[cctalk] Re: Bendix G-15 Restoration
On Sat, 8 Oct 2022, Paul Kimpel wrote: modify a lot of the software. Timing dependencies aside, G-15 instructions didn't have addresses -- they had "timing numbers" that effectively told the hardware how long to wait before reading or writing a word on the drum. Oh really, that is then similar to the addressing scheme of the Diehl Combitron (a marvellous design by Stanley Frankel). Christian
[cctalk] Re: Bendix G-15 Restoration
On Fri, 7 Oct 2022, Chuck Guzis wrote: I recall that the IBM 650 had an upgrade option where core was used for some of the registers. It was small--maybe 50 words. The Z22 had a very small area of core memory, called "fast memory" (Schnellspeicher). And then we have boards out of an LGP-21 (that we still lack in our collection) that replaced the on-disc registers with semiconductor shift registers. I don't really know why they did that. Christian
[cctalk] Re: Bendix G-15 Restoration
On Sat, 8 Oct 2022, Paul Kimpel wrote: modify a lot of the software. Timing dependencies aside, G-15 instructions didn't have addresses -- they had "timing numbers" that effectively told the hardware how long to wait before reading or writing a word on the drum. Well, No, I believe that each instruction had the address of the next instruction in it. That allowed you to jump to another track for the next instruction in the sequence. Instruction addresses were not that many bits. Jon
[cctalk] Re: Apple G5 Rebuild
On Mon, 10 Oct 2022 at 08:20, Kevin Parker via cctalk wrote: > > Problem is my GoogleFoo can't find any diagrams, illustrations etc on how > the internals are put together What? I am *amazed*. I don't know how you could _not_ find the info. There is loads of it. This is the first hit on "apple powermac g5 disassembly" -- https://www.ifixit.com/Guide/Disassembling+Power+Mac+G5+Motherboard/7579 This is the 2nd: https://www.ifixit.com/Device/Power_Mac_G5 It's one of the easiest machines ever to assemble or disassemble and there's tons of info, videos, walkthrough, step by step guides etc. 4 words is not "Google-fu". -- Liam Proven ~ Profile: https://about.me/liamproven Email: lpro...@cix.co.uk ~ gMail/gTalk/FB: lpro...@gmail.com Twitter/LinkedIn: lproven ~ Skype: liamproven UK: (+44) 7939-087884 ~ Czech [+ WhatsApp/Telegram/Signal]: (+420) 702-829-053
[cctalk] Re: Bendix G-15 Restoration
Paul wrote: >> modify a lot of the software. Timing dependencies aside, G-15 instructions >> didn't have addresses -- they had "timing numbers" that effectively told the >> hardware how long to wait before reading or writing a word on the drum. To which Christian replied: > Oh really, that is then similar to the addressing scheme of the Diehl > Combitron (a marvelous design by Stanley Frankel). Indeed, the old drum computers generally had timing information in the instruction set that gave the optimal sector on the drum for the operand address, and the next instruction address. We had an old computer at our high school computer lab (1974-ish) that was designed in the mid-1960's by 3M (the scotch tape company) that was originally a real-time monitor and data reduction system for a natural gas distribution system and was donated to the school when it was retired. The machine had two CPUs that ran in tandem with the ability to detect a fault in one, and switch to the other. The CPUs had 24-bit words, and each had 8K words of magnetic drum memory.They were discrete transistor-based machines and were bit-serial in architecture. An instruction like ADD that operated on an operand to add to the accumulator would have information in the instruction set reference that said "for optimal programming, operand=N+3, next instruction=N+6". The assembler (which was slow!), called SOAP, tried to optimize, but for a lot of things like list processing and such, it really couldn't do much to help. Tables and lists had to be scattered all over the drum for the best speed, and that got kind of difficult because the operand address only had room for a sector number. If the reference was on a different track, you had to prefix the instruction with a modifier instruction that would specify the block and track for the operand (and next instruction if needed). There were no index registers, so the only way to do calculated data fetches or branches was to load the instruction base into the accumulator, then modify it using math