test-drb June 2007

test-drb@ccmp.vtda.org

224 participants
486 discussions

by wacarder＠earthlink.net

>Does the service manual contain schematics? If so, it should >be easy to find out which pins are used. I am scanning the schematics right now and will post them shortly. If somebody can take a look at them and decipher them for me, that would be GREATLY appreciated! Ashley

18 years

(another) Floppy disc reader status update and RFC

by aek＠bitsavers.org

> I'm also thinking about an extension to the ImageDisk file format to allow > storage of raw MFM data, though I'm not sure how to go about doing this... > creating a whole new format may be a better idea. A common low-level format would be a good thing. I don't beleive it exsits in the Catweasel world.

18 years

Dialling up in 1982 (was Re: old modems (was Telephony switches))

by jfoust＠threedee.com

At 09:20 PM 6/28/2007, Ethan Dicks wrote: >Hmm... I know that RLE pictures existed (before GIF), and were >monochrome, not color, but I don't recall experiencing them in 1982. >I'm positive that my BASIC terminal program knew nothing about them. >Perhaps the VidTex client I tested knew what to do with them, but I >don't remember ever viewing any on a C-64. >Does anyone have any RLE files or know more about when and in what >context they appeared (besides, obviously, just "on CIS"). Before researching, my memory was that they were first used for CIS weather maps. In my CCC archive, I found a '98 message between Merch and I that mentioned RLE files stored in his Tandy 600 archive, so I bet the Model 100 and CoCo people have archives, as they certainly have decoders. The Wikipedia entry for Compuserve isn't specific about when they released RLE. The run-length-encoding entry doesn't even mention it. Maybe I'll put it on my to-do list. For perspective, "medium" res was 128 x 96, "high" was 256 x 192. I was surprised to see that the O'Reilly Encyclopedia of Graphics File Formats (of which I was contributor and editor to the second edition) didn't even mention CIS RLE files. RLE is a common technique, so there's a chapter about RLE in general. You can certainly google a number of other references to RLE-based file formats from that decade (Utah Raster Toolkit, Wavefront .rla, etc.). GIF dates to 1987. I would guess RLE was at least three years older. - John

18 years

The late, great TRS-80

by classiccmp＠memory-alpha.org.uk

Hi, > Why? The 8080 has all the processing functions on one chip. The >other chips used with it are the clock generator and bus interface >which IMHO are not processing functions.... I know you can get by without the clock/bus interface chips, but *technically* the 8080 is a 3 chip solution which, by his definition, makes it a mini.... I've also got a vague recollection that the F8 came in 2 seperate packages? I'm just saying, it isn't always quite as cut and dried as it might seem. BTW Although the 8080 can do without the bus interface chip, it does generate a number of fairly important control signals which you would otherwise have to latch and generate yourself "manually" as it were. As such I consider it an important, albeit external, part of the processor (as in, the only reason they made it external was because there weren't enough pins on the processor package to accommodate all the required signals). >> Likewise, would you consider a processor made from bit-slice devices >>to be a mini? > Actually, I would. Those chips are not only used to make that particular >processor. Sorry, bad example....I must've been suffering from severe brain-fade when I wrote that....I've got a mini downstairs, which I think contains a CPU made of bit-slice processors. D'Oh! What I specifically had in mind when I wrote that was the "mathbox" inside my Atari BattleZone (and now I come to think of it, the FPF11). Never mind... ;-) TTFN - Pete.

18 years

Dialling up in 1982 (was Re: old modems (was Telephonyswitches))

