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Seattle Area: The "Interim Computer Festival" is tomorrow ...

by Michael Brutman

We're still waiting for VCF PNW 2020, but while we wait ... https://sdf.org/icf/ (This is a much smaller event than any VCF. It's also quite fun because it's not overwhelming.) -Mike

1 month, 3 weeks

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FSF

by Murray McCullough

The Free Software Foundation(FSF) is 40 this week. Central to the thesis of sharing software this organization has played and continues to play a seminal role. Though it's importance may be waning due to AI its reason to exist can't be overstated. Happy computing Murray 🙂

1 month, 3 weeks

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VCF Tech Swap Meet - Oct. 18 - Wall, NJ

by Jeffrey Brace

VCF Tech Swap Meet Oct. 18 in Wall, NJ INFO: https://vcfed.org/vcf-swap-meet/ VENDOR SINGUP: https://forms.gle/LpzDkF97THFNg3qg9 Jeff Brace VCF/MARCH Fundraising Manager Vintage Computer Federation is a 501c3 charity https://vcfed.org/ <http://www.vcfed.org/>

1 month, 3 weeks

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Esprit Opus 220 serial terminal

by Holm Tiffe

Hi there, at the beginning of the 90ies I've repaired some Esprit Opus220 terminals for an local computer shop. Problem #1 of those seriaal terminals was a bad the Flyback Transformer. The Shop managed to get a bunch of those FBT's new from Taiwan so I could successfully repair approx 10 of those terminals. I'm still own one of them, still in functional condition (orange 12 or 14" CRT).. My stash of goods should still contain two of those Replacement FBT's, but after a move in 2020 I have to locate them.. So far so good. Now the Problem: I have an Grundig CD313 monitor from an CNC EDM Machine on the table, the FBT Grundig 29200-003.05 is bad and I want to repair the monitor for the small company owning that machine. Unfortunaltely they are located some miles away from me.. My hope is to locate the two new FBTs and adapt one of them into the Grundig CD313 Monitor..where I have the schematics for. It where pretty nice if I could get the schematics from one of that Esprit Opus II (220) Terminals to look at the wiring for the FBT ..and that's my problem.. has anyone the scheamtics for those Opus terminals? Regards, Holm -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741

1 month, 4 weeks

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Any Interacts out there? 1978, 8080-based system

by Steve Lewis

Checking on if anyone has an old Interact system out there. It wasn't widely successful, but gained some popularity around Ann Arbor, MI. I've not come across one of these yet. But I've come across one of its "Killer Application", a tape-based program called Message Center that lets users construct banner message scripts with a few video/audio effects. Would be interested to see this "for real" rather than just in the MAME emulator. Or also to hear any stories about the system, such as anyone who actually used one, or saw one being used at a storefront? -Steve

1 month, 4 weeks

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IBM 5110 news - RWS memory replacements

by Steve Lewis

Well, just yesterday I tested a set of RWS (RAM) replacement cards for the IBM 5110 from Patrick Lebbard from Canada - and I'm very impressed. They work well, I had them running for a few hours. Details are described here: https://voidstar.blog/ibm-5110-rws-ram-modern-make-replacements/ or VCF thread https://forum.vcfed.org/index.php?threads/ibm-5110-ram-timings.1253087/ I don't think he plans on becoming a retailer, they've offered up the schematic and such. But he did make these boards for me after I shipped him a set of the base connectors that you need (to adapt them to the 5110's A1 board) that I pulled from a known-broken board. His motivation is that he does have a 5100 also that he's trying to resurrect, so he plans to carry on and make an IBM 5100 version of these modules also (still resolving a few technical differences between them, so it's not working out just yet - but the 5110 version of these I can say seem flawless). Anyway, exciting stuff to see someone technically savvy enough to probe signals and reverse engineer 50+ year old tech! -Steve

