External FastMem with a TF534

psoma · 23 May 2020, 03:18

Hi,

Am looking at getting myself a TF534 accelerator, but currently have a SCRAM 500 with 8MB Autoconfigure RAM. Had a couple of questions I'd like to run past the brains trust...

1) So the TF534 has 4MB of 32-bit RAM. If I disable 4MB in my SCRAM500 (it can run as 0, 2, 4 or 8MB), will Autoconfigure automatically pop 4MB from the TF534 and 4MB from the SCRAM500 in the correct memory addresses, or will they overlap?

2) If the former, will the system preference the 32-bit FastMem over the 24-bit sidecar FastMem?

Cheers!

hooverphonique · 23 May 2020, 16:59

I think the TF uses proper auto-config, so you shouldn't get an overlap - some of the TF's support using an address range outside 24 bits for its onboard ram (so you could keep all 8MB of SCRAM) , don't know about the 534 though.
Regarding the preference, it's entirely up to the priority the developer uses when the memory is added to the system - you can look up the priority of your SCRAM memory using something like SysInfo.

psoma · 24 May 2020, 00:25

Thanks mate - so looks like the TF534 autoconfigures to Zorro III (530 did not), and I just read the SCRAM technical details (God bless the 80s/90s and their desire to share every intricate detail with us):

"Note that BORIS looks at the RAM SIZE jumpers JP1, JP2 to tell the Amiga
how much RAM is available (0/2/4/8 Meg). The DENNIS chip latches the RAM
BASE OFFSET at AutoConfig time. DENNIS then becomes the address space
decoder for RAM, selecting the four banks in ascending order.
The Amiga always allocates RAM from 200000 onwards. None, 2, 4, 8 Meg
are possible configurations. When other RAM devices precede the SCRAM,
the base offset will not be 200000, so note that some memory sizes will
be illegal. Most likely just 8 Megs, as this needs ALL the RAM space to
configure."

Seems like it is compatible, even if the TF534 mapped to Zorro II (I'd just have to disable 4MB on the SCRAM).

Off to market I go...

jbilander · 24 May 2020, 11:41

The TF534 will autoconfig to Z3 space so shouldn't conflict. I think the TF534's 4MB 32-bit RAM will be given higher priority config automatically but I'm not sure. That is however important because the accelerator CPU has to insert wait states when talking to the 7 MHz bus (glue logic) = slow, whilst when talking to the 4MB onboard SRAM it is a matter of "don't tell the Amiga about it" and run full speed. The TF534 is obsoleted/not worked on any more and replaced with the TF536.

psoma · 25 May 2020, 02:01

Yeah, I've ordered a TF534 for now and will report back on the autoconfigure/priority situation. I realise the TF536 is the going concern but my understanding is there are no pre-built boards available yet, so the TF534 will (hopefully) tide me over until I upgrade to the TF536 down the track.

Cheers all!

brufnus · 11 October 2021, 20:33

Hi folks,

Speaking of the TF534... I just got one, which I'm about to install. Does any of you know what the JP1 jumper is for... something with the IDE controller, or?

dalek · 12 October 2021, 03:30

JP1 selects which clock to use - the one on the TF534 or the 7MHz system clock. Make sure it is closed for the two pins closest the cpu socket (left + middle).

I don't know why anyone would bother to install the headers on JP1. I just bridge pins 1-2 with a wire link.

23 May 2020, 03:18	#1
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	External FastMem with a TF534 Hi, Am looking at getting myself a TF534 accelerator, but currently have a SCRAM 500 with 8MB Autoconfigure RAM. Had a couple of questions I'd like to run past the brains trust... 1) So the TF534 has 4MB of 32-bit RAM. If I disable 4MB in my SCRAM500 (it can run as 0, 2, 4 or 8MB), will Autoconfigure automatically pop 4MB from the TF534 and 4MB from the SCRAM500 in the correct memory addresses, or will they overlap? 2) If the former, will the system preference the 32-bit FastMem over the 24-bit sidecar FastMem? Cheers!

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23 May 2020, 16:59	#2
hooverphonique ex. demoscener "Bigmama" Join Date: Jun 2012 Location: Fyn / Denmark Posts: 1,624	I think the TF uses proper auto-config, so you shouldn't get an overlap - some of the TF's support using an address range outside 24 bits for its onboard ram (so you could keep all 8MB of SCRAM) , don't know about the 534 though. Regarding the preference, it's entirely up to the priority the developer uses when the memory is added to the system - you can look up the priority of your SCRAM memory using something like SysInfo.

24 May 2020, 00:25	#3
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	Thanks mate - so looks like the TF534 autoconfigures to Zorro III (530 did not), and I just read the SCRAM technical details (God bless the 80s/90s and their desire to share every intricate detail with us): "Note that BORIS looks at the RAM SIZE jumpers JP1, JP2 to tell the Amiga how much RAM is available (0/2/4/8 Meg). The DENNIS chip latches the RAM BASE OFFSET at AutoConfig time. DENNIS then becomes the address space decoder for RAM, selecting the four banks in ascending order. The Amiga always allocates RAM from 200000 onwards. None, 2, 4, 8 Meg are possible configurations. When other RAM devices precede the SCRAM, the base offset will not be 200000, so note that some memory sizes will be illegal. Most likely just 8 Megs, as this needs ALL the RAM space to configure." Seems like it is compatible, even if the TF534 mapped to Zorro II (I'd just have to disable 4MB on the SCRAM). Off to market I go...

24 May 2020, 11:41	#4
jbilander Registered User Join Date: Jun 2018 Location: Stockholm Age: 48 Posts: 264	The TF534 will autoconfig to Z3 space so shouldn't conflict. I think the TF534's 4MB 32-bit RAM will be given higher priority config automatically but I'm not sure. That is however important because the accelerator CPU has to insert wait states when talking to the 7 MHz bus (glue logic) = slow, whilst when talking to the 4MB onboard SRAM it is a matter of "don't tell the Amiga about it" and run full speed. The TF534 is obsoleted/not worked on any more and replaced with the TF536.

25 May 2020, 02:01	#5
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	Yeah, I've ordered a TF534 for now and will report back on the autoconfigure/priority situation. I realise the TF536 is the going concern but my understanding is there are no pre-built boards available yet, so the TF534 will (hopefully) tide me over until I upgrade to the TF536 down the track. Cheers all!

11 October 2021, 20:33	#6
brufnus Registered User Join Date: Jul 2021 Location: Aarslev, Denmark Posts: 90	Hi folks, Speaking of the TF534... I just got one, which I'm about to install. Does any of you know what the JP1 jumper is for... something with the IDE controller, or?

12 October 2021, 03:30	#7
dalek Registered User Join Date: Nov 2014 Location: NSW/Australia Posts: 462	JP1 selects which clock to use - the one on the TF534 or the 7MHz system clock. Make sure it is closed for the two pins closest the cpu socket (left + middle). I don't know why anyone would bother to install the headers on JP1. I just bridge pins 1-2 with a wire link.

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