operations to calculate the correct sector, then store the accumulator at the address specified by the next instruction address to execute it. It was crazy fun learning it, but in practice, even trying really hard to optimize the code, it could barely drive a Teletype 33ASR to full 10 character-per-second maximum speed.It had a bunch of I/O stuff, including a Parabam transistorized real-time clock that could be read by the computer, a bank of thumbwheel switches that could be read in BCD form, and a whole rack full of A/D (discrete transistor) converters, digital counters, analog outputs, and digital relay outputs that were used for the original data acquisition I/O, but the cables going into them were just chopped off, and I never played with any of that other than to write code to click the relays in pseudo-random patterns to make a noise like the machine was "calculating". Speaking of the Diehl Combitron, it was indeed an amazing transistorized (with only something like ~130 transistors in total) calculator designed by the genius of Stan Frankel (who also designed the transistorized Smith-Corona/Marchant (SCM) Cogito 240/240SR calculator (which was way too slow due to SCM requiring the use of cheap slow-switching diodes), the Royal McBee/Librascope/General Precision LGP-30 vacuum-tube drum computer, as well as consulted in the design of the delay line-based Packard Bell PB-250. The Combitron was an amazing microcoded bit-serial processor designed in around '63-'64 by Frankel. It was user-programmable (but not user microprogrammable, unless...).ROM for storing the microcode was a difficult thing back then, generally taking quite a bit of space (not really practical for a desktop calculator) and were labor-intensive and expensive to build. How did Frankel store the microcode for the Combitron? On a punched stainless steel tape that was optically read a bit at a time at power-up into a delay line. Once the microcode was loaded, the tape would rewind and the microcode engine would start up reading its instructions out of the delay line. Hence the addressing scheme in the microcode to make it as fast as possible. The addressing scheme accounted for the delay time for processing a microcode function such that the next micro-instruction would be right at the output tap of the delay line when it was needed. It takes about a minute for the microcode to load when the machine is powered up. The tape has two channels, one for the clock, and another for the microcode bits. By the way, an end-user could presumably write custom microcode for the calculator if they had the microcode documentation and a way to punch the stainless steel tape. Possible, but not terribly practical. Loading the microcode from a reel of punched metal tape made firmware updates possible by replacing the tape. I do not know if there were different versions of the microcode for the Combitron
[cctalk] Re: Bendix G-15 Restoration
Awesome history, Rick! Sellam On Mon, Oct 10, 2022 at 9:35 AM Rick Bensene via cctalk < cctalk@classiccmp.org> wrote: > > Paul wrote: > >> modify a lot of the software. Timing dependencies aside, G-15 > instructions > >> didn't have addresses -- they had "timing numbers" that effectively > told the > >> hardware how long to wait before reading or writing a word on the > drum. > > To which Christian replied: > > > Oh really, that is then similar to the addressing scheme of the Diehl > > Combitron (a marvelous design by Stanley Frankel). > > Indeed, the old drum computers generally had timing information in the > instruction set that gave the optimal > sector on the drum for the operand address, and the next instruction > address. > > We had an old computer at our high school computer lab (1974-ish) that > was designed in the mid-1960's by 3M (the scotch tape company) that was > originally a real-time monitor and data reduction system for a natural > gas distribution system and was donated to the school when it was > retired. > > The machine had two CPUs that ran in tandem with the ability to detect a > fault in one, and switch to the other. > The CPUs had 24-bit words, and each had 8K words of magnetic drum > memory.They were discrete transistor-based machines and were > bit-serial in architecture. An instruction like ADD that operated on > an operand to add to the accumulator would have information in the > instruction set reference that