and, with a Rev. B ROM and a display adapter, on multiple scan displays at 832 × 624; 16 colours at 1152 × 870 on the 21-inch display and on the Multiple Scan 20 with an adapter; and no support at 1024 × 768 or 1280 × 1024. The same chart marks the 12-inch RGB Display as unsupported.[7] Without an adapter a multiple scan display stays at 640 × 480 unless System 7.5 is installed.[7][3]

Revisions

[edit | edit source]
4•8 revisions
Revision Service part ROM part Notes
A 661-0607 – Exchanged for 661-0677
B 661-0677 341-0868 Page-white colour correction for the 21-inch Color Display

A Rev. A card takes the same ROM upgrade as the 8•24, kit 076-0548. Tell the revisions apart by the part number on the ROM.[8][7]

VRAM upgrade

[edit | edit source]

The Macintosh Display Card VRAM Kit holds two VRAM SIMMs; Apple's service part for each is 661-0609, 256K at 100 ns. With both fitted, a Rev. B 4•8 (661-0677) becomes equivalent to a Rev. B 8•24 (661-0678).[1][8][7]

  1. Work on a grounded bench with a wrist strap.
  2. Check that each SIMM has "VRAM" or "Video" printed on the component side.
  3. Remove the card and fit the two SIMMs in the sockets.
  4. Refit the card and connect the monitor.
  5. Switch on and look for a dark or broken-up screen. If there is one, go to the troubleshooting checklist below.
  6. Open the Monitors control panel. On a Two-Page display it should offer Black & White/Grays with up to 256 greys; on an AppleColor High-Resolution RGB it should offer Colors up to 16.7 million.

The procedure is Apple's.[1] Remove the VRAM SIMMs before returning a card to Apple for exchange.[8]

Compatibility

[edit | edit source]
  • System 6.0.5 or later is needed; the Macintosh II, IIx and IIcx also need the 32-bit QuickDraw file for 24-bit work after the VRAM upgrade.[6]
  • Apple's 1996 service guide lists the Rev. B card for all Macintosh II and Quadra computers.[7] The card works in the Quadra 840AV, where Apple recommends the Rev. B ROM for the 16-inch and 21-inch displays.[9] Low End Mac reports that it does not suit the Centris and Quadra 660AV.[3]
  • An 8•24 GC in the same machine accelerates drawing on the 4•8 through NuBus block transfers.[6]

Troubleshooting

[edit | edit source]

Apple's checklist for its Macintosh II video cards, in order:[1][7]

  1. Reseat the card.
  2. Reseat the VRAM SIMMs, if fitted.
  3. Check the video cable connections.
  4. Run the video tests. Apple specified MacTest IIfx for the 4•8.
  5. Replace the VRAM SIMMs with known-good ones.
  6. Replace the card.

The 4•8 has no convolution, so an interlaced picture flickers on thin horizontal lines; that is normal for this card.[5]

