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I have a few portables and the power supply is designed to act like that. From Sams Photo Fact's;

I have been working on a few of these in the last few weeks. The power supply is switching, so it will need a load on some of the outputs or it will shut down. This is from the Sams PhotoFacts...

I'm working on a 5150 for a friend. It has 64k, monochrome monitor and two 5 1/4" drives. The unit works, but we want to test the drives and make it useable. Perhaps run a few simple games or app's and save some basic programs to disk. What can I expect for hardware and software to make...

My 2810 has a math coprocessor and ndiags detects it and passes the test. I certainly don't need it, so it's available.

I'm resurrecting a 2810HD laptop. I need to HSECT/FDISK the HD. All the versions of DOS I have, lack the HSECT file. Is DOS 4.01 available for download or does anyone have hsect that would work with ver 6.22 ?

Here's a few pic's of my conversion. Two keys don't respond, one will, if you tap it hard (sometimes get multiples) and the other (break) does not. B4 I tear into the actual switch(s), any pointers first so I don't destroy anything ?

Can you debug a CPU board without the keyboard attached ? My keyboard cable is poorly oxidized and is de-laminating. Has anyone tried to upgrade this ? I was thinking you could replace it with a ribbon cable and a IDC connector on the PCB(s). Ribbon cable has a small AWG, is it enough to...

Ok, here's what I have. Composite out from Trs-80; <not right> Composite out from a security camera that the monitor displays correctly. Trs-80 output to monitor <not right> I've been short on time, but I think I'll replace the two transistors in the final output stage and see what...

I recently acquired a Model 1 26-1001. PCB ver. 1700069D One Rom Z33; Motorola "Basic 1" 7814 Not cuts or hacks the the PCB The video output to the original monitor is not correct. It's like the horizontal hold is messed up, no change is seen with keyboard input or a reset. The monitor works...

I've been thinking about buying a TRS-80 Model I. When I was 13 in 1978 my grandmother bought me a Model I 4k. We had to wait a few months to get it upgraded to Level II 16k. I eventually sold it to a a business a few years later. I'd like to get just the keyboard/CPU and power supply. I...

Hey all... I have the board build and I'm in the early testing phase... I have a question about this phrase; Next add U49 (a 74LS125) ...... Temporally tie U9 pin 9 to ground. The input should change to FFh. There is no U9, if you meant U49, that would be the buzzer circuit. Without...

I recently bought another Imsai with a Northstar like Disk Controller and a pair of Shugart 400's. I have been unable to boot from any of the disks that came with the unit. In an attempt to create my own disks I came across Dave Dunfields NST utility. My first step is to create the Monitor...

I recently picked up another Imsai and it came with an external floppy drive(s) and controller card. I haven't been able to find any doc's on the controller; Micro Applications INC. 2100. http://home.mchsi.com/~litterbox99/temp/floppy.jpg I'd like to know more about it before I power it up...

I've have a Microbyte 32k memory board M32KSS rev A. I'm looking for a manual / schematic. I've searched with no luck.... Anyone have a PDF ?

Now that my SSM IO4 card is working, I've been trying to find a boot loader for Basic. There's a youtube video of an Imsai loading basic, displaying incoming bits on the 'programmed output' LED's that would be perfect for my needs, but no code is listed. I've been googling and reading for days...

I have recently built this board. Currently I just use it for a simple program I put into the EPROM... I just do a jump and run. Right now I have been fighting issues with my status word config on my serial port and now my 32k godbout memory board is flaking out on me ! This is all I need...

I'm working on repairing my SSM IO4 (2 serial / 4 parallel) card. I only care about the serial ports for now. I plan to use one port for a console and the other to drive a DECtalk Express speech synthesizer. After replacing a few regulators, I powered it up and used the following code to...

I'm almost finished with the backplane project, but I have a few questions first. For the fuses, I was wondering what the values are? I figure for the +/- 16VDC 3A should be enough. For the + 8VDC. This would be set above the current draw for all the PCB's on the bus. I'll start out at 10A...

I thought I would share some pictures of the System Monitor Board project I recently finished. http://home.mchsi.com/~litterbox99/temp/ssmb1.jpg http://home.mchsi.com/~litterbox99/temp/ssmb2.jpg http://home.mchsi.com/~litterbox99/temp/ssmb3.jpg...

Can someone explain what each dip switch does ? Reading off the s100computers.com it is mentioned that SW2 is for wait states, but later on in the text it states; The switch SW2 allows one to block out or include sections. (of memory, I assume) Looking at the pictures, it looks like SW3 is...