said "for optimal programming, > operand=N+3, next instruction=N+6". > The assembler (which was slow!), called SOAP, tried to optimize, but for > a lot of things like list processing and such, it really couldn't do > much to help. Tables and lists had to be scattered all over the drum > for the best speed, and that got kind of difficult because the operand > address only had room for a sector number. If the reference was on a > different track, you had to prefix the instruction with a modifier > instruction that would specify the block and track for the operand (and > next instruction if needed). There were no index registers, so the > only way to do calculated data fetches or branches was to load the > instruction base into the accumulator, then modify it using math > operations to calculate the correct sector, then store the accumulator > at the address specified by the next instruction address to execute it. > It was crazy fun learning it, but in practice, even trying really hard > to optimize the code, it could barely drive a Teletype 33ASR to full 10 > character-per-second maximum speed.It had a bunch of I/O stuff, > including a Parabam transistorized real-time clock that could be read by > the computer, a bank of thumbwheel switches that could be read in BCD > form, and a whole rack full of A/D (discrete transistor) converters, > digital counters, analog outputs, and digital relay outputs that were > used for the original data acquisition I/O, but the cables going into > them were just chopped off, and I never played with any of that other > than to write code to click the relays in pseudo-random patterns to make > a noise like the machine was "calculating". > > Speaking of the Diehl Combitron, it was indeed an amazing transistorized > (with only something like ~130 transistors in total) calculator designed > by the genius of Stan Frankel (who also designed the transistorized > Smith-Corona/Marchant (SCM) Cogito 240/240SR calculator (which was way > too slow due to SCM requiring the use of cheap slow-switching diodes), > the Royal McBee/Librascope/General Precision LGP-30 vacuum-tube drum > computer, as well as consulted in the design of the delay line-based > Packard Bell PB-250. > > The Combitron was an amazing microcoded bit-serial processor designed in > around '63-'64 by Frankel. It was user-programmable (but not user > microprogrammable, unless...).ROM for storing the microcode was a > difficult thing back then, generally taking quite a bit of space (not > really practical for a desktop calculator) and were labor-intensive and > expensive to build. > > How did Frankel store the microcode for the Combitron? > > On a punched stainless steel tape that was optically read a bit at a > time at power-up into a delay line. Once the microcode was loaded, the > tape would rewind and the microcode engine would start up reading its > instructions out of the delay line. Hence the addressing scheme in the > microcode to make it as fast as possible. The addressing scheme > accounted for the delay time for processing a microcode function such > that the next micro-instruction would be right at the output tap of the > delay line when it was needed. > > It takes about a minute for the microcode to load when the machine is > powered up. The tape has two channels, one for the clock, and another > for the microcode bits. > > By the way, an end-user could presumably write custom microcode for the > calculator if they had the microcode documentation and a w
[cctalk] Re: Apple G5 Rebuild
A few more useful sites: https://tim.id.au/laptops/apple/powermac/powermac_g5.pdf This one includes official Apple “take-apart procedures" http://resale.headgap.com Parts and components, in case you actually are missing something in their catalog. Satisfied customer, no other relation. https://everymac.com/systems/apple/powermac_g5/index-powermac-g5.html https://lowendmac.com/tag/power-mac-g5/ Specifications, benchmarks, etc. Once you get it running, we are headed into winter when electric heaters may be desirable. These two sites: https://www.distributed.net/Main_Page http://tenfourfox.blogspot.com Will give you semi-productive things to do with it; the G5 machines with altivec are pretty good at RC5-72 compared to most CPUs, and TenFourFox is essentially a current web-browser. I’m also not a black-belt goog-fu artist. There is more available. Hope this