test-drb

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101090 discussions

by h.j.stegeman＠hccnet.nl

Hi Mike, Here are the options to attach 3340 DASD emulation to an IBM System/3 1) direct connect to the internal channel of the S/3. Some disk OEM's did this. Requires a FPGA with at one side MST-1 interface logic and at the other side IDE or SCSI interface. The availabe IBM documentation is complete enough to finish this project. You need good IBM HW & VHDL knowledge. 2) direct connect to the BUS/TAG interface connector. This needs a 8+P bit stream. You have to do some reverse engineering to figure out what the exact format is. I have no idea if the HW must be implemented in a FPGA (for timing reasons) or if an AVR processor will do the job. Advantage is that you don't have to modify anything inside the S/3. 3) IBM has implemented an IOP (I/O Processor) between the S/3 CPU and the 3340 drives. This IOP is a modified version of the ones used in the IBM 370/115 & 125. It is a powerfull multi thread capable beast. With small HW modification you can connect an IDE or SCSI drives to it. The difficult part is modifying the firmware of the IOP. This requires a special assembler (to be written) and very good assembler skill's. All options requires quite alot of time to implement. My 2 cents Henk

10 years, 4 months

IBM channel-attached DASD emulation

by tmfdmike＠gmail.com

I've recently been poking about with various bits of emulation with hardware interfaces... Dave's MFM emulator; various SCSI-to-USB or SCSI-to-SDcard devices; my Setasi RP12 Massbus disk emulator; the Sigma Seven Lisa widget/ProFile emulator etc. What about IBM channel-attached DASD? There are various CPUs lying around in private collections and museums - System/360s; System/370s; System/3 Model 15s; all used channel-attached DASD: and working reliable disks are much rarer than the damn CPUs! Questions: 1. There are or were various 3rd party companies producing rather obscure emulated DASD replacement subsystems - Virtualblue and Bustech are two names that come to mind. Has anyone looked into the possibility of using them to emulate older devices that would be usable on the above vintage CPUs? 2. To those with hardware design experience: how big a task do you reckon it would be to do this as a home-brew with modern hardware - exactly as Dave did with his MFM emulator? Is it feasible? Do the entire thing in software - Pi or Arduino or FPGA - with appropriate driver electronics to drive a channel interface? I've BCC'd some experts with experience - Rich Alderson; William Donzelli; Henk Stegeman - in the hope that they'll be able to contribute. What do people reckon would be the best target for emulation? 3340 springs to mind initially... would that work on machines as old as System/360s? It's about the *only* option for 5415 DASD... (To digress briefly - a modern reimplementation of something like the Setasi Massbus disk emulator would also be very useful; Rich - weren't LCM working on something like that?) Mike http://www.corestore.org 'No greater love hath a man than he lay down his life for his brother. Not for millions, not for glory, not for fame. For one person, in the dark, where no one will ever know or see.'

10 years, 4 months

Seasons greetings

by c.murray.mccullough＠gmail.com

To all readers/followers of this website - for those who love classic/vintage computers - I want to wish all the best of the holiday season no matter what your beliefs. In this day of political correctness it is simply to acknowledge Mother Nature's transition >from fall to winter and we should take time from our busy schedules to reflect on this 'special' time of the year. Happy computing! Murray :)

10 years, 4 months

VAX 4000-500 PSU Overload?

by robert.jarratt＠ntlworld.com

My VAX4000-500 will no longer power up, with the PSU starting up and then immediately shutting down. I suspect a possible short somewhere. I have measured the resistance of the load presented to the PSU by connecting probes to the backplane sockets used to power the machine. The odd one is the 5V load. With all the boards in and drives inserted I measure a resistance of about 4R. As I pulled out boards, drives and fans, it gradually crept up to 6R. So with nothing connected to the backplane I get a 6R load across the 5V supply. To my inexperienced mind, that seems a bit low. Should I expect such a value, or should I be dismantling the box to investigate possible shorts or failed components on the backplane? Additionally, the 12V side seems to be charging a capacitor as the resistance slowly climbs to about 130K. Is that reasonable? Again, nothing but the backplane. The 3.3 and -12V show very high resistance at all times. Thanks Rob

