21 August 2013

Contents

1. Machine fails to operate with 30-pin SIMMs installed
2. No monitor with matching display connector
3. LCD displays inconsistent colors, or a narrow dark band appears down the left side of the screen
4. Machine does not detect keypresses
5. No self-test messages are displayed during boot
6. Blit Diagnostics reports Block Mask Error -- Write Mode; Left Mask
7. Miscellaneous Diagnostics reports BPU Function Error -- Function: ZERO

Problem Log

Machine fails to operate with 30-pin SIMMs installed

The InterPro 2020 accepts 30-pin SIMMs. If ordinary 30-pin SIMMs are installed, the system behaves as if no memory were installed and the following message is displayed on the console:

2.001 Invalid memory configuration of 00000000 megabytes
        bank 00000000 contains: nothing
        bank 00000001 contains: nothing
        bank 00000002 contains: nothing
        bank 00000003 contains: nothing

SIMM Module Installation Rules
1. SIMM modules must be installed in groups of four to form banks;
2. All SIMM modules within a bank must be of identical density, ie. all 1Mx9
   or all 4Mx9 modules;
3. Lower-numbered banks must be filled before higher-numbered banks, and banks
   must be filled sequentially (ie., bank 0 must be filled first, then bank 1);
4. All 4Mx9 SIMM modules must be installed in lower-numbered banks than any
   1Mx9 SIMM modules.  For example, if you already have 4Mx9 SIMM modules in
   bank 0 and 1Mx9 SIMM modules in bank 1, to install another bank of 4Mx9 SIMM
   modules would require that the 1Mx9 modules in bank 1 be moved to bank 2, and
   the new 4Mx9 modules be installed in bank 1.

This behavior is unchanged whether 1 MB or 4 MB SIMMs are used, parity or non-parity.

The 30-pin SIMMs that the InterPro 2020 uses are proprietary, and contain a PAL in addition to the DRAM chips. Fortunately, the correct memory is obviously marked with an Intergraph logo and part number (P/N SMT001 for the 1 MB module, SMT003 for the 4 MB module). The modules must be installed in matched sets of four.

No monitor with matching display connector

The InterPro 2020 workstation uses an unusual—but standard—DB5W5 connector to attach a display monitor. Unless you get a matching Intergraph display with a DB5W5 connector, it is unlikely you will find another monitor which can be connected. Therefore, an adapter is required.

The DB5W5 connector on the framebuffer (P/N PCB963) outputs a 1 megapixel overscanned raster (1183×883) with separate horizontal (55.2 kHz) and vertical (60 Hz) sync, using the following cable pinout:

DB5W5		↔	DE15 (VGA)
	BLUE ( 1 )		BLUE ( 3 )
			BLUE RTN ( 8 )
	RED ( 2 )		RED ( 1 )
			RED RTN ( 6 )
	GREEN ( 3 )		GREEN ( 2 )
			GREEN RTN ( 7 )
	HSYNC ( 4 )		HSYNC ( 13 )
			HSYNC GND ( 5 )
	VSYNC ( 5A )		VSYNC ( 14 )
			VSYNC GND ( 10 )

LCD displays inconsistent colors, or a narrow dark band appears down the left side of the screen

When a digitally-controlled multifrequency display capable of displaying the InterPro 2020's video signal is attached, lit pixels appear washed out, or horizontally streaked with inconsistent tinting. A narrow vertical band of darkened pixels may appear near the left-hand edge of the screen. Some parts of the display may be cut off. The tinting may be particularly noticeable in large areas of solid white.

The InterPro 2020 is working normally.

The display adapter utilizes an overscanned display mode. This means that it addresses pixels that are outside what would normally be considered the display area of the screen. With a "simple" CRT display, these pixels can be accessed like any others, if the display signal timing is carefully adjusted. If the picture is too wide or tall to be shown in its entirety and some pixels are hiden behind the CRT bezel, the monitor may be adjusted so that the picture is narrowed, moving the overscanned pixels back into the screen's visible area.

