A Tandy / RadioShack TRS-80 Model 1 Clone

http://www.glensstuff.com/trs80/trs80.htm

by sohkamyung • 7 years ago

81 35 7 years ago

glensstuff.com

gadders2• 7 years ago

Would look much nicer done up as a Dragon 32 :-)

https://en.wikipedia.org/wiki/Dragon_32/64

jhbadger• 7 years ago

That was a 6809 machine that was similar to the later TRS-80 Color Computer from 1980. The TRS-80 Model 1 was a Z80 based machine released in 1977.

gadders2• 7 years ago

I didn't even know there were two versions of the TRS 80 (they weren't very common in the UK). Thanks for educating me.

soegaard• 7 years ago

Great write up in the project document!

jandrese• 7 years ago

I never had a TRS-80, so I didn't know that absolute craziness with the lower case characters. I get that someone wanted to save money by not adding the chip for bit 6, but to add that note that you were intended to magic that bit out of thin air seems absolutely insane.

ineedasername3• 7 years ago

My first computer of any sort was a Tandy Color Computer that I got in the early 90's on clearance at Radio Shack using birthday & Christmas gift money.

I think it cost $75, and I paid an extra few dollars for some old Basic programming books & a few cartridges with games. It was my first experience with programming, and I remember this fun sense of excitement when learning very simple "hacks" like the infinite loop:

  10 print "Name"
  20 goto 10

I had no storage, no disk drive, everything was lost when I powered off, and the games were awful (compared to NES & SNES) but it was a foundational experience for me. Good times.

torgoguys• 7 years ago

It was even better than that, if my recollection is correct. Those computers came with a very readable BASIC tutorial book at no extra charge (at least for the CoCo 1 and 2). I still remember the cartoon computer character that was your teacher in the illustrations. Those books are how I first learned to program.

brlewis• 7 years ago

Much better for me because I had a cassete tape drive where I could save my programs. It had a counter. I kept a piece of paper with the counter numbers so I could fast forward/rewind to get to specific programs I'd saved on tape.

I made games on it. When BASIC wasn't fast enough for what I wanted to do I looked into Assembly. I sent snail mail to Motorola asking where I could buy the 6809E assembler manual, and they sent me one for free.

xhkkffbf• 7 years ago

Anyone cloning the Model 100?

pacman128• 7 years ago

This brings back fond memories, it was my first computer. Learned BASIC and Z-80 assembly on it.

Happy to see it has Level II Basic. Level I was very limited: https://en.wikipedia.org/wiki/Level_I_BASIC

Balanceinfinity• 7 years ago

I did as well - until I got my Apple II+ - which was amazing, but didn't have a built in modem.

gregoryseattle• 7 years ago

Ah the memories....

I cut my teeth on a TRS-80 Model 1 with 4K of RAM. I was like 13 or so and got one in the late 70s. I learned BASIC on it, but quickly ran out of CPU and memory with the interpreted BASIC and switched to Z-80 assembler. I didn't have an assembler however, so would write out all of the Z-80 instructions by hand on paper, then, when I thought I had debugged it enough on paper, I would convert it to the hex OpCodes. At that point I would either use a small BASIC program to POKE the hex into memory and run it, or after I got a hex editor, I would use that to type in the hex values. Of course, all of this was saved to cassette tapes! If there was a bug I would go back to the paper and figure out where I went wrong. I still remember some Z-80 OpCodes to this day from the countless hours of converting assembler to hex.

One really cool way I would use to debug programs, or at least know if they were running, was to keep an AM radio next to the computer. The TRS-80/Z-80 would give off enough RF so you could "hear" the program running on the radio. In fact, you could devise loops and delays in your assembler such that you could "play" music on the radio. :-)

Starwatcher2001• 7 years ago

I did pretty much the same, although I managed to get the 16k RAM version. I've still got my old TRS-80 in the loft, eventually with the expansion box and couple of disk drives. Each single-sided 5.25" floppy held a massive 90k, then someone worked out that if you punched a timing hole in the cover in the right place you could put the floppy in upside-down and use the other side too.

