Sega Dreamcast
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| Dreamcast console and controller with a Visual Memory Unit (photo: Evan-Amos, CC BY-SA 3.0) | |
| Specifications | |
|---|---|
| Manufacturer | Sega Enterprises, Ltd. |
| Type | Home video game console |
| Released | 27 November 1998 (Japan) 9 September 1999 (North America) 14 October 1999 (Europe) 30 November 1999 (Australia)[1] |
| Discontinued | 31 March 2001[1] |
| Intro price | ¥29,000 (Japan) US$199 (North America) £200 (UK)[1] |
| Units sold | 9.13 million[1] |
| CPU | Hitachi SH-4, 200 MHz[2] |
| Memory | 16 MB main, 8 MB texture and frame buffer, 2 MB sound[2] |
| Storage | GD-ROM drive, CAV 4× to 12×[2] |
| Display | Composite, S-video, RGB and VGA[2] |
| Sound | Yamaha AICA (Sega 315-6119; 315-6232 on EU VA1 boards)[2][3] |
| Power | AC 100–120 V, 50/60 Hz, about 27 W (US model)[4] |
| Dimensions | About 7½ × 7¾ × 3 in (W × D × H)[4] |
| Weight | About 3 lb (1.4 kg)[4] |
| OS / Firmware | — |
| Predecessor | Sega Saturn (Model 2) |
| Model no. | HKT-3020 (North America)[4] |
The Sega Dreamcast is Sega's last home video game console, released in Japan on 27 November 1998 and in North America, Europe and Australia in late 1999. It uses a Hitachi SH-4 CPU, a NEC/VideoLogic PowerVR2 graphics chip that Sega's documents call HOLLY, a Yamaha AICA sound processor and Sega's GD-ROM optical drive. It has four controller ports and a modem on the expansion connector. Sega discontinued the Dreamcast on 31 March 2001, after 9.13 million had been sold.[2][1]
The mains power supply is inside the case. Saves are kept on the Visual Memory Unit, a memory card that plugs into the controller, and the console's own clock is held up by a rechargeable cell on the controller-port board.[3][5]
Specification
[edit | edit source]From Sega's block and clock diagrams unless noted.[2]
| Item | Figure |
|---|---|
| CPU | Hitachi SH-4, 200 MHz, 256-ball BGA. 3.3 V I/O; core supply from IC104 (see below) |
| Graphics | VideoLogic/NEC HOLLY, 100 MHz, 500-ball TBGA. 3.3 V I/O; core supply from IC106 |
| Sound | Yamaha AICA, 22/25 MHz, 3.3 V, 100-pin TQFP. Also holds the real-time clock |
| Program and data memory | 16 MB: two 64 Mbit SDRAMs, 100 MHz |
| Texture and frame buffer | 8 MB: four 16 Mbit SDRAMs, 100 MHz |
| Sound memory | 2 MB: one 16 Mbit SDRAM, on the AICA's own bus at 67.74 MHz |
| System ROM and flash | 2 MB mask ROM (16 Mbit) and 128 KB flash (1 Mbit), both 8-bit |
| Optical drive | GD-ROM, CAV, 4× to 12×, with 128 KB decode and buffer RAM. Fed with 12 V and 5 V |
| Video output | 24-bit RGB plus sync from HOLLY to a digital NTSC/PAL encoder; composite, S-video, RGB and VGA at the AV connector |
| Controller ports | Four Maple ports, 3.3 V input tolerance |
| Modem | 33.6 kbit/s on the original Japanese and all PAL consoles; 56 kbit/s on US consoles and on Japanese consoles sold after 9 September 1999[1] |
| Power | AC 100–120 V, 50/60 Hz, about 27 W (US HKT-3020)[4] |
Wikipedia gives the SH-4's performance as 360 MIPS and 1.4 GFLOPS.[1]
Power
[edit | edit source]The supply has three outputs, 3.3 V, 5 V and 12 V. The logic board makes two more from 3.3 V: the SH-4 core supply and the HOLLY core supply.[2]
| Rail | Where it is made | What it feeds |
|---|---|---|
| +12 V | Power supply, CN3 pin 1 | GD-ROM drive |
| +5 V | Power supply, CN3 pin 5 | GD-ROM drive; controller ports and fan[6] |
| +3.3 V | Power supply, CN3 pin 6 | Logic board, and the input to both core regulators |
| +1.95 V | IC104, PQ07VZ1H2Z series regulator | SH-4 core (the block diagram rounds it to 2.0 V) |
| +2.5 V or 2.7 V | IC106, RN5RG25A CMOS regulator | HOLLY core |
The CN3 pin order comes from the power supply schematic hosted here.[7] The regulator part numbers and outputs are from Sega's IC specifications. Sega pairs the IC106 variant with the HOLLY fitted: part 313-5612 with HOLLY 315-6201 or 315-6225, and 313-5553 (2.5 V) with 315-6226.[8] The 5 V feed to the four controller ports and the fan connector is on sub board 2, the controller-port board.[6]
Sega's service manual tells its repair centres to exchange the power supply unit as a whole and gives no parts list for it.[9] The EU console takes power unit 837-13774, "KTN PWR UNIT PANA EU V01".[10] console5 lists the capacitors of the 110 V and 220–240 V supplies; see Sega Dreamcast Capacitor Replacement Guide.
