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Old 26 December 2012, 18:00   #1
SpeedGeek
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A2091/A590 scsi.device 14 MHz patch

Hello my Great Amiga Coding Wizard friends!

I'm looking for ideas and assistance to patch the A2091/A590 scsi.device to provide better support for synchronous mode with the 14 MHz mod.

http://eab.abime.net/showthread.php?t=58433

I've written a small tool to check the 33C93A Config but this does not address a possible problem with the dynamic (software) calculated sync period or the patching of scsi.device itself.

I know that most of you guys are light years beyond my feeble coding skills. I will upload a complete 16KB image of the C= V7 ROMs to the Zone. Thanks for any and all of your help!

Last edited by SpeedGeek; 14 April 2014 at 22:35.
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Old 29 December 2012, 20:33   #2
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More Technical info:

- The A2091 is an Auto-Config device so the board can be located at any 64KB block of Zorro2 I/O space. (The Board is Configed by expansion.library)

- The first 8KB of the 64KB block is where the Auto-config, DMAC and 33C93 registers live.

- The ROMs are offset by $2000 and currently use 16KB of address space with mirror images appearing for the remaining 40KB of address space. (So $2000 is good place to start dis-assembling the ROM binary).

- The ROM's contain the RomBoot device code to install scsi.device bootable volumes which differs from the resident type code of the IDE scsi.devices (and of course they also contain the low level code for SCSI I/O)

Last edited by SpeedGeek; 09 November 2013 at 18:29.
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Old 21 January 2013, 13:11   #3
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This guy seems to have given it a go (and posted the rom code) - at least I think that's what Im looking at..
I cant help you with the code, but I will be doing the A590 14mhz mod will be happy to test this if you make any progress
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Old 05 June 2013, 20:37   #4
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** NEWS UPDATE **

I patched 4 bytes of code in the ODD ROM (U12)* and now I can boot with 33C93A registers set for 14MHz! The 33C93A_14MHz Util is NO longer needed for C= V7.0 ROMs (but a new 33C93A_Config tool is available for testing patched ROMs).

So far working good with old (flaky) Quantum 52 & 105 + 550 MB Compaq HDs. You have to set JP5-4 on + Synch enable jumper on some HDs.

Dynamic calculation of Synch period still not patched but I don't think that's really necessary now since the A2091 scsi.device was ALREADY using the same default value as the A3000 scsi.device.

A very special thanks to Don Adan for his valuable resourced disassembly of this real scsi.device!

*NOTE: The even numbered ROM actually refers to the odd byte!
Attached Files
File Type: zip A2091O14.zip (5.0 KB, 262 views)

Last edited by SpeedGeek; 25 May 2014 at 18:22.
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Old 18 August 2013, 15:01   #5
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I Tried it and it seems to work like a charm.
thank you
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Old 25 May 2014, 19:53   #6
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Quote:
Originally Posted by SpeedGeek View Post
** NEWS UPDATE **

I patched 4 bytes of code in the ODD ROM (U12)* and now I can boot with 33C93A registers set for 14MHz! The 33C93A_14MHz Util is NO longer needed for C= V7.0 ROMs (but a new 33C93A_Config tool is available for testing patched ROMs).

So far working good with old (flaky) Quantum 52 & 105 + 550 MB Compaq HDs. You have to set JP5-4 on + Synch enable jumper on some HDs.

Dynamic calculation of Synch period still not patched but I don't think that's really necessary now since the A2091 scsi.device was ALREADY using the same default value as the A3000 scsi.device.

A very special thanks to Don Adan for his valuable resourced disassembly of this real scsi.device!

*NOTE: The even numbered ROM actually refers to the odd byte!

I have latest (?) A2091 and A590 scsi.device v40+, if you need these versions for your works, send to me mail.
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Old 30 May 2014, 03:09   #7
SpeedGeek
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Quote:
Originally Posted by Don_Adan View Post
I have latest (?) A2091 and A590 scsi.device v40+, if you need these versions for your works, send to me mail.
Hi Don,

OK, I'll send you an email.

P.S. I never did get a resourced version of scsi.device to assemble with DevPac. There are just to many errors. Switching resource to old syntax reduced the errors but doesn't eliminate them completely.
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Old 31 May 2014, 23:39   #8
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OK, here's some good and bad news:

I received the V40+ versions from Don Adan. Thanks!

I tested the two A2091 BindDrivers versions (there are also two separate versions for the A590 but for no practical reason I can think of) and they seem to limit the Max. transfer rate to 1.4MB/sec.

I even patched the latest V40.4 (from the V2 directory) for 14MHz operation and tested it with Synch transfer mode enabled but I still get 1.4MB/sec Max. So, as far as I can tell they're a big downgrade from V37.64 (V7.0) which can easily manage a 3MB/sec transfer rate.

Last edited by SpeedGeek; 01 June 2014 at 01:34.
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Old 01 June 2014, 00:00   #9
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I wonder if it was compiled with debug or some rubbish like that?
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Old 01 June 2014, 17:17   #10
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The v40+ version for A590 supports hdd bigger than 8GB?
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