Re: Modifying microcode
On 06/02/2018 03:33 PM, Antonio Carlini via cctech wrote: On 02/06/18 15:17, allison via cctech wrote: It was my understanding from using the 730 that there was limited (really limited) microcode enough to load the WCS as the tu58 was a serial device (standard tu58) and the 730 had to unpack and stuff the WCS. You need little to do that but far from even PDP11 instruction set. The Microcode was loaded was the "what made it a VAX stuff". Allison Well something has to load the ucode but whether that's a fixed part of ucode itself or whether it's a hardware state machine (or something) that feeds the loaded ucode into the appropriate RAM, I don't know. I've never delved that deeply into the relevant FMP sets. Actually, the 8085 could load a small bootloader from 8085 ROM to the 730 microcode. That would be the most logical way to do it, assuming the microcode bootloader was really small. The IBM 360/25 had all microcode in the top 16K of main core memory, and the emulator of your choice could be loaded from binary punch cards. The microcode bootloader was hand-loaded through the front panel switches, and occupied 16 16-bit words. Jon
Re: Modifying microcode
> On Jun 2, 2018, at 2:08 PM, Robert Armstrong via cctalk > wrote: > >> Tony Duell wrote: >> Incidentally, did DEC ever release any details (flowcharts, source listings, >> etc) of the 11/730 microcode? And what about the control PROMs for the >> memory system. The technical manual implies there was a listing of those, >> but I've never found it. > > I thought that DEC had a whole microcode development suite for the 730 to > support customer written extensions to the microcode, but I've never seen it > nor any documentation for it. If such a thing did exist then I seriously > doubt anybody ever bought it. The 730 was never a super popular machine to > start with, and the market for a customized version would have been very > small. > > I've heard a persistent rumor over the years that the WPS/8 and PDP-8 > software group at DEC had modified the 730's microcode to support a PDP-8 > emulation of some kind, and that they used that internally for development > 'cause it was faster than a real -8. I've not idea if that's true, but it > would be cool if they did. And no, I'm not talking about PDP-11 > compatibility mode - even the stock 730 had that (all the 7xx VAXes did, I > believe). > That would be Ritchie Lary’s microcode implementation for the PDP-11/60 with WCS. John. > Certainly if you had the right tools and the right knowledge, it would have > been easy to modify and replace the 730's microcode with something of your > own. Just copy the binary images to the console tape and reboot. > > Bob >
Re: Modifying microcode
On 02/06/18 19:08, Robert Armstrong via cctalk wrote: Tony Duell wrote: Incidentally, did DEC ever release any details (flowcharts, source listings, etc) of the 11/730 microcode? And what about the control PROMs for the memory system. The technical manual implies there was a listing of those, but I've never found it. I thought that DEC had a whole microcode development suite for the 730 to support customer written extensions to the microcode, but I've never seen it nor any documentation for it. If such a thing did exist then I seriously doubt anybody ever bought it. The 730 was never a super popular machine to start with, and the market for a customized version would have been very small. I've heard a persistent rumor over the years that the WPS/8 and PDP-8 software group at DEC had modified the 730's microcode to support a PDP-8 emulation of some kind, and that they used that internally for development 'cause it was faster than a real -8. I've not idea if that's true, but it would be cool if they did. And no, I'm not talking about PDP-11 compatibility mode - even the stock 730 had that (all the 7xx VAXes did, I believe). Certainly if you had the right tools and the right knowledge, it would have been easy to modify and replace the 730's microcode with something of your own. Just copy the binary images to the console tape and reboot. There was "VAX-11/780 Microprogramming Tools User's Guide" but I don't know if there was ever one for the VAX-11/730. From reading the DTJ article it seems as though there was no set of neatly pre-packaged ucode development tools for the 730. Antonio -- Antonio Carlini arcarl...@iee.org
Re: Whence 556?