A digitally-controlled multifrequency display, however, will typically have specific resolutions it works with, and automatic circuits which adjust the display optimally so that all available pixels are used, and all used pixels are visible. This requires the incoming signal to fall within certain ranges of parameters, so that sensible adjustments can be made. Overscanned display modes have signals which are just outside of these normal ranges, and the circuitry in the display may or may not be able to adequately determine how to correctly adjust the raster. These visual effects are symptoms of the automatic adjustment circuitry being "confused" by the overscanned signal.

The Hitachi CM801U is one example of a digitally-controlled multifrequency CRT display which will reasonably show the raster from an Intergraph 1MP framebuffer, though it exhibits the symptoms described above when attempting to display the raster from a 2MP framebuffer such as the PCBB92 or SMT081.

Machine does not detect keypresses

None of the keys on the keyboard have any effect on the machine, though the Caps Lock and Alt Mode indicators light if these keys are pressed and the keyboard indicator for hard disk activity operates correctly. The keyboard beeps once immediately after the machine is powered on, but does not emit a second beep as it normally should. If keyclicks or membrane clicks are enabled in the setup utility, no clicks are heard when pressing a key or membrane switch. The mouse works normally.

The Zilog 8530 serial communications controller (SCC) has failed. The InterPro 2020 has two SCC chips; the one closest to the keyboard port (farthest from the power supply unit) controls the keyboard. Replace it. If an exact replacement (Zilog Z0853006VSC) cannot be found, a compatible part such as the AMD AM8530H may be used. The replacement part should be PLCC-packaged and rated for 6 MHz operation.

No self-test messages are displayed during boot

During a normal boot process, the InterPro 2020 should display messages about how its self-tests are proceeding, including errors found (if any). But, the machine displays nothing except I/O System Monitor -- Booting System... until the blue setup screen appears. If a serious enough error is encountered, the machine stops and the blue screen never appears. The screen may stay black, or it may show "pixel dust" from the display adapter tests.

Messages describing invalid memory configurations are shown, if the SIMMs are removed or installed incorrectly.

The self-test messages are directed to serial port 2 (2400, 8N1) because the keyboard has not been detected. The three-port serial "pigtail" cable (P/N MCBLQ800C) is required to connect a terminal to serial port 2.

The Forth Diagnostic Monitor can also be accessed on this port.

Blit Diagnostics reports Block Mask Error -- Write Mode; Left Mask

During the power on self tests, the system stops after reporting the following error.

Blit Diagnostics
  2.400  Block Mask Error -- Write Mode; Left Mask
      Wrote 0x00's to Address 0x874f3ffc which contained 0xff's
      Expected:  0x00000000   Found:  0xffffffff   XOR:  0xffffffff

If the boot floppy is used, this test is skipped and the normal blue setup screen appears, though it is drawn incorrectly. If the menus are used, new content is drawn over the old and the screen quickly becomes unreadable.

Faulty display	Normal display
Boot screen	Boot screen
Utility menu
CLIX console

One of the four PLDs labeled MPRGN400A has failed. This error corresponds to the part which is closest to the TC110G17AT. One of the existing MPRGN400A parts may be copied to program a replacement PLD of type GAL22V10-25LP.

An address of 0x874feffc indicates the fault is with the MPRGN400A immediately adjacent to the above.

Miscellaneous Diagnostics reports BPU Function Error -- Function: ZERO

During the power on self tests, the system stops after reporting the following error.

Miscellaneous Diagnostics
  2.300  BPU Function Error -- Function:  ZERO
      Address 0x87400000 contained 0x33553355; Wrote:  0x55335533
      Expected:  0x00000000   Found:  0x03050305   XOR:  0x03050305

One of the two DP8510V bitblt processors has failed. Replace it.

The Found and XOR fields may show 0x30503050 instead, depending on which of the two devices is at fault.

The following diagnostic may also indicate a possible DP8510V failure, though if the address is other than 0x8740000, it is more likely to indicate a VRAM failure. Since the DP8510V are socketed, they may more easily be checked for a fault than the soldered-in VRAM.

RAM Diagnostics
  2.200  Data Test Error -- Video Ram
      Screen:  0   Address:  0x87400000
      Expected:  0x55555555   Found:  0x555d5555   XOR:  0x00080000