NAME

ibm5081, mpel− IBM 5081 Display with MegaPel adapter interface

SYNOPSIS

pseudo-device mpel

DESCRIPTION

The IBM 5081 Display with MegaPel adapter interface is a 16- or 19-inch color CRT.  It provides a 256 color out of a 4096 color palette, all-points-addressable, bit-mapped display with 1,048,576 points on the screen (1024 pixels on each of 1024 displayable lines).  A fast raster-operation processor is provided with built-in capability for a wide range of functions, including bit-block transfer, line draw, image copy/merge and image rotate. A graphics queue mechanism with synchronization and controlled branching allows pre-programmed graphics subroutines. 

The MegaPel adapter is a dual PC/AT card installed in the I/O bus as a sixteen-bit device.  The bitmap is not directly addressable.  There are 3-64K shared banks.  However, if our microcode is used, only two banks at f4c00000 and f4c10000 can be used to share fonts and communicate with the microcode. 

The display operates as /dev/ttympel in glass tty (the default) mode and /dev/mpel in window-manager mode:

−Glass tty mode initialization consists of downloading a character font; the microcode must already be loaded (boot does this).  In this mode, the display driver emulates a smart terminal, similar to an IBM 3101, and can be /dev/console.

−In window-manager mode, a user-level process, such as a window manager, can directly control the display device hardware, loading control programs, issuing graphics orders, etc.  When a process opens  /dev/mpel, output intended for /dev/ttympel is buffered by the kernel until later (see bufemul(4)).  The process must then open /dev/bus to access the display control memory areas for manipulation by the user program if bit 0x8 is not set in the minor device number.  Glass tty mode is reentered when /dev/mpel is closed.  NOTE: We do not recommend changing the MegaPel microcode.  However, if you do, you are responsible for reloading the original microcode when you are finished, since the kernel does not reload the MegaPel microcode. 

NOTES

This adapter can also drive an IBM 5082 projection display. 

Ibm5081 is not supported on the IBM 6152 Academic System. 

To prevent conflicts with the ega adapter and driver, the mpel switch settings must be set to: 1-off, 2-off, 3-off, 4-on. 

ERRORS

The following errors can be returned by the interface:

ENODEV Nonexistent display (on open, close, read, write, or ioctl). 
Unavailable display (on open):  user processes are denied access to this display (see consoles(5), setscreen(8)).

EIO Made an attempt to close a display device that was not open. 

FILES

/dev/mpel
/dev/ttympel
/dev/console
/usr/lib/mpelmicrocode files

SEE ALSO

bufemul(4), bus(4), cons(4), ibm5151(4), ibm5154(4), ibm6153(4), ibm6154(4), ibmaed(4), ibmemul(4), kbdemul(4), tty(4)
“IBM/4.3 Console Emulators” in Volume II, Supplementary Documents

BUGS

Access to the PC/AT I/O and memory busses through /dev/mpel, when bit 0x8 is set in the minor device number, is not limited to the megapel addresses. 

The microcode is over 100K and is not loaded by the kernel. 
 

PRPQs 5799-WZQ/5799-PFF: IBM/4.3  —  Sept 1988