10 years, 4 months

Looking for WinXP drivers for Trident Video Cyber9520

by marc.verdiell＠gmail.com

In the series "looking for drivers". I have taken to using DolchPac 65's as my retro workhorses so I can multi-boot DOS, Win98 , WinNT, WinXP and Linux while sticking weird old PCI and ISA interface cards in it. One of the OS always ends up having some software for the card. It has a custom video card that identifies itself as a "Trident Video Accelerator 3D Cyber9520". I found the driver for Win98 which works very well, the machine came pre-installed running NT, and Linux installs a driver that is a bit glitchy but usable (I can't believe I could run modern Linux on this!). The video is auto-recognized and the right driver installs under XP, but the default version is ultra-buggy, video gets corrupted. Does anyone have an updated driver for this chip? Internet didn't come up with anything apart from the ones necessitating scary hardware scanners that crashed my old machine anyhow. Marc

10 years, 4 months

Merry Christmas

by jwest＠classiccmp.org

Just wanted to say a very sincere Thank You to all the talented folks that hang out here and call this place home, and also to wish you and yours a Merry Christmas. Best, Jay West jwest at classiccmp.org

10 years, 4 months

Piggybacking 74LS logic chips to confirm a suspected fault

by jonas＠otter.se

>> -----Oorspronkelijk bericht----- >> Van: cctalk [mailto:cctalk-bounces at classiccmp.org] Namens Terry Stewart >> Verzonden: dinsdag 22 december 2015 21:50 >> Aan: General Discussion: On-Topic and Off-Topic Posts >> Onderwerp: Piggybacking 74LS logic chips to confirm a suspected fault >> >> Hi, >> >> I've written up my recent third Apple II repair, this time an Apple IIe. >> http://www.classic-computers.org.nz/blog/2015-12-22-appleiIIe-no-video.htm >> >> One interesting aspect of this repair is that piggy-backing a logic chip helped >> confirm a faulty one. I'd only ever used this technique with RAM. >> I'm sure it only works if the chip has a particular type of fault, but it worked this >> time for me. >> >> Terry (Tez) > > I use a HP 10529A logic comparator on regular basis for fault finding in ttl circuits. > It compares a reference chip with the CUT (Chip under test;) it's a very nice diagnostic tool. > It's a bit like piggy backing just a little more sophisticated :0 > > -Rik In my experience, the type of socket you used is quite unreliable and will tend to develop bad contacts. There is a reason they are cheap... I would use a turned pin type socket instead, e g an Augat socket. They will not let you down. More expensive, but considering the work involved in replacing a socket and the risk of messing up the PCB, the cost is negligible. Jonas

10 years, 4 months

More Manuals

by radiotest＠juno.com

BAMA is probably the best known site for old test equipment and amateur radio manuals, followed by Ebaman. Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA http://plymouthcolony.net/starcity/radios/index.html

10 years, 4 months

IBM channel-attached DASD emulation

by jnc＠mercury.lcs.mit.edu

> From: Guy Sotomayor > It's typical of most of the vintage gear. Folks save the CPUs and ditch > the peripherals. It's not entirely sloth and stupidity, though. Disk drives in particular (usually the biggest issue in this area) are complex precision machinery that operate at very high speeds, etc, and working on them is a formidable job, and requires specialized parts which are, in general, no longer available. > I think the biggest problem is that there isn't a spec per-se on > Massbus. A lot of reverse engineering will be required to make it work > properly in all cases. If it were done, though, that would be wonderful, especially for people with PDP-11/70's; the UNIBUS on those machines is reputedly the slowest of any PDP-11, so having mass storage on the MASSBUS is really necessary for good performance. (Apologies for my -11 centrism in an IBM-focused thread... :-) But finding the connectors (and probably the cables too) is going to be a cast-iron nightmare. Maybe we could settle on an alternative (the way I think we should switch to pairs of dual cards with Berg/DuPont headers, with standard flat cables between them, to replace the now-unobtainable BC11-A's - DEC showed this works, with the M9014/M9042..) Noel

10 years, 4 months

The best spreadsheet / database program for Commodore 64?

by tulsamike3434＠gmail.com

Is there anything like Appleworks 1.0 for the commodore 64? if so could you be kind enough to give me the name of the program? I have searched but have found nothing of any value. I just would like a checkbool ledger and a savings spreadsheet.

10 years, 4 months

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