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The 2004 RCS/RI |
The Retro-Computing Society of Rhode Island, Inc. hold their monthly Open House on the third Saturday of every month from 10:00am - 4:30pm at their facility in Providence, RI. See the online directions for instructions on how to get there.
On Open House days, the telephone line, (401) 861-1977, is staffed with bona- fide humans who can answer questions about the organization and give detailed directions to their facility.
Archived calendars for 1998, 1999, 2000 2001, 2002, and 2003 are available on-line.
The Symbolics 3600 series LISP Machines, including the 3640 and 3670.
The Packard Bell pb-250.
The Packard Bell pb-250 (continued.)
Substantial progress was made with our Interdata Model 4 on the 19th. We identified a bad clock pulse- shaper that needs to be replaced in order to continue work on the machine. This problem can be fixed by either replacing a 35-053 R06 daughterboard or a 2N3646 transistor. At the moment we have neither part "in stock".
Substantial thanks go out to Dr. Evan Wasserman for his most generous loan of an otherwise-unobtainable Interdata extender card that was critical in this diagnosis.
Update: Thanks again to Dr. Evan Wasserman, we replaced the faulty 35-053 daughterboard and all the clocks are once more ticking nicely. The machine passes through a nominal initialisation cycle and is capable of reading and writing memory, although there are hints of a memory-selection-logic problem; there is also a stuck bit in the program counter (PC) register that will need fixing before the machine is fully operational again. (In short, this is one sick puppy.)
We hope to have the machine fully functional in the next few months.
The Vintage Computer Festival East 2.0 will be held at Sun Microsystems in Burlington Mass. Due to this event there will not be an open house at the RCS/RI Millspace this month. Instead, RCS/RI will be exibiting at VCF East.
Not a lot happened this month according to plan, and we wound up working on some of our older Cisco kit, getting Ethernet pulled out to our display/working location, and working on the Interdata Model 4 system.
We're in a bit of a quandry at this point in time with the Model 4. There's a stuck bit in the PC (Program Counter) register that resides on a 9030 chip on Bit-Slice 1 (second highest). Unfortunately, without a microcode listing and a way to single-step the microprogram we cannot concretely identify the exact 9030 chip on the board. Since 9030s are (1) rare and (2) are directly soldered to the bit-slice boards we are naturally hesitant to simply guess at which one is defective. If anyone reading this has access to a microcode listing for an Interdata Model 4 CPU and/or the MOTS (test) box, please contact us! We do have a very limited stock of spare 9030 chips, but as these will be coming from a "donor system" (an incomplete Interdata Model 3 belonging to one of the members), hints to an external supply will be enthusiastically welcomed.
In the interim, one of the RCS members is going to try and design a test jig in which he can statically exercise the failed board outside the system in a controlled fashion in an attempt to ferret out the bad chip.
Since we never got to work on the assorted Desktop Generation systems last month, we're going to try again this month. Desktop Generation systems in the RCS/RI inventory include both Model 10 and Model 20 systems. One of the Model 10s is currently inoperable (fried PSU -- dead short across the mains input) and we hope to get it running again; we are also going to identify what Model 20s we have work, and what peripherals are operational.
Well we actually held to our scheduled topic this month and WOW did we make progress! From a pile of Desktop Generation 20 parts we constructed two running systems, one of which has a 15Mo disk and the other a 38.6Mo disk. We discovered a single bad 38Mo disk, a Rodime RO204E, so if readers of this have knowledge of where one may be obtained, we'd appreciate a note.
In addition to the newly-resurrected Desktop Generation 20 machines, we were able to revive a Desktop Generation 10/SP system belonging to one of the principals. We replaced the failled PSU with a spare from the Model 20 haul and managed to get the disk spinning. The Winchester disk on that unit was so wegded up from "stiction" that an appreciable about of manual force was required (several inch-pounds, by estimate) on the bell- brake to get the spindle turning. Once turning, however, the system booted up in 16-bit AOS without problem -- a testament to how robust some of the early hardware is!
Each December, RCS/RI celebrates its anniversary. This year marks their 10th year of existence as a working group and their Copper (7th) Anniversary as a non- profit corporation. This month we will continue work on the systems that were the featured topics of the previous open houses.