Simtel MSDOS 1992 June

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DIAGS.EXE Special Serial, Parallel, Video diagnostics for the PC Written by Joan Riff for: Computerwise Consulting Services P.O. Box 813, McLean, VA 22101 (703) 280-2809 Introduction ____________ DIAGS is a tool for the advanced PC user, period. It is NOT for the general public. This manual will not explain things in elementary terms. If you know what a 6845 is, and what an 8250 is, and what parallel handshaking lines are, then DIAGS will be extremely useful to you. If not, then you may have better things to do with your time than try to figure out this program. DIAGS started out as a testbed for our new interrupt-driven RS232 libraries. The Serial Port Diagnostics were the first written, to test the Microsoft version 3.0 'C' interface to these routines. It has since grown. As we have added more assembler routines to our library, we have added corresponding DIAGS functions to test them. Additionally, DIAGS has been expanded as we experienced the need for new diagnostics capabilities. So the Parallel Port diagnostics were added when we had to debug yet another unknown printer's handshaking. And the 6845 diagnostics were added when we needed to test various video tricks like displaying 30 lines of text, smooth scrolling, etc. As it now stands, DIAGS is a very powerful facility for: 1) Testing all sorts of asynch communications lines 2) Testing printer handshaking and cable wiring 3) Examining an unknown system's DOS environment, including: a) Interrupt vectors b) Resident device handlers 4) Directly manipulating the 6845. Main Menu _________ The main DIAGS menu displays information about the machine and about DOS, and presents a list of the various diagnostics that are available. When you exit a particular diagnostic, you are returned to this main menu. (D)isk Info ___________ Let's describe the weakest and least important diagnostic first. The DISK INFO selection from the main menu displays just about every- thing that can be determined about a disk. Make sure that you have a diskette in the indicated drive before selecting this option. Since there are other utilities which do just about everything that you may want to do with a disk, we haven't done much with this diagnostic. We just display disk information as reported by DOS as well as by the disk's Boot Record. Once in the Disk Info screen, the following keypresses are available to you: ESC - return to the main DIAGS menu ALT-V - verify a diskette by reading every sector via DOS INT 025h. This is SLOW!!!! Think of this as a demo of just how slow INT 025h can be. ALT-R - reset drive. Doesn't do much, huh? That's what we wanted to see. A thru Z - select new drive for which statistics are to be displayed. Again, be sure that you have a disk in whatever drive you select. That's it. Not much to it. If you need to do more, then use: The Norton Utilities Quaid's Disk Explorer Central Point Software's Option Board (I)nterrupt Vector Display __________________________ This selection from the main menu displays the system's Interrupt Vectors. For each interrupt, the following information is displayed: The interrupt number The interrupt vector's address within segment zero The Segment:Offset of its handler The interrupt's name and/or use If an interrupt points to an IRET, then that fact is reported by a highlighted "[IRET]" displayed after the name. Once in the Interrupt screen, the following keypresses are available to you: ESC - exit back to main menu Home - scroll display back to Interrupt 0 End - scroll display to the end of the interrupts (F0 thru FF) PgDn - scroll to the next page of vectors PgUp - scroll up to the previous page of vectors Up Arrow - scroll up 1 line Down Arrow - scroll down 1 line (P)arallel Diagnostics ______________________ This is a more complicated set of diagnostics. It allows you to do all sorts of useful things with the parallel ports. We use these routines when we're trying to figure out whether or not some new printer is working properly with the system. At the top of the screen is displayed: The number of parallel ports on the system (1 thru 4) The number of the currently-selected printer (0 thru 3) The base I/O address of the currently-selected printer The trip character that is currently set (see below) Whether interrupts are allowed or disallowed during sampling The Parallel Port Diagnostics menu gives you the following choices: (I)nit printer - does a ROM BIOS "init printer" call. (E)nable Interrupts during sampling - toggles the indicator on the top line, which indicates whether INTs are to be dis- allowed during sampling. (N)ew Trip character - allows you to specify a new character to be sent to the printer to 'trip' it. This is