The 729 CE manual quotes 555 BPI. I’m not sure when it became 556. http://bitsavers.trailing-edge.com/pdf/ibm/magtape/729/223-6845_729_CEman_1959.pdf The IBM 728 was 248 BPI. Before that it was the nice round number 200 BPI. I tried permutations of standard IPS and round number data rates and don’t see anything that yields exactly 556BPI. Tim
RE: Modifying microcode
On 02/06/18 15:17, allison via cctech wrote: > > It was my understanding from using the 730 that there was limited > (really limited) microcode > enough to load the WCS as the tu58 was a serial device (standard tu58) > and the 730 had to > unpack and stuff the WCS.� You need little to do that but far from even > PDP11 instruction set. > The Microcode was loaded was the "what made it a VAX stuff". > > Allison What you're describing is the 750, not the 730. Unlike the 78x and 730/725, the 750 had no console front end processor. The microcode did it all, including loading any additional microcode from TU58. As others have said, the 730 had an 8085 CFE processor that loaded all the VAX microcode. The main CPU had no ROMs and could do absolutely nothing until the CFE loaded the microcode. FWIW, the CFE in the 730 had a 2K ROM and (I think) about 8K of RAM. The first thing the CFE did after power on, before it did anything with the VAX CPU, was to load the rest of the 8085 code from the TU58 into that CFE RAM. The 2K of ROM had just enough code to type characters on the console and to talk to the TU58, and even the CFE couldn't really do much until the rest of its code was loaded from the TU58. Once that was done, the CFE command line interpreter executed a script (one of four possible ones, depending on the HW configuration) and that script had the CFE commands to load the VAX microcode. FWIW, when you first turn on the 730 it types "CONV11" on the console, followed by the rest of the startup dialog. If you pay attention, there's a tiny pause between the "CON" and the "V11". That's because the first part was typed by the 8085 ROM just to let you know that the CFE was alive, and the version number was actually typed by the RAM part of the CFE code after it was loaded from the tape. Bob
Re: Modifying microcode
On 6/3/18 11:17 AM, Antonio Carlini via cctalk wrote: > From reading the DTJ article it seems as though there was no set of neatly > pre-packaged ucode development tools for the > 730. and the 730 started out in life as a PDP-10 (Minnow)
Re: Modifying microcode
> On Jun 2, 2018, at 2:08 PM, Robert Armstrong via cctalk > wrote: > >> Tony Duell wrote: >> Incidentally, did DEC ever release any details (flowcharts, source listings, >> etc) of the 11/730 microcode? And what about the control PROMs for the >> memory system. The technical manual implies there was a listing of those, >> but I've never found it. > > I thought that DEC had a whole microcode development suite for the 730 to > support customer written extensions to the microcode, but I've never seen it > nor any documentation for it. If such a thing did exist then I seriously > doubt anybody ever bought it. The 730 was never a super popular machine to > start with, and the market for a customized version would have been very > small. Considering that the 730 was a 2901 based machine, and 2901s were widely used, presumably the tools were not a problem around DEC. Perhaps they tweaked the UDA50 microcode toolchain? > I've heard a persistent rumor over the years that the WPS/8 and PDP-8 > software group at DEC had modified the 730's microcode to support a PDP-8 > emulation of some kind, and that they used that internally for development > 'cause it was faster than a real -8. I've not idea if that's true, but it > would be cool if they did. And no, I'm not talking about PDP-11 > compatibility mode - even the stock 730 had that (all the 7xx VAXes did, I > believe). The PDP-8 emulation used for internal PDP-8 software development was on an 11/60 running RSTS/E, I remember that system in the lab in DEC Merrimack (MKO1-1). I would imagine it could have been done on a 730 also but chances are the 11/60 was a whole lot faster. paul
Re: Modifying microcode
On Fri, Jun 1, 2018 at 1:08 PM, Robert Armstrong via cctalk wrote: > You forgot the 11/730 and 725. The KA730 used 2901 bit slicers and the > control store was entirely in RAM. After power on it was a paperweight until > the 8085 CFE loaded the microcode. And one of the big optimizations was to cut a fresh console boot tape with all the required files in sequential order because the 8085 would cache the directory block (thankfully!) so it didn't have to rewind between reading each file. The stock tape was rather random and could take 20-30 min of shoeshining. Putting the files in order brought the boot times down to 10 min or less of console load - i.e. - essentially the serial transfer speed of that many kbytes, or close to it. Today, of course, I would seriously think about a TU58 emulator. There are several projects. -ethan
Re: Modifying microcode
On Fri, Jun 1, 2018 at 2:46 PM, Antonio Carlini via cctalk wrote: > the 78032 chip. The VAX-11/730 was chosen because it was "an entirely 'soft' > machine". > > (The VAX-11/725 is essentially the same hardware but in different > packaging). We used to purchase 11/725s for parts to keep our 11/730 running. Much cheaper because "nobody" wanted an 11/725 in the early 90s (I still have one. I wish I could afford a Unibus controller to replace the KLESI/U and RC25). -ethan
Re: Modifying microcode
> On Jun 3, 2018, at 7:37 PM, Ethan Dicks via cctalk > wrote: > > We used to purchase 11/725s for parts to keep our 11/730 running. > Much cheaper because "nobody" wanted an 11/725 in the early 90s (I > still have one. I wish I could afford a Unibus controller to replace > the KLESI/U and RC25). Back around the early 1990s, a friend of mine had an 11/725 and an 11/730 in his apartment. One of then had a bad PROM chip, so he could only run one at a time. -- Mark J. Blair, NF6X http://www.nf6x.net/
Re: Modifying microcode
On 5/30/2018 7:34 AM, Camiel Vanderhoeven via cctalk wrote: The microcode for the MicroVAX 2 (for which the MICRO2 assembler was used) and the CVAX (which is the CPU in your 3800) is implemented as a mask ROM on the CPU chip itself. No way to change it, and no way you can use MICRO2 to assemble the microcode for the CVAX. Years ago I was playing the the microcode of the DEC Minnow (PDP-10) which was written in MICRO2 - but I don't think I ever found that assembler. Do MICRO2 executables exists? Rob.