by zmerch-cctalk＠30below.com

Rumor has it that Ethan Dicks may have mentioned these words: >(who never once did long-distance modem dialling, especially after >that first CIS bill) Ah, see, it was the opposite for me - Michigan's wide areas & weird laws (I'm guessing, IANAL ;-) made for strange bedfellows in the telecom industry... IIRC, my late-nite long-distance calling options when I was running 300baud on my CoCo2, in the '84-'86 time frame were (closest to farthest): Soo Canada, 2 miles away - IIRC, it was about $1.50+/min "Inter-LATA" calls (which for me, was anywhere in the Upper Peninsula of MI - the part most people think is either Wisconsin or Canada ;-) the closest connection being the city of Marquette 150 miles away, would be about $0.50-0.55/min, "Out of LATA" but still in Michigan (to the Lower Peninsula, "Land of the Trolls" [1] ;-) the closest being Traverse City, also about 150 miles away was around $0.75-0.80/min. Out of State calls depending on distance - Cali was much more expensive than Ohio, but Wisconsin was cheapest of all, so I called Green Bay, WI - 300+ miles (depending on how tired the crow was ;-) was around $0.35-0.40/min. So, for me, out of state was actually cheaper! Laterz, Roger "Merch" Merchberger [1] Until about 5 years ago, the Mackinac Bridge[2] was the longest single-span suspension bridge in the world, and really defines our area. Us'n yoopers (UPers) define "those that live below the Bridge" trolls... think "Three Billy Goats Gruff." It's a term of endearment. Really! ;-) [2] For those who like "Dirty Jobs with Mike Rowe" - he was just up here a week or two ago shooting a segment for a few days -- all about the constant (summertime, anyway) job of painting the steel segments of the bridge. -- Roger "Merch" Merchberger | "Profile, don't speculate." SysAdmin, Iceberg Computers | Daniel J. Bernstein zmerch at 30below.com |

18 years

HP7202A Schematics questions

by wacarder＠earthlink.net

>> Can someone help me understand these old HP schematics? >> I see the 15 adapter pins shown at the top right of the >> page, and see where one of the pins (# 5) appears to go >> to something labeled EIA IN on the "Logic Mother Board" > >FWIW, 'EIA' was commonly used at that time (particularly by HP) to mean >what we'd normally call 'RS232; > >> section. Some pins (3, 4, and 6) appear to not be >> connected to anything. Most of the others seem to go >> to the Analog Mother Board, but I am not sure how to >> follow them from there. What would be nice is if I > >Given the one sheet of schemaatic that I've seen, you can't. You need >detailed schematics of the motherboards to trace the signals to pins on >the plugin cards (I assuem) and then scheamtics of the approprtiate cards >to see where they go in the 'real' electronics. > >Do you have that information? I have spent a little more time looking at the information that I have. My documentation does not include detailed board schematics. However, these boards do not look extremely complex. I have figured out how the pins on the interface are numbered. The top left pin is #1 and the second (lower) row contains pins 9 thru 15 (left to right). I have followed these wires from the adapter to the board, where they are connected. At the point of connection, there is a number like 901, 902, 905, etc. I also found a page in another manual that shows how to hook the interface cable to an ASR-33. It has an "in-line" molex style adapter. I need to look at that connector on the ASR33 and see how many wires it contains. Tony probably knows that answer off the top of his head. It's suppertime. I'll do more digging later. I also will photograph the boards that these wires run into on the plotter. Ashley http://www.woffordwitch.com

