# vintage bits

> Adventures with vintage computers


## Posts

- [Freshly scanned manual for MDB MLSI-CR11 Card Reader Controller](https://avitech.com.au/?p=3749): I came across a hardcopy manual for MDB's MLSI-CR11, which is a QBUS Card Reader Controller.
- [Webster Spectrum PDP-11/73](https://avitech.com.au/?p=3632): This is a PDP-11/73 in a Webster Spectrum enclosure. The 11/73 board (M8192) appears to be the only genuine DEC board in the backplane.
- [Bundoora Computer Market - July 2018](https://avitech.com.au/?p=3352): Melbourne has a number of weekend "Technology Markets" that rotate between venues. Today's market is at RMIT in Bundoora.
- [P/OS for the DEC Professional 300 Series](https://avitech.com.au/?p=2896): I've started sorting through my collection of DEC PRO-350 and PRO-380 equipment.
- [Recently scanned RQDX Field Service Tech Tips](https://avitech.com.au/?p=2858): Going through some boxes of documentation, I found some rather obscure DEC "Field Service Tech Tips" (and DEC uNote #043) that relate to the RQDX controllers.
- [DEC VT340 Internals](https://avitech.com.au/?p=1818): This post has been converted to a webpage. It is available here -> http://avitech.com.au/?page_id=1964 Apologies for the inconvenience.
- [New neon indicator for DEC 871B Power Controller](https://avitech.com.au/?p=1413): The 871B Power Controller is a single-phase 240VAC power controller found in some PDP-11 systems. It has 6 switched power sockets.
- [[Outdated post] Vintage computers for sale or swap](https://avitech.com.au/?p=1285): It's time to thin out my vintage computer collection a little. Below is a list of items currently available.
- [PDP-11/34 decdatasystem](https://avitech.com.au/?p=884): Last weekend I started to investigate a "decdatasystem" in my collection. I thought I only had the TU10W tape drive and RK07 hard drive.
- [RS232 connectors](https://avitech.com.au/?p=794): I've just put up a webpage with some reference information about various RS232 connectors, including the DEC423 MMJ connectors.
- [VCF SE 3.0 Presentations](https://avitech.com.au/?p=696): In May 2015 I went to VCF Southeast 3.0 in Roswell GA.
- [Imaging DEC VAX/VMS CDs](https://avitech.com.au/?p=605): I have some original VMS CDROMs.
- [Mystery IBM Processor](https://avitech.com.au/?p=561): A recently acquired part of my collection includes what I think is an IBM processor presumably from a large system. The mounting frame is in a 3 x 3 grid.
- [Garage Sale on Sat 28-May-2016](https://avitech.com.au/?p=334): I'm having a garage sale on Saturday 28 May 2016 to thin out my vintage computer collection a little.
- [VT220 current loop interface](https://avitech.com.au/?p=252): This post takes a brief look at the current loop connectors used by DEC.
- [PIC USB bootloader](https://avitech.com.au/?p=220): I've got a couple of projects on the go that use the PIC18F2550 (or PIC18F2553) microcontrollers.
- [DECserver 200](https://avitech.com.au/?p=137): The DECserver 200 is a "terminal server". It enables up to 8 terminals to login to various DEC computer systems over an Ethernet link.
- [DECnet Level 2 routing](https://avitech.com.au/?p=285): I have a few VAX/VMS DECnet machines with node addresses in Area 4. Their full DECnet node addresses are 4.200, 4.202, etc.

## Pages

- [TRS-80 Model 4 with FreHD and Gotek drives](https://avitech.com.au/?page_id=13618): I will be building out various sections of this page from time to time, to document the above modifications (which have already been made and are working fine, as at January 2026).
- [Open-SIMH](https://avitech.com.au/?page_id=13241): This page has my notes relating to building and using Open-SIMH, particularly in the context of Windows machines.
