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101090 discussions

resistor packs for terminating SCSI bus inside Exabyte 8020

by nw.johnson＠ieee.org

Hi all, I wonder if anybody has one with the terminators installed that can read off the p/n for these SIPs The manual says they are 8-pin 7 resistor 220/330 ones, but that is not possible! To put 7 resistor pairs to 220 and 330 you need a 9-pin, unless you have one resistor SIP for 220 and another for 330!? But there are 2 so that leaves an odd number! The sockets are 9-pin.? I have yet to find any 9-pin ones on digikey cheers, Nigel -- Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU Amateur Radio, the origin of the open-source concept! Skype: TILBURY2591 nw.johnson at ieee.org

5 years, 2 months

Apple ][+ ic

by david4602＠gmail.com

On 2/10/21 1:00 PM, John Many Jars<john at yoyodyne-propulsion.net> wrote: > So, I have an Apple ][+. It is missing an IC at location a3 on the > motherboard. > > I don't know why. it used to work... I think my mind is going. I have no > memory or removing it. Anyway, I need another one. The board is marked > 74166. > > Can I put any shift register IC with a similar part no, like this one: > > 74166PC | FAIRCHILD | IC DIP-16 Shift Register (icompplus.com) > <https://www.icompplus.com/en/integrated-circuits/24400/74166PC> > > in there, or ? > > Thanks, > > mark aka john I have a mobo that has that very part (Fairchild 74166PC), so it's a good bet it'll work. - David

5 years, 2 months

Part# request: TK70 eject switch

by cz＠alembic.crystel.com

Working on fixing a pair of TK70's here to speed up my backups. The TK50 is fine on a TQK70 controller (it streams perfectly) but I am coming close to filling a tape. I've managed to assemble a working TK70 out of two unhappy ones, but to fix the other I need to replace the eject button switch. The plastic/rubber on it has turned to the usual goo. Does anyone know the part number for that switch? Taller than a usual SMD button switch, so a stock one won't work. I could take it apart but that would be a kludge. Thanks!

5 years, 2 months

APL\360

by paulkoning＠comcast.net

I was just poking around the computerhistory.org website, searching for Knuth stuff. The second or third hit when I search for "Knuth" is this one: https://computerhistory.org/blog/the-apl-programming-language-source-code/ . It's not just about APL, it actually has a downloadable copy of the source code. And it points to an executable version, apparently a packaged up Hercules running that code. Nice. I'll have to give it a try. paul

5 years, 2 months

Digitalker 54104 IC

by brain＠jbrain.com

I suspect the answer to question #1 is no, but thought I would ask. 1) Anyone happen to have a known working Digitalker 54104 IC they are looking to trade for some cash that does not involve me selling an arm or a leg :-)? 2) Barring that, anyone have a known working Digitalker-based unit that might be able to pop in a suspected non working Digitalker IC and test? I have a Jameco (yep, the parts firm) manufactured Digitalker unit here called the JE-520 that is my original unit.? It suffered some ROM bit rot long ago and was not working, but I acquired the ROMs a while back to repair the unit. Now, though, as I pull it out for another project, it seems to be misbehaving.? It's like "address bit 1" on the input commands is acting up.? For instance, word 48 is "zero", and 49 is "one", but zero will be followed by "three" and then "zero" and then "three" as one sends values 48,49,50,51 to the unit.? I'm working to confirm the bit 1 on the cable to the PC is not bad, but initial efforts point to it being the IC. Jim -- Jim Brain brain at jbrain.com www.jbrain.com

5 years, 2 months

DEC RK11-C Disk Controller - on ebay...or is it?

by jnc＠mercury.lcs.mit.edu

> From: Fritz Mueller > In at least one case of attempting to recover a pac BTW, your neat hack to do that only works on the RK11-C, and not the RK11-D: the latter doesn't implement 'Read/Write-All'. Noel

5 years, 2 months

DEC RK11-C Disk Controller - on ebay...or is it?

by jnc＠mercury.lcs.mit.edu

> the Unix V6 RK pack formatter ... sets _both_ 'Format' and > 'Read/Write-All Oooops; my bad; I mis-read the register description. It's setting 'Inhibit Bus Address Increment' and 'Format', not 'Format' and 'Read/Write-All'. So ignore my speculation about 'Read/Write-All' not getting the sector header word from memory. My bad! Noel

5 years, 2 months

DEC RK11-C Disk Controller - on ebay...or is it?

by jnc＠mercury.lcs.mit.edu

> Fron: Jon Elson > The write all function is likely how you format a blank pack. No, 'Format' is a separate bit in the CSR from 'Read/Write-All', and they do different things. The RK11 always re-writes the header word of each sector when it writes a sector in normal operation; when 'Format' is set on a Write operation, it merely supresses the 'read header word and check/compare' function (which normally precedes any disk operation, to make sure the head's at the right place). Format/Write then goes ahead and writes the header word of the sector, just as in normal operation. (It is possible to set 'Format' on a Read operation; that just reads in the sector header words into memory.) Although in theory one could use 'Read/Write-All/Write' to format packs, the Unix V6 RK pack formatter: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/mdec/rkf.s sets _both_ 'Format' and 'Read/Write-All', and _doesn't_ set up the sector header words in the memory buffer, arguing that even with 'Read/Write-All' on, the hardware is still generating the sector header word contents. (I'm too lazy to check the RK11-C and RK11-D engineering drawings to confirm that.) Noel

5 years, 2 months

DEC RK11-C Disk Controller - on ebay...or is it?

by billdegnan＠gmail.com

If you search ebay for "DEC RK11-C Disk Controller", you'll find a listing of a backplane of flipchip cards, but it's not like any RK11-C I have ever seen. Am I right, this is a mis-labeled auction? Bill

5 years, 2 months

DEC RK11-C Disk Controller - on ebay...or is it?

by jnc＠mercury.lcs.mit.edu

> From: Ethan Dicks > I do have a replica KM-11 set that I need to construct. You'll need the RK11-C overlays (shown on pg 6-2 of the RK11-c Manual). (My set of overlays from Guy with his KM11 replica included them; thanks Guy :-). > From: Fritz Mueller > The cables are actually in the correct slots -- they connect A30 and > B30 to the pass-through connectors to support plugging in a pair of > KM11s from the outside of the rack for debug. Ah. The Double-Buffered RK11-C doesn't have those; the slots used (looks like C08 and D08) are used for logic. Noel

5 years, 2 months

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