Big Book of Amiga Hardware

An accelerator for the A2000 which plugs into the CPU Fast slot. The card has the ability to take either the standard 72pin SIMMs, or the proprietary GVP 64pin SIMM32s. The GVP 64pin SIMMs are not compatible with the various other 64pin SIMM formats which existed during the era.  Each 72pin SIMM slot is linked to a 64pin SIMM slot, therefore, if you have a 72pin SIMM plugged in, you cannot also use a 64pin SIMM in the corresponding slot and vice versa. The card contains a 53C710 DMA SCSI-II controller which provides an internal 50pin connector, and an external 50pin connector, and supports autobooting. The card allows you to shadow the Kickstart into Fast RAM for improved performance (via 68060.library or 68040 MMU tools), and has a 68000 fallback mode for compatibility with old software. In order you use this card with a 68040, you must be running at least Kickstart 2.04 and have a motherboard which is revision 4.5 or higher. In order to use this card with a 68060, you must be running at least Kickstart 3.1, update the ROMs on the card to the 68060 version, and have a 4.5 or 6.2+ motherboard revision for best stability.  By default, the card never came with a heatsink or fan installed on the CPU. It may be necessary to add a heatsink and/or fan if other expansion products generate significant heat inside the case. If you find your card's operation is flaky, make sure you are using the latest version of SetPatch and CPU library available for your OS version. 

Jumpers

Memory Model Explained

The memory controller supports 4 overall 'banks' of memory, but the size and type of bank are controlled by jumper settings.  As a general rule, it is best to not try to mix different memory module types and speeds.  The GVP SIMM32 modules are known as a single-sided 4MB or 16MB SIMM module.  The 72-pin SIMMs may be single-sided (4MB, 16MB), or dual-sided (8MB, 32MB) type.  There is no need/support for EDO memory, and it may even cause problems with burst mode settings, so look for Page Mode, if possible.  Stick to 60ns memory (50ns is also okay).  1MB/2MB modules, if used, will result in non-contiguous memory, and are discouraged.

A memory configuration that produces a contiguous memory map is desired.  It is best to start with the largest memory model possible - 128MB.  Four 32MB 72-pin SIMMS fill the 4 'banks' of the memory range.  Jumper settings are set for double-sided and 16MB/side.

The next memory size smaller is 64MB.  You can achieve this two ways.  Have 1) 2x 32MB 72-pin SIMMs installed in sockets 1 & 2, and the 128MB jumper settings, or 2), use the 4x 16MB SIMMS in either the 72-pin sockets or the SIMM32 sockets, and select the single-sided memory setting.  As the SIMM32 and the 72-pin sockets are wired together (socket for socket), you can only populate one socket.  Mixing is not suggested, but if you must, use sockets 1 & 2 of one type, and 3 & 4 of the other type.

The next memory size smaller is 32MB.  It is possible to again use the 128MB setting and use a single 72-pin SIMM.  As most will want to try to use burst mode, this setting is not optimal.  The second 32MB setting is to select the 4MB module setting with double-side SIMMs, and populate with 4x 8MB 72-pin SIMMs.  The third 32MB setting is to select the 16MB module setting, and the single-sided module setting and populate with 2x 72-pin 16MB SIMMs, or 2x 16MB GVP SIMM32s in sockets 1 & 2. The second and third options in this section support burst mode.

The next memory size smaller is 16MB.  It is possible to use a single 16MB SIMM in either the first 72-pin sockets or the SIMM32 socket, and select 16MB and single-sided mode.  As most will want to try to use burst mode, it's not optimal.  The next two preferred options are based upon selecting the 4MB SIMM option, and then either 1) populate the 72-pin SIMM sockets 1 & 2 with 8MB modules and select double-sided module mode, or 2) populate either of the 4 sockets (or 2 and 2) with 4MB modules of the 72-pin or SIMM32 type, and select single-sided module mode.

