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101090 discussions

Drive Type International Memories, Inc. (IMI) 5012H

by billdeg＠degnanco.com

The IMI 5012H is I am told a clone of the Shugart ST-512, which is a type 1 drive, can anyone confirm this? I am, working to resurrect an IBM AT. Silly me I disconnected the battery and lost the configuration settings. I attempted to run setup, but when I declare the drive to be type 1 (or 2), the system returns a 1780 error code (drive seek error)...which makes me wonder if this is not really a drive type=1. Thanks Bill Degnan

15 years, 5 months

Excessive optimization (was Re: what was VMS/OpenVMS written in?)

by ethan.dicks＠gmail.com

On Wed, Dec 1, 2010 at 9:42 PM, Chuck Guzis <cclist at sydex.com> wrote: > The Microsoft issue, I recall was with dead code elimination. ?The C > expression > > ? ? ? ?while( C != 0); > > could normally be eliminated if C was 0... I have used the following in embedded code to tight-loop the CPU in certain circumstances, intentionally requiring a reset of the processor to escape... for (;;) ; I suppose a good optimizer would know that you really meant to do that and should produce something resembling the following $1: JMP $1 ...but I certainly wouldn't want that statement optimized out entirely. > The beauty of a good optimizer is that it allows one to write legible > code that still turns in good performance. Indeed. The horror of a bad optimizer (and I _have_ seen this) is that it introduces bugs that vanish when the optimizer is turned off. -ethan

15 years, 5 months

apple Lisa2. Any advice on non-working floppy drives?

by terry＠webweavers.co.nz

I should add that these readings were taken while the machine was waiting for me to insert a disk (according to the screen icon). Actually a disk was already inserted. I also looked for any change in voltage on any of the pins when I clicked the icon to activate the drive. There was no change in any of the readings. Terry ----- Original Message ----- From: "terry stewart" <terry at webweavers.co.nz> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Sent: Wednesday, December 08, 2010 6:48 AM Subject: Re: apple Lisa2. Any advice on non-working floppy drives? > Hi Tony and others. Progress and pin readings from the Lisa 2 project... > > I've cleaned a couple of the 400k Drives thouroughly just in case the > machine was struggling with the mechanisms. No change. The drives still > sit there on boot in stubborn silence, although the LEDs inside are lit. > No sound or attempt at disk ejection when there is a disk present. > > I did some measurements on the Lisa Lite board input connector, and here's > what I found. I used the circuit diagram at > http://www.freeinfosociety.com/electronics/schemview.php?id=1417 . The > signals in brackets represent the corresponding pins on the sony floppy > drive. A disk was in the drive at the time. > > PH0 (CA0) - 0.2v but rises to 3.5v momentarily when the machine is first > switched on > PH1 (CA1) - 0,2v normally but every 4-5 seconds this pulses to 3.5v > PH2 (CA2) - Same as PH1 > PH3 (LSTRB) - 0.2v > WRQ (WRTGATE) - 4.9v > HDS (SEL) - 4.3v but pulses to 0.2 v every 4-5 seconds > DEN (ENBL) - 0.2v > RDA (RD) - 4.9v but pulses to 0.2 v every 4-5 seconds > WRD (WRTDATA) - 0.2v > MT (goes to Lite Adaptor circuitry) - 0.11 Returns to drive pin as > PWR - 3.6v > All 12v and 5v power and ground pins read what they should. > SNS - 4.9v but pulses to 0.2 v every 4-5 seconds > > I''m still digesting what this all means using the Lisa hardware manual > here > http://lisa.sunder.net/LisaHardwareManual1983.pdf . There is a > comprehensive explanation of how the drive interface works in section 6 > but I'm still digesting this and trying to get my head around it. > Appreciate that I'm not a techie and a lot of this stuff is new to me. > > As I see it at the moment, the drive is certainly getting power, and > appears to be getting signals. Whether these signals are the right ones > are another question? > > Terry (Tez) > > > ----- Original Message ----- > From: "Tony Duell" <ard at p850ug1.demon.co.uk> > To: <cctalk at classiccmp.org> > Sent: Monday, December 06, 2010 10:09 AM > Subject: Re: apple Lisa2. Any advice on non-working floppy drives? > > >>> >>> Tony, thanks for doing that bit of research. > ..... > ..... >>> I have a manual with some schematics and tonight I'll check and see if >>> the >>> LisaLite board is there. >> >> As I said a Google search found it fairly easily. The Lisalite board >> looks quite simple (the schematic is just 1 sheet, and I recognisd all >> the chips on it). I didn't do much more than glance at the schematic, but >> it seemed to be a dairly simple PWM generator using TTL coutners and '85 >> comparators. I think the control vaule is bit-serially loaded into a >> shift register on the board. >> >>> >>> >Firstly, since you have no idea as to the health of any >>> > of the parts, you can't deduce anything from the fact that swapping >>> > them >>> > out makes no difference. >>> >>> Not entirely true, as the Lisa 2 startup checks carry right through >>> until it >>> asks for a disk for inserted. So I can assume most parts are working. >> >> Can you? I have no idea what these startup checks actually test, but I >> would have thouht it as possible for one of the I/O chips that links to >> the drive to havee failed but in a way that it still passes the tests. >> >>> Incidently, the docs I have suggests this routine also checks the >>> LisaLite >>> controllers so (according to the machine anyway) these are ok. It's >>> hard to >> >> I wonder how? I couldn't see any way for the machine ot check that the >> PWM signal (the only signal truely sourced by the Lisalite board) is >> present and corret. >> >>> believe that THREE drives all have the same fault though. All inputs >>> into >>> the drive are from the LisaLite board. Maybe the diagnostic checks are >>> not >> >> Not really. While the only external cable from the drive does, indeed, >> plug into the Lisalite board, the shcmeatics show the most of the signals >> are simply passed (with no buffering or anything) between the 'Twiggy' >> connector back to the Lisa I/O board and the Sony drive connector. I >> think it's likely that any problems iwth those signals are not caused by >> the Lisalite board (broekn PCB tracks are not common). >> >>> as thourough as they should be. >> >> We don;t (or at least I don;t know) what hte diagnostics actually check. >> There's also the issue that you're using a defective system to diagnose >> itseld, and while most diagnostics are written assuming that anythign >> that hasn't been checked could well be defective, some are not. I've seen >> diagnostics that basically assume that the machine is working correctly, >> and which don't help _at all_ if there is a fault. >> >> I really do think you need to start making some measurements on the drive >> connecotr and see just what is, and is not, correct there. >> >> -tony >> >

