Hi Res Image of Card
- 598 x 861, 94K

This board is the last of the original GVP Impact (Series I) disk controllers and RAM expansion technology for the Amiga 2000.  It is based upon a 33C93/33C93A 8-bit SCSI controller chip that can transfer data to/from an onboard 16K SRAM buffer, which is then serviced by the system CPU.  The board has an internal 50-pin SCSI header and an external DB25 interface.  SCSI bus termination resistor packs are soldered in.  Memory capacity is up to 8MB in 2MB increments using pairs of 1Mx8 30-pin SIMMs.  All memory in all configurations was compatible with other Zorro II DMA expansions.

GVP 1.0 (2), 2.0 (2), and FastROM 3.x (1) Autoboot ROM(s) are supported under Kickstart 1.3 and higher.  The single v3.x ROM is used in position U30.

There are jumpers for Autoboot ROM disable (remove J4), and RAM settings (J1, J2, J9).  All others jumpers are reserved, but have been determined.  The J5 jumper disables the onboard SRAM (a test jumper - it will prevent the driver from communicating with SCSI devices).  CN11 is a 7MHZ/14MHz clock select for the 33C93(A) SCSI chip.  The boards mainly came with the non-A version (-02) of the 33C93 chip, and so all drivers driver expects a 7MHZ setting only (CN11 in the forward pair position) for this chip.  A 33C93A chip and the v3.x driver will expect the CN11 jumper moved to the rearward pair position (14MHz) or SCSI errors will be flagged.  Running with the 33C93A at 14MHz will result in a minor (~3-5%) improvent over 7MHz clocking, and also depending on the device being communicated with, and the host CPU performance.  J3 is a test jumper that will disable the AutoConfig signal from passing into the board, and therefore prevent the board and any downstream cards from being configured.  This board does not have a header for an LED activity indcator.

The Impact SCSI product line was replaced by the GVP Series II DPRC-based DMA controllers.

Memory Configurations Notes:

0MB, 2MB, 4MB, 8MB - Autoconfig, populate in pairs from the bottom (edge connector) upward, set jumpers.
6MB* - set jumpers, and insert an AddMem command in the startup-sequence for address range 800000-9FFFFF.

* - this special 6MB setting was intended for compatibility with the Commodore A2086/2286/2386 or GoldenGate Bridgecards, or an RTG graphics board in a stock 68000 system.  These boards, with this memory setting, require that they be AutoConfig-located in the Zorro II Fast RAM (8MB) expansion space as the only AutoConfig memory expansion (>16MB addressed 32-bit Memory is okay).  The AddMem command mapps the additional 2MB of RAM on the card, located in the 3rd pair of SIMM sockets.  It was not possible to Autoconfig the additional 2MB of memory as another 2MB memory board as TTL and PAL logic was at a premium.

Memory Module/Jumper Configuration:
0MB - J1, J2, J9 - ON
2MB - J1, J2 - ON; J9 - Off (CN3-CN4)
4MB - J1 - ON; J2, J9 - Off (CN3-CN6)
6MB - J1, J2, J9 - Off - (CN3-CN8)
8MB - J2 - ON; J1, J9 - Off (CN3-CN10

SCSI performance, which is Async under the v3.x driver, will greatly depend upon CPU and SCSI device performance.  Using A SCSI2SD v5.x, a device which tops out at ~1.1MB/sec in optimal systems, will typicaly see 500-600K/sec on a stock CPU, and 700-800K/sec with an A2620 (68020/4MB/14MHz+Kickstart remap to 32-bit RAM).  At the high end of the performance window, using an Aztek MonsterCF SCSI device, and an A2000 TekMagic 68060/32MB/66MHz, driving the same SCSI+RAM/8 interface, could see ~1.5-1.6MB/sec.

Trivia: Cosmtectic AutoConfig Issue: The board configures as GVP Product ID 1761/8 similar to the HC2.  GVP's original product code is 2017.  A bit was missed in the AutoConfig math.  i.e. - 2017-1761=256.  Also, the board is one of the rare 128K I/O PICs - There is no functional reason for this.  All other boards except the original Impact HC Rev 3 (also 128K) are sized as 64K PICs.  Board registers and 33C93A in 32K, ROM 16K, SRAM 16K (a generalization, not actual order).

Page contributors: NicDouille, Robert Miranda (GVP Tech Support)
Updated: 7/24/2021 . Added: 12/22/2004