- [PDP-8 notes: Dumprest and paper-tape diagnostics](https://avitech.com.au/?page_id=12693): These are my rough notes about using paper-tape diagnostics and dumprest on the PDP-8.
- [George Wiley's RK05 Emulator](https://avitech.com.au/?page_id=12665): This page is a collection of notes made while I was getting familiar with this emulator at the RK8E workshop session in late June 2025 in the U.S.
- [Sodastream Cylinder Replacement Project](https://avitech.com.au/?page_id=11844): This page has my notes for using an industrial-size C02 cylinder with a Sodastream machine.
- [DEC RX01/02 Inventory](https://avitech.com.au/?page_id=10248): This page has a rough inventory of the DEC RX drive units in my collection.
- [My Early x86 Personal Computer Collection](https://avitech.com.au/?page_id=10110): I'm not an intentional collector of x86 PCs.
- [ARpiCADE](https://avitech.com.au/?page_id=7532): I first started experimenting with ARpiCADE in November 2022. These notes relate to version 3.X (for RPi 3).
- [DEC MINC-11 at System Source](https://avitech.com.au/?page_id=5917): This page is about the MINC-11 in the System Source collection in Hunt Valley, Maryland.
- [DEC PDP-8/e H960](https://avitech.com.au/?page_id=5670): Below are photos of my PDP-8/e in a H960 rack. The chassis and paper-tape reader/punch are not shown in these photos as they are currently stored separately.
- [Seeburg Red Box](https://avitech.com.au/?page_id=5279): The "Seeburg Red Box" is the electronic control module in a few models of Seeburg jukeboxes made in the late 1970s.
- [DEC RK05 Notes](https://avitech.com.au/?page_id=4663): Apologies for the rough nature of this page.
- [DEC Cables and Connectors](https://avitech.com.au/?page_id=4482): This page lists the common DEC Cables and Connectors that I have encountered. This is a 40-pin Berg to 4 x DB25 cable.
- [For Sale](https://avitech.com.au/?page_id=4387): These are the items I currently have available for sale.
- [DEC VT180 (aka "Robin")](https://avitech.com.au/?page_id=3801): This webpage has some notes about a few aspects of the DEC VT180.
- [DEC PDP-11/23 in BA11-N Chassis](https://avitech.com.au/?page_id=3713): The table below shows how the H9273-A backplane is currently populated.
- [UNIX V6 on QBUS PDP-11](https://avitech.com.au/?page_id=3697): I've starting playing around with UNIX v6 on the PDP-11.
- [DEC Miscellaneous Information](https://avitech.com.au/?page_id=3660)
- [Garage Sale on Sat 5 October 2019](https://avitech.com.au/?page_id=3623): I'm doing something of a clean out of vintage computer gear, due to downsizing. This Saturday (5 October 2019) from 9am to 5pm.
- [DEC Rainbow](https://avitech.com.au/?page_id=3615): This page is a collection of my notes notes about the DEC Rainbow, which I have recently started to play with.
- [PDP-8/e Line to Earth Capacitors](https://avitech.com.au/?page_id=3585): There are two variants of the power supply used in the PDP-8/E: H724 (115VAC) and H724A (230VAC).
- [DEC MINC RL01 Images](https://avitech.com.au/?page_id=3510): I have two RL01 cartridges that were installed in a MINC system. The two cartridges are marked on handwritten labels as "26b" and "27" respectively.
- [BDV11 Upgrade](https://avitech.com.au/?page_id=3407): This page documents the steps taken to "upgrade" the ROMs in a standard BDV11 in August 2018. This BDV11 had only two ROMs in it. They were marked U49 and U54.
- [EPSON TM-U210D POS Printer](https://avitech.com.au/?page_id=3402): I acquired this printer on 5 August 2018. It's a 9-pin dot-matrix printer that prints on 76mm plain paper. This is an old printer.
- [OMNIBUS Bootstrap Loader Prototype v1.0](https://avitech.com.au/?page_id=3372): This is my first attempt to build a Bootstrap Loader board for the OMNIBUS. The mode of operation is largely modelled on the MI8-E (M847).
