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Questions tagged [trs-80]

Use for questions regarding the z80-based Tandy Radio Shack computers, the TRS-80 Model I, II, III, and 4. Computers using another processor, such as the 6809-based TRS-80 Color Computer, should use a different tag ([color-computer] in that case).

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6 votes
0 answers
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Why did only the TRS-80 see complaints about the screen?

Of the 1977 trinity, the PET and TRS-80 came with monitors built around black-and-white TV tubes, and the Apple II was commonly used with a black-and-white TV set. According to https://en.wikipedia....
rwallace's user avatar
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24 votes
8 answers
7k views

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

As a medium of storing large data, cassette tapes were used just like the following: I wonder what it would sound like if one put the tape in a cassette player and played it as if it were a regular ...
Namudon'tdie's user avatar
3 votes
1 answer
450 views

Interpreting TRS-80 model 1/2 tape cassette audio

I got interested in writing my own code to parse tape cassette formats for a few platforms. I did OK with both Spectrum and Apple 2 tapes based on info I could find online. Speccy and Apple 2 seem to ...
hippietrail's user avatar
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7 votes
2 answers
1k views

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

I'm trying out TRS-80 model I/III emulators. I know there was Level 1 and Level 2. I think this refers both to the ROM and the BASIC on the model I. Level 2 ROMs were a common upgrade to the model I ...
hippietrail's user avatar
  • 6,654
6 votes
1 answer
494 views

Dumb Terminal Access to Tandy TRS-80 Model 100?

How do I setup the TRS-80 Model 100 to use an external 80col. 30 row dumb terminal so I can control the TRS-80 Model 100 ... BASIC from the dumb terminal? I have a VersaTerm connected to a VGA monitor ...
wperko's user avatar
  • 141
7 votes
1 answer
894 views

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

Did the Motorola 6847 (Video Display Generator) have any memory onboard accessible to the user? Looking at this video display generator, which was used in the MC-10 (TRS-80 MC-10 Computer), if memory ...
infomtn's user avatar
  • 287
22 votes
4 answers
4k views

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

The original TRS-80 had a separate bank of static RAM for video memory, so that there would be no interference between display and CPU when the CPU was just doing calculations in main memory. When it ...
rwallace's user avatar
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11 votes
2 answers
1k views

TRS-80 Accessory - Data Drawer File System

I've had this drawer unit for nearly 20 years. I found it left behind in a vacant apartment. The label says "Radio Shack TRS-80 Data Drawer File System" but nothing else. I spent a lot of ...
Mysterfxit's user avatar
9 votes
1 answer
1k views

Understanding the DMK disk image file format used by TRS-80 emulators

DMK is a low-level disk image file format used by TRS-80 Model I & Model III, Tandy Color Computer, Dragon 32 & 64, and MSX emulators. It's capable of representing copy-protected disks and all ...
hippietrail's user avatar
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8 votes
0 answers
147 views

On the TRS-80 models I and III when is the directory track number written in the third byte of sector zero, and when in the second byte?

Earlier I had found that many but not all TRS-80 Model I and Model III disks begin with the three bytes 00h FEh 11h. This is the beginning of the boot sector where the CPU interprets it as a NOP ...
hippietrail's user avatar
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7 votes
2 answers
2k views

Could Tandy TRS-80 Color Computers boot from disk at all?

I'm trying to find out if any of the Tandy CoCos could boot from disk. I'm thinking the answer is no but I'm having trouble confirming it. I believe that non-disk machines booted from the standard ...
hippietrail's user avatar
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3 votes
1 answer
501 views

Do TRS-80 Model I and Model III load and execute /CMD files using specific memory addresses?

/CMD files on the various TRS-80 Model I and III OSes are machine code command files. They seem to have some internal format but not really a file header. They often start with 01 02 and then a 16-...
hippietrail's user avatar
  • 6,654
11 votes
1 answer
235 views

In TRS-80 parlance when talking about disks, what are "granules" and "lumps"?

In my reading to try to learn about the disk layout, directory, and boot process of TRS-80 Model I and Model III, I see some unusual words come up again and again. Along with the common terms "track" ...
hippietrail's user avatar
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4 votes
1 answer
846 views

What is the process for TRS-80 Model I & III to boot from disk?

I can find enough mentions of bootable disks for TRS-80 Model I and Model III to be confident that they could boot from disk, but so far I'm failing to find much info on how that worked. In ...
hippietrail's user avatar
  • 6,654
3 votes
1 answer
262 views

What is the layout of the directory track on a TRS-80 Model I/Model III disk?