much is helpful, though. - Mark On Oct 10, 2022, at 11:33 AM, Liam Proven via cctalk mailto:cctalk@classiccmp.org>> wrote: [EXTERNAL EMAIL] On Mon, 10 Oct 2022 at 08:20, Kevin Parker via cctalk mailto:cctalk@classiccmp.org>> wrote: Problem is my GoogleFoo can't find any diagrams, illustrations etc on how the internals are put together What? I am *amazed*. I don't know how you could _not_ find the info. There is loads of it. This is the first hit on "apple powermac g5 disassembly" -- https://www.ifixit.com/Guide/Disassembling+Power+Mac+G5+Motherboard/7579 This is the 2nd: https://www.ifixit.com/Device/Power_Mac_G5 It's one of the easiest machines ever to assemble or disassemble and there's tons of info, videos, walkthrough, step by step guides etc. 4 words is not "Google-fu". -- Liam Proven ~ Profile: https://about.me/liamproven Email: lpro...@cix.co.uk ~ gMail/gTalk/FB: lpro...@gmail.com Twitter/LinkedIn: lproven ~ Skype: liamproven UK: (+44) 7939-087884 ~ Czech [+ WhatsApp/Telegram/Signal]: (+420) 702-829-053
[cctalk] Re: Apple G5 Rebuild
> TenFourFox is essentially a current web-browser. It's kind of you to say that, but at its core it's still just a hopped-up Firefox 45. Many things work, many things work but look funny, and an increasing proportion of things don't work at all. I myself just use it for basic tasks now that I'm on a Raptor Talos II as my desktop machine, though I do issue security patches on an irregular timeline. -- personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckai...@floodgap.com -- If they give you ruled paper, write the other way. -- Juan Ramon Jimenez ---
[cctalk] Re: Apple G5 Rebuild
On 10/10/22 11:33, Liam Proven via cctalk wrote: On Mon, 10 Oct 2022 at 08:20, Kevin Parker via cctalk wrote: Problem is my GoogleFoo can't find any diagrams, illustrations etc on how the internals are put together What? I am *amazed*. I don't know how you could _not_ find the info. There is loads of it. This is the first hit on "apple powermac g5 disassembly" -- https://www.ifixit.com/Guide/Disassembling+Power+Mac+G5+Motherboard/7579 This is the 2nd: https://www.ifixit.com/Device/Power_Mac_G5 It's one of the easiest machines ever to assemble or disassemble and there's tons of info, videos, walkthrough, step by step guides etc. 4 words is not "Google-fu". Liam, don't be a d**k. Doc
[cctalk] Re: Apple G5 Rebuild
On 10/10/22 10:33 AM, Liam Proven via cctalk wrote: 4 words is not "Google-fu". Sometimes knowing /which/ /words/ to search for is the problem. I've also seen Google return extremely different search results for different people. Let's assume good intention and benign mistake. No need to even passively insult someone. -- Grant. . . . unix || die
[cctalk] looking for DQ696 and RQDX3
Hi folk, I am still looking for a DQ696 to allow me to get ESDI drives going on both my microVAX and 11/73 since the Webster RQD11 controller failed I only have the one. I'd also like to get old of an RQDX3 since I built a Gesswein emulator and have nothing to test it with :-) Any help appreciated, Nigel -- Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU Amateur Radio, the origin of the open-source concept! Skype: TILBURY2591
[cctalk] Re: looking for DQ696 and RQDX3
On Mon, Oct 10, 2022 at 3:06 PM Nigel Johnson Ham via cctalk wrote: > > Hi folk, > > I am still looking for a DQ696 to allow me to get ESDI drives going on > both my microVAX and 11/73 since the Webster RQD11 controller failed I > only have the one. I'd also like to get old of an RQDX3 since I built a > Gesswein emulator and have nothing to test it with :-) Do you have ESDI drives that have been formatted with a Dilog DQ696, and you need a DQ696 to use the drives with their existing format, or would it be OK to low level format the drives and any QBus ESDI controller would work, such as an Emulex QD21, or a RQD11 from various vendors? Where are you located, and what is a QBus ESDI controller worth to you? Here's an Emulex QD21 for around $100 in the US: https://www.ebay.com/itm/372959317948 Does that exceed your budget, or wrong location, or not compatible with your needs? I probably have more Dilog DQ696, Emulex QD21, and SDC-RQD11-EC controllers than I do working ESDI drives. At one point I had several working ESDI drives that have now gone bad over time while not being used. It's been a while since I tried spinning up any of them to see if any still work.
