test-drb January 2003

test-drb@ccmp.vtda.org

388 participants
970 discussions

by rhudson＠cnonline.net

Hi, In the San Jose, CA area... I have a tektronix type 310A o'scope that needs some help in the horz. sweep area. I am not well versed in the art of component level repair. What can I do to get this guy back up and running? Thanks for your help! Ron.

21 years, 10 months

PDP11/73 power-up codes

by david_comley＠yahoo.com

I'm sure this is a familiar question to many - does anyone have a list of the two-digit codes displayed on the PDP11-73 during power-up ? I am resurrecting a dormant unit which stops at '1' (I have only the CPU and memory installed in the backplane) I'm not sure if this is a good or a bad code. Any help would be appreciated. Thanks, David Comley __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com

21 years, 10 months

Two great Finds Today

by jrkeys＠concentric.net

A friend stopped me in the parking lot of an auction today and gave me a box full of computer stuff and in it was a TI-74 BASICALC with a carrying case and 8k RAM module in it. Also it came with a Quick Reference Card for Basic Syntax. At the auction I got something called "The Brick" by Ergo computing Inc.. It's a cool looking 386SX-16 as per this article from a google search: "The Ergo Brick, a 3" x 8" x 11" totable PC, was billed as the "cure for the common computer." With a keyboard and monitor at home, another at work, it gave desktop power in a portable package. Today you could fit three PowerBook G4/500s in almost the same amount of space as the $2,495 16 MHz 386sx-based Brick.". I got the CPU, power supply, manual, and a carrying case. The keyboard was missing.

21 years, 10 months

Two great Finds Today

by healyzh＠aracnet.com

> At the auction I got something called "The Brick" by Ergo computing Inc.. > It's a cool looking 386SX-16 as per this article from a google search: "The > Ergo Brick, a 3" x 8" x 11" totable PC, was billed as the "cure for the > common computer." With a keyboard and monitor at home, another at work, it > gave desktop power in a portable package. Today you could fit three > PowerBook G4/500s in almost the same amount of space as the $2,495 16 MHz > 386sx-based Brick.". I got the CPU, power supply, manual, and a carrying > case. The keyboard was missing. Hey, that's pretty cool. I remember drooling over adds for those around 1990! If you look through issues of "PC Magazine" from about that timeframe you should be able to find the adds. Of course I didn't remember it being so big... Didn't they give it a greyish bricklike finish? Zane

21 years, 10 months

DEC TU-56 & TD8E

by cmcnabb＠4mcnabb.net

I believe I now have my TU-56 and TD8E working. When I mount a tape and attempt to boot my one OS/8 tape it loads to the point of printing "SYSTEM ERR" on the teletype. I strongly suspect that the tape is probably corrupt. I'm wondering if there is anyone out there who would be willing to copy any kind of Bootable PDP-8/E tape for me so I can test with a known good tape. I would be more than willing to provide a couple of tapes for the copy. -- Christopher L McNabb Operating Systems Analyst Email: cmcnabb(a)4mcnabb.net Virginia Tech ICBM: 37.1356N 80.4272N GMRS: WPSR255 ARS: N2UX Grid Sq: EM97SD

21 years, 10 months

M200 interfacing continues...

