sanjaya wrote:
I did further search on this unknown card. Apart from LS74 series chips, it has following important ICs1. DP8390CN / NS32490CN :closest I found was DP8390D and DP8390C, which is a network interface controller for ethernet by National Semiconductors.
One of the classic ones, actually; this chip is what the NE2000 spec was based on, as well as Western Digital/SMC's ISA cards.
2. DP83910: CMOS Serial Network Interface for 10BASE-T by NS
Converts the raw TTL signals coming out of the 8390 to Ethernet AUI pairs...
3. DP8392AN: Coaxial Transceiver Interface
...which this then interfaces to coax. (You could run 10BaseT with a different chip here, but that'd require modifying the board.)
By the way, the "2VP12U9 LAN-PAC" is a DC-DC converter, regulating the 12 volts from the Apple II bus down to 9 volts for the Ethernet.
5. KM62256 SRAM 32K
Packet buffer. Pretty common sight on 8390-based boards; 16k is the norm over in PC-land for NE2000s, so this card might be doing double buffering.
6. 8936 by Innovations in Computing unknown. Did extensive search but didn't found any info. ChipDir website search shows DS8936, which is a LocalTalk Transceiver (can't be as number of pins are totally different.)
It's a custom chip, so detailed information on it would probably be impossible to find. BTW, the "8936" is just a date code (1989, week 36), so the real part number would be the long one just above it.
As for what it actually does, I doubt Localtalk is involved at all; this looks like it's a glue chip to the Apple II bus (sort of like the glue logic NE2000s use), possibly containing some extra functionality like a interval timer. I doubt there are any coprocessors involved, since there's no other ROM around except for the boot ROM.
Another thing I want to know is that whether this is a Apple II compatible card or not.....
From the look of the edge connector and the bevel in the card's rear end, I'd say it is.
-lee