2 months

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Re: IBM 5110 IMFs

by Robert Marinelli

I've been digging through CHM and bitsavers and haven't found an IMF for 5100 or 5110 yet. It seems a lot of CE material was just not saved. However, I've been tracing execution of ExecROS and the APL ROS - thanks to your excellent emulator and the extracted ROS files this works well. Have learned a few things about the jump tables, I'd imagine that the type 23 files would likely install themselves in high memory and modify an IOCB jump entry to point to the new/patch code. Kind of like how you take over the printer IOCB. One little issue I found with your emulator is behavior of interrupts while in HOLD. Per the APL and BASIC manuals, pressing HOLD while a program is running should pause the output (mostly so you can read the screen before output scrolls up), and then pressing HOLD again is supposed to continue execution. In emu5110 that didn't work, pressing HOLD always stopped but a 2nd press wanders off in to never land (hang or bogus error or junk on screen). While tracing & learning I noticed that if code was being executed from one of the language ROS, HOLD would fail. But HOLD/resume worked fine on an idle machine - idle is a short loop that just blinks the _ cursor at location 0x0200+902 in APL. So looking through the pseudo-schematics/block diagrams in SY31-0552-3 IBM 5110 System Logic there is quite a bit of gate logic on the multiple ROS cards, plenty of wires between them. Maybe, hardware interrupts are held off in hardware when we are doing reads from the language ROS cards. The interrupt bits are properly shown in a register, but nothing detailing gating of interrupt -> CPU. To test the idea I made this change in emu.c: 175c175,176 < check_int(); /* check for pending interrupts */ --- >if(curr_ros==ExecROS) /* if in ExecROS we can HOLD/resume */ > check_int(); /* check for pending interrupts */ and now HOLD works as expected. Norbert's JavaScript port had the same issue with HOLD, he ported the above and confirmed that the HOLD now works properly. As a side note, the MAME emulation (which may have been done independently) has the same problem, likely could use the same fix. Anyone know how to contact the MAME author? There was a lot of interest in the CHM release of APL\360 source along with auto-operator and I've tried contact a few of those folks, we just need one CE or user who kept a box of floppies. -Robert

2 months

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50 years of the MOS 6502

by Christian Liendo

https://www.allaboutcircuits.com/news/the-mos-6502-how-a-25-chip-sparked-a-… According to many 50 years ago on September 16, 1975, MOS Technology showed the 6502 at WESCON

2 months

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VCFMW20 recap of highlights

by Steve Lewis

VCFMW in Chicago was this past weekend! Flew up with 2 bags, came back with 4 ! Funny thing is, my wife said she was surprised I didn't come back with anything extra - well, I shipped those extra 2 bags and they haven't shown up yet. Gives me one day to come up with a cover story! :) There is so much going on at the Chicago VCF - I don't think any individual can cover the whole thing. Instead of a blog, this time I'm trying a "video photo album" to cover some of the highlights that I was able to see. Search Xiphod's Photo Album of Vintage Computer Fest (no commentary) - VCF Chicago 2025 or https://www.youtube.com/watch?v=ld1CXUTusDI or https://rumble.com/v6z4aia-xiphods-photo-album-of-vintage-computer-fest-no-… Mainly my goal was to pick up a POLY-88 that folks have been helping to restore off-and-on over the past 18 months. They got it going, so that was one of the shipments back. The other was an Apple TAM at too good a price to pass up. (and yes, wife already knows they are coming) If it's any indicator: come Sunday afternoon, merchants were fairly eager to sell at any offer (some announcing that anything unsold would go straight to scrap - maybe that's a ploy, but there were some under $10 bargains to be had, a kind of "everything must go" vibe). - Steve

2 months

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Fun with PDP11 Assembly Language

by Martin Eberhard

I just love the PDP11's assembly language. I needed a super-tight subroutine to print a 16-bit value as 6 octal digits. This is as tight as I could make it, 16 words (including writing to the serial port, which takes 5 words). Can you beat it? ;*** Subroutine ************************* ;Print a 16-bit value as 6 octal digits ;Calling Sequence: ; jsr PC,PROCT6 ;On Entry: ; R2 = value to print ;Trashes R1,R2 ;**************************************** PROCT6: mov #100030,R1 ;Digit loop ends when '1' lands in C ;..'30' makes it ASCII sec ;All done when this is in C again ;Extract a digit and convert it to ASCII. Check for done. 1$: rol R2 ;Shift digit out of R2 & into R1 beq 3$ ;Return when done rol r1 ;Build next octal digit bcc 1$ ;Done when c = shift pattern bit ;Write digit to the serial port 2$: tstb @#CTXSTA ;Wait for transmitter (clears C) bpl 2$ movb R1,@#CTXDAT ;Transmit now ;Next digit mov #020006,R1 ;Digit ends when "2" lands in C. ;Printing ends when "sec" bit ;..leaves R2. '6' makes ASCII br 1$ 3$: rts PC Martin E.

2 months

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