On Wed, May 11, 2016 at 10:20 PM, Jack Rubin <j...@ckrubin.us> wrote: > I've been looking for a 128K MOS memory board for my PDP-8/A for a while. I > finally got one, but it turned out to be an M8418.
Huh... I'm not sure I've seen that version. > The docs I've seen (bitsavers EK-MS8CD-TM-001, 1980 + printsets) talk about > an M8417 with 4k DRAM chips (MS8-C) and an M8417 with 16k DRAM chips (MS8-D), Right... I remember the MS8DJ in particular as the full part number for the 128K MOS board. > ...but apparently at some point the 16k versions became known as the M8418. > The card I received has 96 Fujitsu MB8116E 16k DRAMs, arranged in two 8 x 12 > chip arrays. The actual circuit board says PDP MOS MEMORY - M8417 - 50 12701B > on the back but the metal card ejector edge is stamped M8418 JC. Chip dates > on the board put it at 1980 production. OK... then that sounds like a later change to help easily distinguish the 16K/32K boards from the 128K boards, rather than a stamped "D" or "C" on one of the handle sections. > None of my literature has the M8418 p/n but most of it may be too old. The > M8418 part number (with JC suffix to indicate Fujitsu RAM) does show up in > the 1988 Options Module List. Well then it sounds like a real thing that lasted long enough to make the list. > I know several list members have similar boards. How are they marked? Can > anyone point to more info on the M8418? I haven't stared at mine in many years, but I'm fairly certain I have an M8417 with "DJ" stamped on the other part of the handle. I would have gotten it from a 3rd-party reseller like Newman Computer Exchange in the late 1980s (I got the PDP-8/a in 1984 but wouldn't have upped it to 128K right away - I was buying a lot of used PDP-8 gear between 1985 and 1987). -ethan
