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54

It definitely does not hurt to open the case and have a look at the PCB. When opening, be especially careful with the keyboard ribbon cables - They are apparently known to become very brittle with age and tend to easily break. The main victims of age and heat are electrolytic capacitors which are known to leak or bulge and leak over time, losing their ...


37

The reason was cost, since neither the original PET nor the TRS-80 required the extra high resolution and finer dot pitch found in more expensive computer monitors. Virtually all of the computer terminals of the time paired a CRTC with a high-resolution green or amber screen to generate an 80x24 text display, as that was the early standard. This required a ...


23

The answer, as always, was cost. 'White' CRTs were cheaper because they were used in B/W TV sets. The color itself has no impact on resolution, but TV tubes didn't need to be as sharp so they could be made cheaper. So why were 'high resolution' monitors green or amber? Because these phosphors have a longer persistence so the image doesn't flicker as much, ...


13

I understand that an RF modulator was used but what kind of circuitry did it use to feed the RF modulator? To start with, the TRS-80 did not use an RF modulator. It delivered composite video (*1) as it was meant to be used with its own brand monitor - which basically was an RCA TV set with the RF part removed. The TRS-80 Color Computer used an MC6847 IC ...


12

Since when do kids need a reason to trashtalk? Especially with an abbreviation calling for such an interpretation? And fans of competing computers where even more eager to jump the train. The war didn't start with Amiga vs. Atari ST :) But (a bit more) serious, there was also a real reason for this name: Early Model 1 where already on itself rather ...


9

Inspired by this question, whilst visiting my parents this weekend (Jan 28th, 2018) I extracted my old TRS-80 .... and here is the result: I did open the case and give it an inspection first - and I also had a fire extinguisher on hand (just in case!) but everything went as smoothly as could be hoped. The build quality is very high - I was concerned about ...


8

The above advice is very good. I'd like to add a few general putpose work methods which will help with any other vintage electronics. My uncle and I recently looked at an old ray-tube oscilloscope he bought in the 60's, which had a faulty op-amp on the trace-auto. Start by checking the capacitors and wiring, and anything else that looks like it's suffered ...


8

I too have an old TRS-80 in the attic, and I wonder the same thing. Last time I powered up a much newer computer that had been off for a couple of years, the power supply exploded with a fizz and some smoke. Probably a large electrolytic capacitor had gone bad. Problem is, these caps need a voltage to form and maintain the insulation layer on the plates. ...


8

I never heard of such a thing. I never read anything in any of the magazines. I've never heard any lingering of "remember when..." that you would think would flood the internet, even in this day in age. We all know about the Microsoft monopoly, but never a word about Radio Shack. That said, I have no "proof" that this didn't happen. I'll tell you what did ...


6

I've gathered some pictures. Here is an early USA advert. Note that it is never referred to as a "Model 1" or "Model I". It's just a "TRS-80". Here is a later USA ad, after the Model II was released. Note that the price has gone down, but there is no indication that they have extended the name for the original model. The new Model II is specifically ...


6

A few points to expand on previous answers: In those days, resolution wasn't limited by phosphor, but by video bandwidth (and video memory). A standard TV had a bandwidth around 2-3 MHz, enough to support a PET or APPLE ][ - style 40x24 text display, or about 320x240 dots. The TRS-80 Model I monitor had slight modifications to the video circuitry to ...


6

The oldest (smart) hardware "dongle" I know of is from 1985 in the ZX Spectrum 48K. To curb Internet piracy and as a "collateral side effect" also having more 16KB (e.g. 64KB for the game), Mikro-Gen Ltd launched the game Shadow of the Unicorn with an external 16KB (EP)ROM board that mapped on top of the internal ROM address space. This game came with ...


6

The oldest dongle like thing I own is a ROM board for the Apple II from 1978, where the whole PCB with all chips was cast in opaque thermoseting resin. This was ment to secure the software and disencurage any duplication. But tieing Software to hardware to restict usage is much older than microcomputers. Unique identifiers for machines and/or CPUs where ...


6

MOD is an operator, not a function. Try ? 10 mod 9 and see yourself.


6

Don't underestimate the cost of additional RAM for display memory! The TRS-80 used seven, not eight, 1x1024 static RAM chips for its display memory. They left off the eighth chip to reduce cost. Without it, the machine was limited to uppercase-only display -- one bit per character cell to specify whether that cell displayed a character or a 3x2 graphic tile,...