- [Arduino - Getting Started](https://avitech.com.au/?page_id=3325): This page has the links and other resources for the Learn Arduino workshops held at the Watsonia Library in 2018.
- [DEC Flip Chip KiCad Template](https://avitech.com.au/?page_id=3319): Here is a KiCad project that contains a DEC Flip Chip template. I have used this for an Omnibus (PDP-8/e) project. It should also work for Unibus and Qbus.
- [OMNIBUS Bootstrap Loader Project - Design Notes](https://avitech.com.au/?page_id=3267): I am in the process of developing a multi-device "Omnibus Bootstrap Loader" board.
- [S100 KiCad template](https://avitech.com.au/?page_id=3240): To help with designing an S100 board in KiCad, a template KiCad project is provided below. This is very much a bare-bones template.
- [OMNIBUS CPLD Prototyping Board #1](https://avitech.com.au/?page_id=3219): OMNIBUS is the name given to the backplane connectors on PDP-8/e computers. It is also used on a few other PDP-8 computers (8/f, 8/m, 8/a and perhaps others).
- [DEC MI8-E Bootstrap loader for PDP-8/e](https://avitech.com.au/?page_id=3204): The MI8-E is a "hardware bootstrap loader" for a PDP-8/e.
- [Getting Started with FPGAs and CPLDs](https://avitech.com.au/?page_id=3195): This page has my rough notes about various CPLD and FPGA development boards. The DE10-Lite is fitted with an Altera MAX10 FPGA.
- [Melbourne Mini Vintage Computer Faire 2018](https://avitech.com.au/?page_id=3132): We are underway...
- [Super 80 - Cassette Software](https://avitech.com.au/?page_id=3106): On this page you will find some cassette-based software for the Super 80. Most of these programs came from super80_software.zip on Justin Kirk's website.
- [Super 80 - Emulator](https://avitech.com.au/?page_id=3088): Back in about 2006, a Super 80 emulator was added to MESS. Until now (March 2017), I've never used MESS. So I have a small learning curve in front of me.
- [Super 80 - Original](https://avitech.com.au/?page_id=3025): I am fortunate to have an original Super 80. It was in a very rough state when I got it.
- [Super 80 - V2 Reproduction](https://avitech.com.au/?page_id=3020): The V2.0 dimensions are 305.0mm by 312.0mm C1 and C3 on the original board are 5600uF electrolytic filter capacitors.
- [Super 80 - Hardware Notes](https://avitech.com.au/?page_id=2983): Using 2532 and 2732A EPROMs Transformers and Power Supplies 2513 Character Generator Heatsink and Temperatures The "standard" (unmodified) Super 80 PCB, and the V1 Reproduction, are wired to work with 2516 or 2716 EPROMs only.
- [Electronic Components Stores](https://avitech.com.au/?page_id=2914): This page is my list of useful electronic component stores. Feel free to send additional suggestions - I'll add them to this list!
- [DEC Professional 300 Series](https://avitech.com.au/?page_id=2887): This page relates to the DEC Professional 300 Series computers, such as the Pro 350 and Pro 380.
- [Super 80 - V1 Reproduction](https://avitech.com.au/?page_id=2873): The Super 80 is a Z80-based single board computer that had 48K RAM, a full-size keyboard and video interface on board.
- [DEC PDP-11/10](https://avitech.com.au/?page_id=2821): I have two PDP-11/10 units. The first one has been upgraded to MOS memory before I received it. The second one still uses core memory.
- [DEC WT78](https://avitech.com.au/?page_id=2772): This is a DEC "WT78" which I think is similar or identical to a DEC VT78. The naming is confusing, because the manuals call this unit a "DECstation".
- [SCSI2SD on QBUS PDP-11](https://avitech.com.au/?page_id=2735): Until recently I was using an MFM hard drive as the primary hard drive on my QBUS PDP-11 systems.