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Apple Computer, Apple Service Technical Procedures: Macintosh Family, Volume Four (March 1991), "Macintosh Family Cards" section 2, "Macintosh II Video Cards": product descriptions p. 2.4 (rev. Nov 1990); Macintosh Display Card 4/8 upgrade pp. 2.10-2.11 (Jun 1990); troubleshooting video/display cards p. 2.12; illustrated parts list pp. IPL.13-IPL.15. Archive.org item Apple_Service_Technical_Procedures_Macintosh_Family_Volume_Four_1991-03_Apple_PN_072-0228 (retrieved 2026-10-04).
  2. ↑ Apple Computer, "Macintosh Display Cards Overview (1 of 3)", Tech Info Library article 5210 (TA40921), revised 16 July 1990, last reviewed 19 March 1990. In the archive.org collection Apple's Technical Information Library Articles, file TIL00001_to_TIL09432.pdf. Source for: the 4•8 supporting 256 colours or greys on the High-Resolution Monochrome and AppleColor High-Resolution RGB monitors and 16 greys on the Portrait and Two-Page displays; the 8•24 and 8•24 GC supporting 256 true greys on all Apple displays and 24-bit colour on the AppleColor High-Resolution RGB; RS-170 timing on all three cards; Apple Convolution on the 8•24 and 8•24 GC; programmable pixel clock and 100 MHz oscillator; 512K of VRAM on the 4•8 and 1 MB on the 8•24.
  3. ↑ 3.0 3.1 3.2 Low End Mac, "Macintosh Display Card 4•8", https://lowendmac.com/1990/macintosh-display-card-4-8/ (retrieved 2026-10-04). Source for: introduction in March 1990; 12-inch card; incompatibility with the Centris and Quadra 660AV; no resolution switching without an adapter on multiple scan displays; Rev. B adding 832 × 624 at 8 bits.
  4. ↑ 4.0 4.1 4.2 Apple Computer, "Display Card 4/8 and 8/24 Specifications (Discontinued)", Tech Info Library article 5422, revised 20 June 1994 (change history 28 June 1993), file TIL00001_to_TIL09432.pdf in the APPLE_TIL_ARTICLES collection. Source for: system requirements; NuBus slave block transfer; 15-pin connector; 1, 2, 4, 8 or 24 bits per pixel; resolution up to 1152 × 870; convolution on the 8•24 up to 8 bits; RS-343 video with RS-170 interlaced timing; sync; 66.7 or 75 Hz vertical refresh; dot clocks of 12.2727, 30.24, 57.2832 and 100 MHz; 7 W power consumption; display modes for each card.
  5. ↑ 5.0 5.1 5.2 Apple Computer, "Macintosh Display Cards Overview (2 of 3)", Tech Info Library article 5205 (TA40917), revised 16 July 1990, file TIL00001_to_TIL09432.pdf in the APPLE_TIL_ARTICLES collection. Source for: convolution (1:2:1 weighting) on the 8•24 up to 8 bits per pixel and none on the 4•8; overscan mode of 512 × 384; the frame buffer controller gate array and its address translation, fitting 24-bit 640 × 480 into just over 900K of VRAM; the 8•24 GC keeping the alpha byte; the GC's Am29000, IPC and 5 to 30 times acceleration.
  6. ↑ 6.0 6.1 6.2 Apple Computer, "Macintosh Display Cards Overview (3 of 3)", Tech Info Library article 5818 (TA43882), revised 16 July 1990, file TIL00001_to_TIL09432.pdf in the APPLE_TIL_ARTICLES collection. Source for: NuBus block transfer (master and slave on the 8•24 GC, slave only on the 4•8 and 8•24); the 8•24 GC accelerating other frame buffers, best on the 4•8 and 8•24; one GC accelerator per system; the VRAM Kit and DRAM Expansion Kit; System 6.0.5 and 32-bit QuickDraw requirements; the DB-15 to DB-25 adaptor for existing Portrait and Two-Page displays; A/UX; 20 W maximum for the GC and NuBus power budgets of 90 W (six-slot) and 45 W (three-slot); original Macintosh II ROMs; DB-15 pinout and DB-15 to DB-25 adaptor wiring.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Apple Computer, Macintosh Displays and Video Cards service guide, September 1996, hosted as File:Apple Macintosh Displays and Video Cards Service Guide (September 1996).pdf (described at Apple Macintosh Displays and Video Cards Service Guide (1996)). Line drawings of the 4/8, 8/24 and 8/24 GC p. 324; video card parts list and notes pp. 325-326; troubleshooting chart p. 327; 4•8 and 8•24 GC upgrade procedures p. 330; Table 16, "Video Cards–Card Compatibility and Video Output Chart", pp. 342-343.
  8. ↑ 8.0 8.1 8.2 Apple Computer, Module Identification, Apple Service part number 072-8124, June 1994, hosted as File:Apple Service Module Identification Manual (June 1994).pdf, "Interface Cards" section: Display Card 8•24 pp. 4.1.8-4.1.9 (PDF pages 232-233), Display Card 4•8 pp. 4.1.10-4.1.11 (PDF pages 234-235), Display Card 8•24 GC p. 4.1.12 (PDF page 236).
  9. ↑ Apple Computer, "AV Series: Apple NuBus Video Card Compatibility", Tech Info Library article 14695 (TA31196), file TA30000-TA39999.pdf in the APPLE_TIL_ARTICLES collection. Source for: the 4•8 and 8•24 (Rev. A and B) compatible with the Quadra 840AV, with the Rev. B ROM recommended for the 16-inch and 21-inch color monitors; the 8•24 GC Rev. A incompatible and Rev. B compatible only unaccelerated; the 24AC compatible with the 660AV and 840AV.


Retrieved from "https://retrotechwiki.com/index.php?title=Apple_Display_Card_4•8&oldid=23577"