15 years, 5 months

ebay: TRS-80 Model 4 (NJ pickup) $0.01

by legalize＠xmission.com

Item # 260703951205 FYI -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/> Legalize Adulthood! <http://legalizeadulthood.wordpress.com>

15 years, 5 months

Drive Type International Memories, Inc. (IMI) 5012H

by billdeg＠degnanco.com

> > > > > The IMI 5012H is I am told a clone of the Shugart ST-512, which is a type 1 > > drive, can anyone confirm this? I am, working to resurrect an IBM AT. > > Silly me I disconnected the battery and lost the configuration settings. I > > Obvious question : Did it work before you disconencted the battery? In > other words do you know the problem is just due to misconfiguration? > Yes. It worked fine before I disconnected the battery. I assumed it was dead and I was planning on replacing it with a new one. > > There is a 3rd party setup program that will run on the real IBM AT (I > know this, becuase it's what I use on mine). I has the advantage that > when you select a particualr drive type, it displays the actual > parameters (cylinders/heads/etc) too. > > That way you could at least check you're selecting someting that makes sesne. > > Are you using the orignal IBM (Western Digital, actually) controller board? > Yes. original board. What I plan to do next is put the drive in an XT, because in an XT there is no battery needed and I can use spinrite to determine the drive number. It's possible given I was getting a 1780 error that there is a problem with both my controllers. Bill

15 years, 5 months

Original HP Laserjet printer, free in Maryland...

by wh.sudbrink＠verizon.net

Owned by a coworker of mine who says it still works fine. He doesn't want to throw it out if there is someone interested in preserving it. Somehow, I've never been interested in adding printers to my collection. In the "nostalgia era" of my computer experience, what I collect, printers were noisy, messy and not worth the bother. Anyway, if you want it and can arrange to pick it up fairly quickly, let me know. Bill

15 years, 5 months

SCSI to SD/IDE

by afra＠aurigae.demon.co.uk

Ok guys, The Good bit.... All this talk of SCSI to whatever got me curious so I started experementing. What I have so far : An AVR ATMega1284 (DIP40), connected to an SD card by SPI and to the SCSI bus via 4 LS chips (1xLS273 and 3xLS240). I currently have implemented just a few of the SCSI command set, Identify, read, write, test ready and request sense. Thist is enough to be able to connect to a PC SCSI card, format the drive and read and write files to it....heheh I can even boot off it ! I'm using Chan's FatFS, and in this way the drive seen by the SCSI is actually a large image file on the SD card, I did this as it will make backing up the drive *MUCH* easier if the target system is not a PC, as you can simply take the SD card out and copy the image file without worrying about it's internal structure. In theory this will also make sharing data between the target system and an emulation running on something more modern. There's a couple of pictures here : http://www.stardot.org.uk/forums/viewtopic.php?f=11&t=3646 The bad bit...... Whilst this all works it's SLOWWWW, using Norton utilities SI, reports that the disk is 0.2x the speed of an original PC, cirtainly bootup times are much more akin to what I would expect from a floppy drive :( So I would sugest that for replacing hard disks that using SCSI->SD is probably not going to be fast enough. My next experements are going to center on replacing the SD with an IDE drive, hopefully this will provide a suitable speed increse, asuming that this works it should be easy enough to use a CF->IDE adapter board to use a CF drive instead of an IDE, which will allow the media to be removable and easiliy swapable. The other thing I want this to support is 256 byte sectors as some old machines rely on this, a feature which is supported by some of the early SCSI/SASI to MFM/RLL boards but very few native SCSI drives, this would be of perticular intrest to some of the Acorn 8 bit machines. Comments & sugestions welcome. Cheers. Phill. -- Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric ! "You can twist perceptions, but reality won't budge" -- Rush.

