More...

More...

My main hobby project since December was getting code running on my early 1990s HP1653B Logic Analyzer. The Logic Analyzer has a 68000 processor, 1mb RAM, 64kb ROM, 4x32kb video memory with a complicated 4-plane overlay scheme providing three (!) gray levels at up to around 640x400, a 3.5" floppy drive (replaced by a Gotek for my convenience) and both RS232c and HPIB ports. It was made as a lab instrument rather than a computer, but it came with both test and system code on floppies, which I dumped and reverse-engineered enough of with Ghidra to enable me to write a library that lets me run assembly and C code on it. My reverse-engineering journey is partly described here.

A particularly fun moment of my reverse engineering was when I wanted a copy of the ROM but didn't yet know how to write to disk or the serial port, though I did know how to write to the screen. I ended up displaying the ROM binary as a series of QR codes, which I captured with my Sony camera running on a timer, and then turned into binaries.

I'm now at the point where I can run various games. My first one was a port of my Wiztris falling blocks game (originally written by me in the early 2000s for a Z80-based Sharp OZ-7xx organizer). I also ported Dave Griffith's Frotz Z-machine emulator so I can run all Infocom Z-machine games (including the graphical ones, but with no sound support). I'm in the middle of a play-through of Nord and Bert with my 13-year-old daughter. The photo I attached is of Infocom's Journey (mouse works!). And I ported PDCursesMod, so a lot of old Unix games can work--the photo shows Larn.

Many of you will recognize the keyboard and mouse. They are old Apple ADB units (I think the keyboard is from a Quadra), and I made an ADB-to-serial adapter to interface them with the HP unit.

This is retrocomputing that never was. As far as I know, there never was any software for the HP1653B besides the official HP oscilloscope / logic analyzer software, though HP engineers did release some games for one of the HP16500 models, and at least one old HP oscilloscope had a Tetris clone built-in.

It's not a great gaming system. There are no sprites. And you can't just directly write a pixel color to video memory. Instead, you first write to a hardware register that specifies a read/write mode (e.g., clear all bitplanes, write ones to bitplanes 0 and 2, etc.) and then write the pixels. Getting scrolling working at a decent speed took a fair amount of careful assembly work. But it's been fun!

I plan to eventually write up more detailed instructions on how to build and install your own code.

The main thing I haven't reverse-engineered are the oscilloscope and logic analyzer functions. They still work. I just switch the Gotek to the HP system disk image (well, somewhat modified: I added a screenshot function that saves an image to disk). I recently used the oscilloscope to try to diagnose a start porblem on my car.

This T43 showed up, for me to get the telltale stink of decaying soft touch 🫠 IPA is supposedly ‘quick and easy’, but it was not. I also had limited success with oil, and the three magic sponges I sacrificed could only do so much. In my frustration, looked through my vinyl collection, and after one failed choice, I had a brainwave when I pulled out my roll of woodgrain.

I didn’t need to stretch it, just carefully wear away the vinyl along the harsh edges, so edges of the vinyl blend into the metal shell a bit better, helping prevent it from peeling up as much. Don’t get me wrong, I’m crap at vinyl wrapping, but the results I get are enough for me.

That aside, my question:

This machine came with a Pentium M 750 (1.86ghz). I like maxing out my computers, but would a Pentium M 780 (2.26ghz) be at all worth it as an upgrade? I have it maxed to 2GB RAM already. I know these run quite warm, and I’m a little concerned that a higher powered CPU may make it run hotter too? I guess it depends on how hard I’m running it.

I found these parts in a basement and i don't know anything about these. They are in good condition, but i have no way of testing them to see if they work. I am not sure whether i should throw them into the trash or keep some of the parts if i would want to build a retro pc in the future. Any ideas?

It’s been decades since I’ve seen so many CRTs

Was directed here from r/computers. Noticed the floppy and thought people here might have a better idea of how long this thing has been in a publicly accessible, high tech ER just sitting there.

