Aleph One Limited Issue 7, October 1998

5.6 Video emulation

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  CGA modes were provided by video cards on early 1980s PCs, and it’s possible you will run into a DOS application or two that will still use a CGA mode.
  
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  VGA modes are used by many older DOS applications for graphics, and are generally regarded as the lowest common denominator. As stated above, mode 13h can be accelerated quite considerably by use of the Fast video option, with no display corruption.
  
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  VESA 1.2 modes are a standardised form of selecting higher-resolution dis-play modes under DOS. They can be accelerated by up to 30-40% by using the Fast video option, but this occasionally results in some display corruption.
  
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  VESA 2.0 modes are a development of the above, where the application in question demands exclusive access to the display memory. Under !PC, if an application selects a VESA 2.0 mode and you are running !PC in multi-task-ing mode, !PC will immediately freeze and prompt you to change to single-tasking. The happy news is that VESA 2.0 is the fastest way that a DOS application can use the display, often improving 400% on a VESA 1.2 mode equivalent.
  
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  Windows will by default use a slow VGA mode (640x480 in 16 colours) until you install ARMDRV, whereupon it makes special arrangement with !PC to speed up the display in a way suited to Windows operation. Note that under Windows 95, all 256-colour modes will report themselves as VESA 2.0 modes, since it uses a separate driver (called ARMDX) for speed, and to sup-port DirectDraw-based applications.
  

The solution to this is to use !MakeModes to define a mode suited to your monitor; details of this utility’s availability can be found in chapter 12.

5.7Transferring files to and from partitions

The most obvious way of transferring files between your DOS partitions and normal RISC OS drives is to open the partitions up like folders and drag the files around. However, there are some caveats here:

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  Make sure you have installed DOSFS 0.62 from InstallPC; older versions will not read partitions larger than 32MB.
  
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  Don’t drop files into a DOS partition while !PC is running. You can easily freeze !PC and open the partition for reading, but writing into it while !PC has it open will almost certainly result in data corruption unless you quit !PC im-mediately afterwards. If you do write a file by mistake while !PC is running, you should use Scandisk as soon as possible to minimise any corruption.
  
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  RISC OS filenames are, as standard, only ten characters long, whereas DOS filenames, when copied out, can be up to 12 (e.g. AUTOEXEC/BAT). Be care-ful if you’re copying from RISC OS directories to DOS partitions, as file-names may have got truncated somewhere along the way.
  

Be sure to have a look at chapter 12, as some recommended third-party software helps to relieve RISC OS of some of these limitations.

5.8Editing DOS text files

DOS text files, including the important AUTOEXEC.BAT and CONFIG.SYS files, have an extra character on the end of each line compared to RISC OS. Be careful, if you’re editing them with !Edit, to copy the [0d] character from the end of the existing lines to the end of any new lines you might add.

Note that [0d] is only !Edit’s representation of this extra linefeed character; you should copy it with the copy + paste functions rather than trying to type the four characters. Our recommendation, instead of !Edit, is to use an editor which can handle DOS text files transparently such as the freely-available !Zap or !StrongED, or to use a DOS editor such as EDIT, or Notepad under Windows.

6Installing operating systems and drivers

Once you’ve set up the RISC OS side of PCPro, you should read this chapter which tells you how to use the boot disc to help set up your ‘PC’.

6.1How is the boot disc used?

The boot disc is merely a bootable DOS floppy that contains:

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  Mouse, CD-ROM and SCSI drivers for DOS / Windows 3.
  
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  ARMDRV, PCPro’s fast display driver for Windows 3 and 95/98, along with ARMDX, a driver used for 8-bit screen modes under Windows 95/98 supporting DirectDraw, which is automatically used when relevant.
  
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  CD-ROM and SCSI drivers for Windows 95/98
  
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  Sound drivers for all versions of Windows
  
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  An automated installation script for all the DOS and Windows 3 drivers
  

To use it to install drivers on an existing DOS and/or Windows 3 installation, you should boot off the disc, type SETUP, answer the questions in order, and the relevant drivers will be installed automatically. The installation process copies the DOS drivers into a folder called ‘PCP3_Drv’ on your drive C, and alters several lines in your AUTOEXEC.BAT, CONFIG.SYS and WIN.INI (for Windows 3 users) files.

Note also that when booting from the boot disc, and after installing the drivers automatically, your CD-ROM drive letters under DOS will start at M. This seem-ingly odd arrangement means that if you change the number of hard drive parti-tions (or network drives) in your setup, your CD-ROM drive isn’t automatically shunted along the alphabet, which would confuse many applications.

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