Buses and clocks
[edit | edit source]Sega groups the peripherals on three buses. G1 carries the GD-ROM (as EIDE) and the boot ROM and flash, with 5 V input tolerance. G2 is a 16-bit bus to the AICA, the modem and the expansion connector, with 3.3 V input tolerance. The Maple interface runs the four controller ports. Sega notes that G1 and G2 share one reset signal, used by every device except the ROM.[2]
A 13.5 MHz crystal, X302, drives the clock generator, which gives 33.33 MHz to the SH-4 and the 54 MHz pixel clock to HOLLY. The SH-4 and HOLLY talk at 100 MHz, and the main and texture SDRAMs run at 100 MHz. HOLLY sends 54 or 27 MHz to the video encoder and 25 MHz to the expansion connector. The AICA takes a 33.8688 MHz master clock, which the clock diagram draws coming from the GD-ROM side; it clocks its sound SDRAM at twice that, 67.74 MHz, and sends 11.29 MHz to the audio DAC. X301, at 32.768 kHz, is the real-time clock crystal.[2][11][12]
Reset follows the supply. Sega's reset diagram says that SRST "becomes active after power has stabilized for a minimum of 300mS"; HOLLY then releases the SH-4 and sends GRESETN to the AICA, the GD-ROM decoder and the expansion connector.[2]
Board revisions
[edit | edit source]The schematic sheets hosted here are VA0 drawings, and their clock generator at IC305 is a BU2179F.[11]
Sega's EU service manual covers the European VA1 boards 837-13820 and 837-13883 (each with a /01 variant) on PCB 171-7965C. On these boards IC305 is a W129A clock generator and IC301 is AICA part 315-6232. The audio DAC at IC303 is a PCM1725 on the 837-13820 and Sega part 315-6262 (PCM1722U) on the 837-13883. HOLLY at IC201 is 315-6201, 315-6225 or 315-6226.[3][8] console5 gives 837-13778 for the VA1 main board it lists.[13]
console5's capacitor list for the VA2.1 board adds positions CE701 and CE801 to CE809.[13]
Clock battery
[edit | edit source]The real-time clock inside the AICA is held up by a rechargeable lithium coin cell, BT1, on sub board 2, the controller-port board. Sega's parts list gives three alternatives for BT1: 401-0066, ML2032T26 (Hitachi); 401-0067, ML2020/G1B (Panasonic); and 401-0068, ML2430-VS1 (Sanyo).[3] The cell is fed from the B.VCC line through R1, 13 Ω 1 W.[6] Sega's US manual says the battery charges while the console is switched on, that the first charge takes about two hours, and that a charged battery keeps the date and time for about 20 days.[14] A plain CR2032 is a primary cell and should not go into this charging position; Sega's own caution is to replace the battery only with the same or an equivalent type.[9] See Battery Refurbishment.
Visual Memory Unit
[edit | edit source]Saves live on the Visual Memory Unit (VMU), which plugs into the controller and has its own LCD, buttons, 128 KB of flash (200 blocks for saves) and an 8-bit Sanyo CPU. It runs from two CR2032 cells when it is out of the controller. A VMU with flat cells still works as a memory card, but it beeps when the Dreamcast is switched on.[5]
Documentation
[edit | edit source]- Sega Service Manual: Dreamcast EU, No. 022-EU (October 1999): disassembly, block diagrams, schematics for the four EU VA1 main boards and the controller-port board, IC specifications, and mechanical and electrical parts lists. It has no power supply schematic or parts list.[3]
- Sega Dreamcast VA0 Schematics: the VA0 logic-board sheets, the block, clock and reset diagrams, a power supply schematic and the VA0 exploded view.
- Sega's US instruction manual, with the user troubleshooting chart and the ratings, is on archive.org.[4]
Related pages
[edit | edit source]- Sega Dreamcast Maintenance Guide
- Sega Dreamcast Troubleshooting Guide
- Sega Dreamcast Capacitor Replacement Guide
- Sega Dreamcast VA0 Schematics
- Battery Refurbishment
- Sega Saturn (Model 2)
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Wikipedia, "Dreamcast", retrieved 2026-10-01. Release dates, launch prices (Japan ¥29,000, citing Kent, The Ultimate History of Video Games, 2001, p. 563; US$199; UK £200), discontinuation on 31 March 2001, 9.13 million units sold, the SH-4's 360 MIPS and 1.4 GFLOPS, and the modem speeds.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Sega Enterprises, Ltd., Dreamcast Block Diagram, Dreamcast Clock Diagram and Dreamcast Reset Diagram, service manual sheets 7-1 to 7-3. Hosted on this wiki as File:Sega Dreamcast VA0 Block Diagram.pdf, File:Sega Dreamcast Clock Diagram.pdf and File:Sega Dreamcast Reset Diagram.pdf (see Sega Dreamcast VA0 Schematics); the same three sheets are pp. 7-1 to 7-3 of Sega's EU service manual No. 022-EU.