- [GRC TBC QBUS Board](https://avitech.com.au/?page_id=2722): The "GRC TBC" is a bootstrap and terminator board designed for PDP-11 QBUS systems. The manufacturer is General Robotics Corporation.
- [DEC RX33 Floppy Drive](https://avitech.com.au/?page_id=2660): The RX33 is an 80-track double-sided 5.25" floppy drive that was used by DEC in some PDP-11 and MicroVAX computers.
- [DEC PDP-11/73 in BA123 cabinet](https://avitech.com.au/?page_id=2634): I have built up a PDP-11/73 system in a BA123 cabinet. My aim is for this system to be able to boot either RT-11 V5.7 or RSX-11M+.
- [Saturn for RSX-11](https://avitech.com.au/?page_id=2570): I found a set of 9 x RX50 disks that appear to be Saturn for RSX.
- [DEC NEMA Power Connectors](https://avitech.com.au/?page_id=2543): This page has some information about the power connectors used in DEC PDP-8 and PDP-11 equipment. For 110V AC, DEC uses the standard 3-prong U.S.
- [PDP-11 Notes](https://avitech.com.au/?page_id=2528): This section contains notes taken from MACRO-11 manuals, primarily PDP-11 MACRO-11 Language Reference Manual (AA-V027A-TC).
- [SerialDisk Integration to SIMH](https://avitech.com.au/?page_id=2514): This page describes the process of setting up an interface between SIMH and SerialDisk, so that SIMH has read/write access to the same image files as SerialDisk serves up to a real PDP-8.
- [SerialDisk Operational Notes](https://avitech.com.au/?page_id=2447): I use Kyle Owen's excellent SerialDisk software to run OS/8 on my PDP-8/e.
- [RQDX Mini-BOB for floppy drives](https://avitech.com.au/?page_id=2402): This simple PCB will enable one or two 3.5" or 5.25" floppy drives to be directly connected to a PDP-11 RQDX-series controller.
- [DEC BA23 Chassis](https://avitech.com.au/?page_id=2393): These are my rough notes regarding the DEC BA23 chassis. The BA23 houses the H9278A backplane.
- [.Info about Cabling and Connectors](https://avitech.com.au/?page_id=2206): This page has my notes about Molex Connectors and Hookup Wire This is the series we used to use for the 24-pin connectors when looming arcade machines.
- [Current Loop: Design Notes](https://avitech.com.au/?page_id=2149): This page has notes of things I've discovered in relation to the current-loop interface as used on PDP-8 and PDP-11 computers.
- [PDP-11 RX02 Bootstraps](https://avitech.com.au/?page_id=2073): This page sets out the source code for a few RX02 bootstraps, as well as some comments about them.
- [MFM Hard Drives](https://avitech.com.au/?page_id=2060): This page is a collection of notes regarding MFM hard drives. When using an MFM drive on my RQDX Breakout Board, install link DS1 on the MFM drive.
- [Links - DEC related](https://avitech.com.au/?page_id=2036): This page is just a collection of links relevant to DEC computers and equipment.
- [Arduino Notes](https://avitech.com.au/?page_id=2031): This is just a collection of notes and links that I have found useful in getting to know the Arduino products.
- [DEC RL Drives](https://avitech.com.au/?page_id=1997): This page is a collection of notes about my experience in working with DEC RL01 and RL02 drives (and their associated controllers).
- [DEC MicroVAX 3600](https://avitech.com.au/?page_id=1983): This page captures what I have discovered so far in bringing up two MicroVAX 3600s. As of 16 May 2017, I have only attempted to bring up one of the two 3600s.
- [DEC VT340 Internals](https://avitech.com.au/?page_id=1964): In early 2017 there was some discussion on the SIMH mailing list regarding the simulation of various DEC VT-series terminals.
- [DEC VAXstation 3100 Model 76](https://avitech.com.au/?page_id=1919): This page will eventually include notes about my experience in setting up VMS, DECwindows and Motif on this machine.
