D-shell sizes [was Re: Slightly rare Mac 512k with

<chuckle> Going back to your earlier topic, so I really should nest another "Was:" up there. :-) Jim's old Mac had the same kind of SCSI connector. You probably never looked closely at it at an early Geekathon. Or maybe he only brought it to the first one and brought the Outbound the next few years. Anyway, the upgrades for the 128K and 512K[E] models which provided a SCSI port, typically routed the ribbon cable around the edge of the battery compartment. A few ran the cable over the floppy connector. The more elegant ones actually provided a replacement battery compartment cover which had the DB25 connector (awww, back to the topic) mounted in the plastic cover. One removed the old battery compartment cover, routed the SCSI ribbon cable out of the case around the edge of the battery compartment and secured the new cover over the battery compartment, which gave one a DB25 connector mounted over the battery compartment. There were several SCSI upgrades for those old machines. The SCSI-only upgrades usually plugged into the ROM sockets, provided sockets on top of the upgrade daughter board for the two ROM chips and then bore a 53C80 and ribbon header. There might have been a bit more logic, but not much. IIRC, they did require that the host machine be upgraded to the later 512KE or Plus ROMs because the original 128K and 512K ROMs did not contain a SCSI port driver. Other upgrades provided additional memory as well and those typically required tapping all the CPU lines, so they either used a Killy Clip (clear plastic receptacle with embedded pins which fits snuggly over the 68000 DIP) which provided a double row of pins above the clip in the standard 64 pin DIP spacing, or they relied on headers soldered directly to the 68000 pins. My favorite was the NewLife brand upgrades because they provided eight SIMM sockets on the daughter board. If one had a 512KE, one could install the NewLife upgrade and add a SCSI port and eight SIMM sockets. Then two 1MB SIMMs and six 256KB SIMMs later, one had a 4MB (maximum) RAM equipped Mac Plus equivalent, which was supposedly somewhat faster for reasons I never really understood. The CPU ran at the same speed, but the Newlife guys claimed some part of their interface to the peripheral logic or maybe to the RAM was faster. The advantage of that memory arrangement was that back at that time (early 90s) 1 MB SIMMs were still close to $100 each, but 256KB SIMMs cost between free and $5, or $10 if one totally failed one's merchant skill. Jeff Walther