+slx Posted June 7, 2020 Share Posted June 7, 2020 I found an Atari Mega ST4 with a daughterboard which seems to labelled Atari C103047 on a local classified site. I don't recall such a daughterboard in other Mega STs. Any ideas what it's good for? I only find that number as C103047-001 for the floppy drive. Quote Link to comment Share on other sites More sharing options...
+poobah Posted June 8, 2020 Share Posted June 8, 2020 The correct part number is C103067. It adds a 16 MHz MC68881 Floating Point Chip to the system. 1 Quote Link to comment Share on other sites More sharing options...
+slx Posted June 8, 2020 Author Share Posted June 8, 2020 3 hours ago, poobah said: The correct part number is C103067. It adds a 16 MHz MC68881 Floating Point Chip to the system. Interesting. Are you aware how that board was marketed? I've been a Mega ST owner for years in the 80's but can't recall that being offered for sale or even mentioned anywhere. Quote Link to comment Share on other sites More sharing options...
MasterMotorola Posted June 8, 2020 Share Posted June 8, 2020 I have never heard of it either. According to this web site, it was manufactured by... Commodore! Perhaps it was an Amiga board that Atari was hoping to adapt? http://130.89.168.1/stefan/chipdir/n/103.htm 1 Quote Link to comment Share on other sites More sharing options...
+slx Posted June 8, 2020 Author Share Posted June 8, 2020 1 hour ago, MasterMotorola said: I have never heard of it either. According to this web site, it was manufactured by... Commodore! Perhaps it was an Amiga board that Atari was hoping to adapt? http://130.89.168.1/stefan/chipdir/n/103.htm I searched for it but only found solutions by other providers (which also fit non Mega STS) in German magazine ST-Computer 11 and 12/87. I rather doubt the Amiga re-use as the board size seems to be based on VME requirements and is rather large for the components. It is interesting that the original concept for the 68881/2 is based on floating point instructions causing an interrupt that is used to execute floating point code in software on machines without the FPU or serve code to the FPU on machines that have it, allowing code to run on either without adaptation. Apparently that interrupt is used for something else on the ST. That probably means there is a good chance that there is no standard method for FPU use on the ST. I wonder if there is any commercial software that uses it or if it was just used for self-compiled stuff. Quote Link to comment Share on other sites More sharing options...
+tf_hh Posted June 8, 2020 Share Posted June 8, 2020 1 hour ago, MasterMotorola said: I have never heard of it either. According to this web site, it was manufactured by... Commodore! Perhaps it was an Amiga board that Atari was hoping to adapt? IMHO this is a hoax. These boards are offered as "Atari SFP004" retail boxes widely availible in Germany during the high-time of the ST era. The most purchasers were universities and mathematical facilities. Only a few program packages (applications) supports this boards, mostly in scientific based areas. At the end of the 90s somebody purchased the last big warehouse in The Netherlands from former Atari Europe Central. Hundreds of this cards were offered at eBay for 1-2 years, like new SF-354 drives and other stuff. 2 Quote Link to comment Share on other sites More sharing options...
+slx Posted June 9, 2020 Author Share Posted June 9, 2020 12 hours ago, tf_hh said: At the end of the 90s somebody purchased the last big warehouse in The Netherlands from former Atari Europe Central. Hundreds of this cards were offered at eBay for 1-2 years, like new SF-354 drives and other stuff. Thanks for the info, wasn't aware of that, but that's probably because it was only marginally useful for the average user. Quote Link to comment Share on other sites More sharing options...
MasterMotorola Posted June 9, 2020 Share Posted June 9, 2020 Obviously that site claiming it was made by Commodore was completely wrong because they claim the Epson floppy drives for Atari were also manufactured by Commodore. Using the SFP004 name provided by tf_hh brings up much more information about his card... Manual... https://archive.org/details/Atari_68881_Co-Processor_SFP004_1988/mode/2up More photos... https://www.maedicke.de/atari/hardware/sfp004.htm 2 Quote Link to comment Share on other sites More sharing options...
Lynxpro Posted June 14, 2020 Share Posted June 14, 2020 Damn. For the size of that board, they should've thrown in extra RAM and/or a socket for a 68020 or 68030... 1 Quote Link to comment Share on other sites More sharing options...
guus.assmann Posted June 14, 2020 Share Posted June 14, 2020 I own at least 2 of those boards, one with original box and documentation. They were designed for the Mega ST and have this size, so the can be securely be mounted in the computer. There's a couple of standoffs at the end of the board, away from the connector. Also there's some metal shielding. There's a 16Mhz oscillator on the board. I've put a socket in and tested with higher frequencies. Above about 24Mhz there's not much improvement anymore. (Gembench test) The speed is determined mainly by the data transfer between CPU and FPU. BR/ Guus 1 Quote Link to comment Share on other sites More sharing options...
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