Re: TRS-80 Question
On Tue, Apr 12, 2022 at 3:46 PM Fred Cisin via cctech wrote: > >> There's a 2K hole in the Model I memory map above the ROM > On Tue, 12 Apr 2022, Yeechang Lee via cctech wrote: > > Is this the hole that causes stock Model I to not run CP/M? > > NO. > The problem with CP/M on TRS80 is that CP/M expects RAM from location 0 on > up. When I was a freshman at Purdue, I lugged my Model III to my dorm room and connected to the ECN network with a 300 baud modem. I used a local editor and wrote a Pascal program to upload my Pascal source to the dual processor VAX-11/780 (Google George Goble), ea or eb, (I don't remember) that was used by our introductory programming class. The terminal program I had was something I found in Byte magazine in assembler and I modified it for the TRS-80. I had BASIC, Assembler and Fortran on the TRS-80 M III, so it was probably all in assembly. There was an article in Byte about CP/M for the TRS-80 Model III that described a hack to swap the ROM for RAM. The idea was to invert bits A15 and A14. That would move the ROM and keyboard from to C000. There was a spare bit in some 4 bit register, so all you had to do was cut a couple traces and insert some XOR gates. I remember doing the modification on a Saturday while listening to the Purdue football game on the radio. I put it all back together and it worked. WoHo! At that point though I had no access to CP/M or where I might get it legal or otherwise, but I was good to go when I found it. I still have the computer and I still have the Byte copy. So 37 years later I should try to complete the project. -chuck
Re: idea for a universal disk interface
Good data, thanks! I kind of like the ESDI disks, they're more solid and reliable than the MFM ones, and to be honest the RQDX3 was not a super fast disk controller. I wonder if it could do block mode DMA. I'll keep an eye out for the Sigma, the only thing I wish I had on the MTI MQD13 would be some disk cache to speed things up. Granted 11/M+ does have disk caching in the OS, I should check to see how much quicker that makes things. Good used ESDI disks come up on Ebay from time to time. A nice 660mb CDC is enough for most general pdp usage... C On 4/19/2022 1:03 PM, Glen Slick via cctech wrote: I also have multiple ESDI controllers, more than one these flavors: Dilog DQ686 http://www.bitsavers.org/pdf/dilog/2120-0137-1_DQ686_Nov89.pdf Emulex QD21 http://www.bitsavers.org/pdf/emulex/QD2151002-J_QD21_Jun90.pdf Sigma SCD-RQD11-EC (There seems to be multiple versions from different vendors of this same basic board). http://www.bitsavers.org/pdf/sigmaInformationSystems/400740-B_SDC-RQD11-EC_Disk_Ctrl_Man_Jul88.pdf They all support block mode DMA transfers, and command queuing with seek optimization. The Dilog DQ686 and Emulex QD21 are dual wide boards. The Sigma SCD-RQD11-EC is a quad wide board and has 1MB of cache memory (which takes up about a quarter of the board area). The examples I have might only be populated with 512KB of cache memory. I might have had close to a dozen working full height 5.25-inch ESDI drives at one point. Unfortunately most of them have failed while sitting idle over the last few years. Without checking now I don't know if any of them still work. So the dozen or so Q-Bus ESDI controllers don't have any use for me now. (Fortunately I also have more Q-Bus SCSI controllers than backplanes to put them in). I also have a single Andromeda ESDC ESDI controller. Never found a manual for that one. Did eventually figure out how to get into the on-board configuration utility. On Tue, Apr 19, 2022 at 8:56 AM Douglas Taylor via cctech wrote: Once upon a time I used an Emulex QD21, but I sold it because the actual ESDI disks I had were a pain in the butt. Always crashing. I still have a Webster (quad board) SRQD something. I think I had a Dilog board also. It's been a while, probably 20 years. Doug On 4/18/2022 9:12 PM, Chris Zach via cctech wrote: Interesting, what kind of ESDI controllers do you have? They got advanced features like cache, ordered seeks, and burst mode/block mode DMA?
Re: idea for a universal disk interface
I also have multiple ESDI controllers, more than one these flavors: Dilog DQ686 http://www.bitsavers.org/pdf/dilog/2120-0137-1_DQ686_Nov89.pdf Emulex QD21 http://www.bitsavers.org/pdf/emulex/QD2151002-J_QD21_Jun90.pdf Sigma SCD-RQD11-EC (There seems to be multiple versions from different vendors of this same basic board). http://www.bitsavers.org/pdf/sigmaInformationSystems/400740-B_SDC-RQD11-EC_Disk_Ctrl_Man_Jul88.pdf They all support block mode DMA transfers, and command queuing with seek optimization. The Dilog DQ686 and Emulex QD21 are dual wide boards. The Sigma SCD-RQD11-EC is a quad wide board and has 1MB of cache memory (which takes up about a quarter of the board area). The examples I have might only be populated with 512KB of cache memory. I might have had close to a dozen working full height 5.25-inch ESDI drives at one point. Unfortunately most of them have failed while sitting idle over the last few years. Without checking now I don't know if any of them still work. So the dozen or so Q-Bus ESDI controllers don't have any use for me now. (Fortunately I also have more Q-Bus SCSI controllers than backplanes to put them in). I also have a single Andromeda ESDC ESDI controller. Never found a manual for that one. Did eventually figure out how to get into the on-board configuration utility. On Tue, Apr 19, 2022 at 8:56 AM Douglas Taylor via cctech wrote: > > Once upon a time I used an Emulex QD21, but I sold it because the actual > ESDI disks I had were a pain in the butt. Always crashing. > I still have a Webster (quad board) SRQD something. > I think I had a Dilog board also. It's been a while, probably 20 years. > Doug > > On 4/18/2022 9:12 PM, Chris Zach via cctech wrote: > > Interesting, what kind of ESDI controllers do you have? They got > > advanced features like cache, ordered seeks, and burst mode/block mode > > DMA?
