Tips & tricks for the GVP-m G-Force 2040/2060 accelerator board
(also known as TekMagic 2060/060)

Stéphane Guillard -


1 - Introduction

The G-Force 2040/2060 was a board made by GVP-m until something like 1999. It is a Motorola 68040/68060 accelerator board for the A 2000. Here it is :

When it works, it is very fast, and can easily be overclocked. Its SCSI controller has some limitations (like not being able to automount other filesystems than FFS), but it is also very fast (one of the fastest I have experimented on the various 68060 Amiga configurations I own) and bug free.

This page aims at collecting info and tips about this board.

2 - Upgrading from 68040 to 68060

In the file area of this site, you will find the 2 necessary EPROM images to burn into 2 27256 when you want to upgrade from 68040 to 68060.

Apart from replacing U11 and U12 (triple check chip orientation and pins), you will need the following :

3 - Common problems

Many owners have experienced trouble in these areas with the board :

> Only when
> mounting the simms on bank 2 and 4 it started but without detecting the simms.

This I can explain : if there is no SIMM in bank 1, the board will skip
detecting the other banks.

> my actual settings are:
> simms on bank 1 and 2
> JR1 off
> JR2 off
> JR3 on
> JR4 on
> JR5 on
> JR6 on (because my simms are double-sided)

64 MByte SIMMs double sided ? I thought they would have been single-sided

> JR7 on (factory setting)
=> With this settings I have a 64mb memory block, with several other
> I got blocks of 4x16mb, 1x48mb/1x16mb,... I never know all the
> I tested.

Okay. I think of two things :
1 - the board can not handle 64 MByte SIMMs
2 - I know that the board is sensitive to the order of your SIMMs. Mine,
with 4 32 MByte EDO SIMMs, will only give 128 MByte with a certain order of
the four SIMMs (which I have marked as 1, 2, 3, 4).

> So this are my questions: 1. under what conditions can I Set the JR1
> burstmode and will this have advantages?

See above. Even with only 2 4 MByte FPM SIMMs, I can not have my board boot
again with JR1 On.

The effects of this is half the memory bandwidth.

> at every time I set the JR1 jumper the card crashed at once.

Normally, as per the doc, JR1 should be only set to on with an even number
of SIMMS (i.e. 0, 2, 4). This has been working for me for several months
with 4 16 MByte FPM SIMMs, and then, one day, without any rational reason
the board would not boot any longer with JR1 on, but would boot normally
with JR1 off.

Not using the burst mode has a side effect : the memory bandwidth, which was around 60 MByte/s (by bustest 1.9 on Aminet with my 60 MHz 68060) went
down to half this : 30 MByte/s :-(

Trust me, I have been trying EVERYTHING to make it boot again with JR1 on (including resoldering everything on the board, cleaning every contact, changing SIMMs, going down to 50 MHz, putting a fan on the SIMMs and on the
060, putting the board in another 2000, etc...). I did not succeed, and since maybe 6 months, the board runs fine, but without the burst mode :-( I have never had any answer from either GVP-m or the dealer who sold me the

I may have an explanation : the flashlogic chip used on the DRAM controller onboard has a fanout which is not high enough to sustain burst mode ; it works for a certain period of time, slowly screwing the gates, and then one
day, it will only work with burst off.
The board, when operated w/ a 50 MHz 68060, has a flaw that will make it freeze every 2 or 3 day.

> 2. is the external SCSI connector an standard 50pin hd finepitch
> so I can buy a normal adapter at a computer shop?

Yes. The onboard SCSI-2 controller is an excellent one, which gives me 10 MByte/s out of my IBM 4.3 GByte HDD, in synchronous mode. The backside connector is a standard one.

> 4. Can I upgrade the scsi
> controller with a guru-rom and if this is possible, will there be
> advantages in speed, compatibility,...

There is no guru rom for this board, and it is not necessary, since the
hardware (NCR 53c710) and software (tekscsi2.device) sides of the SCSI-2
controller onboard is excellent.

Jumper OFF or 1-2 ON or 2-3 Default
J1 CPU 5V (040) CPU 3.3V (060) Depends on your setup
J2 Clock : 040 Clock : 060 Depends on your setup
J3 Clock enabled Clock disabled OFF
J4 CPU : 68000 CPU : 040 or 060 ON
J5 No DTACK pull up DTACK pull up OFF
J6 SCSI term No SCSI term OFF
J7 DMA ignores IRQ DMA back off IRQ OFF
J8 ? ? ?
J9 Rom 27c256 Rom 27c512 1-2
J10 12 V Fan
J11 5 V Fan
JR1 Non burst Burst ON
JR2 60 ns SIMMs 70 ns SIMMs OFF
JR3 Burst write off Burst Write on ON
JR4 Burst read off Burst read on ON
JR6 Single side SIMM Dbl side SIMMs OFF (for 72 pin SIMMs)
JR7 Reserved ON
JR8 2K or 4K refrsh 4K refresh only OFF