The 8MB setting again has a less than optimal mode with a single 8MB 72-pin SIMM along with the 4MB module setting, and the double-sided module setting.  The optimal setting is to use a pair of 4MB modules in either socket 1 & 2 positions, and select 4MB module setting, and single-sided setting.

Burst mode.  The highest performance setting on this card.  Cherished by most, obtained by few, and not all of the time are the reasons clear for why it doesn't work.  Here are the most commonly observed items:

- use memory of the same maker, size, and type.
- use memory in pairs
- try with just two modules instead of 4
- avoid EDO memory (72-pin type)

It has been speculated that sometimes the performance of the output buffers of the Altera FlashLogic part(s) become marginal, and over time their electrical output may weaken.  This is based upon the Burst Mode initially working, and then one day years later stop working in that mode altogether.  Others are able to get it to work with only 2 SIMM modules present in either or one pair of the sockets, but not with all 4.  The use of GVP SIMM32 memory (original or clone, 16MB or 4MB) has not proven to be better or worse once the board has stopped supporting 4 SIMMs with burst mode.  In fact, it has even occurred that it works with 2x 32MB 72-pin non-EDO SIMMs, but not with a pair or four of 16MB SIMM32 or 72-pin type, and not with the preferred 4x 32MB modules.

The board has a refresh option for the DRAM of 2K and 4K.  Inspection of the markings on the chips of each module, and a reference to the part datasheet online, is needed to determin this.  Try not to mix the refresh types even with the 2K/4K option selected.

Armed with the better memory configuration information above, try other settings, if possible.  At worst, disable burst mode.


Unique Card AutoConfig

This board has a unique AutoConffig behavior.  Unique, as in it does not have any Hardware AutoConfig design of any sort.  It has a $F00000 'diagnostic' ROM image that the Amiga OS polls very early upon power up, and the code software-detects/maps the memory (>16MB address range) and SCSI controller addresses (located in the range below $F80000 but above the ROM code space) into the system.  In the version intended for the 68060, it also tames the 68060 FPU as some other cards of the initial 68060 era also do even under OS 3.1, without an exec.library hack required in the ROM image.

A patched ROM image (two bytes are swapped) can be made and re-programmed to address the known boot-block (RDB) filesystem load issue.

Overclocking: The board, if the clock component is socketed, can support a number of frequencies between 40Mhz and 66Mhz.  By trial and error it appears that there is a Phase Lock Loop clock design on the board, and this affects the possble clock speeds.  i.e. - An 80Mhz oscillator component will be ignored, and it will result in an (approximate) 66-70Mhz clock when benchmarking with a CPU frequency detect is done.

As a general rule, do not overclock Rev 1 and Rev 5 68060's by much, and always try to use heat sinks even at rated speeds.  Rev 6 runs cooler, but use a heat sink over 66Mhz.  Use the CPU060 tool or WhichAmiga to ID your chip's internal revision, and do not rely on chip labels.

This board supports the Ralph Babel 68060.library or the Commodore 68040.library (preferably the V44.2 from OS3.9, or the V37.30 from the last 3.1 OS release for A4000/A3640).  Kickstart remap with the Babel 68060.library is documented along with the latest library download here.  The MuLibs CPU library is also supported, and can be found on Aminet, search for 'MuLibs'. The board support tools are available on the GVP-M website under the A2040/A2060 product listing.

Zorro II Memory Note: It has been discovered with extensive testing that allowing a 68040 or a 68060 to run 'burst' cycles against Zorro II 16-bit 7MHz memory is an inefficient activity.  Most 16-bit Memory in fast systems like this is relegated to last-resort use and I/O buffering activity (for 24-bit DMA controlers like the A2091 and GVP Series II SCSI controllers).  Use of the MuTools mmu.library, and using MuSetCacheMode (or the mmu-configuration file) to render any 16-bit memory in the system as NoCache will prevent burst cycles, and improve performance/stability when set.  If the 16-bit memory is already only used for 24-bit DMA buffering, the CPU data cache has no benefit in any case.