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Re: Micro SCI disk controller, mystery solved
- Subject: Re: Micro SCI disk controller, mystery solved
- From: mjmahon@aol.com (Michael J. Mahon)
- Date: 29 Jan 2004 05:29:59 GMT
- Newsgroups: comp.sys.apple2
- Organization: AOL http://www.aol.com
- References: <%D_Rb.25956$5D.7107@clgrps13>
- Xref: archiver1.google.com comp.sys.apple2:2889
Wayne Stewart wrote:
>Ethereal wrote:
>
>> If the chip is made by National Semiconconductor then it's a good
>> possibility that it's a PROM chip. NS used to make some low density PROMs
>> with 74LS and 74S prefixes (e.g. 74LS471, 74S287, 74S573, etc.)
>
>Unfortunately there's no manufacturers name on the top of the chip.
>I'm tempted to pull the chip and try a 74LS125 but it's a pain when
>you don't want to risk damage to either the chip or board.
I haven't seen the back of the board, but if you check, I'm quite
sure you'll find that it is a 256-byte PROM, wired to the address
and data lines.
The card could not function as described without a boot PROM.
-michael
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