Macintosh Computers

MS-DOS/MAC Connectivity

 

Paquetes Interactivos S.A. of C.V.

Ing. Pedro Baram K.
General Manager

In 1984, the year in which the Macintosh computer appeared on the North American market, the resistance to these computers in the corporate world was tough and for good reason. Although the graphical interface of this machine allows users of all levels access to computing in an easy and intuitive way, the Macintosh with 128 Kb memory at that time did not have the power that business users required.

 

The software wasn't ready to do the job either. Even in 1985, when more powerful Macintoshes began to be produced and the software base grew in both size and quality, companies had already invested large sums of money in MS-DOS-based equipment and software and users were already generating large volumes of information with these devices. Apple recognized that to penetrate the corporate world, its own merits were not enough, but also the ability of its machines to share information with the installed base of PCs.

Thus, the people of Cupertino, California, starting in 1987, decided to develop products with connectivity capabilities. Some of them are an integral part of the Macintosh hardware and operating system, and others were developed by third parties.

Users want to be able to connect different types of computing equipment to each other. Likewise, we find different schemes to network the different types of existing computers. In order to cover all the relevant topics in depth it would be necessary to write one or more books. As MS-DOS computers outnumber any other type of computers, and as the most common is the need to communicate PCs with Macintosh, we selected on this occasion to write about this topic and we will leave the connectivity of Macintosh with minis and for another article. main frames as well as other related aspects.

Information sharing implies that information generated by a program on one computer is accessible and intelligible to another program on a different computer. To carry out this process, two interrelated problems must be solved. First, there is the issue of physically transferring information from one machine to another, and second, the issue of the data itself. Although we can transfer, for example, a Word PC file to a Macintosh, it will not be possible to read this file if we do not have the necessary programs and/or filters to translate the information.

File Transfer

Transferring files between PCs and Macintosh can be extremely simple. The best solution fundamentally depends not only on the budget available to carry it out but also on the type of information involved.

There are three basic ways to transfer information between PCs and Macintosh: (1) Direct connection through serial ports (including connections through Modems); (2) Use of Apple SuperDrive; and (3) Networking. There is also a fourth way, using cards with PC processors that are installed in the Macintosh, or using PC emulation software on the Macintosh, however this way involves the use of one of the three previous methods to transfer information between the cards. computers.

Direct connection through serial ports

The simplest and most economical connectivity solution is to obtain a serial cable that can be manufactured or purchased and two telecommunication packages, one for the Macintosh and one for the PC. If the two computers cannot be placed next to each other to achieve a direct connection, they can be connected through modems. Of course, buying modems involves a greater investment than purchasing a serial connection cable and they are also slower. A direct connection can transmit information at a speed of up to 57,600 baud while most common modems transmit information at a speed of up to 57,600 baud.ocity of 2,400 baud.

There is a product made by DataViz called MacLink Plus. The complete package includes a serial cable, a software disk for the Macintosh and another disk for the PC, as well as a manual.

The PC disk contains a batch file that automatically creates a DOS subdirectory and copies all required files into it. File transfer control is done from the Macintosh.

The software on the Macintosh contains some filters that allow you to preserve the original format used in both PC and Macintosh word processors.

The direct connection between serial ports is most commonly used to transfer information from a Lap Top computer running MS-DOS where the information is collected, to a Macintosh computer, where documents can be formatted with ease and elegance.

Using Apple SuperDrive

When it comes to transferring files no larger than 1.4 Mb, Apple provides as standard equipment on all its current Macintosh computer models, a high-density 3.5-inch floppy disk drive, capable of reading and writing various formats in addition to the original Macintosh format. . The drive, called SuperDrive, supports MS-DOS and PRO-DOS formats. The second is the format used by the Apple // family of computers, which continues to be supported by Apple Computer's.

Included as a utility, Apple provides along with the Macintosh operating system, a program called Apple File Exchange, which allows you to exchange formats from Macintosh to MS-DOS or PRO-DOS and vice versa.

