7568 Processor Card

@8FFB.ADF - IBM Gearbox Model 800 486 Processor Card
@8FFF.ADF - IBM Gearbox Model 800 Processor Card

192-217 IBM Gearbox Model 800 (7568-D40)
191-152 IBM Gearbox Model 800 (7568-C40)
189-155 IBM Gearbox Model 800 (7568-040 and 150)

10G7021 D40 BIOS 06/07/92,AMD AM27C010-200
91F8150 C40 BIOS 06/21/91, AMD AM27C010-200

7568-150 (386DX-25)
US_7568.EXE Reference Diskette
M41G3668.EXE 7568 Reference Companion Diskette Image
Note: The Companion Diskette is to upgrade the Model 150 (386DX-25) Refdisk ONLY. The files are dated 1992. The C40 and D40 refdisks are 1993.

7568-C40 (486DX-25)
7568_C40.EXE Reference Diskette

7568-D40 (486DX-25)
M82G3252.EXE Reference Diskette

Processor Cards
   D40 / C40 (486-25)
   040 / 150 (386-25)
     ADF 8FFB and 8FFF Sections 
System Firmware
   ROM Images
Available User Memory
   Installed System vs. User Memory
Processor Card SVAI CP Codes

C40 / D40 (486DX-25) Processor Card

DS1 Run/Check LED
DS2 Memory/Check
DSP1 Alphanumeric display
J1 72 pin SIMM that provides ECC
J2-J5 72 pin SIMMs for System Memory
P1,2 Backplane connectors
U1 Processor card BIOS
U11,107,128 57X4111
U28,100 N82C54-2
U43 Xilinx XC2018-70
U53 5v 486DX socket
U64 Xilinx XC2064-70
U65,99,131 Xilinx XC3020-70
U123 Xilinx XC3030-70
U126,137  8259-A
Y1 50.0000 MHz osc

U1 Processor Card BIOS The updated BIOS that makes a C40 into a D40 (and D40 comes stock with) is 10G7021, AMD AM27C010 -200

CPU Upgrades
  I have used a 486DX4-100 ODPR and an Evergreen 486DX4-100 (?) successfully, while a Kingston TC133 would not start.

Memory Supported
C40 supports 2MB and 4MB 80 ns FPM. D40 supports 2, 4, and 8MB 80 ns. (Ed. 70 ns tested out fine, works fine with the D40 BIOS) All SIMMs MUST be the same size.

Installing Memory There are five memory module positions on the processor card. Position J1 is dedicated to providing error correcting code (ECC) capability, and is therefore not available as system memory.  You MUST have a SIMM in J1 and J2. If you are installing more SIMMs, install each in the next avalable slot (J3, then J4, and then J5.

Note: The SIMM in J1 is normal FPM memory. The ECC functionality is provided by circuitry on the processor card.

XGA-2 and 4 DASD Only Supported by D40

C40 Processor Card
Intel 80486 microprocessor operating at 25MHz, thereby offering improved processor throughput speed.  This card can upgrade the 040/150 models..

Initial setup and loading of diagnostic software on Gearboxes with no DASD requires the use of the Setup and Service Device (#6230).
  The 486 DX2-50MHz Processor Card is compatible with and may be installed in earlier versions of the Model 800. Full support for 8MB memory modules and for system memory greater than 16MB requires that this feature be installed in earlier Model 800 systems. The 7568-D40, and earlier systems with the 486DX2-50MHz Processor Card installed, do not support the 0-16MB Extended Memory Adapter (#6345)

040 / 150 (386DX-25) Processor Card

Uses an Intel 80386DX-25 (w/32KB of L2 cache) and has a socket for an 80387. The base memory is 8MB on the Model 150, or 4MB (expandable to 8MB) on the Model 040. In addition, the Model 800 will support the 0-16MB Extended Memory Adapter (#6345). All memory is Error Correcting Code (ECC).

80387 MATH CO-PROCESSOR (25 MHZ) (INDUSTRIAL) (#6532): The 80387 Math Co-Processor (Industrial) has been modified to meet the environmental requirements of the GEARBOX system. (Ed. maybe one of the ceramic capped chips?)

Memory Supported
040/150 2MB 80 ns SIMMs (supports 0-16MB Memory Expansion Adapter)

Same as the 150, but no SCSI drive OR floppy drive. 4MB base memory, expandable to 8MB. Supports the 0-16MB Extended Memory Adapter (#6345).

AdapterId 8FFB (486) and 8FFF (386)

Bus Arbitor Fairness
   Whether the Processor Card arbitor should support  bus access fairness.
     <"Enable">, "Disable"

Burst Mode
   This item together with the previous one determine the type of bus fairness is employed.
     <"Enable">, "Disable" 

Bus Arbitration Level - F
   Arbitration level used by this processor card when requesting system bus usage (ownership). (Ed. There are a bunch of commented out choices)
  <"ONLY CHOICE" (arb 15)>

32 Bit Transfers - Enabled
   Sets the processor's transfer rate to 32 bits.

System Firmware (POST & BIOS)

Firmware stored in EPROM.

ROM Images

"Gearbox 800" (C40)

91F8150 - 21 Jun 1991, rev. 0, 27C010-200 (U1)

"Gearbox 800" (D40)

10G7021 - 07 Jun 1992, rev. 10, 27C010-200 (U1)

Available User Memory
   Memory available to the user will be less than the total system memory installed on the processor card for several reasons.

1. BIOS Mapping Uses 128KB  and applies at all total memory levels.
2. Loss of Split Memory At 16MB or greater 256KB of  memory is lost.
3. Memory "Gap" Support If an adapter requires memory below 16MB, up to 2MB will be lost if system has 16MB or greater. Varies based on individual adapters.

   If five of the 8MB memory modules were installed on the processor card, (one module provides ECC), results could be as follows:

   32,000KB  32768KB Total system memory
    - 128KB  Required for BIOS (0.125MB)
    - 256KB  Loss of split memory mapping (0.250MB)
   - 2048KB  Memory gap support to adapters (2MB)
   30,336KB Net available to the user

Net: Memory available to the user can be up to 2.375MB less than total system memory. This applies at total memory levels of 16MB or greater, if an adapter requires use of the 2MB "gap".

Installed Sytem Memory vs. User Memory
     4                    3.875
     8                    7.875
    12                   11.875
    16                   13.625 min / 15.625 max
    24                   21.625 min / 23.625 max
    32                   29.625 min / 31.625 max

Processor Card SVAI CP Codes

CP  Code Description
0   Normal Operations
1   Initialized the PPIS
2   Start scanning for the Processor card
3   Processor scan error
4   System Resource scan error
5   Cached SCSI card initialization

Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
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