15 years, 5 months

L6: Bell Telephone Laboratories Low-Level Linked List Language (film)

by legalize＠xmission.com

In 1966, Ken Knowlton created a 16-minute black and white film showing animated algorithms for the L6 language. Does anyone know if this film is online anywhere or if the film has been archived anywhere (CHM perhaps?). Bell Labs used to have a historian, but since Bell Labs no longer exists, I have no idea who to contact anymore about this sort of thing. Does anyone know? -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/> Legalize Adulthood! <http://legalizeadulthood.wordpress.com>

15 years, 5 months

AT&T 3B1 / 7300 / UNIX PC: Boot sequence from floppy

by philpem＠philpem.me.uk

Hi guys, I've got my 3B1 emulator "mostly working" in that it runs the Boot PROM, sees the floppy disc in the drive, and proceeds to boot from it, getting as far as the Loader. When it gets to the Loader, I get the following display: AT&T UNIX(tm) pc Loader version 3.51 Copyright (c) 1985, 1986 AT&T All Rights Reserved Searching floppy disk... #### Searching hard disk... ... and it stops there. I can tell from the emulator log that it's trying to get the hard drive controller to read CHS 0:0:0 and DMA the data into RAM at 0x77830, but because the HDC isn't implemented, it locks. What I expected was for the Loader to pick up the boot files on the Diags disk, boot from that, and ignore the HDD. Does anyone know what "typical boot behaviour" is for a 3B1, 7300 or UNIX PC, when booted from the Diagnostics floppy (Foundation Set, disk 1) ? This is a bit of a head-scratcher -- I'm trying to figure out if there's a problem with my FDC driver (wouldn't be the first one) or the DMA/interrupt controller, or if the Loader really needs a hard drive controller (or a really good fake) to boot the system. I'd also really like to know why the DMA controller has two separate direction control bits -- DMAR/W- and IDMAR/W-... this seems downright silly, though in keeping with the rest of the TechRef. My "annotated edition" corrects about a dozen minor and major errors in the register set descriptions, and adds a bunch of informational sticky-notes and scribbly comments to reinforce certain points. Ewwww... If anyone's interested in playing with my emulator -- go to <http://www.philpem.me.uk/code/3b1emu/>. Hit the link under "Mercurial repository", then ".tar.bz2" to get a Tarball of the sources. Untar it. Grab the boot PROMs, and put them in a directory called 'roms' as '14c.rom' and '15c.rom'. Use IMDU (Imagedisk utility) on a DOS PC (or inside Dosbox) to convert the Foundation Set disks from IMDs to binary files, then copy the first Foundation disk (Diagnostics) as 'discim'. Compile (you'll need libsdl, aka the Simple DirectMedia Layer) and run. I know the code is a mess, patches to rectify this (or any of the other millions of bugs) would be almost certainly be accepted :) There's also no keyboard or mouse emulation yet, just the CPU, video, RAM, ROM and a basic memory mapper and DMA emulation. As for Ethernet emulation... that's on the "maybe later" list, right after "learn how to send and receive Raw Ethernet frames on Linux". Thanks, -- Phil. philpem at philpem.me.uk http://www.philpem.me.uk/

15 years, 5 months

Free SCSI CD-ROM drives -- last stop before the dumpster!

by a50mhzham＠gmail.com

At 03:14 PM 12/4/2010 -0600, you wrote: >On Sat, Dec 4, 2010 at 2:39 PM, a50mHzHam <a50mhzham at gmail.com> wrote: > > WANTED: A good home for my last three RACK'O'CD boxes by MDI. > >I'd be interested if it's easy (which means no shipping). Where are >you located? > >brian Southeast Wisconsin-- Milwaukee metro area. ----- 350. [Computing] "Formal specifications yield correct programs." No. Formal specifications yield PhD theses. They may also occasionally yield programs as by-products, but no useful ones. --Ronald F. Guilmette --... ...-- -.. . -. ----. --.- --.- -... tpeters at nospam.mixcom.com (remove "nospam") N9QQB (amateur radio) "HEY YOU" (loud shouting) WEB: http://www.mixcom.com/tpeters 43? 7' 17.2" N by 88? 6' 28.9" W, Elevation 815', Grid Square EN53wc WAN/LAN/Telcom Analyst, Tech Writer, MCP, CCNA, Registered Linux User 385531

15 years, 5 months

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