18 years

Billy Pettit real disappointment

by Billy.Pettit＠wdc.com

Roger Holmes wrote: MOST????? STANDARD????? Rubbish! IBM 7094 - 36 bits. ICT 1301 - 48 bits. CDC 6600/7600 60 (or was it 64?) bits. CDC SC17 (not sure exact era) - 16 bits. Elliott 903/920B/905/920C/920ATC - 18 bits. Many of the BCD machines used 4 bit words I believe. Mid 60s ICL 1900 - 24 bits. What used 40 bits? > What about the MicroData machines with a build your own > instructions on the fly? Tell us more please. Microcoded or 'Extra code' ? > And then there were the ultra-strange like the G-15 - 29 bit word > size, all > instructions were modified moves through arithmetic logic or I/O > devices. > The I/O devices were actually part of the internal logic - no > channels. Actual physical memory, access my DMA from the device or just memory mapped I/O ? ----------------- Billy replies: This was a serial machine using a magnetic drum for memory. So the registers and memory were all bit serial and on the drum. I/O was accomplish by moving data from one line to another. The logic at each end of the line was in peripheral but the bits were on the drum. So it really doesn't fit the standard definition of memory mapped I/O, though that is the closest description. There were no channels per se. Al has just posted most of the G-15 manuals. Have a look. It certainly qualifies for the weirdest machine I ever worked on. ---------------- Roger Holmes: Remember? I am restoring/maintaining an ICT 1301 which has individual Germanium transistors, wire-OR, four and gates to a PCB, one flip- flop one a PCB, a clock derived from the timing track of the last addressed drum store, a core store unit weighing half a ton an stores just 2000 x 48 bit words (plus 2000 x 2 parity bits). Its got Ampex TM4 mag tape drives (not industry standard 7 or 9 track, these are ten track units with hubs the same design as professional audio tapes and the 2 and 3 inch wide video tapes once used by TV broadcasters). [Snip] --------------------- Billy: I salute you. I wish more people on this list had your energy and love of old metal and were restoring it. I enjoy hearing about your efforts. I'm also working on a germanium transistor wired-AND core memory machine. It used TM2's not TM4's. And I've been unable to find any tape units. Did find the original card reader, a modified Burroughs. Still, I consider what you are doing to be the true goal of classic computers. I read, enjoy and participate with the microprocessor based list threads. But my real love is in truly "classic" computers like yours. ---------------- Roger Holmes: > And many of them were wonderfully different and creative. Indeed. And some of them almost make you cry because so much more could have been done with the same amount of electonics. My machine has been modified to implement an index instruction. Previously all indexing and indirection had to be done by program modification, and even now subroutine return is done that way (see my previous e-mail). I have one machine in 'conserved' state, unmolested, unrepaired non- runner, and one with extra tweeks and darn right mass rewiring which runs and I can't stop thinking about how it could be improved, yet somehow manage to stop myself doing so. There are so many gaps in the instruction code and spare bits in the instructions etc. The only modification I am working on plugs into an extension port lashed up by a previous owner. This is to capture the data from the machine onto modern media. May replace with an RS232 interface later to drive a teletype and/or pen plotter, and/or a parallel inteface for a Friden Flexowriter. [sni] Roger Holmes. Classic computer collector, classic car collector, machine tool collector/user (for the prior mentioned hobbies), and for a job, programmer of CAD and graphic software and printer/plotter drivers for Apple computers.

18 years

What are the really unusual or weird computers?

by Billy.Pettit＠wdc.com

Jay West wrote: SortofKindaNotReally MicroData Reality machines were firmware implementations of Pick (Reality), not software implementations. As a result, you couldn't actually microprogram the thing as an end user (normally). There *WAS* an EEPROM board that would replace the firmware board, but I don't believe that was typically released to the field. I used to have two M1600's (the early ones with the wood panels). One of them did have the EEPROM microcode option but I do know that particular unit was sent out from microdata "under the table". I had let these two machines slip through my fingers many years ago, long before I got into collecting. BUT - on the bright side - I found out a year or so ago that those two machines actually did wind up in the hands of another collector who is known to another listmember! I now have an M1600 that is the later metal panel variety, waiting to be restored. Even on the software implementations (which the microdata's weren't), you could create new missionary instructions from native instructions by playing some games in the 5-pass assembly process. However, this wouldn't technically be considered microprogramming as the "native" instructions would be just whatever the underlying cpu was (68000, PDP11, RS6000, x86, etc.). So you could create new virtual instructions, but still not really microprogramming. Jay -------------- I always thought the early MicroData systems were different from the Reality series. Looks like I was wrong. (Where is Jim Stephens when you need him? He has all these systems and the software to go with them.) Billy

18 years

What are the really unusual or weird computers?

by Billy.Pettit＠wdc.com

Chuck Guzis wrote: Quite honestly, I didn't know what the time frame of the original question was--I did mention the Univac SS-80, however--and I did make reference to strange designs of the 50s. But "computer" isn't very specific. How about the hybrid computers of the 60s? How about the "mostly diodes and not a lot of transistor" machines like the PB250? Some parameters for the original question might be helpful. Cheers, Chuck ----------------- Chuck, I agree with you on all your points. And add the Recomp jukebox series to the all diode machines. They had less than 100 flip-flops per system! Billy

18 years

MP3 players

by Billy.Pettit＠wdc.com

Jay West wrote: I find it exceedingly difficult to consider this type of thread on-topic. Jay ---------------------- Jay, I agree with you in principle. But I've spent the last two years working on interfacing hard drives to MP3 players. They aren't old enough for the list, but technically, they employ a lot of computers folks like me. Billy

18 years

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test-drb June 2007