by dwightk.elvey＠amd.com

>From: "Sellam Ismail" <foo(a)siconic.com> > >On Thu, 2 Jan 2003, Tony Duell wrote: > >> > The main problem I'm having is reading the control lines of the 6522. >> > According to the spec sheet, CB1, CB2 and CA2 are all supposed to be TTL >> > level outputs when programmed for such. So they are, but I'm having >> >> Do you mean output or input here? If you're reading a pin, then I would >> have assumed you were using it as an input. > >Sorry for confusing the hell out of anyone. I meant input. From the 6522 >datasheet: > >"CA1 is a high impedance input, while CA2 represents one standard TTL load >in the input mode." > >...and regarding CB1 and CB2... > >"Each control line represents one standard TTL load in the input mode and >can drive one TTL load in the output mode." > >> Try a pull-up instead (TTL sinks a lot better than it sources). In other >> words change the end of the resistor from ground to +5V >> >> make this +5V >> | >> V >> > READER SIGNAL----+----/\/\/\-------GND >> > | >> > | >> > 6522 CB2 > >Wouldn't this give me a default state of logical true on the input pin? Hi For a TTL, one normally has an open pin set to one. One pulls it to zero to be active. Ever notice that all of the strobes and such for things like parallel ports on a PC are always negative. For those pins that you are using as inputs, make sure that you've set the direction register correctly. Dwight > >> If you still have problems, then maybe the driver chip in the M200 has >> died. It happens. I've had a couple of HP9810 calculators across my bench >> where there were 10 or so dead TTL chips (74Hxxx TTL chips especially) >> that appeared to work, but which couldn't give a proper output signal, >> so the chip it was connected to didn't always get the right logic level. > >Well, it works, just not all the time. So from what John has told me, it >seems like the signal is just being lost half the time. > >Sellam Ismail Vintage Computer Festival >------------------------------------------------------------------------------ >International Man of Intrigue and Danger http://www.vintage.org > > * Old computing resources for business and academia at www.VintageTech.com * > >

21 years, 10 months

M200 interfacing continues...

by vcf＠siconic.com

Ok, I'm almost there. I've got everything wired up and most of the driver software done. The main problem I'm having is reading the control lines of the 6522. According to the spec sheet, CB1, CB2 and CA2 are all supposed to be TTL level outputs when programmed for such. So they are, but I'm having trouble reading CB2 reliably. I put a pull-down resistor on it but that doesn't help. The signal to it is spotty for some reason. I've got the PICK CHECK signal from the reader going into CB2. I have a 1K resistor going from CB2 to ground. READER SIGNAL----+----/\/\/\-------GND | | 6522 CB2 If there's an error (misfeed for instance) CB2 should get a logical TRUE. This works sometimes, but not always. And it's the same whether I have the pull-down resistor or not. I'm using CB1 reliable without the need of a pull-down resistor. I don't know if it's sloppy code or a bug, but the Apple doesn't seem fast enough to read and process the data character by character. I would think that it should be fast enough to do so but I'll have to check the timing on the loop and see if it falls within the specs of each column read from the reader. For now I've switched to buffering the data and then processing it after each card read, controlling the picker with the software to control the flow of cards. I'm figuring out the code for the last piece which decodes the row pin into a decimal number. What's the best way to do an nth root operation in 6502 assembly? :) Crummy way: LDY #00 LOOP INY LSR BCC LOOP This assumes only 1 bit is set in the accumulator. It loops until the bit falls off from the LSR operation. Assuming the accumulator has #80 to begin with, the Y-register result should be 8. -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *

21 years, 10 months

Oersted Ratings of DC300A and DC600 Tape Cartridges

by aek＠spies.com

http://www.qic.org/html/standards/9x.x/qic95-101e.pdf dc300 dc300xlp 310 Oe dc600A 550 Oe I have a curve in an early wangtek manual about this, too.

21 years, 10 months

PDP9 Control Store on eBay

by jpl15＠panix.com

Browsing along, found this: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1247&item=2085798445 Listed (and pictured) as a MC09 (G920D) card. Hex-height, four green tabs. The description says it's 64 words of 36 bits each, Read Only. Minimum bid: $30.00. No buy-it-now. Cheerz John

21 years, 10 months

Compaq 286/SLT (was RE: Anyone have any experience replacing a Dallas 1287 with a 12887?)

by Robert_Feldman＠jdedwards.com

According to the Guide, the p/n's should either be 110091-011 and 110092-011 (for ROM Revision H.6) or 110091-0012 and 110092-012 ( for Revision H.7). Bob -----Original Message----- From: Ethan Dicks [mailto:erd_6502@yahoo.com] Sent: Thursday, January 02, 2003 10:09 AM To: cctalk(a)classiccmp.org Subject: Compaq 286/SLT (was RE: Anyone have any experience replacing a Dallas 1287 with a 12887?) <snip> My ROMs have stickers with p/n 110091-011 and 110091-012, (c) 1988. -ethan

21 years, 10 months

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test-drb January 2003