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It's a Mac. It's a PC. It's DOS-Compatible!

[This article originally appeared in CLiCKS, the newsletter of the Macintosh User Group in Ithaca, New York. In this article, Steven shares his experiences with Apple's Power Macintosh 6100/66 DOS Compatible system, which TidBITS reported on briefly back in TidBITS-257.]

My family had been strictly Macintosh since we entered the computing age six years ago with a Mac Plus. The time came when we needed a DOS machine, and to continue the Mac tradition and utilize our existing hardware (such as a printer and external hard disk), we opted for a Power Macintosh 6100/66 DOS Compatible. The computer has a PowerPC 601 processor running at 66 MHz on the Macintosh motherboard, and a 486DX/2 running at 66 MHz on the DOS card, which occupies the only expansion slot. My configuration came with 16 MB of RAM, a 500 MB hard disk, and a CD-ROM drive.

The computer comes with MS-DOS 6.22 and Windows 3.1 (and does not "support" versions of DOS before 6.0). It offers SoundBlaster compatibility, 512K of video RAM for an optional PC monitor, a PC game port, and the ability to share monitor, keyboard, mouse, floppy, hard disk, CD-ROM, printers, and so on between the Macintosh and the DOS card. The computer also supports a Macintosh ODI driver for NetWare IPX and TCP/IP protocols. [Though you cannot have active TCP/IP connections from the DOS Compatibility Card and from the Macintosh at the same time. -Tonya]

I chose not to purchase additional RAM for the DOS card, so I share the 16 MB between the Macintosh and the RAM-less DOS card. Since I only expect casual use on the DOS side, I can get by with 16 MB and a little help from virtual memory. If you need to run Mac and PC applications at the same time, you'll definitely need more RAM, and putting a SIMM (up to 32 MB) in the DOS card's single slot can improve performance. Although the DOS card can share RAM with the Mac, the Mac can't use RAM on the DOS card.

The Power Mac's DRAM-based internal video supports 16-bit display (thousands of colors) at 640 x 480 resolution or 8-bit (256 colors) at 832 x 624 with impressive speed. Although the DOS card uses the only expansion slot, sound input, sound output, and Ethernet are built into the Mac, so most users in general computing situations won't need to further expand the computer.

All software, including the programs driving the DOS card, is pre-installed on the hard disk. After plugging in the peripherals, the computer worked fine right out of the box. However, I like to partition my hard disk, so I reformatted the disk and started from scratch. The C: drive for the DOS card is pre-configured at 80 MB, which is hardly sufficient. Installing Microsoft Word 6.0 and Excel 5.0 for Windows (along with all that OLE stuff) took more than 70 MB of hard disk space! [A source in Microsoft technical support suggested that this could be decreased to 40-50 MB for typical use. -Tonya] If you don't re-partition the hard disk, at least increase the size of the C: drive in the PC Setup control panel to something more usable. I set mine to 250 MB.

The main software for configuring the DOS card in the Macintosh environment is the PC Setup control panel. The C: and (optional) D: drives are huge Macintosh files which the software tricks the DOS card into believing are DOS disks. I allotted 8 MB of RAM to the DOS card, and that 8 MB appeared to be used by the System software in the About This Macintosh window. The PC and Macintosh share the keyboard and mouse. There is a video port on the back of the DOS card, and you can use a dedicated monitor for DOS computing, or you can opt for the cheaper option of sharing one monitor between the Mac and the DOS card. A hot-key combination (Command-Return by default) toggles the display between the Mac and the PC. The DOS card can also print to Mac printers via PC Print Monitor whose interface, as its name implies, resembles the familiar Print Monitor. I have printed several Word for Windows documents to my six-year-old ImageWriter II with acceptable quality. Also, you can map the PC serial ports (COM1 and COM2) to the printer and modem ports on the Macintosh so you can attach PC peripherals.

Average DOS users should have no problem setting up the DOS card. Apple did a good job writing the software interfacing the DOS card with the Macintosh hardware. The only problem I encountered was the lack of DOS mouse driver (on real PCs, mouse drivers normally come with the mouse). Fortunately, the DOS mouse driver for any Microsoft or PS/2 mouse should work just fine. [Apple's Tech Info Library suggests, "The MS-DOS 6.2 software, which comes with the DOS Compatibility Card, does not have drivers for any mouse pointing devices. Window 3.1, also included with the DOS Compatibility Card, does provide a driver that you can use. The driver is located on Windows Disk 4." -Tonya]

I am quite satisfied with the performance of the DOS card. Because I use shared memory, my DOS card runs like a mid-range 486, instead of a high-end one equipped with a comparable processor. This speed is more than adequate for home and business use. I have tried Microsoft Word 6.0 and Excel 5.0 for Windows, the two monolithic programs whose Mac equivalents run like molasses in an Ithaca January on anything less than a Power Mac. Both programs are fast and responsive running on the DOS card.

The DOS card is not without limitations. Apple named it the DOS Compatibility Card, not PC Compatibility Card, because DOS is the only operating system it supports. If you need to run other operating systems such as Windows NT, OS/2, or Linux, the DOS card is not for you. People on the Internet have reported successes with beta versions of Windows 95 on the DOS card. However, if you want to run other operating systems, a real PC is still the only choice for now.

Unfortunately Apple has discontinued both the Extended Keyboard II and the Adjustable Keyboard. The only keyboard Apple offers now is the AppleDesign keyboard. The AppleDesign keyboard has all the keys of the Extended Keyboard II (at half the price), but it's not nearly as responsive. If you are replacing a computer that has an Extended Keyboard II, you might want to keep your old keyboard.

More trouble started the first night. The left Shift key suddenly stopped working in the DOS environment. I checked the cables and software settings in both Macintosh and DOS environment, but still couldn't locate the source of the problem. After I "broke" two more replacement keyboards and spoke with three technicians at CIT Sales (Cornell University's computer store), someone there called Apple. The Apple technician hadn't heard of the problem, but was eventually able to confirm that there was a defective batch of AppleDesign keyboards which don't work with the DOS card. The replacement that Apple sent arrived two days later, and so far has worked fine.

The Power Mac 6100/66 DOS Compatible provides a good integrated Macintosh and DOS environment on one machine. If you have a Mac-oriented setup and need a DOS machine at minimum cost, I highly recommend the machine. If you already have a Power Macintosh 6100 and nothing in the expansion slot, you can add the DOS card. Although Apple doesn't officially support this approach, you can also add a DOS card to a Power Mac 8100, Quadra or Centris 610, or Quadra 800. Apple also recently introduced a DOS card with similar capabilities for the 630-series Macs.

[Similar (if not identical) cards for a number of Macintosh types are also available from Reply Corporation. Also, if this article has piqued your interest in a DOS Compatible system (or raised some questions), read the "Pwr Mac DOS Compatibility Card: Read Me File" in Apple's Tech Info Library.

The document addresses a number of issues regarding networking, attaching modems and printers, and more. To find that document (and others, including information on TCP/IP connections), search on "DOS Compatible" in the Apple Tech Info Library. -Tonya]

Reply Corporation -- 800/801-6898 -- 408/942-4804
408/956-2793 (fax) -- <>


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