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Cromemco System 1 12v (U2) Repairby billdeg Total messages in this thread: 4 Updated: [ Repairs Completed ] 06/03/2014  Cromemco System 1 LAS1412 12v regulator in power controller, position U2. The system started to smoke while performing disk operation (directory), so I cut power before damage. I did not see any carbon residue. After a more controlled smoke test I found that I could root to the monitor prompt but I had no more 12V to drives, thus could not boot to a disk. Ordered new part. Not sure if the fault was the regulator or something that caused the regulator to over-work, but I could not find any other electrical fault. Click image for larger view.
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PET 2001-8 Internal Cassette Restorationby billdeg Total messages in this thread: 1  Commodore PET 2001-8 internal cassette drive with cover removed. This photo was taken after two repairs were made. First the original belt was removed and replaced using a donor CN2 cassette. Second I repaired the cable that connects to the motherboard. Click image for larger view.
The Commodore CN2 drive belt can be transplanted into the internal cassette drive. It's easy to remove the belt from a CN2 external cassette. To install into the internal cassette just loosen the ... [ read more ]
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Digital PDP 8 OS/8 Help Filesby billdeg Total messages in this thread: 1 Uploaded the contents of the .HL files from various RK05 disk packs. Chock full of useful info. Each file is unique, but they all share similar text. Enjoy. Dump 1 Dump 2 Dump 3">... [ read more ] |
Apple /// Plus and Microsoft Softcardby billdeg Total messages in this thread: 1  Click on image to see the box with label - Apple Softcard /// System by Microsoft - Adding CP/M capabilities to the Apple ///. Click image for larger view.
 Installation of the card was easy...Find an open slot and boot with an Apple III compatible CP/M disk and go! Regular SOS disks still work just fine. Click image for larger view.
 Here is a closeup of the boot screen. Note t">... [ read more ]
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Zorba for Cross-System CP/M Copy?by billdeg Total messages in this thread: 1  Zorba CP/M boot screen apparently is capable of reading various CP/M system files. Click for larger view.
I created a Zorba boot disk using Dunfield's ImageDisk. Upon boot, I noticed that the Zorba apparently is capable of reading multiple types of CP/M systems' files. When I get the chance I'd like to see what kinds of IBM PC CP/M stuff you can do with a Zorba.">... [ read more ]
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PEEKing Into BASIC (VCF 9 Presentation)by billdeg Total messages in this thread: 1 You can now download a PDF of my lecture from VCF East 9.1. -------------- Notes If you're so inclined, here is a listing of my class notes that go along with the PDF link above. Not all slides have notes/I didn't need them. SLIDE 3: Original scope of the program, has evolved over time to include more hardware interaction. Timesharing BASIC was not designed for hardware interaction. SLIDE 4: This class is intended for those who have been introduced to the BASIC language and want to go further with the language in the “vintage computer” perspective. It is also intended for those who have already learned another older language and need only a brief introduction to what is for them a second or third programming language. SLIDE 6: Constants. BASIC programs are made up of statements that contain keywords, variables, operators,">... [ read more ] |
Digital PDP 11/44by billdeg Total messages in this thread: 1  KD11-Z cards - the main card array. This unit also has an expansion backplane connected to the KD11-Z with a UNIBUS 9302
 Front view of the Digital PDP 11/44
 The orginal 11/44 Module Utilization Chart. My system does not have all of these installed.
Here's a good page that describes the system
http://www.pdp-11.nl/pdp11-44star">... [ read more ]
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Vintage Computer Festival East 9.1by billdeg Total messages in this thread: 1  Mother and child playing a tank game made for the Cromemco Dazzler video card, running on an IMSAI with Cromemco CPU card. Click image for larger view.
 Francois Lanciault (Blainville, QC, Canada) brought his HP-9845 exhibit "Dawn of the Workstation". We also had exhibitors and contributors from Europe, Australia and points between. Click image for larger view.
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Heathkit ET-3400 / ETA-3400 Expansionby billdeg Total messages in this thread: 3 Updated: [ How to Load Monitor and Tiny BASIC ] 04/03/2014  View of the Heathkit ETA-3400 mainboard. The ETA-3400 expansion unit was an add-on to the ET-3400 6809-based trainer. Click image for larger view.