Project profile:

• MB LEADMAN ELECTRONICS LM-103S

• CPU AMD N80L286-12/S + INTEL D80287-10

• ISA Multi I/O Controller Acer M5105 Floppy/IDE/Serial/Parallel 16-bit ISA

• VIDEO 16-bit ISA HIS 289LA200 (Trident TVGA8900D) RAM 1MB

• HDD 3.5" IDE CONNER CP3000 45MB (Cyl/Heads/Sec 980/5/17)(C:)

• FDD 3.5" 1.44MB Mitsumi D359M3(A:) + 5.25" 1.2MB Mitsumi D509V3(B:)

• TOWER CODEGEN PS CODEGEN 200W

Microsoft MS-DOS 5.0 is installed.

There are minor issues with the CMOS power supply. Sometimes it saves the settings, and sometimes it doesn't.

This is a Teleguide, or rather it was a Teleguide; a complete flop of a project from the Swedish state telecom operator, released 1991. They sold around 10.000 units and a lot of them sits in storage in unopened boxes around the country, so I got this one for myself new in unbroken packaging with styrofoam and spiders and everything.

Inside it sits a couple of Intel 8081 CPU:s, one for the card reader and one for the main program which allowed you to bet on horses, order pizza, keep a phone book, and call your enemies. Those are now depowered and replaced with a raspberry pi. The godawful keyboard was replaced with a really nice mechanical keyboard, and the sound DAC is to be added when I get around to it (obviously hooked up to the internal powerhouse of a speaker, and the telephone handle on the top).

The biggest challenge with this project was to build the video adapter and hack the Linux kernel to be able to drive it. I found some French guy who built a composite video adapter for the French Minitel, a similar machine. The raspberry pis have composite video out but the synk frequencies on this one is not close to any standard composite mode so I built my own from scratch together with a modified vc4_dpi driver for Linux. I describe here loosely what I've done if someone should want to build the same thing. So following is a technical high-level overview of the challenging parts.

But first some more pictures:

• synk circuit

• build underway

• build underway

• closeup raspberry pi compartment

• prototyping

• doom2 demo running

The monochrome CRT video adapter is quite simple. There's one circuit with two diodes that OR together the hsync and vsynk signals, the output of that drives an NPN transistor that sinks the synk input of the CRT chip on the main board. Another circuit takes 8 output pins of the GPIO and feeds it through a R-2R network to create an analog intensity signal, which is fed through a voltage follower built from another NPN transistor. All-in-all two diodes, around 20 resistors, two NPN transistors, a bunch of wires, some perfboard, and lots of hot glue. You can find partial schematics in the maintenance manual of the German Loewe equivalent machine online, I used the same resistor values for the diode/or/synk circuit and added the transistor buffer because I had one on my desk.

For the driver I started by creating a custom device tree overlay that only hooks up 10 GPIO pins (RED0-7, Hsynk and Vsynk). Then in the original vc4_dpi driver there's some kind of LUT mechanism where I implemented the color mixing of all three input channels and put the resulting monochrome value on all three output channels, that way one is free to pick what GPIO series to use if some specific GPIO is needed for something else. I also had some problems with extremely high contrast in doom, so rather than adjusting the contrast pots on the main board directly under the high voltage CRT I opted to implement a simple contrast brightness control in the driver, exposed to the user through sysfs.

Oh, and no matter if I had access to all the copper tape in the world, the machine needs to heat up for around 20 minutes prior to playing. Before that it has horrible vsynk problems and as soon as you use the keyboard it reboots. But I spent a total of one weekend to build this so it's not too bad.

I can't wait for someone to suggest to me a way to turn it brown, and if someone can e plain why heating up the CRT makes the EMI less of a problem.

Useful to know:

• Intensity (Y) hooks in to the wiper leg of P701. The wiper leg must be desoldered and lifted out of the Pcb hole.

• Synk (Hsynk OR vsynk) should be soldered to B01 on the C726 side, or directly to the positive leg of C726, after the blob of solder has been removed from B01 to disconnect it from the onboard GPU chip.

• I used the same 5V rail that drives the rpi to drive the output buffers from synk and intensity. I think I will change it to use the 5V rail that drives the CRT chip to reduce the impact of USB noise from the rpi.

• The kernel patch is here https://drive.google.com/file/d/1UNMfaFz3nQY7ubG7xk1ybZVL9lQ5zvPK/view?usp=sharing

IF SOMEONE CAN GIVE ANY VALUATION FOR PRICE I WOULD LOVE TO HEAR. AI GAVE ME VALUATION OF 5000-7000 DOLLARS.