I've decided to add support for some more classic Z80 computers I used to use to my Ghidra modules, and the first Z80 systems I used were the TRS-80 model I and model III. I've found documentation ...
hippietrail's user avatar
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16 votes
1 answer
2k views

What are the "ports" used via IN/OUT, vs. the PEEK/POKE address space?

This is something of a followup to How much control of TRS-80 Model III disk drives was possible from its Cassette (ROM) BASIC? but on a more general topic: I know that PEEK and POKE enable direct ...
natevw's user avatar
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10 votes
2 answers
491 views

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

How much control over the TRS-80 Model III's floppy drive controller can be effected via relatively simple commands, typed into its built-in Cassette BASIC? My understanding is that general usage of ...
natevw's user avatar
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12 votes
4 answers
3k views

Accelerators for Z80 micros?

I am familiar with the various accelerator products that were developed over the years to improve the performance of popular 6502 home micros. A short list of the particularly well known devices would ...
Brian H's user avatar
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9 votes
3 answers
2k views

What's the first use of the term, "1977 Trinity"?

The term "1977 trinity" has been used, here on Retrocomputing SE and elsewhere, to refer to a set of three computers that started shipping in mid- to late-1977: the Apple II, the TRS-80 ...
cjs's user avatar
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7 votes
1 answer
430 views

How to get BBC BASIC to TRS-80?

I recently discovered there's BBC BASIC for CP/M machines. Having had my fill of Microsoft Basic, I need to get BBC BASIC onto a disk I can boot on a TRS-80 Model 4P. I have no CP/M disk (or image) ...
Brian H's user avatar
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2 votes
1 answer
449 views

Decoding the Workings of the TRS-80 BASIC Game "Escape!"

I've decided to port Chase! to Swift, apparently because I am insane. In any event, I'm trying to collect the various switches in versions from the era. One of these is unique, found here under the ...
Maury Markowitz's user avatar
10 votes
1 answer
1k views

How did the original TRS-80 generate video?

I'm curious how the original (Model 1) TRS-80 generated video. I understand that an RF modulator was used but what kind of circuitry did it use to feed the RF modulator? The TRS-80 Color Computer ...
cbmeeks's user avatar
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5 votes
3 answers
694 views

What to check before powering on TRS80 Model III in unknown condition [duplicate]

Having managed to source a TRS-80 Model III that I'm told hasn't been powered on for quite some time (and I suspect this is a massive understatement), I'm worried that the first thing that might ...
user avatar
6 votes
1 answer
895 views

Which DOS for a TRS-80 Model 4P?

Looking at the TRS-80 Disk Software Page, there's a rather extensive selection of DOS options that seem to work with the 4P and also claim high compatibility with the Tandy "TRSDOS" option. ...
Brian H's user avatar
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9 votes
4 answers
1k views

Columns of text in early microcomputers

As discussed in some previous questions here, 80-column text was established by IBM as the standard for business computing as early as the sixties, but monitors capable of displaying that resolution ...
rwallace's user avatar
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30 votes
5 answers
10k views

Why were early personal computer monitors not green?

Green was traditionally the most common color for computer monitors; it combines strain-free readability with low cost. Given this, it's surprising that the first versions of the Commodore PET and ...
rwallace's user avatar
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13 votes
3 answers
952 views

Origin of copy-protection dongles

The first time I ever heard of a dongle was when it was used on a text processor called Wordcraft on the Commodore 8032. It was around 1980. We had three machines and had to share the dongle amongst ...
cup's user avatar
  • 2,527
19 votes
3 answers
1k views

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

In the U.S. in the early 1980's (1980-1982, roughly), the TRS-80 Model I/III computers were commonly referred to by teens and youngsters as the "Trash-80". The best reason I can attribute to this ...
Brian H's user avatar
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9 votes
3 answers
754 views

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

When Tandy introduced the TRS-80, the computer we know now as the "Model 1" or Model I" was simply called the TRS-80. No "Model" designation was necessary. The early releases were as follows: TRS-80, ...
RichF's user avatar
  • 9,336
7 votes
1 answer
389 views

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

This question is about the era of the TRS-80 Model I, ca. 1977-1979. Originally there was no software you could buy, other than BASIC itself, which was in ROM. You would write your own, or type in ...
user avatar
62 votes
5 answers
14k views

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

My father is a retired programmer. When I was in high school in the late 1970s, he purchased a TRS-80 model 1 (on which I learned to program in BASIC). At some point in the early 1980s it, together ...
John Coleman's user avatar