>Date: Wed, 26 Mar 2003 18:29:20 -0800 (PST) >From: Dave Lee <[EMAIL PROTECTED]>
>This Mac has the same ports as the 128k (and 512k) but has 2mb of >RAM. The SCSI >port is where the battery door was. > >Is this in fact a Plus motherboard or a modified 128k/512k/512ke >board? I haven't >openend it up yet to see what the motherbaord looks like so I >thought I would ask >here. It does have the 800k internal disk drive. Sadly, the >external SCSI port in >the battery door location is not working... It is a pre-Plus board with one or two upgrades installed. A Plus board will have DIN8 (round) serial ports. A Mac 128K, 512K, or 512KE will have DB9 (two rows of pins in a trapezoid) serial ports. There were separate memory upgrades and SCSI upgrades. The memory upgrades typically installed by removing a couple of chips from the memory circuitry, installing raised sockets and plugging the memory upgrade into that. The SCSI upgrades I have seen were installed by removing the ROM chips, plugging the SCSI upgrade into the ROM sockets and plugging the ROM chips into sockets on the SCSI board. There were probably other versions which clipped over the CPU. Several companies made a combined upgrade. These clipped over the existing CPU and provided memory expansion and a SCSI bus. Some included a faster 68000 CPU, or even a 68030 chip. There were a few that included video circuitry for a separate monitor. Brands included Dove, Marathon, Gemini (brand or model?), Applied Engineering (I think, hazy here), and Newlife. I was fond of the Newlife upgrades for the 512KE because RAM was very expensive back then and the Newlife upgrade has eight SIMM sockets. So, on a Mac 512KE you could get to 4 MB by installing two expensive (like $80 each) 1 MB SIMMs, and six inexpensive ($5 each or free) 256K SIMMs. That added to the RAM on the motherboard took the machine to 4 MB. The Newlife upgrade had its own 68000 CPU on board but it was not any faster than the Mac CPU. The guys at Newlife explained that it was just easier to put the Mac CPU to sleep and have their own CPU on their board than it was to arrange to use the Mac CPU. 68000 chips were under $10 back then, IIRC. Newlife also had an upgrade which I could never afford. It installed in a Plus or 512KE and provided a fast 68030, memory expansion, SCSI and video out. I really wanted that one. I think it's memory could go to 16 MB. The Mac ROM didn't support more than 4 MB, but the way I understood it, the extra memory became a RAM disk, and then one took advantage of the 68030's PMMU to implement virtual memory which turned around and used the RAM disk for its scratch space, thus turning the extra RAM into available RAM in an bass-ackwards kind of way. One had to have Connectix's "Virtual" to make this work. It's possible that the board that supports your SCSI upgrade has simply popped loose and would function if reseated. Note, that you can't slide the motherboard out in most machine that have an upgrade installed, because the board is too tall. You must sort of ply one edge of the logic board out of the rails and tilt the board out of the chassis. Many Mac Pluses were Beige. The later ones were platinum. Jeff Walther -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> The FAQ: <http://macfaq.org/> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