Re: idea for a universal disk interface
Once upon a time I used an Emulex QD21, but I sold it because the actual ESDI disks I had were a pain in the butt. Always crashing. I still have a Webster (quad board) SRQD something. I think I had a Dilog board also. It's been a while, probably 20 years. Doug On 4/18/2022 9:12 PM, Chris Zach via cctech wrote: Interesting, what kind of ESDI controllers do you have? They got advanced features like cache, ordered seeks, and burst mode/block mode DMA? C On 4/18/2022 6:09 PM, Douglas Taylor via cctech wrote: Because of this I'm holding on to my DEC Qbus ESDI controllers!!! You never know Doug On 4/17/2022 4:35 PM, Guy Sotomayor via cctech wrote: I chose ESDI and SMD fundamentally because the interface is 100% digital (e.g. the data/clock separator is in the drive itself). So I don't need to do any oversampling. TTFN - Guy On 4/17/22 11:12, Paul Koning via cctalk wrote: On Apr 17, 2022, at 1:28 PM, shad via cctalk wrote: hello, there's much discussion about the right method to transfer data in and out. Of course there are several methods, the right one must be carefully chosen after some review of all the disk interfaces that must be supported. The idea of having a copy of the whole disk in RAM is OK, assuming that a maximum size of around 512MB is required, as the RAM is also needed for the OS, and for Zynq maximum is 1GB. For reading a disk, an attractive approach is to do a high speed analog capture of the waveforms. That way you don't need a priori knowledge of the encoding, and it also allows you to use sophisticated algorithms (DSP, digital filtering, etc.) to recover marginal media. A number of old tape recovery projects have used this approach. For disk you have to go faster if you use an existing drive, but the numbers are perfectly manageable with modern hardware. If you use this technique, you do generate a whole lot more data than the formatted capacity of the drive; 10x to 100x or so. Throw in another order of magnitude if you step across the surface in small increments to avoid having to identify the track centerline in advance -- again, somewhat like the tape recovery machines that use a 36 track head to read 7 or 9 or 10 track tapes. Fred mentioned how life gets hard if you don't have a drive. I'm wondering how difficult it would be to build a useable "spin table", basically an accurate spindle that will accept the pack to be recovered and that will rotate at a modest speed, with a head positioner that can accurately position a read head along the surface. One head would suffice, RAMAC fashion. For slow rotation you'd want an MR head, and perhaps supplied air to float the head off the surface. Perhaps a scheme like this with slow rotation could allow for recovery much of the data on a platter that suffered a head crash, because you could spin it slowly enough that either the head doesn't touch the scratched areas, or touches it slowly enough that no further damage results. paul
Oracle Releases Solaris 11.4 "CBE" Free For Open-Source Developers / Non-Production Use
I don't know if this has been posted already or not so I thought I would show it here. https://www.phoronix.com/scan.php?page=news_item=Oracle-Solaris-11.4-CBE
Re: IMSAI SIO2 cable part number
probably others out there that can use some of these cables too... sad but true I wish I had bought up all the loose IMSAI parts Micro-age redistribution had way back then in the early 1980s they had parts and pieces of leftovers and half disassembled IMSAI atuff stuff their techs screwed up! Ed# In a message dated 4/18/2022 10:45:44 PM US Mountain Standard Time, cctech@classiccmp.org writes: Bill, Let me know right quick if you'll be at VCF East and I'll make you a pair, I have both kinds of IDC ends. I'm heading out first thing tomorrow morning though as I have work in the northeast before VCF East. Thanks,Jonathan --- Original Message ---On Monday, April 18th, 2022 at 15:03, Bill Degnan via cctech wrote: >>> Hi all...> What is the cable partnumber for the IMSAI SIO2? I need to order a> set of cables. I thought in all of my boxes and boxes of cables I> might have one...but nope.>> Here is a picture:>> https://deramp.com/downloads/mfe_archive/010-S100 Computers and Boards/00-Imsai/10-Imsai S100 Boards/Imsai SIO-2 dual serial IO/SIO with cables.JPG>> Thanks in advance.>> BIll