[cctalk] Re: Apple G5 Rebuild
I blame Google: it's complete trash now. Sellam On Mon, Oct 10, 2022 at 2:40 PM Grant Taylor via cctalk < cctalk@classiccmp.org> wrote: > On 10/10/22 10:33 AM, Liam Proven via cctalk wrote: > > 4 words is not "Google-fu". > > Sometimes knowing /which/ /words/ to search for is the problem. > > I've also seen Google return extremely different search results for > different people. > > Let's assume good intention and benign mistake. No need to even > passively insult someone. > > > > -- > Grant. . . . > unix || die >
[cctalk] Re: Apple G5 Rebuild
On 2022-10-10 17:39, Grant Taylor via cctalk wrote: On 10/10/22 10:33 AM, Liam Proven via cctalk wrote: 4 words is not "Google-fu". Sometimes knowing /which/ /words/ to search for is the problem. Indeed. Also, I have added more words and received more search results. One would expect the opposite. I've also seen Google return extremely different search results for different people. Google also tailors results to location and cookies. (I always search in private mode.) Not what it once was...(Sigh) N.
[cctalk] Re: Bendix G-15 Restoration
*From:* Jon Elson via cctalk *Subject:* [cctalk] Re: Bendix G-15 Restoration *Date:* Monday, October 10, 2022 at 7:35 AM *To:* Christian Corti via cctalk *Cc:* Jon Elson On Sat, 8 Oct 2022, Paul Kimpel wrote: modify a lot of the software. Timing dependencies aside, G-15 instructions didn't have addresses -- they had "timing numbers" that effectively told the hardware how long to wait before reading or writing a word on the drum. Well, No, I believe that each instruction had the address of the next instruction in it. That allowed you to jump to another track for the next instruction in the sequence. Instruction addresses were not that many bits. Jon Not quite. A G-15 instruction had two fields, T and N, each seven bits, that looked like sector addresses, and you could often think of them as sector addresses, but doing so carelessly could get you into trouble. N is the easiest one to understand. That was the sector "address" of the next instruction to be executed, which except in the case of two instructions had to be in the same line (track) of the drum as the current instruction. The problem is that the field could hold values from 0-127, but the words around the drum were numbered 0-107, and it was perfectly valid (and sometimes even useful) to specify a value of N in the range 108-127. What actually happened is that the processor subtracted the N value from the word number of the current instruction (termed L), stored the truncated difference in a seven-bit field of a hidden register on the drum named the Command (CM) register, and then as each word passed the read head of the drum, counted that field up until it overflowed its seven-bit size. At that point the drum was in the correct position to read the next instruction. Actually, it was a bit more complicated than that, because the arithmetic in CM was being done modulo 128, but the word addressing was modulo 108. The processor handled that by adding an additional 20 to the CM field if the drum passed word 107 before the count overflowed. There was an additional complication in that the adjustment did not take place if you executed an instruction from word 107, in which case the programmer had to bias their timing numbers by 20 instead to accomplish the adjustment. It was a lovely machine to program. You can read how the sausage was made in the Theory of Operation manual, section C-17, starting on page 40 (page 46 of the PDF): http://bitsavers.org/pdf/bendix/g-15/60121600_G15_Theory_Of_Operation_Nov64.pdf There were 20 108-word lines (0-19) and four 4-word lines (20-23) on the drum that software could access, but instructions could be executed only from lines 0-5, 19, and 23. A register in the processor determined which line was currently selected to execute instructions, so execution stayed on that line until it was changed by either a Select Command Line/Mark Exit or Select Command Line/Return Exit instruction. Those were the only ways to branch from line to line. The T field in an instruction can be thought of as the operand address, and often effectively was, but you had to be careful with that idea, too. It was called T because it was the "timing number" for the instruction's execution. Instructions had two modes, Immediate and Deferred, determined by the I/D bit in the instruction word. Deferred mode is easier to understand. Like N, the difference between it and L was stored in a field of CM and counted up until it overflowed. At