- [Digital Electronics QBUS Cabinet](https://avitech.com.au/?page_id=1887): In my collection I have this rather interesting third-party QBUS system. The manufacturer was an Australian company called "Digital Electronics".
- [VAX 11/750 Parts](https://avitech.com.au/?page_id=1867): This is a temporary page. If you are interested in any photos here, please take a copy ASAP. I'm in the process of parting out a VAX-11/750.
- [Konan Blue Sky MFM Controller](https://avitech.com.au/?page_id=1840): I have a "Blue Sky" Konan MFM controller board in an SD Systems S-100 machine.
- [Data I/O 29B Universal Programmer](https://avitech.com.au/?page_id=1755): This page is a collection of notes relating to the setup and use of the Data I/O 29B.
- [SD Systems SBC-200 S-100 Board](https://avitech.com.au/?page_id=1727): This board is part of an SD Systems 600 computer that I am attempting to restore.
- [QBUS Notes](https://avitech.com.au/?page_id=1664): This page captures my rough working notes regarding QBUS systems. You probably won't find anything greatly useful here.
- [QBUS Front Panel Project](https://avitech.com.au/?page_id=1657): This project is an Arudino-based front panel for a bare QBUS PDP-11 chassis.
- [DEC BC01V RS232 Cable](https://avitech.com.au/?page_id=1628): For the PDP-8, the KL8-E (M8650) and KL8-JA (M8655) connect to the outside world via a 40-pin "Berg" connector, arranged as 2 rows of 40 pins as shown here.
- [VAXmate](https://avitech.com.au/?page_id=1552): The VAXmate is an IBM PC/AT compatible personal computer produced by DEC.
- [MFM Hard Drive on Pentium II PC](https://avitech.com.au/?page_id=1524): The "older" PCs that I have laying around in the workshop all tend to be Pentium II era machines or later.
- [Pertec T8640A Tape Transport](https://avitech.com.au/?page_id=1468): I have a Pertec T8640A Tape Transport that is now working nicely on a QBUS PDP-11 system.
- [Space Invaders](https://avitech.com.au/?page_id=1445): Back when I was in High School, my father and I started a business operating pinball machines and video games.
- [DEC 871B Power Controller](https://avitech.com.au/?page_id=1439): The 871B Power Controller is a single-phase 240VAC power controller found in some PDP-11 systems. It has 6 switched power sockets.
- [DEC InfoTower](https://avitech.com.au/?page_id=1292): Here's some photos of what I think is a VAX InfoServer system. On the outside, it's called an InfoTower. On the inside, it's labelled as an InfoServer 1000.
- [DEC DCT11-EM Evaluation Module](https://avitech.com.au/?page_id=1254): Here are some pictures of the DEC T11 microprocessor trainer that I have. It has a power supply fault. With a little luck it will otherwise work OK.
- [SMD Drives](https://avitech.com.au/?page_id=1111): This page is where I am writing up my initial notes and experiences in playing with "Storage Module Device" (or SMD) drives.
- [VAXmate Software](https://avitech.com.au/?page_id=1068): I have 5 VAXmates and what appears to be a full set of manuals and software for them. Below are images of the VAXmate software, in ImageDisk format.
- [DEC RX01 floppy disc drives](https://avitech.com.au/?page_id=1008): The RX01 is an 8-inch floppy disc drive device for PDP-8 and PDP-11 computers. It was available in a single-drive or dual-drive configuration.
- [DEC TU60 Dual Cassette Transport](https://avitech.com.au/?page_id=1005): The TU60 is part of the "TA11 Cassette System Interface" for the PDP-11.
- [Transferring RX01 discs to SIMH](https://avitech.com.au/?page_id=986): Dave Dunfield's ImageDisk software includes two utilities that are very useful for moving a real RX01 disk to a virtual disk file that can be used with the SIMH PDP-11 simulator.
- [KED Mini How-To Guide](https://avitech.com.au/?page_id=959): This is a short guide to using the text editor called "KED" in RT-11 on the PDP-11.
