exxos's Atari, Amiga & retro forum

TF534 on A2000
Motherboard Rev: 6.2
CPU: 030 @ 40mhz
FPU: Yes
Fit with Relocator: Yes
Relocator: Matze open – source
RTG Card: Matzes a1k.org Graphics Adapter
AmigaOS: 3.1.4 w/ bestwb 1.1; also 3.1 / classicwb

This post is confirmation that the TF534 works correctly with an A2000 and the RTG card mentioned above. I see no graphics distortion as has been seen by 8-bit dreams with his configuration, which is similar to mine other than A2000 Rev 4.2 motherboard.

Thank You for this update Adrian,
Seems that my A2000 is a bit picky about Zorro expansions, will try to find a rev 6.x motherboard to make my tests more reliable..

Realised that Your TF534 is 40Mhz while all my tested TF534 cards are clocked @50Mhz this makes big difference...will wait on Steves test to be sure...
For now seems to be a rev 4.x issue.. Maybe Commodore built another "oooops" mistake just like a wrong routed ks socket on rev 3 & 5 A500 amigas, who knows...

I cannot get my A2000 rev 4.4 mobo to even recognise either my EGS Spectrum or my Picasso 2 with a TF534 @ 50MHz in. On the plain old 68010 though, no problem.

What on earth can I do about it though?

Any ideas gratefully received.

Cheers

Luke

Havent got any capacity to look at 534 issues. Sorry,

i can talk about my findings only. first thing about are graphical glitches ive got on my setup and reported to Stephen back in 2019
it turned out this was caused by my Megachip upgrade (well, actually not Megachip itself, but VBB 8375 Agnus ive used).

VBB stands for Voltage Back Bias. It is a voltage generated by an internal DC / DC converter. This voltage is applied to the substrate and "improves" the function of the IC. Commodore may not have used back bias in older 8372 Agnus generation or the capacitor was on the chip, who knows..Back in the days when the chips were delivered as a replacement for 8372 - there was no specific information except that the 8375 Agnus chips have no NTSC/PAL switch on pin 41 and the pin should be connected to a capacitor to ground and a pull-up resistor. However, it was not described why.

Incidentally, this chip is often a problem in A2000 boxes. Because if the 2000 had an 8372 chip and should run on PAL, JP102 was pulled (PAL operation). If you then use an VBB 8375 Agnus - Amiga becomes unstable and produces graphical errors and glitches because the 2000 has a pull-up to 5 volts. The VBB Agnus thinks it's stupid for some reason. So if you connect that pin over a capacitor to ground - the haunt is over. This also works if you put the pin directly to ground (without a capacitor) or left this pin completely unconnected. (This is also the reason why the VBB 8375 in A500 Amigas did not cause the problem - cause A500 boards at pin 41 either are ground connected or the pin is open..

So Yeah, TF534 works on A2000+RTG without any problems, even better, if You use an RTG - You have full 2MB of Chip RAM after system is loaded :idea:

Attention!
REV 4.x need some resistor fixes in order to use accelerator cards!

I have tried to msg you 8bit but you are not responding..

I did notice this post, I have the thread on the slow IDE.

My MB on my A2000HD is rev 4.2

What modifications are needed?

James

8 Bit Dreams wrote: 07 Jun 2020 18:13 Attention!
REV 4.x need some resistor fixes in order to use accelerator cards!

Is there somewhere I can get this information? what mods are required by a 4.x board? I have 4.2

James

I think it would be really useful if someone could do a post in the amiga section for general recommended patches to A2000s. And other machines (like the A1200 patches). In the hardware guide section .