 Rear ports include cassette and RS232/teletype connectors. Click image for larger view.
Initiated a project to add an ETA-3400 to a Heathkit ET-3400. The main computer seems to work fine. Step one, complete the connector cable from parts on hand. With additional RAM and I/O ports, the ET-3400 becomes a lot more useful. I">... [ read more ]
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PC to Serial Terminal Screen Dumpby billdeg Total messages in this thread: 1 It's kind of a pain to send a "printout" of an ASCII file to a vintage printer from a modern computer over the serial port. Here is how I sent a set of ASCII art prints to a Digital Equipment Corp Decwriter II. This technique would work with any serial terminal ("dumb" terminal), but you may need to change the settings to match your terminal/printer. 1. Find a computer with a real serial port. Did you know even today many PC motherboards have a serial port built in, even if you don't have an external port? You'd just need to find an internal serial port adapter. A true serial port is better than a "USB to Serial conversion dongle" in that using the real thing eliminates variables associated with converting the signal. 2. I used TeraTerm software from the PC. From TeraTerm locate the setup tab. There are two places you need to access to make changes a. serial port setup">... [ read more ] |
MITS Altair 8800b T with Dual Drivesby billdeg Total messages in this thread: 6 Updated: [ Serial Settings for Altair Disk BASIC ] 03/08/2014  Two MITS model 88-DCDD Single 8" disk drives. These are the older design made to match the 8800a system faceplate. Serial numbers DD 2100 and DD 3216
I have initiated work on MITS Altair 8800b Turnkey System with Dual 8" disk drives. It's a complete system with cables, cards, and a custom MITS desk to hold everything. The 8800b turnkey was first produced during the takeover of MITS by Pertec corporation. At some point, Pertec started calling an 8800b turnkey with dual drives the "300/25" system, but this particular system was sold before that. The serial number plate for the 8800b is still MITS, later versions' s/n plate read Pertec.
8800b T System Photos
NEXT: List of the components replaced, and a video of the system in action.
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More Unidentified Cards - Can you Help?by billdeg Total messages in this thread: 2 Updated: [ UNIVAC 1108 board ] 03/06/2014  This board has "Control Amplifier" printed on the back.
 IBM? The board has markings from 1967. Odd connector.
Can you help ID these? More Photos">... [ read more ]
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System Source Classic Computingby billdeg Total messages in this thread: 2 Updated: [ Baltimore Workshop / Meet and Greet ] 02/18/2014 
See photos">... [ read more ]
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Processor Tech SOL 20 Terminal Computerby billdeg Total messages in this thread: 5 Updated: [ 9090909090 ] 02/14/2014  The Processor Technologies SOL-20 Computer
As with most projects, the first thing that needs to be done is check the 5V output to the motherboard.
I assisted Dan Roganti test the power supply and we compared with another power supply to confirm the results. The SOL supply is OK, or at least it compares with a known-working supply. The voltage reading on the board however is not OK.
 The DC Voltage is consistently below 5V, something is shorting out.
The next step is to remove all socketed chips to see if there are bad TTL chip causing the voltage problem.
 The SOLOS Personality ROM daughterboard.">... [ read more ]
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Using a synthesizer to generate sounds that will render shapes and pictures on an oscilloscope in X-Y mode... http://youtu.be/O_EyJIlLbGM Here is how I did it. 1. Set 5A48 (in left bay) to 1 volt per division. Display on, channel one output to AC, mode to channel 1. Plug 10x scope into channel 1 2. Set 5A48 (in middle bay) to 1 volt per division. Display off, channel one output to AC, mode to channel 1. Plug 10x scope into channel 1 3. Set 5B31 (in right bay) sec/div to AMPL. Auto trigger 4. Attach probe connector 1 into the left stereo channel, probe connector 2 into the right stereo channel. Attach the probe ends with alligator clips to the individual segmented ends of a 1/4 in stereo jack cable. The other end of the audio cable would be plugged into the headphone jack of the amplifier unit or mixer. The synthesizer is plugged into the mixer like any musical">... [ read more ]