initially a Linefeed. (P)rinter switch - selects next printer (in sequence) as the current printer. (T)rip printer - sends the current Trip character to the printer, and then captures the printer Status port lines using a special high-speed capture routine. These lines are dis- played in oscilloscope format, allowing you to see at a glance the operation of the BUSY line, ACK line, etc. Interrupts will be inhibited during the sampling if the top line of the display shows "No Ints". Press ESC to exit from the display of the status lines. (U)nique Printer setup - sends custom codes to set various specific printers into various modes. The printers currently supported are: Data Products 8070 (and perhaps IDS Color Prism) IBM Graphics Printer (and certain Epsons) Fujitsu DL-2600 (and perhaps Epson JX color series) Okidata Microline 93 Diable 630 (and C.ITOH Starwriter, F-10, etc) C.ITOH Prowriter Follow the prompts that are displayed when you make this selection. (Q)uit parallel diagnostics - to return to main menu The following three selections are invaluable for checking proper printer cabling and handshaking: (D)ata lines - displays the parallel port Data I/O port lines in oscilloscope-like format. Press ESC to exit the oscillo- scope display. (S)tatus lines - as above, but lines displayed are from the parallel Status I/O port. (C)ontrol lines - as above, but lines displayed are from parallel Control I/O port. The following selections send various strings to the printer: (F)ox message - sends a continuous FOX message to the printer via direct I/O (bypassing the ROM BIOS). Press ESC to stop it. (A)scii character set - sends the complete ASCII character set to the printer via direct I/O (bypassing the ROM BIOS). No carriage returns are sent. Press ESC to stop it. (H)oriz and vert alignment tests - send various Formfeed, Tab, line spacing and Backspacing sequences to printer. This is useful for testing the results of (U)nique printer setups, and to see if the printer supports true backspacing. This selec- tion has its own submenu, which is exited via ESC. (S)erial Port Diagnostics _________________________ If you do PC communications as much as we do, then this part of DIAGS is for you! It provides a very powerful look at the comm line. Its most intriguing feature is the ability to serve as a line monitor between two serial devices. When you select "Serial Diagnostics" from the main menu, your screen becomes a terminal screen. At the top of the screen is displayed various port information as follows: Whether the port is open ("OP") or closed ("CL") The current serial port number The current baud rate The number of data bits being used The type of parity being used The number of stop bits being used Whether the existing 8250 parameters are being re-used (this feature is only used by us, for internal testing) What port is being wrapped to (more on this later) Whether keypresses are echoed to the screen Whether DEBUG mode (HEX display) is set To the right of this information are various stats, displayed only if the port is open and stats have been enabled. These stats include: The size of the RS232 output queue (in HEX) The size of the RS232 input queue (in HEX) The status of Carrier Detect and DSR The number of times (in HEX) that the following have occurred: RING BREAK Framing Error Parity Error Overrun Error Once the port has been opened, any "normal" keys that you press are sent over the comm line by being queued into the output queue. Incoming data appears on the screen. Incoming and outgoing characters are displayed in different colors, so that you can tell what's what. The RS232 routines are entirely interrupt-driven. The output queue will be serviced only if the 8250 is properly interrupting the 8088. This in itself is a valuable test of proper system operation. If the output or input queue sizes stay "stuck" at a non-zero value, then something is wrong with your system. Besides the "normal" keys, you may use the following key presses: ALT-S - switch display between port 0 and port 1 (COM1: and COM2:). ALT-M - bring up a menu of miscellaneous features: HANGUP the phone by dropping DTR PICKUP the phone by raising DTR RESET the Hayes 1200b by OUT1 toggle FLUSH input and output queues CRLF control (how to display incoming CR and LF) STATS control - turning the stats off can speed up the terminal display considerable TRAP - control what happens when you press ALT-T to trap some 8250 register ALT-X - initiate an XMODEM transfer. This we use to test the accuracy of XMODEM as implemented in other software packages. ALT-P - control port parameters. This includes: port OPEN and CLOSE BAUDRATE DATA bit selection PARITY setting STOP bit selection REUSE of the 8250 params (for our internal use) ECHO (of local keypresses) on/off WRAP of incoming data to another comm port DEBUG display toggle ALT-T - to trap the data lines from a previously-defined 8250 register ALT-R - display various 8250 registers ALT-B - to send a BREAK ALT-W - wait (do nothing) till next keypress. This is useful for pausing a fast-miving display. ALT-Q - quit back to main menu ALT-F - send a single FOX message over comm line Most of these functions contain their own prompts, and require no further explanation. Some, however, need to be explained in detail. The continuous updating of the stats on the top line can slow down the terminal display. Turning stats off (ALT-M S) can speed things up considerably. The baud rate is continuously variable, from 2 to 38400. You are not limited to "standard" PC baud rates. If you want to clear the screen and reset the stats, try switching ports twice (ALT-S ALT-S). To trap and display an 8250 register in the middle of communication, you must first define the register to be trapped (ALT-M T) and whether INTs are to be allowed during the sampling that follows. Having done that, you cause the trap by pressing ALT-T. At that instant, a special high-speed assembler routine is executed which samples the designated register once every 50 machine cycles or so until 420 samples have been taken. These sample bytes are then displayed as a screenful of HEX bytes. You may highlight a particular byte via the arrow keys. The highlighted byte's interpretation is displayed on the message line toward the top of the screen. Press ESC to exit this trap display. The "wrap" feature is very useful. It may be used to allow DIAGS to serve as a line monitor located between two serial devices, among other things. Every incoming character is "wrapped" as an output to whatever port you have specified as the "wrap" port. If you select as the "wrap" port the same port that you're using, then you have in effect become a full-duplex system. The serial device connected to that port will see its "keypresses" echoed back to itself. Assuming that you have two serial ports, you may use DIAGS as a line monitor by wrapping each port's input to the other port. You can then switch between ports (ALT-S) and generally watch everything that goes in either direction. You can turn on the DEBUG display (ALT-P G) to see things in more detail. (R)esident device handler display _________________________________ This main menu selection allows you to see a list of all resident device handlers. As you highlight each handler's name (via the left and right arrow keys), the device's attributes are expanded on the screen. Press ESC to exit this display. Block devices are indicated by device names of the form "BLOCKnnn", where nnn is the number of devices supported by this block device handler. (V)ideo Manipulation ____________________ If you want to do some fancy 6845 programming, then the Video diagnostic will be of great interest to you. It allows you to examine and alter the 6845 registers in a most graphic fashion. Toward the top of the screen is a two-column list of all 6845 registers, and one or two of the special IBM PC video registers (the MODE and/or COLOR registers). There is a ">" pointer, showing you which register is being worked with. For each 6845 register, two values are shown: 1) The original value, as set by the ROM BIOS 2) The current value as set by you You move the ">" pointer to various 6845 registers via the up and down arrow keys. As you select each 6845 register, that register's bit pattern is expanded on the bottom half of the screen. You can change the currently-selected 6845 register's value by using the "+" or "-" keypad keys to increment or decrement its value. You can also use the left and right arrow keys to move the "bit pointer" across the various bits of the expanded byte on the bottom half of the screen. Pressing "1" or "0" sets or clears the bit currently pointed to. This is an alternate way to change the current value of a 6845 register. The updated 6845 registers are loaded into the 6845 ONLY WHEN YOU PRESS RETURN. This allows you to make extensive changes to registers without having intermediate states foul up the display. If you hose things up and get an unreadable screen, just press ESC to exit the Video Diagnostics, then enter it again. The 6845 is reset on exit from the Video Diagnostics. If you are using a Color/Graphics Adapter, then you may press "S" to toggle Snow on or off. The upper-right corner of the display shows the current status of snow as follows: "Snow: YES" means that no effort is being made to eliminate snow, and that snow is present (although you won't see it if you have a good Color/Graphics board) "Snow: NO" means that snow is being eliminated by our video software.