- ↑ 3.0 3.1 3.2 3.3 3.4 Sega Enterprises, Ltd., Service Manual: Dreamcast EU, No. 022-EU, October 1999, pp. 13-2 to 13-10, electrical parts list for main boards 837-13820, 837-13820/01, 837-13883 and 837-13883/01 and accessories list for sub board 2 (PCB 171-7946C). Hosted on this wiki as File:Sega Dreamcast EU Service Manual 022-EU.pdf.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Sega, Dreamcast instruction manual (US, 2000), p. 30, "Ratings and Specifications": Model HKT-3020, AC 100 V to 120 V 50/60 Hz, approximately 27 W, 41 to 95 °F, approximately 7 1/2 × 7 3/4 × 3 inches, approximately 3 pounds. Scanned at archive.org.
- ↑ 5.0 5.1 Wikipedia, "VMU", retrieved 2026-10-01. Two CR2032 cells, 128 KB flash with 200 blocks for saves, and the beep at power-on from a VMU with no battery power.
- ↑ 6.0 6.1 6.2 Sega Enterprises, Service Manual: Dreamcast EU, No. 022-EU, p. 8-25, schematic of KATANA SUB BD 2, 839-1124: controller port VCC through F1 (RF25SCVTP, 0.39 Ω), fan connector CN4 (pin 1 +5 V, pin 2 GND), BT1 fed from B.VCC through R1 (13 Ω 1 W), CE1 47 µF on 5 V.
- ↑ Power supply schematic marked "COD. SEGA 837-13570". Hosted on this wiki as File:Sega Dreamcast Power Supply Schematic.pdf. console5 lists it among the Tec Toy schematic sheets. Output header CN3: 12 V, GND, GND, GND, 5 V, 3.3 V.
- ↑ 8.0 8.1 Sega Enterprises, Ltd., Service Manual: Dreamcast EU, No. 022-EU, October 1999, p. 11-9 (IC104 "Series Regulator (3.3VDC to 1.95VDC)", 315-6192, PQ07VZ1H2Z; IC106 "CMOS Voltage Regulator (3.3VDC to 2.5 or 2.7VDC)", RN5RG25A). Hosted on this wiki as File:Sega Dreamcast EU Service Manual 022-EU.pdf.
- ↑ 9.0 9.1 Sega Enterprises, Service Manual: Dreamcast EU, No. 022-EU, p. 2-1, "Cautions To Be Observed": laser safety, fuse replacement, lithium battery replacement ("Replace only with the same or equivalent type recommended by the manufacturer"), and "Exchange the entire power supply unit if repair is required".
- ↑ Sega Enterprises, Service Manual: Dreamcast EU, No. 022-EU, p. 13-1, mechanical parts list: assembly 610-7214 (KATANA EUR VA1), main boards 837-13820 and 837-13883 (with /01 variants), sub board 2 839-1124, GD unit 610-6923-02 (Yamaha) or 610-7292 (Samsung), power unit 837-13774, fan 260-0082 (UDQFFAB03F, Matsushita), modem board 837-13771/00, Molycoat YM-103 (item 1-101).
- ↑ 11.0 11.1 Sega Dreamcast VA0 logic-board schematic sheets (CPU and DRAM, GPU and VRAM, sound and clock generator, video DAC, ROM, flash and I/O, connectors). Hosted on this wiki; see Sega Dreamcast VA0 Schematics. console5 lists them as Tec Toy sheets. IC301 315-6119 (AICA), IC303 PCM1725, IC305 BU2179F with X302 13.5 MHz, IC401 BU1426KS, X301 32.768 kHz; CN602 AV connector, Sega part 212-5710.
- ↑ Sega Enterprises, Service Manual: Dreamcast EU, No. 022-EU, pp. 11-25 and 11-26, IC301 AICA terminal functions: CK33 33.8688 MHz master clock input; RTCKI/RTCKO real-time clock crystal; MCCK 25 MHz G2 bus clock; MCLK 67.7376 MHz sound memory clock, "twice that of the master clock"; VRTC backup supply for the RTC.
- ↑ 13.0 13.1 console5 TechWiki, "Dreamcast", retrieved 2026-10-01. Capacitor lists for the VA0, VA1 and VA2.1 logic boards, the controller-port board, three GD-ROM boards and the 110 V and 220–240 V supplies; IC list for the VA1 171-7965C board.
- ↑ Sega, Dreamcast instruction manual (US, 2000), p. 12 "Rechargeable battery", pp. 28-29 "Troubleshooting". Scanned at archive.org.