Like you, I cut my teeth on the TRS-80 and wrote my first commercial program around 1982, a graphics drawing tool (written in Z80). It sold maybe a dozen copies, but was a start. I've got fond memories of EDTASM and T-BUG, the assembler and debugger.

jlv2• 7 years ago

I'm also have a similar background (although the first computer I used was my school's PDP-8i via a teletype). I still have my Model I and all the assorted accessories. I remember moving from EDTASM to Microsoft's Macro Assembler for the Z-80 assembler I write.

simmons• 7 years ago

I didn't have an assembler however, so would write out all of the Z-80 instructions by hand on paper...

I'm glad I'm not the only one who hand-assembled like this! :) Only for me, it was several years later, on a C64 with 6502 assembly, and I had the extra step of converting the hex values to decimal for DATA statements. Assemblers cost money. And my friends were more into playing games, so none of them had an assembler I could "borrow".

jefurii• 7 years ago

I was blessed/cursed to use Radio Shack's standard cassette player/recorder with my TRS-80 Model I. You had to use the proper volume settings when loading and saving data. The settings were different for BASIC and machine code, and the volume controller was very imprecise. I enjoyed typing in programs from BASIC Computer Games but I was really happy to upgrade to a C-64 with a dedicated tape drive...

Also my dad had recently gotten into HAM radio and we had to negotiate our hobby times because of the Trash-80's RF interferance.

stevekemp• 6 years ago

That's almost exactly my route to coding too - though I used the ZX Spectrum in the UK. I started with BASIC, then "assembled" programs by hand, looking up the opcodes in the back of the manual.

Even now I remember a lot of Z80 opcodes, largely as a result of hacking and patching games to get infinite lives.

I'm slowly working on building my own computer at the moment, with a real Z80 processor and an arduino to drive it. Fun stuff, but I've stalled for the past few months.

VikingCoder• 7 years ago

Is there a TRS-80 emulator in a browser? Found one:

http://trsjs.48k.ca/

gwbas1c• 7 years ago

http://www.glensstuff.com/trs80/trs80.htm is not secure! Most bargain-basement hosts support https by now.

Egads!

justin66• 7 years ago

THEY are using news of seventies-era computer clones to hack your PC and ruin your life. You know... them.

musicale• 7 years ago

It's harder to support https on an 8-bit web server. ;-)

http works great though.

jhallenworld• 7 years ago

I know someone who built a Model 1 clone in the 70s.. to get the ROM he went to a Radio Shack store and ran a little BASIC program that printed it.

(This guy worked at HP, on their calculator chips).

mixmastamyk3• 7 years ago

My 5th grade teacher had a TRS-80 in class and we would occasionally learn a bit of programming or (I think) take quizzes on it. This was approximately 1981, talk about ahead of his time!

Around that time I got a VIC-20 for Christmas with cassette drive, a great time to be alive.

Funny, almost a decade later in high school, I took a programming class and they were still using the same computer, a TRS-80 all-in-one. Talk about behind the times, haha.

(Recently I've found out that writing assembly on both computers was a thing, a shame no one ever told me at the time.)

seanmcdirmid2• 7 years ago

I went to high school in Mississippi, my sophomore year in 1989 they still had all-in-one TRS-80s in the computer lab. They were actually good enough for learning some programming at the time.

mixmastamyk3• 7 years ago

Yes, if you had never used a computer it was probably fine, but I was disappointed I didn't get to learn anything new. Although as a teenager I appreciated being able to slack off with an easy class.

But again, no one told me assembly language (or C) even existed. Didn't learn about it until I got to college many years later. Same old 10 PRINT, 20 GOTO 10. Sheesh.

protomyth• 7 years ago

The TRS-80 Model 1 was the first computers the local community college had. I was in HS and my dad was teaching the computer classes. They did earn their name Trash 80, but they were for the most part good, solid machines. I think we got them because someone else didn't want them anymore. It would interesting to find out how learning on those machines affected the students.

(I could go for a modern clone of the Model 100)

[edit: also the parallel (or serial? haven't looked in a while) port switcher so everyone could print is still in the equipment room, older than many of the current students]

gdubs• 7 years ago

That’s one beautiful case. Really impressive documentation too. I have some Tandy nostalgia: my first computer was a “Sensation” from RadioShack. 486sx processor that we needed to add an after market math co-processor to for floating point so I could run Calagari TrueSpace.

codezero• 7 years ago

I wonder what the story about the chicken in the image in the middle of the PDF description is :)

A Tandy / RadioShack TRS-80 Model 1 Clone

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