Mega PC
From Sega Retro
The Amstrad Mega PC is a special Amstrad computer with the added features of a Sega Mega Drive. It was initially released in 1993 in PAL regions for the expensive price of £999.99 (later £599.99). It is unrelated to the Sega Teradrive, though shares similar specifications as the computer side is also powered by an Intel 80386sx processor.
Though a rare collector's item now, at the time of release the machine was unsuccessful due to its high retail price (made worse by the fact in 1993 a 386 processor was considered outdated). A later revision, named the Amstrad Mega PC Plus used an 80486 processor and had a RAM upgrade.
The Mega PC can also play any Japanese and/or US-localized game as well as unlicensed games.
Althrough the video is always coming out of the 15-Pin VGA connector, the video timings differ between Mega Drive mode and PC mode. The original monitor as a Multisync VGA monitor, which accepted 15Khz video from the Mega Drive part and the 31Khz signal from the onboard VGA.
The hardware of the PC part is a design entirely based on a chipset from Western Design Center. (The company that made the CPU for the Super Famicom.) The ISA Bus/Memory controller, Combined Floppy/Harddisk controller, Multi-IO Controller, SVGA Chipset are entirely made by WDC.
2 ISA connectors from the ISA riser-card are 16Bit, althrough, one is reserved for the Mega Drive itself. The Mega Drive connection to the ISA bus is 8Bit though. The only connection between the Mega Drive and the PC part is the Yamaha FM Soundchip that can be used as an Adlib-Compatible soundcard, including the 15-Pin connector for a PC-Style Analogue Joystick or a Midi Interface. Whether the Mega Drive can make use of this connector, it is unknown. One can change the IRQ of the card between IRQ2/3/5. But an Adlib Card normally doesn't make use of it. Original Adlib Cards and clones always use a Fixed IRQ and Port address.
The SVGA Graphics memory can be upgraded to 512KB by using 2 additional 1Mbit chips. (Proably 2 chips of the 414256/411000 kind with 20 pins.) Despite the printing on the mainboard, 41464 chips could not be very useful, since the total amount of video memory would be 320KB.
The Board also has holes for a Feature Connector of the graphics card to allow the SVGA graphics Pass-through to cards like MPEG Accellerators or TV cards. The pins would be needed to be soldered in, to enable this "feature".
The onboard memory consisted of 4 30-pin SIMM sockets. (Up to 4MB/16MB of RAM) But there are prepared connectors on the mainboard to allow up to 8MB of total RAM with 1MB modules.
Beside these obvious features, there are other leftovers that didnt made it into the final unit: -PC-type Joystick port on the mainboard, right to the serial ports. The entire hardware is missing, the case is not designed for this. -Onboard PC Speaker. The speaker was raplaced with a bigger one, with volume control ont the back. -Front Panel connector for things like Reset, etc.
It seems like Amstrad bought the design from WDC and just added a Mega Drive in form of a 8Bit ISA Card.
Specifications
- Processor: Intel or AMD 80386sx @ 25 MHz, Motorola 68000 @ 7.14 MHz
- Memory: 1MB SIMM RAM (expandable to 16MB)
- Storage: 3.5" FDD, 40MB HDD
- Video: Western Design Center WD90C11A-LR SVGA Graphics with 256KB RAM (Upgradeable to 512KB) + VDP of the Mega Drive passed through with a ribbon cable.
- Operating System: MS DOS 5.0 with Amstrad Desktop
- Dimensions: 325 mm(w) x 78 mm(h) x 292 mm(d)
- Power Usage: ~50W
- Connectors: (Mega Drive): Cartridge, 2 Game controller ports, "Headphone Jack" identical to the one on the first Mega Drive, Expansion connector for a planned MEGA CD upgrade.
- Connectors: (PC): Power cord connector of the AT-Style Power Supply with pass-through to a monitor, PS/2 style connectors for Keyboard and Mouse, DB25 Printer port, 2x RS232 Serial port, DB15 VGA connector.
Physical Scans
- Megapc uk ad.jpg
UK advert