Big Book of Amiga Hardware

An accelerator designed to plug into the CPU Fast slot of the A2000. The card takes GVP SIMM32 modules, which are custom 64pin 32-bit SIMM modules that are not the same as other 64-pin and 72-pin modules of the era. The card also contains a SCSI-II controller providing both an internal 50pin SCSI connector, and an external DB25 connector. A total of four board revisions cover all 'products' marketed by GVP Sales by various names.

To clean up confusion, all other related GVP Combo/G-Force 68030 accelerator card pages with SCSI will eventually point here.

All boards will have the Combo-030 markings on them, but they are broken down into two sub-groups:

Combo-030 Accelerators
- Surface mount 68030/68882 CPU/FPU @ 22/33MHz with no option to change/update.
- MMU functionality is used to remap Kickstart to 32-bit RAM.
- Two PCB Revisions: Rev 3 (original), and Rev 4 (fixed a logic flaw in >16MB DPRC DMA)

G-Force 030 Accelerators
- PGA 68030 CPU and 68882 FPU, with optional seperate clocking.
- 25MHz & 40MHz shipped with 68EC030 CPUs, 50Mhz with full CPUs.
- 68EC030 chips can be replaced with full 68030 versions.
- The MACH130 gate array absorbed some PCB PAL and TTL logic from the earier series.
- Support onboard Kickstart Remap with GVPCPUCtrl, or via MMU (if present).
- Rev 3 (Cost-reduction/enhancement of earlier Combo-030 series), Rev 4 (FCC-related changes only)

Minimally Documented Differences

- The Rev 3 Combo-030 (22/33MHz) has a logic flaw which will cause the DPRC DMA disk reads to wrap (write) over the motherboard 16MB address space when transferring directly to >16MB 32-bit FastRAM.  The v3.14 (or higher) gvpscsi.device ROM works around this by using the buffered DMA method through Zorro II FastRAM space (or ChipRAM) and a CPU data copy (similar to a Zorro II DMA controller would need to do with >16MB addressed memory).
- The Rev 4 Combo-030 22/33MHz) resolved the DMA logic flaw.
- The Combo-030 22/33MHz boards have a 33C93A chip clocked at 7MHz, and are not good candidates for the GuruROM V6 in terms of SCSI speed improvements.
- The G-Force 030 boards gained GVPCPUCtrl FastROM hardware logic to make up for the non-MMU 68030 CPUs in the lower-speed CPU offerings.
- All boards can benefit from the GVPCPUCtrl MoveSSP option, particularly if all onboard 32-bit RAM is mapped >16MB addressing and (with functional MMU) if you do not make use of another tool like MuMove4K/MuFastExec in the MuLibs package to remap certain system structures in the low memory region.
- G-Force 030 cards have their 33C93A clocked at 14MHz by default, so Sync SCSI via GuruROM V6 is an option.

(To be added/merged: Jumpers for the Combo-030 22/33MHz cards)

Jumpers

The reference to 'Omni' is a marketing label related to the driver ROM.  The v3.x AT/IDE driver was in one half of the ROM, and the v3.x SCSI driver was in the other half.  See J8 below.  This was done for awhile to reduce the number of ROM kits that dealers and GVP needed to keep track of, providing a common kit.  Later v4.x ROM kits had the SCSI driver programmed into both halves of the device, and the selection function was unimportant.

J8 - Selects upper or lower ROM bank image.  The earlier v3.x gvpscsi.device was paired with the (then) A3001/A3033/A3050 v3.x gvpat.device driver in the other half of the ROM image.
J9 - The ROM appears in the card's I/O space when shorted.  Dissappears when open.
J14 - This jumper tells the ROM driver that there is either a SCSI device connected (activate/poll for boot), or none (just detect the board's RAM, if applicable, and set up any configuration communications ports (i.e. misc board register initialization)
CN8 and J11 dissappeared on the Rev 4 G-Force030 PCB - purpose undocumented, but related to clock options. 
J16 appeared on the G-Force Rev 4 - purpose undocumented.
(If anyone has a Rev 4 of this card in the field, please contact Robert Miranda.  Rev 3 is common)

Some boards will have a 4th SIMM socket (bank #1), which is directly mapped to the surface-mount memory chip space.

The G-Force models always expect 4MM SIMM32 modules in banks #2-4.

The 25MHz board memory configuration can be slightly confusing.  With J12 shorted, and the default 1MB in bank #1, a Zorro II FastRAM board of 1MB is AutoConfigured.  With a 4MB SIMM32 installed in bank #2, a Zorro II FastRAM board of 4MB is AutoConfigured, and the bank #1 1MB is mapped high to $0100.0000.  All additional 4MB modules added in banks #2-3 will stack into the memory zone >$0100.0000.

PAL chips differed between board revisions and clockspeeds, and part speeds do matter in some places.  This affects attemps at higher CPU clocking.

If CN8 is incorrectly set on the 25MHz and 40MHz speeds, 32-bit FastRAM performance will be slightly lower.

All G-Force boards have a different back-side connector gendering pattern from the earlier Combo-030 (22/33MHz) models.  The change was related to the EGS 110/24 graphics board compatiblity which was developed later.

The later G-Force revisions were further developed into the A530 for the A500.

The boards have the F1 and D1 markings for components to provide SCSI bus +5v power, but they are omitted.

SCSI termination resistor packs are soldered in, making simultaneous use of the internal and external SCSI bus difficult to maintain proper termination.