5

The TRS-80 Model III is a pretty robust machine but there is one common problem -- the RIFA capacitors on the power supply. These were paper-type and very often short out producing lots of smoke though generally don't cause any damage to the machine itself. There is an excellent page devoted to that procedure: http://www.akhara.com/trs-80/psrepair/index....


5

The Model 1 was a self contained computer that plugged in to, essentially, a TV set. And that was all well and good, if feature light (16K RAM, Cassette port, limited text and graphics). But it was plug and play. The original version, w/4K and Level 1 BASIC was notorious, for example, for key bounce. You could buy a simple mod to fix it, and it was remedied ...


4

This answer has the Commodore 64, the Amstrad and the Sinclair ZX Spectrum and QL series in mind. Note these home computers did not have a real "text" mode (as opposed to the more professional systems like IBM MDA, for example). This means text needs to be displayed as graphics, and graphics needs resolution. A reasonably readable text font needs at least ...


4

First, do a visual inspection. Make sure it's reasonably clean, no liquid damage etc. Check for foreign objects and possible shorts. Then check the power supply. It's easier with external types but some internal ones can be disconnected from the main board and tested individually. At the very least, check for shorts between the supply rails and ground. Also ...


4

Your question isn't very clear. If the question is "Would it be possible to design a memory expansion module for the Model 100 that adds large amounts of additional memory?", then the answer is yes. The Model 100 has its system bus exposed on the expansion connector. It would certainly be possible to design a memory expansion that adds a memory window to ...


3

Most TRS80 folks today run LSDOS 6.3.x as the main OS on the Model 4. The source is published, it's hackable and it is well supported by modern hardware like the M3SE and the FreHD. TRSDOS 6 was basically the same thing rebadged. For Model III mode you need to get a copy MODELA/III and add it to a TRSDOS 1.3 or LDOS 5 diskette. It's documented in the Disk ...


3

I did browse some of my racks and found that thruout all Tandy Computer Catalogues, starting with RCS-3 in 1979 the original TRS-80 was called TRS-80 Model I (Roman Numeral). But in original Tandy manuals and documentations I did find many spellings as TRS-80 Model 1. So it seams as if they did keep the Model I seplling thruout all advertisement, but not ...


3

The biggest single problem with long-persistence green monitors is that they were extremely vulnerable to burn-in unless you kept the intensity relatively dim. Amber monitors were usually a lot brighter. Computers like the TRS-80 Model I and Commodore PET didn't use long-persistence grayscale... they used picture tubes literally manufactured for use in ...


2

Early research found that green or amber was easiest on the eyes of people looking at CRT monitors all day. Actually, I preferred amber, myself.


2

That makes it almost 50 years old. After you open it, Check for any worn out wires or cables(as mentioned by @tofro) and copper tracks on the mainboard. You don't want them to touch and short the circuit when you turn the power on. That may damage your precious vintage machine. When you check the components, check for disconnected solder joints. Sometimes ...


2

As I understand it, a black-and-white TV tube with no color burst signal and the RF stage skipped, while it could not quite reach 80 columns, could handle 64 columns well enough, It can do 80 as well, but that's already borderline. which raises the question of why Apple and Commodore didn't try for that, or at least for something a bit beyond 40. 64x25 = ...


2

This is not a full answer, feel free to improve it. Let's start with the basics: Use ESD protection when touching any PCBs. Clean the PCBs.Inspect for any physical damages. Inspect all capacitors to see if any is leaking. Check any batteries. If possible, check the function of the power supply when it is not connected to any PCBs.


2

Here's one possible approach (which I haven't tried myself): Create a TRS/80 CPM boot disk Transfer BBC BASIC to the TRS/80 separately Creating a TRS/80 CPM Boot Disk David Keil's TRS-80 Emulator is able to use both emulated virtual floppy drives, and actualy hardware floppy drives, using the host PC's floppy interface. It's system requirements are ...


2

It's just a single page ... of true spaghetti code :)) AFAICT the tank (A(x,y)=25 and B(1/2,1)) elimitnates everything on it's way. Moves of attackers into him (line 610) eliminate them (line 630). If the player runs into him (line 540) game is lost. There are like a dozend or more places where the code can be straightened and some other where it can be ...


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