This extensive program, in addition to having a consistent and intuitive interface, contains a series of filters that allow information to be transferred in both directions, preserving the original format of the document. The filters provided by MacLink Plus can be used in the Apple File Exchange program by simply saving the filters in the same folder in which this program is located.

Network Connection

The networks to connect PCs with Macintosh can be of two types. The first consists of including a PC in a predominantly Macintosh environment, and the second, the most common given the number of PCs installed, consists of including one or more Macintosh computers in a predominantly MS-DOS network.

The entire line of Macintosh computers includes as an integral part of the hardware the possibility of connecting them to a network to share both printing and disk storage resources. This standard connectivity between Macintoshes is called Apple Talk. To connect two or more Macintosh computers together, you only need to install an Apple Talk connector in the serial port corresponding to the printer of each of the network nodes. Apple sells its own connectors and cables for the connection or these can be purchased from other manufacturers, who, unlike Apple, use twisted pair cable for the connection, which is much cheaper.

To connect a PC to a Macintosh computer network, you need to install a card on the PC that provides the PC with an Apple Talk port. These cards (PC Cards) are sold by Apple and other manufacturers, and allow PCs connected to the network to automatically share printing resources.

When the number of computers on the network is large and/or the volume of information transmitted through it is intense, the transmission capacity of a network based on Apple Talk (23 Kbits) may be insufficient. If you want to improve the operation of the network, it will be necessary to install an EtherNet card (10 Mbits) in each of the computers, whether Macintosh or PC. If even greater capacity is desired, a Token Ring card (16 Mbits) must be installed in each of the machines.

Not all Macintosh computers allow you to install a communication card. If you want to connect the old Macintosh Plus or their current replacements, the Macintosh Classic, to an EtherNet network, it will be necessary to include them using EtherNet emulators connected to their SCSI port.

Depending on the number of computers on a network, there are two ways to share information recorded on disk:

The first is commonly used in a network that includes a few machines that will sporadically share information between them, without dedicating a computer as a central server, but rather allowing querying from any machine on the network, the disks and/or the files contained in them, which are published from other computers connected to the same network.

The most commonly used software for these types of networks is a program made by Sitka Corporation called Tops. There are versions of Tops for both PCs and Macintosh. The corresponding version must be installed on each machine. Each user on their machine defines which files they want to publish and is allowed to restrict indiscriminate use of the published files using a password. Tops contains some filters that allow you to preserve the original format used in both PC and Macintosh word processors.

The Macintosh operating system 7.0, which will soon be released here in Mexico, will allow up to 10 Macintosh computers to be connected on a network to share files, without the need to purchase additional software.

There is another program called Timbuktú, which allows any Macintosh on the network to observe and/or control another Macintosh computer on the same network. There is another version of this same program, which allows you to access the network remotely via modem, and thus observe and/or control any of the Macintoshes connected to the network.

The second way to share files on a network that includes Macintosh computers and PCs is to designate one or more machines on the network as a file server where other machines on the network will go to consult or modify documents. Unlike the previous way, in this type of network, machines designated as servers cannot be used for other functions.

Depending on the prevailing environment, the designated server may be a Macintosh or a PC. When using a Macintosh server, the commonly used software is called AppleShare which is sold by Apple Computer's. When the server is a PC, the most commonly used software is Novelco's NetWare and lately, Microsoft's Lan Manager.

AppleShare allows up to 50 computers to simultaneously access the server. It is made up of two applications, one for the server and another for each of the nodes on the network. Installation of the software is extremely simple and network access is achieved using the Selector accessory under the apple menu of the Macintosh operating system. Connecting to any of the servers on the network is carried out easily and intuitively. The server administrator can assign users to different groups and voluntarily restrict the type of access to certain information to a user or the group to which the user belongs. An additional program sold separately, a Print Spooler, installed on the server, allows you to quickly free up computers on the network when using shared printing resources.