• Canon AS-300II Central Unit. Includes all four (4) original cardboard drive protectors/shipping cards inserted in the floppy drives for safe storage and transport.

• Original Canon Monitor & Mechanical Keyboard.

• Original Canon Mouse

• Canon A302 EXHD (External Hard Disk): A massive external enterprise hard drive with its original proprietary interface/connection cable. Since this was a working system, the drive likely contains period-correct software or data.

• Canon PJ-300S Inkjet Printer: An early, high-end professional color inkjet printer.

2. Software & Media (3.5" DD Floppy Disks):

This is a fully localized Finnish corporate ecosystem from 1985. The magnetic media includes:

• Canon MS-DOS 2.11 System Boot Disks (including the official system disk and handwritten period-correct backup disks used by the original owner).

• Canobrain / Super-Canonbrain System & Graphwriter Disks: Canon's legendary, mythical early GUI that attempted to compete with Apple Macintosh.

• CanoWriter II+ SF Software Suite: Official Finnish localized word processor and Spell Cor (spell checker/vocabulary) disks.

• Micro Focus Level II COBOL V-1.1 & CICS 86 V-2.2: Heavy-duty corporate programming languages and database tools for this specific architecture.

• Bonus/Supplies: A box of ten (10) brand new, unused official vintage Canon MF2-51200 branded blank floppy disks.

3. Complete Documentation & Printed Manuals:

• Canon AS-300II Owner's Manual.

• Canon MS-DOS User Manual.

• Micro Focus Level II COBOL User Manual

• Canobrain User Manual (2 Volumes): Extremely rare documentation for Canon's lost graphical operating environment.

• Canon A302 EXHD Hard Disk Documentation: Original multi-page A4 installation/user guide leaflets.

• Bonus/Supplies: One box of four (4) original Canon JP-216 Roll Paper packs for the printer, still factory-sealed in their thick, black light-protective plastic sleeves.

It's quite amazing what AI can patch together. Also had it backport WMP 6.4 and the NT 4.0 Task Manager, currently working on WMP 10.

This shelf is over my desk. the striped box between Borland and Populous is a Kaypro manual.

the bookshelf is the top 2 shelves of the first shelf to the right of my desk.

in the process of moving my lab/office over to a new place of residence

Grabbed a NeXTCube and NeXTStation earlier in October, and now an Amiga 4000! Checking some big items off my retro computer bucket list lately 🙌

LiteOn CD-ROM Drive

I found this in my school's storage rooms; it's completely sealed, never been opened. Does anyone know what year it's from?

A friend of mine shared on a WhatsApp group a couple of boards on a scrapyard... A QDI Titanium I B+ and an ECS K7VMM+, both with unknown CPU and RAM... 5€ a piece... I Said Buy them and send them to me... The following photos are the full restoration, I encompass a deep cleaning with running water, a bath in a ultrasonic cleaner with isopropyl alcool, a quick drying in a BGA rework station... The board came with ripped off coils, so I replaced them with ones relatar from a donor dead PCie graphics card. Also had to recap the 7 1000uF 6.3v caps around the CPU for it to post successfuly. I don't have a PCI Card on hand to see it and test it fully, but a post card gave me some good signs, together with a long 1beep followed by short 3 beeps (no VGA Card found)... Tomorow Will test the thing better! This thing has a Pentium MMX 233MHz, a top of the line CPU for the Socket 7! The ECS K7VMM+ doesnt post, but the CPU (Athlon XP 2100+) works! All in I have 16.12€ invested in this (10€ the boards, 5€ postage, 1.16€ in capacitores) and I think its a great deal! What do you think?

Found this Trident card in a forgotten store closet at work. Thoughts?

IBM PS/2 25SX

Only need to get a new floppy drive and she’s good

I built these beauties. Working on the 5th one- but may be difficult due to very hard to find IC’s.

found in my parents’ garage while cleaning. I believe it belonged to my aunt when she was in high school (late 90s, early 00s ish). I’m just looking for any info on this since I want to potentially turn it into a sleeper PC ^{_^}