@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
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.EXE Reference Diskette
M82G3252.EXE Reference Diskette
D40 / C40 (486-25)
040 / 150 (386-25)
ADF 8FFB and 8FFF Sections
Available User Memory
Installed System vs. User Memory
Processor Card SVAI CP Codes
C40 / D40 (486DX-25) Processor Card
DS1 Run/Check LED
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
U13 AMD AM29C660BJC
U43 Xilinix XC2018-70
U53 5v 486DX socket
U64 Xilinix XC2064-70
U65,99,131 Xilinix XC3020-70
U123 Xilinix XC3030-70
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
I have used a 486DX4-100 ODPR and an Evergreen 486DX4-100 (?) successfully,
while a Kingston TC133 would not start.
C40 supports 2MB and 4MB 80nS FPM. D40 supports 2, 4, and 8MB 80nS. (Ed.
70nS tested out fine, works fine with the D40 BIOS) All SIMMs MUST be the
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
XGA-2 and 4 DASD Only Supported by D40
C40 Processor Card
Initial setup and loading of diagnostic software on Gearboxes with no DASD
requires the use of the Setup
and Service Device (#6230).
Intel 80486 microprocessor operating at 25MHz, thereby offering improved
processor throughput speed. This card can upgrade the 040/150 models..
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
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
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?)
040/150 2MB 80nS 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).
8FFB (486) and 8FFF (386)
Bus Arbitor Fairness
Whether the Processor Card arbitor should support bus
This item together with the previous one determine the type
of bus fairness is employed.
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.
"Gearbox 800" (C40)
91F8150 - 21 Jun 1991, rev. 0, 27C010-200 (U1)
"Gearbox 800" (D40)
10G7021 - 07 Jun 1992, rev. 10, 27C010-200 (U1)
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
- 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".
Sytem Memory vs. User Memory
SYSTEM MEMORY (MB) USER MEMORY (MB)
13.625 min / 15.625 max
21.625 min / 23.625 max
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