- [Scanned documents](https://avitech.com.au/?page_id=951): Camintonn Camintonn CM-DLV11-J 4-Channel Serial Interface Installation Manual Webster Webster PCLV11-J Multifunction Unit Technical Manual Webster WQSMD QBUS Winchester Disc Controller GRC DLV11: GRC DLV11 Interface Specifications GRC DLV11 Schematic GRC RXV21: General Robotics Corporation: RXV21 User Manual GRC TBC (Terminator / Bootstrap / Clock): General Robotics Corporation: TBC User Manual GRC TBC-11 Specifications GRC TBC-11 Schematic TBC Hard Bootstrap for Cartridge Disk and RX01 Floppy GTSC Model 304 I/O Board: GTSC Model 304 Serial I/O Board Instruction Manual MDB MLSI-CR11 Card Reader Controller (QBUS): MDB MLSI-CR11 Instruction Manual PDI Model 2022 Card Reader: PDI 2022M Supplementary Manual Memory boards by Fourth Generation Systems: Brochure for FGSV11 Memory Boards Manual for LS256-1 LSI-II Memory Schematics for LS256-1 LSI-II Memory DEC RQDX MSCP Controllers DEC uNote #043 (RQDX Controller Status/Information) DEC Field Service Tech Tip No.
- [RT-11 drive partitions](https://avitech.com.au/?page_id=934): If you are using RT-11 on a PDP-11 that has physical drives that are larger than 32MB, you'll probably want to know about drive partitioning.
- [RT-11 boot floppy](https://avitech.com.au/?page_id=914): This page steps through the process of building an RT-11 floppy disk that can be used to boot a PDP-11.
- [PDP-11/34 decdatasystem](https://avitech.com.au/?page_id=903): In my collection I have a blue-and-white "decdatasystem" consisting of a TU10W drive and an RK07 drive.
- [Dilog DQ419](https://avitech.com.au/?page_id=847): The Dilog DQ419, when coupled with one or two industry-standard 8-inch floppy drives, provides a PDP-11 QBUS system with an RX02-compatible floppy drive system.
- [Webster SRQD11](https://avitech.com.au/?page_id=807): This page is about a PDP-11 QBUS non-DEC MFM Winchester Disc Controller that I really like: the Webster SRQD11-A.
- [RT-11 Logical Disks](https://avitech.com.au/?page_id=796): RT-11 has a flat directory structure. So all your files (operating system, applications, data etc) are stored in that one directory.
- [RS232 Connectors](https://avitech.com.au/?page_id=766): This page sets out some basic information about serial connectors used for RS232-level asynchronous serial communications.
- [Install Log: VAX/VMS 5.3](https://avitech.com.au/?page_id=735): This page shows the install log from the process of installing VMS 5.3 on a VAXstation 3100 M90.
- [PDP-11 Paper Tape BASIC](https://avitech.com.au/?page_id=709): This page provides an overview of PDP-11 paper tape BASIC, and the computer equipment it was typically used with.
- [Floppy Disk Imaging](https://avitech.com.au/?page_id=690): Floppy disks that are recorded in conventional "FM" or "MFM" format can often be imaged, and images can be written back to real floppy disks, using commonly available older-model PCs and peripherals.
- [RQDX Breakout Board](https://avitech.com.au/?page_id=645): DEC made a series of "RQDX" controllers back in the day.
- [Williams Firepower Pinball Machine](https://avitech.com.au/?page_id=641): In June 2016 I bought an old Firepower pinball machine in Tasmania. The playfield is in good condition, but the rest of the machine needs significant work.
- [PDP-11/70](https://avitech.com.au/?page_id=366): I was lucky enough to pickup a PDP-11/70 last week, thanks to the generosity of a fellow collector.
- [Current Loop Interface #2](https://avitech.com.au/?page_id=318): Introduction Description Settings Project Status Downloads This board is useful for connecting a computer to a current-loop peripheral.


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