that point the processor would access the word(s) under the read and/or write head on the line(s) selected by the S and D fields of the instruction. In this mode, T effectively told the processor how long to wait until the operand word(s) were in position, so it was very much like an operand address. In Immediate mode for most instructions, however, the operand data started at L+1, the word number immediately after that of the instruction. T specified how many words the instruction would process, but in a weird way -- processing started with the word at L+1 but ended at T-1. A really lovely machine to program. In Immediate mode for a few instructions (multiply, divide, the shifts), T actually specified the number of word-times the instruction would take, but instead of processing words from the storage lines on the drum, it processed them in the double-precision registers, which were also on the drum. For shifts, each two counts of T would shift one bit; for multiply and divide, each two counts of T would develop an additional bit of the result. See the ToO manual, section D-10, D-11, D-12, and D-13 starting on page 53. So that's why I say the G-15 didn't have addresses. But then, it didn't really have op codes, either. For some insight into how advantageous use could be made of non-obvious values for the N and T fields in G-15 instructions, see this blog post describing a program that would clear the G-15 drum memory, its
[cctalk] PDP 8a front panel hardware
Is there a 3D print gcode for the hardware that connects a PDP8a front panel to the chassis? Is there anyone who has a spare clips/clamps hardware to attach a PDP 8a console to the chassis? I picked up the donated PDP 8a mentioned earlier on this list, I got it up and running. I need to track down the hardware to attach the front panel to the chassis. I do have spares of the hardware that attaches the ON/OFF panel to the chassis. AS with all "free" donations it's the final mile that costs the big $$ Thanks Bill
[cctalk] Re: PDP 8a front panel hardware
theres 3d print models made of them theres the orig design with does not prit very well and a modified design thats better list forget where might be buried on this site? https://so-much-stuff.com/pdp8/repair/repair.php On Mon, Oct 10, 2022 at 7:53 PM Bill Degnan via cctalk < cctalk@classiccmp.org> wrote: > Is there a 3D print gcode for the hardware that connects a PDP8a front > panel to the chassis? > > Is there anyone who has a spare clips/clamps hardware to attach a PDP 8a > console to the chassis? > > I picked up the donated PDP 8a mentioned earlier on this list, I got it up > and running. I need to track down the hardware to attach the front panel > to the chassis. I do have spares of the hardware that attaches the ON/OFF > panel to the chassis. > > AS with all "free" donations it's the final mile that costs the big $$ > > Thanks > > Bill >
[cctalk] Re: PDP 8a front panel hardware
On 10/10/2022 11:00 PM, Adrian Stoness via cctalk wrote: theres 3d print models made of them theres the orig design with does not prit very well and a modified design thats better list forget where might be buried on this site? https://so-much-stuff.com/pdp8/repair/repair.php I tried to do one here: https://so-much-stuff.com/pdp8/cad/3d.php but I haven't actually printed or used it yet. (I have the original parts, and no free access to a 3D printer at the moment.) Vince On Mon, Oct 10, 2022 at 7:53 PM Bill Degnan via cctalk < cctalk@classiccmp.org> wrote: Is there a 3D print gcode for the hardware that connects a PDP8a front panel to the chassis? Is there anyone who has a spare clips/clamps hardware to attach a PDP 8a console to the chassis? I picked up the donated PDP 8a mentioned earlier on this list, I got it up and running. I need to track down the hardware to attach the front panel to the chassis. I do have spares of the hardware that attaches the ON/OFF panel to the chassis. AS with all "free" donations it's the final mile that costs the big $$ Thanks Bill
[cctalk] 8" floppy diskette storage cases
Does anyone have, or know of a reasonably priced supplier of good clean used, or new 8" floppy diskette boxes? The kind made of plastic like these? https://www.ebay.com/itm/134258177087 I have one 8" box with Xerox software in which the plastic literally crumbling. The price this seller wants for the case itself is reasonable but I find the price of shipping outrageous. Total shipping price for three boxes is shown to be $21.35. I may be crazy, but this seems nuts for something so light. Thank You Don Resor