Both NetWare and Lan Manager emulate the AppleShare software on the PC server, making any Macintosh connect to the network in exactly the same way as it would through AppleShare and allowing it to function as another terminal on the server.

PC Emulation on Macintosh

Sometimes, it is not enough to transfer information from a PC to a Macintosh, but this information must be processed using a program designed specifically for the PC.

The Macintosh can emulate the operation of a PC in two different ways:

The first is to install a card containing a PC processor inside the Macintosh and use the Macintosh's memory, screen, and keyboard to operate the programs. The cards can have an 8086, 80286 or 80386 processor and in the Macintosh // family with a color monitor the operation of the MDA, CGA and Hercules monitors that are common in PCs can be emulated.

These cards are produced and sold by third parties. To be able to use them, a Macintosh with at least one expansion slot is required, so the Macintosh Plus and its current replacement, the Macintosh Classic, cannot use them.

The second way to run PC software on a Macintosh is to emulate the operation of the PC via software. Insignia Software markets a product called SoftPC that emulates a PC-AT with an EGA monitor on a color Macintosh //, offering expanded memory of up to 4 Mb for the PC and also emulates the use of an 80287 mathematical coprocessor. SoftPC has a program which allows you to use disks with MS-DOS, OS2, or Macintosh formats.

If you have a hybrid network containing Macintoshes and PCs, a PC on the network can be used to run the software specifically designed for it, without having to resort to emulation.

File Translation

Once the physical connection is made to transfer files between PCs and Macintosh, it is still necessary to be able to translate the files between one computer and the other, which can be carried out in any of the following ways:

Direct Translation

There is an increasing number of programs for Macintosh that have their counterparts in the world of PCs and therefore can exchange files directly between them. Excel, WorPerfect, Word and PageMaker are examples of these.

Microsoft's Excel is one of the most widely used electronic spreadsheets both in the world of Macintoshes and in the world of PCs. In order to use a file recorded by one machine on the other machine, it is necessary that the file has been recorded using Excel's SYLK (Symbolic Link) format. This format will allow you to translate the formulas and values with their respective numerical formats as well as the printing areas and the created graphics. A notable difference that must be taken into consideration is that Excel PC considers dates starting from January 1, 1900 while Excel on the Macintosh considers dates starting from January 1, 1904. To prevent any errors arising from this difference in dates , it is necessary to modify the base date to 1904 in the calculation options window of the PC version of Excel.

Both WordPerfect and Microsoft Word are word processors commonly used on Macintosh and PC platforms. Both can directly read the files generated on both platforms without losing the features such as margins, tabs and typography with which they were created. It is advisable to ensure that the font with which they were created exists on the second machine so as not to lose the format.

PageMaker by Aldus is the most used program for page formation in both the Macintosh world and the PC world. As with the word processors mentioned above, it allows direct conversion of files between PCs and Macintoshes while preserving the original characteristics with which they were created.

Indirect Translation

Files generated by programs that have no counterpart can be translated using an intermediate format.

The intermediate format acts as a pivot, serving as a transition between the program with which the file is created and the program with which it will be collected. The intermediate format does not correspond to the native format of either program. So, for example, a spreadsheet generated by a program like Lotus 123 running on a PC that does not yet have a Macintosh counterpart can be read on the latter using a program like Excel that allows reading the Lotus 123 format.

Files generated with other word processors can be translated using the filters mentioned in the previous section of this article.

In an extreme case of not finding a suitable intermediate format, the information can always be recorded in ASCI format by one machine and read with the same format by the other, even if the original characteristics with which they were prepared are lost. This last resort will always be better than nothing.

In the best of all worlds, no one should worry about anyone else's machine. In the next best of all worlds, no one would have to worry about the compatibility of one machine with another. In this real world there are incompatibilities, but none of them are insurmountable.

For more information about the products described here, please contact:
 

INTERSOFT S.A. de C.V.

Palacio de Versalles 100 Local C

Col. Lomas Reforma

México D.F. 11930

Tel. +52 55 5596-2518 Cel. +52 55 2878-7602