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56 votes
Accepted

What did it sound like when you played a cassette tape with programs on it?

It sounds like a high-pitched noise, somewhat like you would hear from a modem. Here's a little TRS-80 Model 1 BASIC program that plots every pixel on the screen: 10 FORY=0TO47 20 FORX=0TO127 30 SET(...
George Phillips's user avatar
54 votes
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Is it safe to turn on a 40-year old TRS-80?

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 ...
tofro's user avatar
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40 votes
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Why were early personal computer monitors not green?

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 ...
Brian H's user avatar
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28 votes
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Why did the TRS-80 CPU have priority over the display?

Why did they instead give the CPU priority? It's the lowest effort solution. It needs no additional hardware (*1). At the same time it's a transaction safe solution. Whatever the CPU writes gets ...
Raffzahn's user avatar
  • 220k
26 votes

Why were early personal computer monitors not green?

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 ...
Bruce Abbott's user avatar
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23 votes
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What are the "ports" used via IN/OUT, vs. the PEEK/POKE address space?

The TRS-80 series is Z80 based, and Z80 uses, like all 8080 offspring (*1,3) a separate address space for I/O. It allows easy decoding for I/O. Thus memory address 0000h is different from I/O ...
Raffzahn's user avatar
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19 votes
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Who coined the nickname "Trash-80" and what was the source of their animosity?

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'...
Raffzahn's user avatar
  • 220k
19 votes

Why did the TRS-80 CPU have priority over the display?

First of all: The TRS-80 was not the only computer with this problem, but there were many computers with this problem. The effect you describe is sometimes called "CGA snow" because before ...
Martin Rosenau's user avatar
18 votes

What did it sound like when you played a cassette tape with programs on it?

I understand this question is about the Tandy, so I'll move this to a self-answered question if necessary, but I believe you'd be interested in this information. On a ZX Spectrum (at least, the ...
knol's user avatar
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17 votes
Accepted

How did the original TRS-80 generate video?

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 ...
Raffzahn's user avatar
  • 220k
14 votes

Was the TRS-80 Model 1 ever actually sold new with that name?

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....
RichF's user avatar
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13 votes

Why did the TRS-80 CPU have priority over the display?

Most of the times when a lot of stuff was being written to the screen, people would want to wait for the display to be done updating before trying to read it. Letting the update get done faster was ...
supercat's user avatar
  • 35.7k
13 votes

Did the Motorola 6847 have any memory onboard accessible to the user?

Did the Motorola 6847 have any memory onboard accessible to the user? No it does not. It uses its 13 address lines to address up to 8 KiB of external display memory. In the MC-10 it uses part of the ...
Raffzahn's user avatar
  • 220k
13 votes
Accepted

Can you load machine code programs for cassette tape on a TRS-80 model 1 level 1?

It is possible to load and run machine language programs on a Level I TRS-80 Model I. This was done by various programs, including the monitor program T-BUG, the editor/assembler program EDTASM, and ...
David Moews's user avatar
12 votes

Was the TRS-80 Model 1 ever actually sold new with that name?

Radio Shack product names not infrequently differed from country to country, even if only subtly. This answer covers only U.S. naming. But yes, the TRS-80 Model I was sold new under that name and ...
cjs's user avatar
  • 25k
11 votes

Who coined the nickname "Trash-80" and what was the source of their animosity?

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 ...
Will Hartung's user avatar
  • 12.2k
11 votes

Origin of copy-protection dongles

The oldest (smart) hardware "dongle" I know of is from 1985 in the ZX Spectrum 48K. To curb piracy and as a "collateral side effect" also having more 16KB (e.g. 64KB for the game), ...
Rui F Ribeiro's user avatar
11 votes

Is it safe to turn on a 40-year old TRS-80?

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 ...
Rags's user avatar
  • 213
11 votes

Accelerators for Z80 micros?

I'm not familiar with the C64, and didn't do much with the Apple ][ back in the day, but I did spend a lot of time under the hood of my TRS-80. There wasn't a lot of room for plugin accelerators in ...
jeffB's user avatar
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11 votes
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In TRS-80 parlance when talking about disks, what are "granules" and "lumps"?

OK, this is very dusty material in my memory, so I'm relying a bit on Google/Wikipedia here. I may be able to find some of my printed documentation, but it will take a while. The granule was the ...
jeffB's user avatar
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10 votes
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Could Tandy TRS-80 Color Computers boot from disk at all?

Thanks to RichF's answer I looked for information specifically on booting OS-9 and found that you definitely did have to manually launch even an alternative operating system. From OS-9 Level Two ...
hippietrail's user avatar
  • 6,646
10 votes
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Understanding the DMK disk image file format used by TRS-80 emulators

I support DMK in my MSX emulator, and bear in mind that it's a bit of a confused file format. It has a bunch of design deficiencies, and was clearly tightly coupled to the program that originally ...
Tommy's user avatar
  • 36.6k
9 votes

Did Radio Shack initially attempt to get a monopoly on commercial software for the TRS-80 Model I?

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 ...
Will Hartung's user avatar
  • 12.2k
8 votes

Is it safe to turn on a 40-year old TRS-80?

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 ...
Nathan's user avatar
  • 81
8 votes

Is it safe to turn on a 40-year old TRS-80?

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 ...
StessenJ's user avatar
  • 413
8 votes

Origin of copy-protection dongles

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 ...
Raffzahn's user avatar
  • 220k
8 votes

Why were early personal computer monitors not green?

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 ...
jeffB's user avatar
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8 votes
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Accelerators for Z80 micros?

The main TRS-80 line (Model I, III and 4) had several third party Z-80 accelerator boards. The Archbold board could bring the Model I up to 5.3 MHz from 1.77 MHz. The Holmes Sprinter boosted the ...
George Phillips's user avatar
8 votes
Accepted

How much control of TRS-80 Model III disk drives was possible from its Cassette (ROM) BASIC?

ROM BASIC does not support any handling of floppies at all, but System ROM allows boot thru it's function table. Of course one could handle the disk controller 'manually' from BASIC - which is what ...
Raffzahn's user avatar
  • 220k
8 votes
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TRS-80 Accessory - Data Drawer File System

Page 3 of this 1983 Radio Shack catalog shows the Data Drawer in two different sizes, "printout" which holds 14-7/8×11-inch 132-column printer paper, and "letter" which holds up to ...
snips-n-snails's user avatar

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